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STUDIES ON SOLID POLYMER ELECTROLYTES

BASED ON POLY(VINYL CHLORIDE)

By

RAHMAT GUL

NATIONAL CENTRE OF EXCELLENCE IN

PHYSICAL CHEMISTRY

UNIVERSITY OF PESHAWAR

PESHAWAR (PAKISTAN)

MARCH 2011

STUDIES ON SOLID POLYMER ELECTROLYTES

BASED ON POLY(VINYL CHLORIDE)

By

RAHMAT GUL

A dissertation submitted to the University of Peshawar

in the partial fulfillment of the requirements for the

degree of

DOCTOR OF PHILOSOPHY IN

PHYSICAL CHEMISTRY


PHYSICAL CHEMISTRY


PESHAWAR (PAKISTAN)

MARCH 2011


PHYSICAL CHEMISTRY


It is recommended that the thesis prepared by Rahmat Gul

entitled STUDIES ON SOLID POLYMER ELECTROLYTES BASED

ON POLY(VINYL CHLORIDE), be accepted as fulfilling this

part of the requirements for the degree of “DOCTOR OF

PHILOSOPHY IN PHYSICAL CHEMISTRY”.

______________________ ________________________ RESEARCH SUPERVISOR DIRECTOR OF THE CENTRE

EXAMINATION SATISFACTORY

COMMITTEE ON FINAL EXAMINATION

__________________ __________________ INTERNAL EXAMINER EXTERNAL EXAMINER

IN THE NAME OF ALMIGHTY ALLAH,

THE MOST BENEFICENT,

THE MOST MERCIFUL

DEDICATED TO

My Parents

i

All praises be to Allah, the lord of universe, whose benevolence and

glory enabled me to carry out this task in the field of scientific research,

inspite of so many weakness and limitations. Blessings be upon his last

Prophet Muhammad (Peace be Upon Him).

I feel a very pleasant satisfaction to express my deepest gratitude to my

noble and worthy supervisor Dr. M. Saleem Khan, Professor of Physical

Chemistry, National Center of Excellence in Physical Chemistry,

University of Peshawar whose keen interest, supervision, guidance,

valorous encouragement, valuable suggestion and sympathetic attitude

enabled me to complete this project.

I would like to extend my thanks to Professor Dr. H. M. Khan, Director,

of National Center of Excellence in Physical Chemistry, University of

Peshawar and my all teachers, who provided me all the necessary

facilities to complete this project.

I would like to record thanks for polymer group scholars who helped me

in every possible way during this research project.

I am under greatest obligations of the Higher education commission

(HEC) for providing financial assistance for pursuing this research

project.

Finally, I thank the staff of N.C.E in Physical Chemistry, especially Mr.

Ikhtiar Gul for his cooperation during my research project.

Rahmat Gul

March, 2011

ACKNOWLEDGEMENT

ii

LIST OF ABBREVIATIONS

SEM: Scanning electron microscopy

XRD: X-ray diffraction

σ: Conductivity

EC: Ethylene carbonate

PC: Propylene carbonate

PEO: Poly(ethylene oxide)

PAN: Poly(acrylonitrile)

PVdF: Poly(vinylidene fluoride)

PMMA: Poly(methyl methacrylate)

DBP: Dibutyl phthalate

VTF: Vogel-Tamman-Fulcher

PVA: Poly(vinyl alcohol)

PVP: Poly(vinyl pyrrolidone)

NMR: Nuclear magnetic resonance spectroscopy

PPG: Poly(propylene glycol)

OEGMA: Oligo(ethylene glycol) dimethacrylates

DSC: Differential scanning calorimetry

PVAc: Poly(vinyl acetate)

PS: Polystyrene

MEK: Methyl ethyl ketone

DMF: Dimethyl formamide

THF: Tetrahydrofuran

iii

TABLE OF CONTENTS

Chapter No Title Page No.

ACKNOWLEDGEMENT

ABSTRACT

CHAPTER # 1

INTRODUCTION 1 1.1 Conducting Polymers 1

1.1.1 Structural Features of Polymer Electrolytes 7 1.1.2 Transport Properties and Chain Dynamics 9 1.1.3 Conductively Filled Polymers 10 1.1.3.1 Polymer Filled with Conductive Solids 11 1.1.3.2 Polymers Filled with Conjugated Conducting Polymers 12 1.1.3.3 Charge Transfer Polymer 12 1.1.3.4 Ionically Conducting Polymer 12 1.1.3.5 Metal Filled Conducting Polymer 13 1.1.3.6 Carbon Black/Carbon Fibre Reinforced Conductive Polymer

Composites 13

1.1.4 Correlation of Chemical Structure and Electrical Conductivity 14 1.1.5 Charge Transportation 15 1.1.6 Stability of Conductive Polymers 16

1.2 Factors Affecting Electrical Conductivity 16 1.3 Applications of Conductive Polymers 18

1.3.1 Batteries 21 1.3.2 Light Emitting Diodes 22 1.3.3 Electroluminescence 22 1.3.4 Electrochromic Cells 22

1.4 Limitations of Conductive Polymers 23 1.5 AIMS AND OBJECTIVES 24

CHAPTER #2

LITERATURE REVIEW 26

CHAPTER #3

EXPERIMENTAL 60 3.1 Materials 60

3.2 Preparation of PVC-based Solid Polymer Electrolyte System

60

3.2.1 Samples of Pure PVC based Polymer Electrolyte Systems 62 3.2.1.1 Samples of pure PVC based polymer electrolyte systems

without plasticizer 62

3.2.1.2 Samples of pure PVC based polymer electrolyte systems with plasticizer

62

3.2.1.3 Samples of pure PVC based polymer electrolyte systems containing inorganic filler

63

3.2.2 Samples of PVC-blend Polymer Electrolyte Systems 63 3.2.2.1 Samples of PVC-PMMA blend polymer electrolyte systems 63

iv

(a) Samples of PVC-PMMA blend polymer electrolyte system without plasticizer

63

(b) Samples of PVC-PMMA blend polymer electrolyte system with plasticizer

64

(c) Samples of PVC-PMMA blend polymer electrolyte system containing inorganic filler

64

3.2.2.2 Samples of PVC-PEO blend polymer electrolyte systems 65 (a) Samples of PVC-PEO blend polymer electrolyte system

with plasticizer 65

(b) Samples of PVC-PEO blend polymer electrolyte system containing inorganic filler

65

3.3 Sample Characterization 66 CHAPTER# 4

RESULTS AND DISCUSSION 68

CONDUCTANCE STUDIES 68 4.1 Conductance Studies of Pure PVC based Polymer

Electrolyte Systems 68

4.1.1 Conductance Studies of Pure PVC based Polymer Electrolyte Systems without Plasticizer

68

4.1.2 Conductance Studies of Pure PVC based Polymer Electrolyte Systems with Plasticizer

71

4.1.3 Conductance Studies of Pure PVC based Polymer Electrolyte Systems containing Inorganic Filler

78

4.2 Conductance Studies of PVC-PMMA Blend Polymer Electrolyte Systems

82

4.2.1 Conductance Studies of PVC-PMMA Blend Polymer Electrolyte System without Plasticizer

82

4.2.2 Conductance Studies of PVC-PMMA Blend Polymer Electrolyte System with Plasticizer

84

4.2.3 Conductance Studies of PVC-PMMA Blend Polymer Electrolyte System containing Inorganic Filler

93

4.3 Conductance Studies of PVC-PEO Blend Polymer Electrolyte Systems

96

4.3.1 Conductance Studies of PVC-PEO Blend Polymer Electrolyte System without Plasticizer

96

4.3.2 Conductance Studies of PVC-PEO Blend Polymer Electrolyte System with Plasticizer

97

4.3.3 Conductance Studies of PVC-PEO Blend Polymer Electrolyte System containing Inorganic Filler

98

THERMOGRAVIMETRIC AND DIFFERENTIAL THERMOGRAVIMETRIC ANALYSIS

129

4.4 Thermal Studies of Solid Polymer Electrolytes without Inorganic Fillers

129

4.5 Thermal Studies of Polymer Electrolytes containing Inorganic Fillers

131

X-RAY DIFFRACTION STUDIES 150 4.6 X-ray Diffraction Studies of Pure PVC based Polymer

Electrolytes 150

4.7 X-ray Diffraction Studies of PVC-PMMA Blend Polymer Electrolytes

152

v

4.8 X-ray Diffraction Studies of PVC-PEO Blend Polymer Electrolytes

154

MECHANICAL STUDIES 163 4.9 Mechanical Properties of PVC-PEO Blend System 163

4.9.1 Mechanical Properties of PVC-PEO System without Plasticizer

163

4.9.2 Mechanical Properties of PVC-PEO Polymer Electrolytes with Plasticizer

164

4.9.3 Mechanical Properties of PVC-PEO Polymer Electrolytes containing Inorganic Filler

165

4.10 Mechanical Properties of PVC-PMMA Blend Polymer Electrolyte Systems with Plasticizer

166

SCANNING ELECTRON MICROSCOPY 177 4.11 Scanning Electron Microscopy of Polymer Electrolytes

without Inorganic Filler 177

4.12 Scanning Electron Microscopy of Polymer Electrolytes containing Inorganic Filler

180

VISCOMETRIC STUDIES 198 4.13 Viscometric Studies of PVC and PVC Blend with other

Polymers 198

CONCLUSIONS 211

REFERENCES 220

vi

LIST OF FIGURES

Figure No. Title of Figures Page No.

1.1 Arrhenius plots of conductivity for PVC-NaClO4 polymer

electrolytes

101

1.2 (a) Plot of log conductivity vs. reciprocal temperature for (a)

Pure PVC, (b) PVC-KClO3 (94-6), (c) PVC-KClO3 (88-12), (d)

PVC-KClO3 (82-18)

101

(b) Plots of log conductivity vs. composition for PVC-KClO3

polymer electrolyte systems at various temperatures

102

1.3 (a) Plots of log conductivity vs. 1000/T for PVC-Li2SO4

polymer electrolyte systems

102

(b) Plots of log conductivity vs. composition of PVC-Li2SO4

polymer electrolyte system at different temperatures

103

1.4 (a) Temperature dependence of ionic conductivity for ternary

polymer electrolyte system of PVC:EC:LiClO4

103

(b) Log conductivity vs. salt concentration of PVC-EC-LiClO4

polymer electrolyte system at various temperatures

104

(c) Log conductivity vs. PVC content of PVC-EC-LiClO4


104

1.5 Log conductivity vs. reciprocal temperature for ternary system

of PVC-EC-LiClO4

105

1.6 Variation of log conductivity vs. weight fraction of PVC of

ternary polymer electrolyte systems (PVC-Plasticizer-LiClO4)

at 25oC

105

1.7 (a) Arrhenius plots of ionic conductivity for PVC-Li2SO4-EC

polymer complexes

106

(b) Log conductivity vs. EC concentration of PVC-Li2SO4-EC

polymer electrolytes at different temperatures

106

(c) Log conductivity vs. PVC concentration of PVC-Li2SO4-EC


107

vii

1.8 (a) Plot of log conductivity vs. reciprocal temperature for (a)

pure PVC-EC, (b) PVC-EC-KBrO3 (70-25-5), (c) PVC-EC-

KBrO3 (65-25-10), (d) PVC-EC-KBrO3 (60-25-15)

107

(b) Plots of log conductivity vs. composition for PVC-KBrO3-

EC plasticized polymer electrolyte system at various

temperatures

108

1.9 (a) Temperature dependence of the conductivities of PVC-EC-

PC-LiClO4 plasticized polymer electrolyte systems

108

(b) Plots of log conductivity vs. reciprocal temperature of PVC-

EC-PC-LiClO4 polymer electrolyte system

109

1.10 (a) Log conductivity vs. EC content of PVC-LiClO4-LiBF4 (75-

15-15) system at room temperature

109

(b) Log conductivity vs. PC content of PVC-LiClO4-LiBF4 (75-

15-15) system at room temperature

110

1.11 Arrhenius plot of log conductivity of PVC-ZnO-LiClO4 (60-25-

15) with 25 wt% ZnO

110

1.12 (a) Log conductivity vs. reciprocal temperature for PVC-

Li2SO4-EC-ZrO2 complex polymer electrolyte system with (a)

0% (b) 6% (c) 12% (d) 18% of ZrO2

111

(b) Plots of log conductivity vs. composition of PVC-Li2SO4-EC

polymer electrolyte system at different temperatures

111

1.13 (a) Arrhenius plot of log conductivity against reciprocal

temperature for PVC-LiClO4-EC-ZrO2 polymer complexes

112

(b) Plot of log conductivity vs. composition of PVC-LiClO4-EC-

ZrO2 at various temperatures

112

1.14 (a) Plot of log conductivity against reciprocal temperature for

pure PVC and PVC doped with activated charcoal

113

(b) Plots of log conductivity vs. composition of PVC doped

with CB

113

1.15 (a) Log conductivity vs. reciprocal temperature for (a) pure

(PVC-PMMA), (b) PVC-PMMA-NaClO4 (70-25-5), (c) PVC-

PMMA-NaClO4 (67-23-10), (d) PVC-PMMA-NaClO4 (65-20-

15)

114

viii

(b) Plots of log conductivity vs. composition of PVC-PMMA-

NaClO4 polymer electrolyte system at various temperatures

114


temperature for PVC-PMMA-LiClO4-EC polymer electrolyte

systems

115

(b) Log conductivity vs. composition of PVC-PMMA-LiClO4-EC

polymer electrolyte system

115

(c) Log conductivity vs. PVC content of PVC-PMMA-LiClO4-

EC polymer electrolyte system

116

1.17 Ionic conductivity of the electrolytes as a function of

PVC/PMMA blend ratio. (EC=70%)

116

1.18 Ionic Conductivity of the electrolytes as a function of

plasticizer content for the blend of PVC/PMMA.

(PVC/PMMA=5/2)

117

1.19 Arrhenius plot of ionic conductivity for various plasticizer

contents for the blend of PVC-PMMA-EC-LiClO4.

PVC/PMMA=5/2

117



systems

118

(b) Log conductivity vs. composition of PVC-PMMA-LiClO4-EC


118



system

119

(b) Log conductivity vs. reciprocal temperature of PVC-

PMMA-LiClO4-EC polymer electrolyte system at various

temperature

119

1.22 (a) Variation of conductivity with plasticizer content for PVC-

PMMA-EC-LiClO4 polymer electrolyte systems

120

(b) Variation of conductivity with plasticizer content for PVC-

PMMA-EC-NaClO4 polymer electrolyte systems

120

ix

(c) Variation of conductivity for PVC-PMMA-EC-LiClO4

polymer electrolyte with different polymer blend ratio

121

(d) Variation of conductivity with plasticizer content for PVC-

PMMA-EC-NaClO4 polymer electrolyte systems

121

(e) Effect of temperature on ionic conductivity of PVC-PMMA-

EC-LiClO4 polymer electrolyte systems

122

(f) Effect of temperature on ionic conductivity of PVC-PMMA-

EC-NaClO4 polymer electrolyte systems

122

1.23 Arrhenius plot of PVC-PMMA-LiX-PC (20-10-10-60 wt%)

complexes

123

1.24 (a) Arrhenius plot of PVC-PMMA-LiClO4-PC complexes for

different concentrations

123

(b) Log conductivity vs. salt concentration of PVC-PMMA-

LiClO4-PC polymer electrolyte systems at different

temperatures

124

(c) Log conductivity vs. PVC content of PVC-PMMA-LiClO4-

PC polymer electrolyte systems at various temperatures

124

1.25 Arrhenius plot of ionic conductivity for various PVC/PMMA

blend ratio of PVC-PMMA-EC-PC-LiClO4 system

125

1.26 (a) Plot of conductivity vs. reciprocal temperature for PVC-

PMMA-Li2SO4-EC complex polymer electrolyte systems

containing different content of ZrO2. (a) 0%, (b) 5%, (c) 10%,

(d) 15% ZrO2

125

(b) Log conductivity of the PVC-PMMA-Li2SO4-EC polymer

electrolyte system as a function of ZrO2 concentration at

different temperatures

126

1.27 (a) Arrhenius plot of conductivity for PVC-PMMA-EC-LiClO4

(20-5-65-10 wt%) polymer electrolytes with different TiO2

concentrations

126

(b) Log conductivity vs. TiO2 concentration of PVC-PMMA-

EC-LiClO4 polymer electrolyte system at various temperatures

127

1.28 Arrhenius plot of log conductivity against reciprocal

temperature of PVC-PEO-LiX (60-30-10). (X=ClO4-, BF4

-)

127

x


temperature for PVC-PEO-EC-LiClO4 polymer electrolyte

systems

128


temperature for polymer electrolytes containing various

inorganic fillers

128

2.1 (a) DTA and TGA scans of PVC 134

(b) DTA and TGA scans of PMMA 134

(c) DTA and TGA scans of PVC-PMMA 135

(d) DTA and TGA scans of polymer complex PVC-PMMA-EC 135

2.2 (a) DTA and TGA scans of polymer complex PVC-PMMA-EC-

Li2SO4 (20-10-60-10 wt%)

136

(b) DTA and TGA scans of polymer complex PVC-PMMA-EC-

LiClO3 (20-10-60-10 wt%)

136

(c) DTA and TGA scans of polymer complex PVC-PMMA-EC-

LiBF4 (20-10-60-10 wt%)

137

(d) DTA and TGA scans of polymer complex PVC-PMMA-EC-

LiClO4 (20-10-60-10 wt%)

137

2.3 (a) DTA and TGA scans of polymer complex PVC-PMMA-

LiClO4-EC (20-5-10-65 wt%) with 0% TiO2

138

(b) DTA and TGA scans of polymer complex PVC-PMMA-


139

(c) DTA and TGA scans of polymer complex PVC-PMMA-


140

(d) DTA and TGA scans of polymer complex PVC-PMMA-


141

(e) DTA and TGA scans of polymer complex PVC-PMMA-


142


LiClO4-EC (20-5-10-65 wt%) with 0% Al2O3

143



144

xi


LiClO4-EC (20-5-10-65 wt%) with 10 % Al2O3

145



146



147


LiClO4-EC (20-5-10-65 wt%) with 0% ZrO2

147



148



148



149



149

3.1 XRD patterns of (a) PVC (b) 10% PVC/NaClO4 (c) 20%

PVC/NaClO4 (d) 30% PVC/NaClO4 (e) NaClO4

155

3.2 XRD patterns of (a) Plasticized PVC (b) KBrO3 (c) Plasticized

PVC-KBrO3 (95-5) (d) Plasticized PVC-KBrO3 (85:15) (e)

Plasticized PVC-KBrO3 (75:25)

156

3.3 XRD patterns of (a) Pure PVC (b) Li2SO4 (c) PVC-Li2SO4-EC

(10-10-80) (d) PVC-Li2SO4-EC (20-10-70) (e) PVC-Li2SO4-EC

(30-10-60) (f) PVC-Li2SO4-EC (40-10-50)

157

3.4 XRD patterns of (a) TiO2 (b) PVC (c) PVC-LiClO4-EC (20-10-

70) (d) PVC-LiClO4-EC-TiO2 (20-10-65-5) (e) PVC-LiClO4-EC-

TiO2 (20-10-60-10) (f) PVC-LiClO4-EC-TiO2 (20-10-55-15) (g)

PVC-LiClO4-EC-TiO2 (20-10-50-20)

158

3.5 XRD patterns of (c) XRD pattern for ZrO2 (d) PVC-Li2SO4-

DBP-ZrO2 (0) (e) PVC-Li2SO4-DBP-ZrO2 (6) (f) PVC-Li2SO4-

DBP-ZrO2 (12) (g) PVC-Li2SO4-DBP-ZrO2 (18)

159

xii

3.6 XRD patterns of (a) PVC (b) Pure PMMA (c) PVC-PMMA-

NaClO4 (60:35:5) (d) PVC-PMMA-NaClO4 (60:30:10) (e) PVC-

PMMA-NaClO4 (60:25:15)

160

3.7 XRD patterns of (e) PVC-PMMA-Li2SO4-DBP-ZrO2

(15:15:10:60:0) (f) PVC-PMMA-Li2SO4-DBP-ZrO2

(15:15:10:50:10) (g) PVC-PMMA-Li2SO4-DBP-ZrO2 (15-15-10-

45-15) (h) PVC-PMMA-Li2SO4-DBP-ZrO2 (15:15:10:40:20)

161

3.8 XRD patterns (a) PVC (b) PEO (c) LiClO4 (d) LiBF4 (e) PVC-

PEO-LiClO4 (60-30-10) (f) PVC-PEO-LiBF4 (60-30-10)

162

4.1 Stress versus strain curve for pure PVC 168

4.2 Stress versus strain curve for pure PEO 168

4.3 Stress versus strain curve for PVC:PEO (75:25) blend

polymer system

169

4.4 Stress versus strain curve for PVC-PEO:LiClO4 (90:10) blend


169



170



170



171



171

4.9 Variation of Young’s modulus values in PVC-PEO blend with

respect to LiClO4 salt

172

4.10 Variation of stress at peak values in PVC-PEO blend with


172

4.11 Variation of elongation at peak values in PVC-PEO blend with


173

4.12 Stress-strain curve for PVC-PEO-LiClO4-EC blend polymer

electrolyte system

173

4.13 Stress-strain curve for PVC-PEO-LiClO4-EC-PC blend


174

xiii

4.14 Variation of Young’s modulus with respect to silica content in

PVC-PEO complexes

174

4.15 Variation of modulus with blend composition of PVC-PMMA-

LiClO4-EC polymer electrolyte system

175

4.16 Variation of tensile strength with blend composition of PVC-

PMMA-LiClO4-EC polymer electrolyte system

175

4.17 Variation of percent elongation at break with blend

composition of PVC-PMMA-LiClO4-EC polymer electrolyte

system

176

5.1 (a) SEM image of PVC 183

(b) SEM image of PVC-PMMA-EC (30-5-65) system 183

(c) SEM image of PVC-PMMA-LiClO4 (60-30-10) system 184

(d) SEM image of PVC-PMMA-NaClO4 (60-30-10) system 184

(e) SEM image of PVC-PMMA-Li2SO4 (60-30-10) system 185

5.2 (a) SEM image of PVC-PMMA-LiBF4 (60-30-10) system 185

(b) SEM image of PVC-PMMA-EC-Li2SO4 (20-10-60-10)

system

186

(c) SEM image of PVC-PMMA-NaClO4-EC (20-5-10-65)

system

186

(d) SEM image of PVC-PMMA-EC-LiClO4 (20-10-60-10)

system

187

(e) SEM image of PVC-PMMA-EC-LiClO3 (20-10-60-10)

system

187

(f) SEM image of PVC-EC-NaClO4 (30-60-10) system 188

5.3 (a) SEM image of PVC-PMMA-LiClO4-EC (60-20-10-65) with

0% TiO2

188

(b) SEM image of PVC-PMMA-LiClO4-EC (20-5-10-65) with

5% TiO2

189

(c) SEM image of PVC-PMMA-LiClO4-EC (20-5-10-65) with

10% TiO2

189

(d) SEM image of PVC-PMMA-LiClO4-EC (20-5-10-65) with

20% TiO2

190

xiv


5% Al2O3

190


10% Al2O3

191


15% Al2O3

191


20% Al2O3

192


10% ZnO

192


20% ZnO

193


10% ZrO2

193


20% ZrO2

194

5.6 (a) SEM image of PVC-PMMA-NaClO4-EC (20-5-10-65) with

10% ZnO

194

(b) SEM image of PVC-PMMA-NaClO4-EC (20-5-10-65) with

20% ZnO

195


10% TiO2

195


20% TiO2

196


10% Al2O3

196


15% Al2O3

197

(c) SEM image of PVC-PMMA-NaClO4-EC (20-5-10-65) with

20% Al2O3

197

6.1 Variation of reduced viscosity with concentration in

PVC/PMMA in THF at room temperature

204

xv

6.2 Variation of reduced viscosity with concentration in PVC/PEO

in THF at room temperature

204

6.3 Plot of reduced viscosity against concentration for PVC-

PMMA-THF polymer electrolyte systems

205

6.4 Plot of reduced viscosity against concentration for pure PVC-

based polymer electrolyte systems

205

6.5 Plots of reduced viscosity vs. concentration for PVC, PVAc,

and PVC/PVAc at room temperature in THF

206

6.6 Plots of reduced viscosity vs. concentration for PVC, PVAc

and PVC/PVAc at room temperature in MEK

206

6.7 Plots of reduced viscosity vs. concentration for PVC, PVAc

and PVC/PVAc at room temperature in DMF

207

6.8 Plots of reduced viscosity vs. concentration for PVC in THF,

DMF and MEK at 25°C

207

6.9 Plots of reduced viscosity vs. concentration for PVC/PS (1:1)

in different volume ratios of THF/DMF at room temperature

208

6.10 Plots of reduced viscosity vs. concentration for PS in THF and

DMF at room temperature

208

6.11 Plots of reduced viscosity vs. concentration for PVC and PS in

three different solvents at room temperature

209

6.12 Plots of reduced viscosity vs. concentration for PVC, PS and

(1:1) blend in three different solvents THF, DCE and DMF at

room temperature

210

xvi

LIST OF TABLES

Tables No. Title of Tables Page No.

1.1 Activation energies of pure PVC and PVC-NaClO4 polymer

electrolyte system (From fig 1.1)

99

1.2 Activation energies of pure and PVC-KClO3 polymer


99

1.3 Activation energies of pure PVC-EC and PVC-EC-KBrO3

polymer electrolyte system (From fig 1.8 a)

99

1.4 Activation energies of PVC-PMMA and PVC-PMMA-NaClO4

polymer electrolyte system (From fig 1.15 a)

100

1.5 Activation energies of PVC-PMMA-EC-LiClO4 polymer

electrolyte system (From fig 1.16 a)

100

1.6 Activation energies of PVC-PMMA-EC-PC-LiClO4 polymer


100

xvii

Solid polymer electrolytes have been proven to be prospective candidates for

advanced electrochemical applications on basis of their characteristics such

as flexibility, viscoelasticity and ionic conductivity. The ionic conductivity of

solid polymer electrolytes is very low at ambient temperature. Several

attempts have been carried out to improve ionic conductivity of solid polymer

electrolyte systems. The ionic conductivity of these solid polymer electrolytes

can be improved by incorporation of plasticizers, which impart the necessary

salt solvating power and ionic mobility.

Solid polymer electrolyte system based on PVC containing ethylene

carbonate and propylene carbonate as plasticizers have also found

applications in lithium secondary batteries. PVC shows immiscibility with

plasticizer thereby acts as mechanical stiffener in solid polymer electrolyte

system. In the present work solid polymer electrolyte systems based on PVC

containing alkali metal salts (LiClO4, LiClO3, LiBF4, Li2SO4, NaClO4),

plasticizers(EC, PC), inorganic metallic oxides (ZnO, TiO2, Al2O3, ZrO2) and

PVC blended with PMMA and PEO were prepared and examined as solid

polymer electrolyte with improved desired properties. The prepared

polyelectrolytes were characterized by conductivity, Thermogravimetric,

Differential Thermogravimetric Analysis, X-ray diffraction, Scanning electron

microscopy and viscosity methods.

The conductance studies of different polymer electrolyte systems showed that

conductivity values exhibit enhancement with increase in concentration of

salts which may be due to the development of amorphous regions in the

polymer matrix which facilitates the mobility of ions through the polymer

matrix. The increase in ionic conductivity with salt may be attributed to the

increase in the number of ions of salts.

The effects of different plasticizers on the behavior of polymer electrolytes of

different compositions at various temperatures were also observed. The

addition of PC was found more effective as compared to EC. The ionic

conductivity increased with rise in temperature for all different polymer

ABSTRACT

xviii

electrolyte systems containing various content of PVC, salts and plasticizers.

The studies of incorporation of various inorganic fillers showed increase in

ionic conductivity with increase in concentration of filler up to certain limits of

filler concentration beyond which ionic conductivity decreased. At higher

concentration of fillers, the formation of crystallites may be responsible for the

decrease in ionic conductivity of the polymer electrolyte systems.

The activation energies of different polymer electrolyte systems of various

compositions at various temperatures were calculated and found that Ea value

showed decrease with rise in temperature. Similarly Ea also decreased by

addition of salts or plasticizers thereby increasing the ionic conductivity of the

polymer electrolyte systems.

The effects of addition of salts, plasticizers and polymer on the mechanical

properties of polymer electrolytes were also studied. It was found that

mechanical strength of polymer electrolytes deteriorated with increase in

concentration of salts. The effect of EC and PC as plasticizers on the

mechanical strength were studied and found that Young’s modulus and stress

at peak values decreased by incorporation of low molecular weight

plasticizers while elongation at peak values revealed that elongation

decreased by addition of salt. The variation of modulus and tensile strength of

PVC-PMMA blend polymer electrolyte system regarding concentration of

PMMA was also studied and it was found that Young’s modulus and tensile

strength decreased with increase in concentration of PMMA up to 15 wt%

concentration of PMMA beyond which both these parameters showed

increase. The influence of silica exhibits improvement in mechanical

properties. SEM studies of various PVC based polymer electrolyte systems

showed that by incorporation of inorganic fillers, the surface becomes rougher

as compared to the films without any filler. The effects of salts on the SEM

micrographs were also studied. SEM micrographs showed that surface

morphology of pure PVC to be similar to rigid and glassy surfaces while

blends of PVC with PMMA showed two phase morphology without any sharp

boundary between these two phases.

CHAPTER # 1

1.1 Conducting Polymers

Conductive polymers are organic polymers that exhibit electric conduction

through the migration of ions. The transport properties of the polymer

electrolyte membranes are comparable with that of liquid ionic solutions.

Conductive polymers combine the properties of metals and organic

compounds [1]. These materials combine the high conductivities behavior of

metals, with the mechanical properties of the polymers. The mechanical

properties of polymers include flexibility, elasticity, malleability and toughness.

Polymer electrolyte was first launched by Fenton in 1973 while its

technological importance was appreciated in 1980. There are three stages of

development of polymer electrolyte. These stages include (i) Dry solid

polymer electrolyte (ii) Gel polymer electrolyte (iii) Polymer composites.

Poly(ethylene oxide) based system is the example of dry solid polymer

electrolyte. The ionic conductivity of the poly(ethylene oxide) based solid

electrolyte is very low of the order of 10-8 S cm-1 at ambient temperature. The

polymer host in this system is used as solid solvent due to the absence of any

organic liquid [2]. The cycling performance of this dry solid polymer electrolyte

was not satisfactory with lithium metal electrode.

Gel polymer electrolyte is the second stage of the polymer electrolyte. Gel

electrolyte is neither liquid nor solid because it exhibit properties of both

INTRODUCTION

2

liquids and solids [3]. It possesses diffusive property of liquids and cohesive

property of solids.

Polymer composite is the sub set of polymer electrolyte. Polymer composite is

the macroscopic combination of two or more materials which are having

identifiable interface between them. Polymer composite mostly contain fibres

or particles supported by matrix materials. The fillers impart many advantages

such as fire/flame retardancy, improved thermal and electrical conductivity

and cost benefits [4]. The light weight and high strength of polymer composite

are useful features for application in automotive and aerospace technology.

Polymer composites are also used in construction of transport, aerospace,

sports, buildings and many other sectors.

Polymer composite is obtained by incorporation of insoluble and

electrochemically inert fillers in to polymer matrices. The most common inert

filler includes Al2O3, TiO2, SiO2 and ZrO2. Such polymer electrolytes are

composite ceramic electrolytes or composite polymer electrolytes. The

incorporation of filler results in improved stability at the interface of the

electrode and increase ionic conductivity at lower temperature of the polymer

electrolyte. The examples of polymer host which have been developed and

characterized include poly(ethylene oxide), poly(methyl methacrylate) and

poly(vinyl chloride). Solid electrolytes which show very low values of activation

energy for ionic transportation at temperatures much below their melting point,

negligible electronic conductivity, and high ionic conductivity are referred as

fast ion conductors [5]. Solid electrolytes have been classified as Li+, Na+,

Ag+, O-2, F- ion conductors on basis of the nature of conducting species. Li+

ion solid conductors are used in high energy density batteries due to light

3

weight and high electrochemical potential. Solid electrolytes of high ionic

conductivity at ambient temperatures have been obtained by various

methods. These attempts include (i) dispersion of insoluble, insulating,

particles of oxides such as Al2O3, SiO2 in to ionic matrices (ii) complex

formation between polymer and metal salts. The physiochemical properties of

lithium and sodium are similar. The lithium metal is much costly compared to

sodium metal. The soft nature of sodium metal perform very important role in

the development of good contact with the components in the solid state ionic

devices such as batteries during charging and discharging.

Organic materials which show electrical conductivity under various conditions

are described as organic semiconductors. The electrical conductivity behavior

of such material lies intermediate between metals and non conductive

materials. The electrical conduction through conductive materials is purely

electronic instead of ionic [6]. The example of the organic conductor is

graphite and the electrical conduction through graphite may be interpreted as

a semi conducting materials.

Organic polymers are poor conductors of electricity compared to

semiconductors and metals. The electrical conductivity in Metals and

semiconductors is due to the presence of delocalized electrons. In case of

organic polymer, large energy gaps are available between conduction bands.

The most energetic electrons in organic polymer are localized due to large

energy gaps. It was found in 1977 that polyacetylene shows metallic

conductivity. Such polymers which exhibit electrical and optical properties of

metals while mechanical properties of polymers are known as synthetic

metals or intrinsically conductive polymer.

4

In the doped polymer pi system is delocalized in the conjugated backbone of

the polymer. The conductivity of the polymer increases up to about 10-4 S cm-1.

It was found that conductivity increases by addition of small amount of

chemical species. The doping may cause increase in conductivity up to about

10 orders. The doped conductive polymer may be converted in to original

polymer. The doping and undoping process may be carried out either

chemically or electrochemically. The conductivity between doped and

undoped polymer may be obtained by adjusting the doping level of the doped

polymer. Conducting polymers such as polyacetylene, polypyrrole,

polyaniline, polyparaphenylene exhibit change in the number of electrons

associated with the polymer backbone due to chemical or electrochemical

process during p or n-doping. The number of electrons associated with the

backbone of polyaniline remains unchanged during doping. The conductivity

of conducting polymers may remain same or exceed pure conducting

polymers by blending either with polyamides or polyethylene but mechanical

properties of blends remains same to the host polymer. The thermal stability

of the conducting polymer exhibits improvement in the form of blend with

polymers.

Polyaniline, polypyrrole and derivatives of polythiophene are the leading

conducting polymers which have significant technological applications. Ionic

conducting polymer electrolytes are used in electrochromic displays and

batteries but the conductivity value is very low [7]. The significant lower

conductivity of the ionically conducting polymer electrolyte may be due to the

tight ion pairing of cations and polymer bound anions.

5

The conductivity of the conductive polymers can be increased by

incorporation of carbon fillers for instance carbon black, graphite and carbon

fibers. The resulting conductive materials have advantages due to lighter

weight, the ability to be readily adapted to the needs of specific application

and resistance to corrosion.

The conductivity of the pure polymer ranges between 10-14 and 10-17 S cm-1.

The polymer materials with specific properties can be obtained by

incorporation of appropriate amount of conductive fillers. The conductivity of

the polymer composites have been improved by incorporation of conductive

filler such as metal or carbon. The examples of metal conductive fillers include

aluminum, copper and nickel. Carbon fibers improve both electrical and

thermal conductivity. While carbon black can improve only electrical

conductivity and show no affect on the thermal conductivity.

Conducting polymers have been classified in to four major classes. These

conducting polymers include conjugated conducting polymers, ionically

conducting polymer, conductively filled polymers and charge transfer

conducting polymers [8]. The conductively filled conducting polymers were

developed, in order to prevent the corona discharge problems, in 1930. These

conductively filled polymers have significant potential technological

applications on basis of their good environmental stability, ease of processing

and good electrical properties. These conductively filled polymer lack

homogeneity and reproducibility. Therefore quality of dispersion to obtain

homogeneous conducting polymer should be controlled.

Ionically conducting polymers were developed in 1975 [9]. Various ionically

conducting polymers have been prepared. These ionically conducting

6

polymers have wide range of applications. Ionically conducting polymers

exhibits lower conductivity because ionic conduction mechanism requires

dissociation of oppositely charged ions and migration of ions between

coordination sites. The migration of ions may be due to the segmental motion

of polymeric chains [10].

Charge transfer conducting polymers have been developed in 1950. These

charge transfer conducting polymer lead to the findings of superconductivity in

1980. In these charge transfer complexes electron donors or acceptors are

introduced, in order to improve the processability and stacking properties of

these materials [11].

Various electrically conductive conjugated polymer electrolytes have been

synthesized during the past 25 years. On basis of delocalization of electrons

these conjugated polymer electrolytes also exhibit optical and magnetic

properties. These properties of conjugated polymer enable these materials to

be used in various applications such as sensing devices, light emitting

displays and plastic transistors.

The bulk conductivity of the conducting polymers is contributed by intra-chain

and inter-chain transportation of electrons. The conductivity of the conjugated

polymers is influenced by various factors such as doping, crystallinity and

purity of the conjugated polymer systems. Various methods of doping such as

chemical doping, electrochemical doping, photo-doping, non redox doping,

secondary doping can be used.

The solid polymer electrolytes with high ionic conductivity have been

developed due to its potential applications in electrochemical devices such as

high energy density batteries, chemical sensors, and electrochromic devices.

The first and most extensively studied polymer electrolytes is poly(ethylene

oxide) based polyelectrolyte. The poly(ethylene oxide) based polyelectrolyte

7

lack practical applications at ambient temperature due to coordination of

cation with oxygen atom in the PEO crystalline phase and high melting point

of PEO crystalline phase. The ionic conductivity of these solid electrolyte

systems is very low, at room temperature. The mechanical strength of

polymer electrolyte can be improved by using PVC/PMMA blend electrolytes.

Polyvinyl chloride is inexpensive and commercially available polymer. PVC

exhibit much compatibility with various plasticizers such as ethylene

carbonate (EC), propylene carbonate (PC), dibutyl phthalate (DBP) [12]. The

plasticized PVC is extensively used in the form of films, sheets, flooring and

wallboard due to its good mechanical strength [13-15].

1.1.1 Structural Features of Polymer Electrolytes

Ionically conducting polymer is obtained by dissolving a salt in a polymer. The

conductivity in these polymer electrolyte systems is due to the mobility of ions

between coordination sites. The mobility of ions is caused due to the

segmental motion of polymers. The host polymer must posses, electron

donating sites for the formation of coordinate bond with cations, an

appropriate distance between coordinating sites for formation of multiple intra

polymer bonding with cations, low bond rotation barriers for facilitating

polymer segmental motion. Polyethylene oxide is the most suitable polymer

for solid polymer electrolytes. Various salts which can be dissolved in

polyethylene oxide but lithium and sodium salts are the most suitable. The

conductivity of the polymer electrolyte exhibit improvement above glass

transition temperature due to the increase in segmental motion thereby

improving ionic mobility [16]. The segmental motion of the polymer is very

slow below glass transition temperature resulting in decrease of ionic

8

conductivity due to decreased ionic mobility. Polymer electrolytes exhibit

advantages such as solid state devices free from seals, availability in various

geometries, replacement of liquid electrolytes used in batteries.

The structure of the polymer should be such that in addition to presence of

charge carrier species, these charges can easily move through polymeric

materials. The conjugated polymer structure can meet this requirement by

overlapping the orbitals along the polymer backbone. Polyacetylene is the

most suitable conductive polymer on basis of its simple conjugated molecular

structure and fascinating electronic properties. Most organic polymers lack

intrinsic charge carriers which may be incorporated by doping either by partial

oxidation (p-doping) of the polymer with electron acceptors such as I2 or by

partial reduction (n-doping) with electron donors such as Na. The transition of

non conductive polymer to conductive polymer is not simple but band theory

may provide some useful information about the changes in electronic

structure induced by doping. According to band theory the conductive

behavior can be determined by their electronic structures and electrons can

only move through band of discrete energy states. The lowest unoccupied

band is called as conduction band while the highest occupied band is called

as valence band. The energy difference between these two bands is called as

band gap. The electrons need energy for transition from the valence band to

the conduction band. The valence band and conduction bands of the

conventional polymer are separated by large band gaps. While in conjugated

polymers the band gaps are very small. The band structures of the conjugated

polymer can change either by removal of electrons from the valence band or

by addition of electrons to the conduction band.

9

1.1.2 Transport Properties and Chain Dynamics

The charge transport through the polymer matrix is due to the improved local

segmental motion of polymer chain above glass transition temperature. The

ionic conductivity of the polymer electrolyte system containing cations of unity

charge with constant salt concentration is considered to be directly related

with the mobility of the charge carrier species [17]. The ionic conductivity of

the polymer electrolyte system shows enhancement at low temperature by

incorporation of various kinds of plasticizers. These plasticizers may be in the

form of liquids or solids. The liquid plasticizers include low molecular weight

polyethyleneglycols or aprotic organic solvents while solid plasticizers include

nanoparticles and ceramic particles. By incorporation of liquid plasticizes into

polymer electrolytes the ionic conductivity exhibit improvement but the

compatibility with lithium electrodes in lithium secondary battery decreases

and mechanical properties of these materials also affected. There are several

advantages of addition of ceramic particles in to polymer electrolytes such as

enhancement in ionic conductivity by developing localized amorphous regions

due to the large surface area of the ceramic particles, improved mechanical

stability by the network formation of the particles, improvement in polymer

electrolyte compatibility with the lithium electrode. It is generally believed that

ionic conductivity in polymer electrolytes exhibit enhancement by increase in

the amorphous regions but recently it has been investigated that there are

some polymer electrolytes in which ionic conductivity of the crystalline

polymer electrolytes demonstrate high values compared to their

corresponding amorphous polymer electrolytes e.g. the ionic conductivity of

the crystalline polymer electrolyte PEO-LiSbF6 is higher compared to it

10

corresponding amorphous materials. The effect of temperature on the ionic

conductivity of such polymer electrolyte materials can not be explained on the

basis of William-Landel-Ferry (WLF) equation. It has been shown from the

structural studies of these crystalline materials that lithium ion becomes

coordinated by the ether oxygen atoms inside the cylindrical tunnels,

developed by folding of the polymer chains in the polymer electrolytes. The

anions of the polymer electrolytes remain outside of the cylindrical tunnels

without any coordination with the cations. The free movement of the cations

inside the cylindrical tunnel of the polymer electrolytes contributes to the

enhanced ionic conductivity. The highest conductivity of the of the

conventional polymer electrolytes is 1-3 orders lower compared to the ionic

conductivity of polymer electrolytes containing crystalline ceramic particles

[18]. It has also been found that ionic conductivity of the plastic crystalline

materials is also very high due to the motion of lithium. Therefore the ionic

conductivity of the crystalline polymer electrolytes may be higher compared to

the amorphous polymer electrolytes due to the availability of ordered

structures which provides vacancies in the lattices.

1.1.3 Conductively Filled Polymers

The electrical conductivity can also be induced in the polymer by incorporation

of conductive additives or fillers. The conductive additives may be conducting

solids or conjugated conducting polymer. The conducting solids include

carbon black, carbon fibers, stainless steel, metal particles. Various polymeric

materials including amorphous polymers such as PVC, PMMA and crystalline

polymers such as polyethylene, polypropylene can be made electrically

conductive by incorporation of conductive components [19]. Various methods

can be used to prepare the conductively filled polymers.

11

1.1.3.1 Polymer Filled with Conductive Solids

The insulating polymer matrix can be made conductive by dispersion of

conducting particles, provided that the volume fraction of the incorporated

particle is greater than the percolation threshold. The electrical conductivity

behavior of the composite polymer electrolyte could not be observed below

percolation threshold because the number of conductive particles is not

sufficient to form continuous conducting path thereby the conducting domains

remain insulated from each other by the non conducting polymer medium.

The incorporation of conductive particles results in the formation of continuous

network for the transportation of electrons at the percolation threshold.

Beyond the percolation threshold, the bridges in the conducting networks may

be increases by slight increase in the concentration of the conducting

particles. The non conductive polymer composite will suddenly transform into

conductive polymer. Any further increase in the concentration of the

conducting particles may not increase the pathways for electrons but only the

volume of the conducting domains increase [20]. Several factors can affect

the precise location of the percolation threshold. These factors include the

size and size distribution of the incorporated conductive particles in the

polymer systems. To explain the percolation behavior of the conductive

polymer electrolyte systems containing conductive particle various theories

have been developed but these theories can only explain the general aspects

of the influence of the filler content on the variation of electrical conductivity

[21-23]. The scaling law of percolation theory is one of the most important

theory which gives information about the change in electrical conductivity near

the percolation threshold only but it not explain the variation of percolation

12

threshold with particle size and particle size distribution. The influence of

particle size distribution on the percolation threshold can be investigated by

the formulation developed by Wu [24-25].

1.1.3.2 Polymers Filled with Conjugated Conducting Polymers

Conducting polymer composites with much improved environmental stability

and very low percolation threshold compared to conjugated polymers could be

obtained from conjugated conducting polymers and non conducting polymers

e.g. conducting polymer composites with very low percolation threshold could

be obtained from conjugated conducting polymer PANI and non conducting

polymer poly(methyl methacrylate). The low percolation threshold of the

resulting conducting polymer composite may be attributed to the formation of

the continuous network formation of the conducting pathways along the

networks of the non conducting polymer component.

1.1.3.3 Charge Transfer Polymer

The electrical conductivity through charge transfer polymer can be attributed

to two major factors, the formation of appropriate stacks of donors and

acceptors and transfer of charges between the resulted stacks.

1.1.3.4 Ionically Conducting Polymer

Ionically conducting polymers are used for various important applications such

as secondary lithium batteries, electrochromic devices, thermoelectric

generators [26]. Therefore the development of ionically conducting polymers

is considered very important like electronically conducting polymers. The solid

state ionic based on polymers is considered as new class of materials while

the development of solid state ionics based on ceramics, glasses or crystals

has been studied for decades.

13

1.1.3.5 Metal Filled Conducting Polymer

Metals can be used as filler in the polymer composites to induce good

electrical and thermal conductivity. The metals can be incorporated in various

forms such as powders, filaments, cords or wires. These materials can be

made with any combination of particulate fillers and polymer matrix. The

polymer composite with stable electrical conductivity can be obtained only

when the filler particles and the polymer matrix remains chemically inert [27].

The polymer matrix should prevent the surface oxidation of the incorporated

filler particles. The examples of metals include aluminium, iron and silver. The

conductivity of the composite exhibit much enhancement by incorporation of

silver as filler but silver is much expensive. Aluminium is not much expensive

but it readily oxidized.

1.1.3.6 Carbon Black/Carbon Fibre Reinforced Conductive Polymer Composites

Carbon black are introduced to induce the electrical conductivity in to polymer

composite. These particles have smaller particle size and forming fibrous

aggregates. The addition of porous carbon black is much effective to increase

the electrical conductivity of the composite polymer electrolytes. The

incorporation of carbon fibres impart higher electrical conductivity compared

to particulate carbon black. The electrical conductivity depends on the intrinsic

features of filler and matrix-filler interactions. The electrical conductivity also

depends on the processing conditions.

14

1.1.4 Correlation of Chemical Structure and Electrical Conductivity

Polymeric materials such as poly(ethylene) are insulators due to the low

mobility of sigma bonding electrons. These electrons bound in the sp3

hybridized orbital do not contribute to the electrical conductivity of the

polymeric materials. But in conjugated polymeric materials there is backbone

of sp2 hybridized carbon centers. When these materials are doped by removal

of electrons, then electrons in their delocalized orbitals exhibit mobility. The

electrons present in the band of p-orbitals become mobile when it is partially

emptied by doping. The polymeric materials can also be made conductive by

doping through reduction which leads to the generation of unfilled band of

orbitals. Organic conductors are mostly doped through oxidation resulting p-

type conductive materials. The doping by oxidation or reduction of organic

conductive materials is similar to the doping of silicon semiconductors. By

doping, silicon is either converted in to n-type or p-type semiconductors by

replacing small fraction of silicon atoms either by electron rich atoms such as

Phosphorus or by electron poor atoms such as Boron. Doping of conductive

materials involves either oxidation or reduction but the organic conductive

polymers may be self doped provided they are associated with aprotic

solvents. The mobility of the charge in the conductive polymers is lower

compared to the inorganic semiconductors. The conductivity of the organic

conductive polymers has been improved by invention of new polymer

materials and by employing modern new processing techniques. The lower

mobility of the charges may be due to the structural disorderness of the

conductive materials. The conduction depends on the mobility gaps of the

relatively disordered conductive organic materials.

15

The undoped conjugated polymeric materials are either insulators or

semiconductors e.g. undoped conjugated polymers such as polyacetylenes

and polythiophenes exhibit a very lower electrical conductivity which may be

due to higher energy gaps for thermally activation conduction. The electrical

conductivity of conductive organic polymers exhibit much enhancement even

at very low level of doping. Polyacetylene shows highest increase in electrical

conductivity by doping [28]. The enhancement in electrical conductivity of

polyacetylene may be due to the diminishing of bond alteration by doping

thereby increase in electrical conductivity.

Polyacetylenes, polypyrroles, polyanilines and polythiophenes are the well

studied conductive organic polymers whereas polyindole, polynaphthalene

and polyfluorenes are the classes which are not well studied.

1.1.5 Charge Transportation

The precise mechanism of transportation of charges through conductive

polymers is not yet fully understood. The problem arises due to tracing the

exact path of the charge carriers through the conductive polymers.

Conductive polymers are mixtures of amorphous and crystalline regions

resulting in highly disordered structure. The transportation is considered along

and between the chains of polymeric materials. The transport of charges may

also through the complex boundaries developed by multiple numbers of

phases. The mechanism of the electrical conduction through polymer system

may be studied by observing the influence of the temperature, magnetism,

frequency of the current and doping. Various mechanisms can be considered

for the conduction but the mechanism based on the movement of charge

carrier, between localized sites are the most important. The movement of

these charges through conductive polymers may be due to thermally activated

hoping or tunneling. The electrical conductivity of the conductive polymers is

considered proportional to the temperature.

16

1.1.6 Stability of Conductive Polymers

Conductive polymers may exhibit degradation even in oxygen free, dry

environmental condition with time. The intrinsic instability is due to the

irreversible chemical reaction between charged sites of the conductive

polymer. Such situation may arise due to the loss of dopant. The loss of

dopant occurs due to the unstability of the charge sites, which happens during

conformational changes in the polymer backbone.

1.2 Factors Affecting Electrical Conductivity

The increase in electrical conductivity depends on the properties of the filler.

For instance the incorporation of various form of carbon filler have different

effect on the enhancement of electrical conductivity. The electrical

conductivity for carbon black is 102, for graphite is 105. The value of electrical

conductivity of the composite also depends on the size of the filler.

The values of conductivity and percolation threshold of the composite also

depend on the surface properties of the filler and polymer. The interaction

between two materials is influenced by the surface free energies of the filler

and matrix and the difference between the surface energies of the two

materials shows that how the polymer wets the surface of the filler. The

increase in the difference between the surface energies of the two materials

leads to the poor wetting of the filler by the polymer. While the decrease in the

difference of the surface energies resulting in better wetting of the filler by the

polymer. The dispersion of the filler within the matrix depends on the wetting

of the filler. It means that larger difference between the surface energy of the

filler and the polymer resulting in lower ionic conductivity while smaller

difference causes higher ionic conductivity of the composite material.

17

The ionic conduction through conducting polymers depends on the sizes and

structural perfection of the chains, sheets or networks, bonding between the

polymeric chains, the presence of the foreign particles which generates

deficiency or excess of the electrons in the conductive polymer system [29].

The conductivity of the conductive polymers exhibit variation with composition

and treatment of the polymer but the influence of the changes of composition

and treatment on the mechanism of the electronic conduction is not yet

obvious. It has been found that electrical conductivities of the conductive

polymer systems partly depend on the conjugation of the double bonds [30-

31]. The conduction behavior of the polymers also depends on the electron

deficient and electron excess sites and the mobility of these sites along the

polymeric backbone. The electrical conduction in the conductive materials can

be correlated with the electron paramagnetic resonance spectra. The

incorporation of impurities influence the electrical conduction in the organic

conductive polymers to a very less extent but the conduction behavior of their

inorganic conductive counterparts are much influenced. The ease of

production of charge carriers and the mobility of these charge carriers within

and between the conjugated polymers can be greatly influenced by

incorporation of appropriate impurities in to the organic conductive polymers.

The ionic conductivity of the conductive polymers increases about one to

three orders by incorporation of inert phase particles (second phase or

dispersoids) for instance Al2O3, Fe2O3, SiO2, ZrO2 in to an ionic conductor

(first phase host materials) such as LiI, AgCl. Such polymer electrolytes are

referred as composite solid electrolytes [32]. The enhancement of ionic

conductivity of the composite solid electrolytes depends on the concentration

18

and size of the inert phase particles. The resulting composite solid electrolytes

can be used in electrochemical devices such as cellular phones. The lower

values of these electrolytes restrict the application of these materials in solid

state batteries and electrochemical display devices. The mechanical and

thermal stability of these materials cam be improved by incorporation of

plasticizers while the ionic conductivity of these solid electrolytes by addition

of dispersed second phase particles.

1.3 Applications of Conductive Polymers

Polymer electrolytes find applications not only in the lithium batteries but

these materials may be used in other electrochemical devices such as super

capacitors and electrochromic devices. Solid polymer electrolytes have

various advantages over liquid electrolytes for instance no leakage of

electrolytes, no internal shorting and the formation of noncombustible reaction

products at the surface of electrode.

Conductive polymers are rapidly becoming adaptable to the applications

which previously belong to metals and their compounds. The advantage of

using polymer instead of metals is of weight saving. Therefore polymers are

used as construction materials. Polymer materials can also be used as

current carriers in electronic components. Conductive polymers are potentially

less damaging and less toxic to the environment compared to that of metals.

Solid polymer electrolytes have been used in electric vehicles which play very

important role in reduction of pollution. Solid polymer electrolytes are used in

small and light weight, high energy density rechargeable power sources which

play important role in development of toys, computer memory backup, electric

vehicles and electrochromic devices [33-34]. The gel polymer electrolytes

19

have found application in the high energy electrochromic devices [35]. The gel

polymer electrolyte is obtained by mixing of lithium salt and plasticizer. The

lithium salt dissolves in organic solvent. The plasticizer maintains the liquid

like state of the material while the polymer component provides mechanical

strength to the composite material. The resulting material minimize leakage

problem. It also retains ionic conduction properties of liquids. Gel polymer

electrolytes have high mobility of charge carrying species. The mechanical

and electrochemical properties of the polymer electrolyte depend on the

properties of the individual components of the composite material. The

variation of components and their relative amount in the composite polymer

electrolyte causes changes in the properties of the gel polymer electrolyte.

The ionic conductivity of the polymeric materials depends on their phase

structure. Various examples of gel polymers can be used as polymer

electrolytes. The examples of these polymers include poly(vinyl chloride) and

poly(acrylonitrile).

The main objective of the Polymer research is focus on the development of

polymer electrolyte which exhibit high ionic conductivity in addition to high

mechanical strength. These materials are much lighter and can be easily

processed. The polymeric materials with a wide variety of properties can be

obtained by blending of polymer [36]. Polymer blend is obtained by mixing of

two or more different polymers or copolymers. The constituent polymers are

present in significant weight or volume proportion in the polymeric blend. The

components of polymer components may be of equal or different proportions.

The blending of two or more polymers are considered similar but not equal to

the alloying of two or more metals. The fine particles of one component are

20

uniformly dispersed through the matrix of other component in the polymer

blend. The characteristics of the blends are uniform due to uniform distribution

of components of blend.

Polymer blends are classified into various classes. These classes include

mechanical polyblends, chemical polyblends and mechanochemical

polyblends, solution polyblends, and latex polyblends. The properties of the

components of polymers in a blend may be different from the behavior

exhibited by the components in their isolated forms. The glass transition

temperature of the miscible polymer blends are single and sharp which lies

intermediate between the constituent polymers of the blends while polymer

blends with phase heterogeneity exhibit glass transition temperature for each

polymeric components. The behavior of the polymer blends depends on

various factors such as nature of the dispersed phase provided by the matrix

material, character of the dispersed phase, and interactions between the

component polymers.

Ionically conductive polymer electrolytes have received wide attention for

application in the electrochemical devices such as batteries, electrochromic

devices and capacitors. Conductive polymers are the most suitable

candidates to construct solid state batteries because the polymeric material

can easily adjust to the change in volume occurring during charging and

discharging of the batteries. Solid polymer electrolytes have been developed

for the most prominent alkali metal ions such as Li+ and Na+.

These materials are used as antistatic materials, batteries and commercial

displays but the applications of the conductive organic polymers have

limitations on basis of their poor processability, toxicity, poor solubility in

21

solvents, manufacturing costs. These conductive materials also found

applications in the organic light emitting diodes, organic solar cells,

biosensors, super capacitors, transparent displays and electromagnetic

shielding. Conductive polymers provide better electrical and physical

properties to the materials.

1.3.1 Batteries

Metallic conductors are used as electrodes in batteries. The utilization of

conductive polymers in the batteries was one of the first suggestions. There

are various advantages of using conductive polymers as electrode instead of

metals because conductive polymers have shown much lighter weight, lower

cost, improved recyclability and lower toxicity [37]. Besides these, the

charging and discharging reactions create charge carriers through the

conjugated backbone of the polymer and there is no problem of dissolution of

the electrode materials of the batteries. While in case of metallic electrodes

there is problem of repeated dissolution or deposition of electrode materials.

The substitution of metals by conductive polymers is highly successful

commercially. These polymers can easily be obtained from the natural gas,

deep oil wells and from residual plant materials compared to the metals which

are obtained from mines.

22

1.3.2 Light Emitting Diodes

The conductive polymer can be used in the devices which provide an

alternate method to backlit LCD displays. The conductive polymers are used

as sandwitch-type structures in these devices. The active polymeric films are

packed between anode and cathode. Light emitting diodes emits uniform light

over the entire device. These devices are used in the displays for home

appliances, industrial devices of readout display, cellular telephones.

1.3.3 Electroluminescence

Electroluminescence is the phenomenon in which light emission is stimulated

by electrical current. The phenomenon of electroluminescence in organic

compounds was first shown by Bernose in 1950 in crystalline thin films of

acridine orange and quinacrine [38-41]. This phenomenon in conductive

polymer may be produced by applying voltage to a thin layer of these

materials. The enhancement in electrical conductivity leads to the generation

of practical amounts of light at low voltage.

1.3.4 Electrochromic Cells

The conductive polymers are used in the flat screen displays for computers

and mobile phones [42]. The electrochromic materials can be made to change

colour, under the effect of electric current. Solid polymer electrolytes contain

less hazardous chemicals and more convenient to handle therefore it is used

in electrochemical cells and light emitting diodes.

23

1.4 Limitations of Conductive Polymers

The conductive polymers are considered as complementary instead of

competitive to silicon and metal devices. The conductive polymer materials do

not exhibit the conductance and electrical behavior like that of metallic and

semi conductive materials. The speed of electrical conduction in silicon chips

is faster compared to conductive polymers [43].

The advantage of the conductive polymers is that they demonstrate high

degree of elongation and moldability behavior. Conductive polymers also

show some disadvantages such as the mechanical behavior of these

conductive materials are better than silicon based devices but much weaker

compared to that of metals. Polymeric materials are more likely to be

damaged by scratching compared to metals because polymers are very soft.

The scratching problem of the conductive polymers may be solved by

developing some new polymers which exhibit resistance to scratching.

Polymeric devices exhibit conductivity in one or two dimensions while the

metallic conductor shows conductivity in all three dimensions. The directional

conductivity behavior of the conductive polymers is due to the linear or planar

structures. The directional conductivity of the conductive polymers might have

some advantages to resist conductivity in vertical directions but in some cases

it may be of disadvantage.

24

1.4 Aims and Objectives

A number of methods of modification of solid polymer electrolytes based on

complexes of PVC with alkali metal salt, leading to an improvement in their

mechanical properties and ionic conductivity have been developed in the last

few years. In the present research work, solid polymer electrolytes obtained

from PVC blended with PMMA containing LiClO4 salt and metallic oxide as

filler exhibit much improved room temperature ionic conductivity and stability

compared to analogue materials based on PVC.

The aim of this research work is to study the effect of composition and

temperature on the conductivity and stability of solid polymer electrolytes

based on PVC of various compositions containing different alkali metal salts

(LiClO4, LiClO3, LiBF4, Li2SO4, NaClO4), inorganic metal oxides (ZnO, Al2O3,

ZrO2, TiO2) and plasticizers (EC and PC).

In this research work activation energies of different polymer electrolyte

systems at some particular temperature were calculated and the relationships

between various factors have been investigated.

In the present research work the effect of polymers such as PMMA and PEO

on conductivity and stability of PVC based polymer electrolyte systems were

also studied. To improve the conductivity and stability of the polymeric

systems, organic solvents were added as much as possible and similarly

PMMA and PEO were also added in different concentrations to the hybrid

solid polymer electrolyte systems consisting of PVC, salts, plasticizers and

fillers.

Measurements of conductivity, thermogravimetric, differential

thermogravimetric analysis, X-ray diffraction and viscosity have been carried

25

out. Various compositions of PVC based polymer electrolyte systems have

been tested in order to obtain the best compromise between high conductivity,

homogeneity and stability.

In this way the polymer electrolyte systems were examined to overcome the

problems inherent to gel polymer electrolytes and plasticized PVC based


26

CHAPTER # 2

R. H. Y. Subban and A. K. Arof44 studied the preparation and characteristics of

the composite polymer electrolyte films consisting of PVC-LiCF3SO3-SiO2

based on Poly vinyl chloride (PVC). These composite polymer electrolyte films

were prepared by solution casting method. The ionic conductivity was

investigated at various temperatures. They also evaluated the charge-

discharge characteristics of the battery at room temperature in order to

ascertain the viability of these polymer electrolytes in lithium polymer

batteries.

P. S. Anatha and K. Hariharan45 studied the preparation and characterization

of solid polymer electrolyte films of various compositions based on

poly(ethylene oxide) containing NaNO3 as salt. They investigated the

complexation of these films through X-ray diffraction (XRD), differential

scanning calorimetry (DSC) and Fourier transform infrared spectroscopy

(FTIR) measurement. They also studied measurement of electrical properties

as a function of composition and temperature.

Z. Osman, A. K. Arof and Z. A. Ibrahim46 investigated the mechanism of ionic

conductivity in the cast films of chitosan acetate, plasticicized chitosan

acetate, chitosan acetate containing salt and plasticized chitosan acetate-salt

complexes. They found that the enhancement of ionic conductivity may be

due to the dissociation of salt. The ionic conductivity of these polymer

LITERATURE REVIEW

27

electrolytes were calculated using the bulk impedance plot obtained through

impedance spectroscopy.

B.K. Choi, K.H. Shine and Y.W. Kim47 examined solid polymer electrolyte films

consisting of poly(ethylene oxide) (PEO), LiClO4, mixture of ethylene

carbonate (EC), butyrlactone (BL) and poly(acrylonitrile) (PAN) in order to

obtain the best compromise between high conductivity, homogeneity and

stability. They carried out measurement of electrical conductivity and

differential scanning calorimetry. They found that with decrease in the ratio of

LiClO4/ (EC/BL), crystallinity of the polymer electrolyte films increased. It was

also found that materials having higher content of EC/BL were more likely to

be a gel electrolyte compared to that of PEO-salt polymer electrolytes.

S. Selvasekarapandian and others48 prepared PVAc-LiClO4 solid polymer

electrolytes of various compositions by solvent casting technique. They

studied structure, surface morphology, thermal and conductivity behavior of

solid polymer-salt complexes by employing X-ray diffraction (XRD) analysis,

scanning electron microscopy (SEM) measurement, differential scanning

calorimetry (DSC), and ac impedance measurements respectively. They

found that these polymer electrolytes are amorphous and show decrease in

glass transition temperature with increase in concentrations of LiClO4.

E. Zygadlo-Monikowska and other co-workers49 studied the preparation and

transport properties of solid polymer electrolyte containing poly(ethylene

oxide) (PEO), LiCF3SO3 and aluminum carboxylate. They investigated the

interaction of aluminum carboxylate with various Li salts. It was found from

transport properties of Li ion that triflate salt anions are completely

28

immobilized which may be due the complete dissociation of the aluminum

carboxylate and lithium salt complex.

W. Krawiec, E. P. Gianneis and others50 studied the ionic conductivity and

lithium electrode-electrolyte stability for polymer electrolytes containing Al2O3

as inorganic filler and LiBF4 as salt in polyethylene oxide (PEO). It was found

that ionic conductivity and interfacial stability exhibits increase by

incorporation of Al2O3 in to polymer electrolytes.

N. Ogata, S. Yamada and others51 studied the preparation and ionic

conductivities of polymer electrolytes containing various polycation salts. It

was found that ionic conductivities of these polymer electrolytes were 10-100

times higher than the polymer electrolytes based on polyethylene oxide (PEO)

at room temperature.

F. Alloin, D. Benrabah and J. Y. Sanchez52 studied comparative transport

number of various lithium salts dissolved in a polyether network. They found

that ionomer based on perfluorosulfonate exhibit transport number close to

unity.

S. Rajendran and T. Uma53 studied preparation and characterization of

polymer electrolytes consisting of poly(vinyl chloride)-LiBF4-dibutyl phthalate

(DBP) containing various concentrations of ZrO2. They were investigating the

complex formation between polymer, salt and plasticizer by FTIR. It was

found that polymer electrolyte systems obeyed VTF relation and ionic

conductivity values depend on the ZrO2 concentration.

A. A Mohamad, A. K. Arof and others54 observed the effect of plasticizer on

ionic conductivity, thermal stability and surface of polymer electrolytes. They

found that ionic conductivity and dielectric constant shows enhancement by

29

the addition of propylene carbonate (PC) as plasticizer to the PVA-KOH-

Al2O3-H2O. It was observed that thermal stability decreases by the addition of

PC to the polymer electrolytes.

P. Periasamy Y. Saito and other co-workers55 developed gel polymer

electrolytes based on polyvinyidene fluoride containing ethylene carbonate

and propylene carbonate as plasticizers and Li BF4 as salt. They investigated

the influence of the amount of polymer, plasticizer and salt on the polymer

electrolytes by using DSC, XRD and AC impedance.

C. C. Tambelli, J. P. Donoso and others56 studied the effect of concentration of

Al2O3 on the behavior of PEO-LiClO4. It was found from DSC results that

glass transition temperature is not influenced but the quantity of crystalline

phase exhibits variation by addition of filler in to the polymer electrolyte.

C. Zahriddine and Y. S. Pak and G. Xu57 investigated the conductivities of

polymer electrolytes containing various content of water by ac impedance

method. It was found that ionic conductivities enhances by uptake of water

molecules. It was also observed from the logarithmic plots of ionic

conductivities against reciprocal temperature that polymer electrolytes shows

VTF behavior.

P. P. Chu and S. S. Sekhon58 studied the effect of dimethylacetamide (DMA)

and Oxalic acid on the ionic conductivity of polymer electrolyte based on

polyvinyledenefluoride-hexafluoro propylene (PVdF-HFP). It was found that

ionic conductivity exhibit enhancement by addition of small amount of DMA in

to the polymer electrolyte. The increase of ionic conductivity was due to the

interaction of polymeric media, acid and basic plasticizer components. These

interactions were confirmed by FTIR studies.

30

S. Sreepathi Rao, U. V. Subba Rao and other co-workers59 prepared and

studied transport properties of poly(ethylene oxide) based polymer electrolyte

containing NaYF4 salt. They also prepared electrochemical cell with the

configuration Na/PEO+NaYF4/(I2+C_electrolyte).

A. Andrieu, C. Fringant and T. Icedo60 investigated the influence of low

molecular weight poly(ethylene oxide) as plasticizer on the conductivity of

cross-linked poly(ethylene oxide)/poly(propylene oxide) copolymer

electrolytes containing LiClO4 salt. It was found that ionic conductivity shows

increase by addition of plasticizer in to polymer electrolytes.

S. A. Agnihorty and V. D. Gupta61 studied the effect of solvents and lithium

salts on the ionic conductivity of polymer electrolytes based on poly(vinyl

butyral). Solid polymer electrolytes were prepared by solution cast technique.

It was shown that ionic conductivity varies with solvents and solid polymer

electrolytes with n-butyl alcohol shows highest ionic conductivity.

Qi Wang, Jun Gao and Yaqin Qian62 studied the effect of plasticizer,

temperature and polymer mole ratio on the ionic conductivity of solid polymer

electrolytes. It was found that ionic conductivity exhibit enhancement with

decrease in molecular weight or increase in the content of plasticizer. It was

also found that polymer electrolytes show higher ionic conductivity at higher

concentration of salts and equal mole ratio of P(MMA-MAA) to PEO. In

addition, ionic conductivity of the system shows increase by incorporation of

salts containing smaller cation or larger anion.

Z. Florianczyk, K. Such and others63 investigated ionic conductivity of solid

polymer electrolytes containing various lithium salts, prepared by thermal

polymerization of methyl methacrylate in the presence of poly(ethylene oxide).

31

They found that these polymer electrolytes contained amorphous phase with

low glass transition temperatures. The high ionic mobility of these polymer

electrolytes may be due to the presence of amorphous phase by addition of

plasticizer.

H. Bischoff, R. Sandner and other co-workers64 studied the enhancement of

the ionic conductivity and amorphous state of solid polymer electrolytes

obtained by complexation of LiCF3SO3 with polymer obtained by

polymerization of triethylene glycol dimethacrylate (TRGDMA) and

copolymerization with acrylonitride (AN) at various molar ratios, in the

presence of plasticizer. It was found that ionic conductivity shows increase

with growing ratio of AN:TRGDMA. In addition, the ionic conductivity was

found to be independent of the AN content in the solid polymer electrolytes.

S. Ramesh and K. Y. Ng65 observed, ionic conductivity of the solid polymer

electrolytes consisting of poly(vinyl chloride) and lithium sulphate salt in the

temperature range of 303-373 K with various concentration of PVC. Arrhenius

behavior was observed before while VTF behavior was observed after glass

transition temperature. Complexation between PVC and Li2SO4 was

confirmed by Fourier transform infrared study in the polymer electrolyte

systems.

Y. W. chen-yang, T. L. Chen and others66 studied the influence of Al2O3 on the

ionic conductivity of polymer electrolyte based on

poly(methoxyethoxyethoxy)phosphazene (MEEP) containing lithium

perchlorate salt. It was observed that addition of Al2O3 in the polymer

electrolytes leads to an increase in ionic conductivity.

32

D. Y. Zhou, Y. H. Liao and other co-workers67 reported the preparation of

copolymer, polyacrylonitrile-methyl methacrylate P(AN-MMA) by suspension

polymerization of acrylonitrile (AN) and methyl methacrylate (MMA). They

characterized P(AN-MMA) copolymer by employing FTIR, SEM, DSC and TG.

It was found that polymer membrane was stable up to 300°C.

P. Santhosh, T. Vasudevan and A. Gopalan68 investigated the preparation and

characterization of composite polymer electrolyte comprising of polyurethane

(PU) and polyvinyledene fluoride) (PVdF). Thermal properties and bulk

conductivity of the polymer composites were studied by DSC and impedance

spectroscopy respectively. The effect of the PVdF content on the bulk

conductivity was studied. The molecular interactions in the composite polymer

electrolyte were monitored by FTIR studies.

A. Bac, W. Wieczorek and others69 reported the effect of addition of inorganic

filler on the electrode interfacial behavior of composite polymer electrolyte. It

was observed that both concentration of LiClO4 salt and the type of inorganic

filler monitor the formation and growth of the resistive layer at the polymer

electrolyte-lithium electrode interface layer.

T. Kuila and S. Kureti and other co-workers70 investigated the influence of

addition of LaMnO3 nanofiller on the ionic conductivity of PEO based

composite polymer electrolyte. It was found from SEM analysis that by

addition of plasticizer, the large spherulites in the crystalline domain of PEO

disappear in the PEO-NaClO4-LaMnO3 composite polymer electrolyte. It was

further reported that room temperature ionic conductivity shows enhancement

by addition of poly ethylene glycol in to PEO-LiClO4 polymer electrolyte. XRD

33

and DSC studies reveal the increase in the amorphous phase in the polymer

electrolyte by addition of plasticizer.

R. Baskaran, T. Hattori and others71 studied the ionic conductivity and thermal

behavior of polymer electrolyte comprising the blend of poly(vinyl acetate)

(PVAc) and poly(methyl methacrylate) (PMMA) containing LiClO4 as salt. XRD

analysis shows the amorphous nature of polymer electrolyte. It was found that

increase in concentration of salt in the polymer complexes leads to an

increase in ionic conductivity. Conductivity-temperature studies were found to

obey Arrhenius nature.

V. Arivandan and P. Vickramann72 reported the effect of lithium

difluoro(oxalate)borate on ionic conductivity of polymer electrolyte based on

polyvinyledenefluoride-hexafluoropropylene polymer. Nanocomposite polymer

electrolytes were prepared by addition of ethylene carbonate and diethyl

carbonate mixture as plasticizer and Sb2O3 as the filler. It was found that

addition of Sb2O3 leads to enhanced ionic conductivity. The increase in ionic

conductivity was explained in terms of Vogel-Tamman-Fulcher (VTF) theory.

J. F. Le Nest, M. Armand and others73 investigated the enhancement of ionic

conductivity of polymer network based on polyethylene oxide triols and

polyethylene oxide diisocyanates. Ionic conductivities, mechanical properties

and glass transition temperature of polymer electrolytes were reported both in

the presence and in the absence of LiClO4 and LiN(CF3SO2)2 salts. The

enhancement of ionic conductivity was observed by addition of salts and

plasticizer in to the polymer electrolytes.

C. S. Harris and T. G. Rukavina74 developed lithium ion and proton conductors

with good thermal and electrochemical stability. It was found that ionic

34

conductivity shows enhancement by addition of propylene carbonate to the

polymer-salt complexes. It was reported that physical properties of polymer

electrolytes does not show any degradation by addition of propylene

carbonate.

S. Ramesh and S. C. Lu75 observed the influence of addition of nanosized

silica poly(methyl methacrylate)- lithium bis(trifluoromethanesulfonyl)imide

based polymer electrolytes. These polymer electrolytes were analyzed by

employing FTIR, conductivity and thermal properties. Complexation between

PMMA, LiTFSI and SO2 were observed by FTIR spectra. Thermal properties

and the ability to retain conductivity for longer time were found to increase by

addition of silica.

Z. Yue, I. J. McEwen and J. M. G. Cowie76 studied and prepared gel polymer

electrolytes comprising of a hydroxypropylcellulose ester, LiCF3SO3 and

propylene carbonate. It was reported that ionic conductivities and mechanical

strength increased with increasing concentration of ethylene carbonate in the

polymer electrolytes.

S. R. Majid and A. K. Arof77 studied the characterization of proton conducting

polymer electrolyte films of chitosan acetate-ammonium nitrate by solution

cast technique. It was found by Fourier transform infrared spectroscopy that

complexation has occurred in the polymer electrolytes. The highest

conductivity was reported for the polymer electrolytes containing 45%

ammonium nitrate at room temperature.

F. Ciuffa, B. Scrosati and other co-workers78 reported the characterization and

properties of lithium ion transport and proton conductive membranes. They

found lithium ion conductive membrane suitable to be used as separator in

35

advanced lithium ion plastic batteries while proton conductive membrane were

shows to have good properties use in polymer electrolyte fuel cells.

J. Travas-Sejdic, P. Pickering and others79 studied the polymer electrolyte gel

system comprising of a copolymer of N,N-dimethylacryl amide and lithium 2-

acrylamido-2-methyl-1-propane sulphonate. This copolymer electrolyte were

prepared in the form of three dimensional network in solvent mixture of N,N-

dimethylacetamide and ethylene carbonate. They investigated the effects of

composition, concentration and temperature on the ionic conductivity of

polymer electrolyte.

P. Manoravi, K. Shahi and other co-workers80 studied the influence of variation

of ratio of the metal salt and poly(ethylene glycol (PEG) on the conductivity

behavior of poly(ethylene glycol)-sodium iodide. It was found that ionic

conductivity increased by addition of NaI in to PEG due to increase in the

number of ionic carriers. The increase in ionic conductivity was found to be

similar to poly(ethylene oxide) system.

F. Croce, L. Settimi and B. Scrosati81 presented the influence of addition of

superacid ZrO2 on the transport properties of composite polymer electrolytes

comprised of poly(ethylene oxide)-lithium tetrafluoroborate. It was found that

addition of superacid ceramic leads to higher ionic conductivity of the polymer

electrolytes.

S. Rajendran and T. Uma82 described the influence of concentration of salt

and temperature on the ionic conductivity of polymer electrolytes comprising

of poly(vinyl chloride) (PVC), poly(methyl methacrylate) (PMMA), LiBF4 and

dibutyl phthalate (DBP). The ionic conductivity of polymer electrolytes was

investigated at various temperatures and at different concentrations of salt.

36

J. Bradshaw, S. B. Tain and G. Xu83 characterized copolymer comprising of

lithium-doped 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA), 4-

aminophenyl ether (ODA), aminopropyldimethyl terminated

polydimethylsiloxane (PSX) and 2,5 diaminobenzene sulphonic acid

(DABSA). It was reported that ionic conductivity shows enhancement due to

the motion of flexible PSX chains.

G. C. Li, Y. P. Wu and others84 studied porous polymer electrolyte based on

poly(vinylidene difluoride-co-hexafluoropropylene) copolymer of low apparent

activation energy for transportation of ions by SEM, XRD and DSC. It was

found that the resulting polymer electrolytes exhibit high ionic conductivity and

provide promise for practical application in polymer lithium ion batteries.

G. B. Appetecchi, S. Passerini and other co-workers85 studied thin films of

polymer electrolyte based on poly(ethylene oxide), prepared by blown-

extrusion method. The ionic conductivities and interfacial properties of

resulted polymer electrolytes thin films were investigated.

Y. Liu, J. Y. Lee and L. Hong86 reported the effect of functionalized SiO2 on

ionic conductivity, stability of Li-polymer interface and mechanical properties

of polymer electrolytes. The functionalized silica was characterized by thermal

gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The

functionalized SiO2 were found more effective compared to untreated SiO2 as

ceramic filler in polymer electrolyte system.

P. K. Singh and S. Chandra87 characterized complex polymer electrolyte

based on poly(ethylene oxide)-Ammonium iodide containing PbS and CdS as

semiconductors in various ratios by weight. It was described that 10-20% of

ionic conductivity was given by solution casting method.

37

W. Chen, Q. Xu and R. Z. Yuan88 described the influence of modification of

poly(methylmethacrylate) and temperature on ionic conduction in

poly(ethylene oxide) layered silicate nanocomposite. It was reported that

modification of poly(methylmethacrylate) (PMMA) leads to enhancement of

ionic conductivity and decrease in apparent activation energy. The ionic

conductivity values of nanocomposite exhibit improvement at high

temperature.

M. M. Doeff, L. C. De Jonghe and others89 reported the effect of salt

concentration on the ionic conductivities of binary salt polymer electrolytes.

The ionic conductivities of several binary salt-polymer systems were

compared. The result out polymer electrolytes was considered most useful in

rechargeable lithium batteries as polymer electrolytes.

S. S. Sekhon and G. S. Sandhar90 studied the effect of concentration of SiO2

on the ionic conductivity of PEO-AgSCN polymer electrolytes. Complex

formation in the amorphous phase of the material was investigated by FTIR

and X-ray diffraction studies. It was found that ionic conductivity depends on

the concentration of SiO2. The conductivity results were compared to other

composite polymer electrolytes containing Al2O3 and Fe2O3 in PEO-AgSCN.

D. R. MacFurlane, M. Forsyth and other co-workers91 reported the effect of

plasticizer on the ionic conductivity and thermal properties of solid polymer

electrolytes. The ionic conductivity of polymer electrolytes was increased by

addition of various kinds of plasticizers. The addition of plasticizer leads to

increase in ionic conductivity due to increase in chain flexibility and by acting

as cosolvent for the salt thereby increasing number of charge carrier species

in the system.

38

V. Aravindan, P. Vickraman and T. Prem Kumar92 investigated the effect of

addition of ZrO2 nanofiller on ionic conductivity of PVC-PVdF blend-based

composite polymer electrolytes containing lithium bis(oxalate)borate as salt.

The resultant composite polymer electrolytes were subjected to AC

Impedance, XRD and SEM studies. It was reported that addition of ZrO2 leads

to increase in ionic conductivity up to 2.5 wt%. It was investigated by XRD

studies that beyond 2.5 wt% of filler content, degree of crystallinity increases.

T. Steekanth, U. V. Subba Rao and others93 characterized polymer electrolyte

based on poly(ethylene oxide) (PEO), containing potassium bromate as salt,

by employing differential scanning calorimetry (DSC) and dc conductivity. It

was investigated from conductivity temperature relationship that charge

transport through polymer electrolyte may be due to ions.

V. Arivandan, P. Vickraman and T. Prem Kumar94 studied the effect of Al2O3

on the ionic conductivity of composite polymer electrolyte based on poly

vinylidene fluoride-hexafluoropropylene containing LiPF3(CF3CF2)3 as salt and

a mixture of ethylene carbonate and propylene carbonate as plasticizing

agent. It was shown that beyond 2.5wt% content of Al2O3 there was decrease

in ionic conductivity.

F. Forsyth, A. J. Hill and others95 studied influence of TiO2 filler on structure

and ionic conduction in polymer electrolyte system based on polyether. It was

found by multinuclear magnetic resonance spectroscopy that environment of

lithium ion changed by addition of filler. It was reported that free volume

increases by addition of filler in to polymer electrolytes. It was also

investigated from impedance spectroscopy that the inter-phase region may be

more or less conductive compared to that of bulk polymer electrolyte region.

39

J. M. G. Cowie and G. H. Spence96 studied the effect of concentration of salt

on the ionic conductivity of branched copolymer of poly(ethylene oxide

methoxy) and lithium 1,1,2-trifluorobutane sulfonate acrylate. It was found that

the resulting copolymer electrolytes facilitates Li+ conduction due to effective

electron withdrawing properties of the fluorines which leads to higher ionic

conductivity.

V. Gentili, B. Scrosati and other co-workers97 studied the influence of

dispersion of ceramic fillers on the properties of composite gel-type lithium

conducting polymer electrolytes. It was observed that there are no pronounce

effect of surface functionalized fumed silica and alumina on PVdF-carbonate

solvent-lithium salt polymer electrolytes but it stabilizes the lithium-metal

interface and mechanical properties of the resulting gel type polymer

electrolyte system.

G. B. Appetecchi, B. Scrosati and others98 reported the effect of dispersion of

ceramic powders on the interfacial stability and transport properties of

composite polymer electrolytes based on poly(ethylene oxide) containing

lithium salts. It was found that dispersion of ceramic powders leads to

improvement in interfacial stability and ionic conductivity.

M. Rikukawa and K. Sanui99 investigated the chemical and electrochemical

properties of proton conducting polymer electrolytes based on hydrocarbon

polymers. It was found that hydrocarbon polymers were promising material to

obtain high performance new proton conducting polymer electrolytes.

E. M. Shembel, D. Meshri and others100 reported ionic conductivity, thermal

and electrochemical stability of polymer electrolytes based on poly(vinyl

chloride) (PVC) and its chlorinated derivative. Ionic conductivity was

40

investigated by impedance spectroscopy of resulting PVC based polymer

electrolytes.

M. Walkowiak, M. Osinka and others101 studied the new lithium ion conducting

polymer electrolytes based on polysiloxane grafted with Si-tripodand centres.

The resulting polymer electrolytes demonstrated very high ionic conductivity

at room temperatures. In the studied polymer electrolytes the exceptionally

high ionic conductivity was described to be due to addition of LiPF6.

L. Reibel, H. Majastre and others102 studied thermal and conductive behavior

of polymer electrolytes containing aromatic lithium sulfonylimides salts. It was

reported that below 50°C temperatures, polymer electrolytes exhibit typical

behavior of semicrystalline systems by using high molecular weight PEO as

solid solvent. By further increase in temperature above 50°C, the polymer

electrolytes become amorphous.

C. Liebenow103 investigated the effect of temperature and composition on the

ionic conductivity of gel like magnesium ion conducting polymer electrolytes

comprising of ethyl magnesium bromide dissolved in poly(ethylene oxide).

The ionic conductivities of the studied polymer electrolytes exhibit

improvement with increase in the content of monomer ether per magnesium.

The highest conductivity was obtained with 5-6 wt% magnesium content.

K. Nairn, D. R. Macarlane and other co-workers104 studied the effect of

addition of ceramic ion on the ionic conductivity of polymer-ceramic ion-

conducting composites. It was observed that ionic conductivity of composite

polymer electrolytes was higher compared to polymer electrolyte without

ceramic powder.

41

J. G. Cowie, C. Roberts and others105 investigated the influence of divalent

cation salts such as Ca(ClO4)2 and Mg(ClO4)2 on the ionic conductivities of

polymer electrolytes based on polymers with comb branched structures with

oligo(ethylene oxide) and oligo(propylene oxide) side chains. The highest

conductivities were found for system containing divalent salts of Ca and Mg.

R. J. Latham, R. G. Linford and R. A. J. Pynenberg106 reported the effect of

microwave drying on the morphology and ionic conductivity of polymer

electrolytes based on poly(ethylene oxide). They prepared polymer

electrolytes films complexed with NiBr2 and ZnCl2 by normal solvent cast

technique and reported thermal and conduction behavior by DSC and ac

conductivity measurement of these polymer electrolytes.

P. Ferloni, A. Buttafava and others107 studied the effect of gamma radiation on

the thermal and conductivity behavior of polymer electrolytes based on PEO

containing LiClO4 as salt. It was observed that irradiated polymer electrolytes

showed improved mechanical and ionic properties compared to that of non-

irradiated polymer electrolytes.

D. R. MacFarlane and M. Forsyth108 studied the mechanical properties of

polyether-plasticizer-salt polymer electrolytes. It was investigated that

increase in concentration of salt leads to decrease in the elastic modulus and

tensile strength.

T. Mimani, K. C. Petal and S. V. Bhat109 studied the effect of MnZnAl2O4

nanoparticles on the ionic and thermal properties of composite solid polymer

electrolyte comprising of poly(ethylene) Glycol (PEG), lithium perchlorate

(LiClO4). Various experimental techniques such as complex impedance

analysis, DSC and X-ray diffraction were used to characterize the resulting

42

complex solid polymer electrolyte systems. It was observed that there were

two regions in the conductivity-temperature relationship, out of which one can

be explained by Arrhenius behavior, while the other region consistent with

VTF. The addition of nanoparticles leads to enhancement of ionic conductivity

due to decrease in the glass transition temperature and degree of crystallinity

of complex polymer electrolytes.

S. Rajendran, M. Savakumar and R. Subadevi110 studied the effect of various

lithium salts on the ionic conductivity of plasticized PVA based solid polymer

electrolytes. X-ray diffraction, FTIR spectroscopy and AC Impedance

spectroscopic studies were employed to characterized the resultant solid

polymer electrolytes. Conductivity against temperature behavior was

explained by employing VTF relation.

M. A. K. L. Dissanyake, I. Albinsson and others111 studied the effect of

concentration and grain size of alumina filler on the enhancement of ionic

conductivity of composite polymer electrolyte (PEO)9LiCF3SO3 + Al2O3. It was

observed that ionic conductivity increased by addition of alumina filler. The

enhancement of ionic conductivity may be attributed to the surface interaction

of ionic species with the groups on the filler surface. There were two maxima

observed in the conductivity-filler relationship which were explained on the

basis of surface interactions.

M. M. E. Jacob, S. R. S. Prabaharan and S. Radhakrishna112 studied the effect

of addition of PEO on the conduction and thermal behavior of PVdF-LiClO4

polymer electrolytes. Chemical compatibility between PVdF and PEO were

performed by employing XRD and DTA. XRD studies were also carried out for

structural characterization of polymer electrolyte. The ac conductivity studies

43

were employed to investigate the ionic conductivity of the system. It was

found that addition of PEO leads to enhancement of ionic conductivity and

thermal stability.

J. Siva Kumar, U. V. Subba Rao and other co-workers113 studied the effect of

composition and temperature on the ionic conductivity of polymer electrolyte

system (PEO + NaClO3). The conductivity of the PEO containing salt was

found much higher compared to PEO without salt. It was investigated by

measurement of transport number that charge transport was due to the

mobility of ion in the system.

A. Subramania, N. T. Kalyana Sundaram and N. Sukumar114 studied the effect

of concentration of lithium salt on the ionic conductivity of micro-porous

polymer electrolyte obtained from PVA-PVC polymer blend films. It was

reported that removal of PVC leads to enhancement of ionic conductivity of

micro-porous polymer electrolyte. X-ray diffraction and SEM analysis were

employed to studies complexation and surface morphology. It was found from

TG/DTA analysis that the resulting micro-porous polymer electrolytes were

thermally stable up to about 277°C.

V. Madhu Mohan, V. V. R. Narasimha Rao and others115 studied the effect of

addition of NaBF4 salt on the ionic conductivity of polymer electrolyte based

on PEO. It was found that ionic conductivity increased while activation energy

decreased with increase in concentration of salt. The transport of charge was

found mainly due to the ions in the polymer electrolytes. The increase in ionic

conductivity was attributed to the increase in the number of ions by

dissociation of salt.

44

A. M. Stephan, N. Muniyandi and other co-workers116 investigated the

influence of polymer blend ratio, plasticizer content and salt concentration on

the ionic conductivity of PVC/PMMA blend polymer electrolyte at various

temperatures. Ionic conductivity of the polymer electrolytes were studied by

employing AC. Impedance spectroscopy. It was found that PVC/PMMA

polymer electrolytes containing 70% plasticizer content showed good ionic

and mechanical properties.

P. Sathya, A. N. Durga Rani and S. Radhakrishna117 reported the effect of

mixed glass former effect on the ionic and electronic conductivities and glass

transition temperature of AgI-Ag2O-V2O5-P2O5 quaternary amorphous solid

electrolyte system. The plots of ionic conductivity observe two double

maxima. The properties of the quaternary system were compared to the

properties of ternary systems AgI-Ag2O-V2O5 and AgI-Ag2O-P2O5.

D. R. MacFarlane, M. Forsyth and others118 reported the effect of plasticizer

on the electrical conductivity and thermal properties of solid polymer

electrolyte systems. It was found that by addition of plasticizer, the ionic

conductivity increased. The enhancement of ionic conductivity of polymer

electrolytes was attributed to the increase in the number of ions and improved

chain flexibility by addition of plasticizer in to polymer electrolytes.

T. Streekanth, M. Jaipal Reddy and U. V. Subba Rao119 studied the effect of

KBrO3 salt on the conducting behavior of ion conducting polymer electrolyte

system. The resulting polymer electrolyte system were characterized by

employing various experimental techniques such as conductivity, differential

scanning calorimetry (DSC) and transference number measurement. The

plots of conductivity against temperature were observed to have two regions.

45

P. Lobitz and H. Fullbier studied120 the effect of composition and temperature

on the transport properties of polymer electrolytes based on block copolymers

of polyethylene oxide containing lithium iodide salt. The transport number of

mobile ions was determined by impedance method. It was observed that

transport numbers shows variation with concentration and temperature.

S. Rajendran, M. Sivakumar and R. Subadevi121 observed the effect of various

lithium salts on the ionic conductivity of solid polymer electrolytes based on

plasticized poly(vinyl alcohol) (PVA). Various experimental techniques such

as X-ray diffraction, FTIR spectroscopy and ac impedance analysis were used

to characterized the resulting polymer electrolyte system. The conductivity

results were explained on the basis of VTF relation.

H. Cheradame, J. F. Le Nest and others122 studied the mechanism of high

ionic conductivity in elastomeric networks comprising of polyether-

polyurethane and alkali metal salts. They reported the effect of temperature,

salt concentrations and network structures on the viscoelastic and ionic

conductivity behavior of the resulting material.

K. Naresh Kumar, U. V. Subba Rao and other co-workers123 studied the effect

of composition and temperature on the conductivity of solid polymer

electrolyte system comprising of poly(vinyl pyrrolidone) (PVP) and sodium

chlorite (NaClO3). The ionic conductivity of the PVP based polymer electrolyte

system containing NaClO3 salt was found much higher at room temperature,

compared to pure PVP.

P. Balaji, V. V. R. N. Rao and others124 studied the electrical properties of solid

polymer electrolytes comprising of poly (vinyl alcohol) (PVA) and various

concentrations of sodium fluoride (NaF) salt. Various experimental techniques

46

such as XRD, FTIR and impedance analysis were employed to examine the

structural properties, complexation of the salt with the polymer and

conductivity respectively of the resulting solid polymer electrolytes. It was

found that dielectric constant increases with increase in temperature and

decreased with the increase in frequency.

G. G. Cameron, M. D. Ingram and K. Sarmouk125 studied the conductivity and

viscosity of polymer electrolytes comprising of plasticized

poly(tetrahydrofuran) and copolymer of ethylene oxide and propylene oxide. It

was shown that conductivity increased while viscosity showed decrease with

plasticizer.

S. Ramesh and M. F. Chai126 investigated the effect of temperature on ionic

conductivity of polymer electrolyte based on high molecular weight poly(vinyl

chloride) (PVC) containing lithium triflate (LiCF3SO3) salt. The ionic

conductivity was measured at various temperatures and it was shown that

conductivity against temperature plots could be explained by Arrhenius

relationship.

N. Kaskhedikar, H. D. Wiemhofer and others127 investigated the effect of salt

concentration and temperature on the ionic conductivity of polymer electrolyte

membrane based on polyphosphazene with oligo(propylene oxide) side

chains. It was found that stable polymer electrolyte membrane can be

obtained by exposing to UV radiation. It was observed that glass transition

temperature increased by radiation and by addition of LiF3SO3 salt.

Impedance spectroscopy was employed to measure the ionic conductivity at

various temperatures.

47

D. Saikia, S. I. Lin and other co-workers128 investigated the influence of

variation in the plasticizer-filler ratio in the polymer electrolyte films. The

structural properties and interaction of various groups in the composite

polymer electrolyte were studied by X-ray diffraction and FTIR studies

respectively. It was found by DSC studies that glass transition temperature

and crystallinity decreases with increase in concentration of SiO2 up to 4 wt%.

SEM studies showed the porous structure of the resulting membrane due to

the presence of silica.

C. S. Ramya, P. C. Angelo and others129 characterized the polymer electrolyte

films of various compositions based on poly(N. vinyl pyrrolidone) (PVP) and

ammonium thiocyanate (NH4SCN). X-ray diffraction analysis was used to

confirm the amorphous nature of the system. It was found by conductivity

analysis that ionic conductivity improved by addition of ammonium

thiocyanate salt up to 20 wt%. The activation energy was investigated from

the admittance plot and found very low for polymer electrolyte containing 20

wt% of salt.

S. Panero, W. Wieczorek and others130 studied the effect of additives on

conductivity behavior of lithium ion conducting polymer electrolyte system

based on PEO-LiX. One of these additives was used to improve lithium ion

transference number while the other additive used to increase ionic

conductivity of the polymer electrolyte system. It was observed that the

resulting polymer electrolyte system exhibit high ionic conductivity.

K. S. Sidhu, S. Chandra and others131 reported the effect of concentration of

CuSCN salt on the characterization of polymer electrolyte based on

poly(ethylene oxide) (PEO). The formation of complexation in the amorphous

48

phase was confirmed by differential scanning calorimetry and X-ray diffraction

analysis. It was found by ac impedance analysis that the resulting polymer

complexes exhibit higher ionic conductivity.

G. P. Pandey, S. A. Hashmi and R. C. Agrawal132 reported the influence of

SiO2 content on the conductivity of polymer electrolyte based on poly(ethylene

oxide) (PEO) containing NH4HSO4 salt. Various experimental techniques such

as electrical conductivity, X-ray diffraction analysis, Scanning electron

microscopy and Fourier transform infra-red spectroscopy were employed to

characterize the polymer-salt complexes. It was found that complex polymer

electrolyte system containing silica content of 5 wt% showed 2.5x10-4 S/cm

ionic conductivity at room temperature.

S. Pantaloni, M. Andrei and others133 studied the ionic conductivity, lithium ion

transport numbers and electrochemical properties of polymer electrolytes

based on ethoxy-ethoxy-ethoxy-vinyl ether containing various lithium salts

such as LiClO4 and LiBF4. It was found that conductivity of the resulting

system was three orders higher compared to that of polyethylene oxide based

polymer.

S. H. Chung, E. Plichta and other co-workers134 investigated the enhancement

of ionic conductivity by addition of inorganic oxide in to the polymer electrolyte

system comprised of poly(ethylene oxide) (PEO) complexed with LiClO4.

Various experimental techniques such as electrochemical and Li nuclear

magnetic resonance spectroscopy (NMR) methods were used to study the

desired properties of the resulting polymer electrolyte systems. It was found

that addition of inorganic oxides such as TiO2 increases ionic conductivity.

49

T. Mani, R. Mani and J. R. Stevens135 studied the physical characteristics of

the polymer electrolyte blend based on poly(propylene glycol) (PPG)-

poly(methyl methacrylate) (PMMA)-lithium triflate (LiCF3SO3). It was reported

that PPG molecular weight, concentration of salt and PMMA content

influences physical characteristics of the polymer blend electrolytes. Phase

separation of blend polymer electrolyte was confirmed by SEM studies.

S. I. Moon, W. S. Kim and others136 investigated the ionic conductivity of

cross-linked polymer electrolytes comprising of oligo(ethylene glycol)

dimethacrylates (OEGDMA), polyethylene oxide as polymer matrix, lithium

perchlorate salt, ethylene carbonate and propylene carbonate as a mixed

plasticizer. It was found that ionic conductivity exhibited enhancement with

increasing content of repeating unit of ethylene oxide in the OEGDMA.

K. M. Nairn, M. Forsyth and other co-workers137 studied the effect of solvent

vapours such as DMF, acetonitrile or water and preheated ceramic on ionic

conductivity of composite polymer electrolytes of lithium aluminium titanium

phosphate and polyetherurethane polymer electrolyte complexed with lithium

triflate salt. It was reported that by exposing to solvent vapours such as

acetonitrile, the resulting polymer electrolytes exhibited much increase in ionic

conductivity compared to polymer electrolyte sample containing plasticizer. It

was observed that by addition of preheated ceramic particles, the conductivity

of the sample electrolyte exhibited decrease while the adhesion at the

interface of the polymer showed improvement.

H. Eliasson, I. Albinsson and B. E. Mellander138 reported the effect of

AgCF3SO3 salt on the ionic conductivity of polymer electrolyte based on

poly(propylene glycol). It was found that the polymer electrolyte containing 6

50

mol% AgCF3SO3 salt shows highest conductivity at 70°C. The plot of

equivalent conductivity against AgCF3SO3 salt shows a minimum and a

maximum similar to that obtained in other polymer electrolytes based on

poly(propylene glycol) containing other salts.

S. Guinot, J. F. Fauvarque and others139 studied the conductivity of solid

polymer electrolyte based on PEO containing potassium hydroxide and water.

Several experimental techniques such as DSC, TGA and X-ray diffraction

were employed to characterize the resulting solid polymer electrolyte system.

The variation of conductivity with temperature was investigated by using ac

impedance technique.

S. H. Chung, Y. Onada and others140 reported the effect of addition of

plasticizer such as propylene carbonate on the enhancement of ionic

conductivity of lithium monoconducting polymer electrolyte based on maleic

anhydride-styrene copolymer. It was observed that addition of propylene

carbonate as plasticizer, facilitate the transport of ions through the resulting

materials. The enhancement of ionic conductivity by addition of plasticizer

may be due to weakening of ion-polymer interactions in polymer electrolytes.

J. Kang, S. Fang and other co-workers141 reported the effect of ammonium

iodides on the conductivity of PEO-based polymer electrolyte. It was found

that by addition of ammonium iodide salt in to polymer electrolyte, the

crystallinity decreases. It was also investigated that ionic conductivity exhibit

improvement by incorporation of plasticizer in to the system.

M. watanabe, K. Sanui and N. ogata142 studied the relationship between

structure and conductivity of polymer electrolyte comprising of

poly[dimethylsiloxane(ethylene oxide) and lithium perchlorate. These polymer

51

electrolyte systems exhibit room temperature ionic conductivity of about 10-6 S

cm-1. it was shown that poly(dimethylsiloxane) did not contribute to the ionic

mobility while segmental motion of poly(ethylene oxide) showed contribution

to the ionic conductivity of the resulting polymer electrolyte system.

N. K. Chung, Y. D. Kwon and Kim143 investigated thermal, mechanical and

electrochemical properties of poly(vinyledenefluoride)-co-

hexafluoropropylene/ poly(ethylene glycol) hybrid polymer electrolytes. It was

found that extraction of PEG play significant role in change of structure and

pore size thereby thermal, mechanical and electrochemical properties of the

polymer electrolytes may be influenced.

G. Girish Kumar and N. Munichandraiah144 studied the influence of

incorporation of plasticizers such as ethylene carbonate and propylene

carbonate on the ionic conductivity of poly(ethylene oxide)-based solid

polymer electrolytes containing magnesium triflate salt. Various experimental

techniques such as ac impedance, measurement, differential scanning

calorimetry were carried out to characterize the resulting solid polymer

electrolyte system. The ionic conductivity showed enhancement from 10-6 S

cm-1 to 10-5 S cm-1 by incorporation of plasticizer. The increase in ionic

conductivity with temperature was explained by VTF relationship.

M. L. Kaplan, E. A. Reitman and R. J. Cava145 reported the influence of

incorporation of salt, soluble and insoluble additives on the improvement of

ionic conductivity of the sample electrolytes. They prepared and evaluated

various complexes of poly(vinyl acetate) and crown ether containing polymer

with metal ions. The maximum conductivity of 10-3 S cm-1 was obtained by

using complex sample of polymeric crown ether with poly(vinylene carbonate).

52

It was shown that ionic conductivity of silver oxide with poly(ethylene oxide) as

host polymer was 100 times better as compared to the complex of mercury-

poly(ethylene oxide). It was concluded that ionic conductivity was not

influenced by incorporation of larger surface area materials such as carbon

black and silica gel in to the polymer electrolyte samples.

M. Forsyth, J. H. Strange and others146 reported the effect of plasticizer and

salt content on the conductivity of solid polymer electrolyte system based on

poly(ethylene oxide-co-propylene oxide) complexed either with LiCF3SO3 or

LiClO4 salt. The ionic mobility showed enhancement by incorporation of

plasticizers such as propylene carbonate, tetraglyme or dimethyl formamide in

to the polymer electrolytes. The ionic conductivity and thermal stability of the

solid polymer electrolytes showed best compromise, on optimizing the

concentration of plasticizer and salt.

S. Sreepathi Rao, K. V. Satyanarayana and U. V. Subba RaO147 observed the

ionic conductivity of the conducting polymer electrolyte system comprising of

poly(ethylene oxide) (PEO) host polymer complexed with AgNO3 salt. The

highest electrical conductivity was reported for the sample with composition

80:20. XRD studies were carried out to confirm the salvation of Ag+ with the

host polymer PEO.

J. F. Fauvarque, J. F. Penneau and others148 studied the hydrated and

anhydrous alkaline solid polymer electrolyte system based on poly(ethylene

oxide) host polymer of various compositions. The ionic conductivity and

thermal stability of the resulting samples were studied and the influence of

temperature on the ionic conductivity was discussed. The highest ionic

conductivity of 10-3 was reported for the resulting polymer electrolyte sample.

53

S. Rajendran, M. Ramesh Prabhu and M. Usha Rani149 reported the effect of

various lithium salts on ionic conductivity of poly(vinyl chloride)/poly(ethyl

methacrylate)-based complexed polymer blend electrolytes. The resulting

blend polymer electrolytes were subjected to characterization by various

experimental methods such as ionic conductivity, X-ray diffraction, Fourier

transform infrared spectroscopy and thermogravimetric-thermal analysis. It

was concluded that these polymer electrolyte samples were stable up to

254°C and LiBF4 containing poly electrolytes exhibit highest ionic conductivity.

D. Y. Kim, J. K. Kim and C. Y. Kim150 presented the effect of lithium

perchlorate on the ionic conductivity of polymer electrolyte based on ethylene

oxide-phosphate copolymer. The glass transition temperature of the sample

was raised from -61°C to -48°C by mixing with salt in the mole ratio of 60:1. it

was found that there are no significant variation in the glass transition

temperature by further increase in the weight of incorporated salt. There was

no more enhancement occurs in the ionic conductivity by further incorporation

of salt beyond the 60:1 mole ratio of polymer and salt.

A. Manual Stephan, J. Wilson and others151 studied the effect of incorporation

of nanofiller on the electrical conductivity behavior of composite polymer

electrolytes comprising of poly(vinyledene fluoride-hexafluoropropylene),

aluminium hydroxide and LiN(CF3SO2)2 salt. The resulting composite polymer

electrolyte was subjected to characterization by impedance spectroscopy,

transport number and X-ray diffraction studies. The ionic conductivity of the

sample electrolytes enhance by incorporation of nanofiller.

S. Ramesh and A. K. Arof152 reported the influence of salts and plasticizers on

the ionic conductivity of polymer electrolyte comprising of poly(vinyl chloride),

54

LiCF3SO3 and LiBF4 salts and plasticizer ethylene carbonate. Various

experimental methods were employed to characterize the sample such as

complex impedance, complex admittance and complex electric modulus. The

improved ionic conductivity was attributed to the incorporated plasticizer.

N. S. Mohamed and A. K. Arof153 observed the influence of incorporation of

LiCF3SO3 salt and plasticizer ethylene carbonate (EC) on the ionic

conductivity of PVdF-based polymer electrolytes. It was found that the ionic

conductivity exhibit much enhancement by incorporation of trifluoromethane

sulfone salt compared to addition of ethylene carbonate plasticizer. They

studied the conductive behavior of the sample films over a wide range of

temperature (-100 to 100°C).

A. Manuel Stephan, R. Nimma Elizabeth and others154 studied the effect of

incorporation of plasticizer and inorganic filler on the ionic conductivity and

stability of polymer electrolytes comprising of poly(vinyl chloride)

(PVC)/poly(methylmethacrylate) (PMMA) blends containing LiN(CF3SO3) salt

and combination of ethylene carbonate and propylene carbonate plasticizers.

The prepared films were subjected to ac impedance measurement and

TG/DTA analysis. The conductive behavior of the prepared polymer

electrolyte films as a function of temperature was investigated.

E. Morales and J. L. Acosta155 presented the conductive behavior of the

composite polymer electrolyte systems with composition of poly(ethylene

oxide) blend with perfluorinated polyphosphazene complexed with LiAlO2 as

ceramic filler. The ionic conductivity of the prepared polymer electrolytes was

evaluated by employing complex ac impedance analysis at various

concentrations of salt and at various temperatures. It was found that ionic

55

conductivity of the sample films showed enhancement at higher concentration

of ceramic filler while at lower concentration the ionic conductivity decreases.

Y. W. Chen-yang, C. C. Chen and others156 observed ionic conductivity and

mechanical properties of the composite polymer electrolytes comprising of

polyacrylonitrile (PAN), LiClO4 salt and Al2O3. The ionic conductivity and

mechanical properties were measured by optimizing the concentration of

Al2O3 and LiClO4 in the resulting composite polymer electrolyte system. The

effects of incorporated ceramic fillers on the conduction mechanism were also

investigated.

M. Hema, H. Nithya and others157 studied the effect of NH4Br salt on the

conductive behavior of polymer electrolyte based on PVA. Various

experimental techniques were employed to characterize the resulting polymer

electrolytes such as X-ray diffraction and Fourier transform infrared

spectroscopy (FTIR). The ionic conductivity of the sample films were

improved by optimizing the concentration of salt. The conductive behavior of

the films was explained on the basis of Arrhenius law.

R. Kumar, I. Baskaran and other co-workers158 reported the influence of

incorporation of MgO nanoparticle on the behavior of composite polymer

electrolyte. The polymer electrolytes were characterize by using various

experimental methods such as X-ray diffraction studies, differential scanning

calorimetry, scanning electron microscopy and ac impedance analysis. The

ionic conductivity was found to increase by incorporation of ceramic fillers.

The enhancement of ionic conductivity by addition of filler may be due to the

decrease in glass transition temperature.

56

E. Morales and J. L. Acosta159 observed the influence of chemical nature of

lithium salts such as lithium perchlorate (LiClO4), lithium

triflouromethanesulfonate (LiCF3SO3), lithium hexafluorophosphate (LiPF6) on

the ionic conductivity and thermal behavior at various temperature, of solid

polymer electrolytes based on poly(methylalkoxysiloxane). It was found that

the behavior of the prepared polymer electrolytes attributed to the chemical

nature of the incorporated lithium salts. The presence of amorphous region in

the sample films was confirmed from the results.

G. B. Appetecchi and S. Passereni160 reported the conductive behavior of

composite lithium polymer electrolyte based on PEO-carbon. The conductive

and mechanical behavior of the prepared sample materials were found

excellent.

S. Rajendran, R. Kannan and O. Mahendran161 observed the variation of ionic

conductivity of hybrid polymer electrolyte system comprising of

poly(methylmethacrylate), poly(ethylene oxide), LiX (X= BF-4, CF3SO3, ClO-

4)

salts and dimethyl phthalate (DMP). It was found that polymer electrolyte

comprising of PMMA-PEO blend polymer exhibit excellent behavior and

proved very promising material for the lithium battery.

W. Wieczorek, Z. Florianczyk and other co-workers162 investigated the ionic

conductivity and phase structure of the composite polymer electrolyte based

on poly(ethylene oxide) blended with methacrylic monomers and containing

inorganic and organic additives. They studied the behavior of polymer

electrolytes containing aluminas, ceramics and low molecular weight

plasticizers.

57

Z. Florianczyk, M. Wasiucionek and others163 studied the effect of method of

preparation and nature of salts on the ionic conductivity of blend polymer

electrolyte system based on poly(ethylene oxide)-poly(methyl methacrylate)

blends complexed with either NaI, LiI, LiBF4 or LiClO4. It was found that the

prepared polymer samples were stable up to about 60°C. The presence of

amorphous region in the sample was confirmed by differential scanning

calorimetry. It was suggested that the low glass transition temperature of the

samples might be due the incorporated plasticizer. The ionic conductivity of

these complexed polymer electrolytes exceeds 10-5 S cm-1.

E. M. Woo, S. C. Lee and others164 carried out the miscibility studies of

poly(ethylene oxide)-poly(phenyl methacrylate) system. Various experimental

methods such as differential scanning calorimetry, scanning electron

microscopy and infrared spectroscopy were employed to characterize and

demonstrate the miscibility of the PEO-PPhMA sample system. It was

investigated from the glass transition temperature behavior that weak

interactions are involved between the pairs. The existence of interaction was

also confirmed by the Fourier transform infrared spectroscopy.

T. Uma, T. Mahalingam and U. Stimming165 studied ionic conductivity of the

polymer electrolytes based on poly(vinyl chloride) containing lithium sulfate as

salt and dibutylphthalate as plasticizer at various temperature. Various

experimental techniques such as X-ray diffraction, Fourier transform infrared,

thermal analysis and scanning electron microscopy were used to characterize

the resulting solid polymer electrolyte system. It was found that the effect of

temperature on ionic conductivity follows the Vogel-Tammann-Fulcher

relation.

58

S. Rajendran, M. Nirmala and others166 reported the properties of PVA-PVdF

based solid polymer electrolytes consists of PVA, PVdF and LiClO4. XRD and

FTIR analysis were used to confirm the complex formation in the polymer

electrolyte samples. The ionic conductivity of the polymer electrolyte was

evaluated by subjecting the sample to conductivity. It was found that the

polymer electrolyte system containing 10% of salt exhibit maximum ionic

conductivity. The polymer electrolytes of maximum ionic conductivity were

subjected to thermal stability studies.

R. H. Y. Subban and A. K. Arof167 reported the influence of addition of

plasticizer on the behavior of polymer electrolytes comprised of PVC-

LiCF3SO3-DMF. It was observed that the interactions were involved between

lithium ion and chlorine atoms in the PVC-LiCF3SO3 polymer electrolyte

system. The interaction of lithium ion with oxygen and nitrogen atom was

found in the sample of LiCF3SO3-DMF. The ionic conductivity of the resulting

system showed enhancement due to the presence of free ions and ion pairs

in the PVC-LiCF3SO3-DMF system.

Z. Florjanczyk, F. Krok and others168 studied the polymer electrolyte system

comprising of acrylonitrile, butyl acrylate and lithium

bis(triflouromethanesulfone)imide. These polymer electrolytes were

characterized by employing various experimental techniques such as DSC, IR

methods and impedance spectroscopy. The properties of the new system and

poly(ethylene oxide)-LiTFSI were compared with each other.

M. Jaipal reddy, U. V. Subba Rao and other co-workers169 reported crystallinity

and ionic conductivity of the samples comprising of PEO, LiClO4 and iron

oxide. It was found that degree of crystallinity decreased by addition of LiClO4

59

salt and Fe3O4 nanoparticles. It was found that incorporation of Fe3O4 in the

presence of LiClO4 resulting in improved miscibility and decrease in the

degree of crystallinity of PEO. The maximum ionic conductivity were found for

polymer electrolyte system containing 10 wt% Fe3O4, beyond this

concentration of iron oxide, the ionic conductivity showed decrease due to the

aggregation of Fe3O4 in the sample.

60

CHAPTER # 3

3.1 Materials

Poly(vinyl chloride) (PVC, average mol. wt. 1.5 x 105), poly(methyl

methacrylate) (PMMA, average mol. wt. 3.5 x 105) and poly(ethylene oxide)

(PEO, average mol. wt. 1.5 x 105) (Aldrich, USA) which were dried at 100ºC

for 12 h were used in the present study. The plasticizers ethylene carbonate

(EC), propylene carbonate (PC) (E. Merck, Germany) and dibutyl phthalate

(DBP, Aldrich, USA) were used as such without any further purification. The

lithium salts LiBF4 (Aldrich, USA) were kept under vacuum at 70ºC for 24 h

before use. Special grade tetrahydrofuran (THF, E. Merck, Germany) was

used as received. The inorganic filler ZrO2 powder [zirconium (IV) oxide

particle of size 20.5 µm], fumed silica (11 nm size, Cabo-sil) were used.

3.2 Preparation of PVC-based Solid Polymer Electrolyte System

Two types of PVC based solid polymer electrolyte systems were prepared.

A. Preparation of pure PVC based polymer electrolyte systems

In this preparation of pure PVC polymer electrolyte systems are given.

B. Preparation of PVC-blend polymer electrolyte systems

We have also prepared PVC-blend polymer electrolyte systems with other

polymers i.e. PMMA and PEO.

Different samples of various compositions of solid polymer electrolyte systems

(pure PVC systems and PVC blend system) were prepared by using solution

cast technique.

EXPERIMENTAL

61

A. Preparation of pure PVC-based Solid Polymer Electrolyte Systems

Solid polymer electrolytes systems of various compositions were prepared by

using solution cast technique. PVC was dried under vacuum for one day at

100°C temperature. Tetrahydrofuran was distilled. Alkali metal salts (LiClO4,

LiClO3, LiBF4, Li2SO4 and NaClO4) were dried for 48 h at 70°C under vacuum.

EC and PC were used without any further purification. Inorganic fillers (ZnO,

TiO2, Al2O3 and ZrO2) were also used without any further purification.

5 wt% solutions of PVC and PMMA in tetrahydrofuran were prepared. The

resulting mixtures were stirred for about 12 h by magnetic stirrer, so that

homogeneous solutions were obtained. The solutions of various compositions

were poured in to the identical Teflon moulds and allowed to evaporate off the

excess solvent for more than three weeks in an evacuated desiccator at room

temperatures. After partial evaporation of solvent, mechanically stable free standing

thin solid polymer electrolyte films were obtained. The resulting thin films were

further dried for 48 h in vacuum oven to remove any remaining trace of solvent.

B. Preparation of PVC-Blend Solid Polymer Electrolyte Systems

Two types of PVC based polymer blend electrolyte systems were prepared.

a. Preparation of PVC-PMMA Blend Solid Polymer Electrolyte Systems

b. Preparation of PVC-PEO Blend Solid Polymer Electrolyte Systems

Both PVC-PMMA and PVC-PEO blend polymer electrolyte systems of various

compositions were prepared by dissolving appropriate quantities of PVC,

PMMA, PEO, salts (LiClO4, LiClO3, LiBF4, Li2SO4 and NaClO4) and inorganic

fillers (ZnO, TiO2, Al2O3 and ZrO2) in predistilled THF solvent. The resulting

solutions of various compositions were magnetically stirred at room

temperature for about 12 h to obtain homogeneous solutions and after stirring

at room temperature these solutions were further stirred at 40°C for about 4 h.

By stirring, the components of the solutions were completely mixed and then

films of desired compositions and thickness (150 μm) were obtained by

casting the films on polypropylene dishes. The solvent of the films were

62

allowed to evaporate at room temperature. After evaporation at room

temperature, the films were dried further at 303 K temperature in vacuum

oven to ensure complete evaporation of solvent. The dried films were stored

inside evacuated dry container.

Stock solution of various systems for measurement of viscosity were prepared

by dissolving weighted amount of polymer in THF solvent and ternary

solutions of different systems were obtained by mixing of two different

polymer solutions in various weight ratios. The stock solution of each system

was diluted to various lower concentrations by adding appropriate aliquots of

solvent. The PVC solution was prepared by slight heating and continues

stirring in order to facilitate the dissolution of PVC.

Various types of samples of solid polymer electrolyte (pure PVC based and

PVC blend) were obtained by mixing appropriate amount of components.

3.3.1. Samples of Pure PVC based Solid Polymer Electrolyte Systems

Three different types of pure PVC based solid polymer electrolyte systems

were prepared.

3.2.1.1 Samples of pure PVC based polymer electrolyte systems without plasticizer

o PVC-NaClO4 solid polymer electrolyte system (a) PVC-NaClO4 (95-

5) (b) PVC-NaClO4 (90-10), (c) PVC-NaClO4 (85-15)

o PVC-KClO3 solid polymer electrolyte system (a) PVC-KClO3 (94-6)

(b) PVC-KClO3 (88-12) (c) PVC-KClO3 (82-18)

o PVC-Li2SO4 solid polymer electrolyte system (a) PVC-Li2SO4 (95-5) (b)

PVC-Li2SO4 (90-10) (c) PVC-Li2SO4 (85-15) (d) PVC-Li2SO4 (80-20)

o PVC-LiClO4-LiBF4 (70-15-15) solid polymer electrolyte system

3.2.1.2 Samples of pure PVC based polymer electrolyte systems with

plasticizer o PVC-LiClO4-EC solid polymer electrolyte system (a) PVC-LiClO4-EC

(65-5-30) (b) PVC-LiClO4-EC (40-10-50) (c) PVC-LiClO4-EC (30-15-55)

o PVC-KBrO3-EC solid polymer electrolyte system (a) PVC-KBrO3-EC

(70-5-25) (b) PVC-KBrO3-EC (65-10-25) (c) PVC-KBrO3-EC (60-15-25)

o PVC-KBrO3-EC solid polymer electrolyte system (a) Plasticized

PVC-KBrO3 (95-5) (b) Plasticized PVC-KBrO3 (85:15) (c)

Plasticized PVC-KBrO3 (75:25)

63

o PVC-Li2SO4-EC solid polymer electrolyte system (a) PVC-Li2SO4-

EC (10-10-80) (b) PVC-Li2SO4-EC (20-10-70) (c) PVC-Li2SO4-EC

(30-10-60) (d) PVC-Li2SO4-EC (40-10-50)

o PVC-LiClO4-EC-PC solid polymer electrolyte system (a) PVC-

LiClO4-EC-PC (30-30-5-35) (b) PVC-LiClO4-EC-PC (30-28-10-32)

(c) PVC-LiClO4-EC-PC (30-25-15-30)

o PVC-EC-NaClO4 (30-60-10) solid polymer electrolyte system

3.2.1.3 Samples of pure PVC based polymer electrolyte systems containing inorganic filler

o PVC-LiClO4-ZnO (60-15-25) solid polymer electrolyte system

o PVC-LiClO4-ZrO2-EC solid polymer electrolyte system (a) PVC-

LiClO4-ZrO2-EC (30-5-0-65) (b) PVC-LiClO4-ZrO2-EC (30-5-5-60)

(c) PVC-LiClO4-ZrO2-EC (30-5-10-55) (d) PVC-LiClO4-ZrO2-EC (30-

5-15-50) (e) PVC-LiClO4-ZrO2-EC (30-5-20-45)

o PVC-LiClO4-EC-TiO2 solid polymer electrolyte system (a) PVC-

LiClO4-EC-TiO2 (20-10-65-5) (b) PVC-LiClO4-EC-TiO2 (20-10-60-

10) (c) PVC-LiClO4-EC-TiO2 (20-10-55-15) (d) PVC-LiClO4-EC-TiO2

(20-10-50-20)

o PVC-Li2SO4-ZrO2-EC solid polymer electrolyte system

o PVC-Li2SO4-DBP-ZrO2 solid polymer electrolyte system (a) PVC-

Li2SO4-DBP-ZrO2 (0) (b) PVC-Li2SO4-DBP-ZrO2 (6) (c) PVC-

Li2SO4-DBP-ZrO2 (12) (d) PVC-Li2SO4-DBP-ZrO2 (18)

3.3.2. Samples of PVC-Blend Polymer Electrolyte Systems

Two different types of PVC based polymer blend electrolyte systems (PVC-

PMMA and PVC-PEO) were prepared by mixing PMMA and PEO with PVC.

3.2.2.1 Samples of PVC-PMMA blend polymer electrolyte systems

Three different types of PVC-PMMA blend polymer blend electrolyte systems

were prepared. The details are given below.

3.2.2.1(a) Samples of PVC-PMMA blend polymer electrolyte system without plasticizer

o PVC-PMMA-LiClO4 solid polymer electrolyte system (a) PVC-

PMMA-LiClO4 (60-30-10) (b) PVC-PMMA-LiClO4 (55-25-20) (c)

PVC-PMMA-LiClO4 (50-20-30) (d) PVC-PMMA-LiClO4 (45-15-40)

64

o PVC-PMMA-NaClO4 solid polymer electrolyte system (a) PVC-

PMMA-NaClO4 (70-25-5) (b) PVC-PMMA-NaClO4 (67-23-10) (c)

PVC-PMMA-NaClO4 (65-20-15)

o PVC-PMMA-NaClO4 solid polymer electrolyte system (a) PVC-

PMMA-NaClO4 (60:35:5) (b) PVC-PMMA-NaClO4 (60:30:10) (c)

PVC-PMMA-NaClO4 (60:25:15)

o PVC-PMMA-Li2SO4 (60-30-10) solid polymer electrolyte system

o PVC-PMMA-LiBF4 (60-30-10) solid polymer electrolyte system

3.2.2.1(b) Samples of PVC-PMMA blend polymer electrolyte system with plasticizer

o PVC-PMMA-LiClO4-EC solid polymer electrolyte system (a) PVC-

PMMA-LiClO4-EC (20-10-5-65) (b) PVC-PMMA-LiClO4-EC (20-10-

10-60) (c) PVC-PMMA-LiClO4-EC (20-10-15-55) (d) PVC-PMMA-

LiClO4-EC (20-10-20-50)

o PVC-PMMA-LiClO4-PC solid polymer electrolyte system (a) PVC-

PMMA-LiClO4-PC (42-22-4-50) (b) PVC-PMMA-LiClO4-PC (26-18-

6-50) (c) PVC-PMMA-LiClO4-PC (28-14-8-50) (d) PVC-PMMA-

LiClO4-PC (30-10-10-50)

o PVC-PMMA-LiClO4-EC-PC solid polymer electrolyte system (a)

PVC-PMMA-LiClO4-EC-PC (30-0-20-10-40) (b) PVC-PMMA-LiClO4-

EC-PC (20-10-20-10-40) (c) PVC-PMMA-LiClO4-EC-PC (10-20-20-

10-40) (d) PVC-PMMA-LiClO4-EC-PC (5-25-20-10-40) (e) PVC-

PMMA-LiClO4-EC-PC (0-30-20-10-40)

o PVC-PMMA-EC-Li2SO4 (20-10-60-10) solid polymer electrolyte system

o PVC-PMMA-NaClO4-EC (20-5-10-65) solid polymer electrolyte system

o PVC-PMMA-EC-LiClO3 (20-10-60-10) solid polymer electrolyte system

3.2.2.1(c) Samples of PVC-PMMA blend polymer electrolyte system containing inorganic filler

o PVC-PMMA-Li2SO4-ZrO2-EC solid polymer electrolyte system

o PVC-PMMA-LiClO4-TiO2-EC solid polymer electrolytes with different

TiO2 concentrations

o PVC-PMMA-NaClO4-EC (20-5-10-65) solid polymer electrolyte

system with different TiO2 concentrations

o PVC-PMMA-LiClO4-EC (20-5-10-65) polymer electrolyte system

with different Al2O3 concentrations

65

o PVC-PMMA-NaClO4-EC (20-5-10-65) polymer electrolyte system

with different Al2O3 concentrations

o PVC-PMMA-LiClO4-EC (20-5-10-65) polymer electrolyte system

with different ZnO concentrations

o PVC-PMMA-NaClO4-EC (20-5-10-65) polymer electrolyte system

with different ZnO concentrations

o (a) PVC-PMMA-Li2SO4-DBP-ZrO2 (15:15:10:60:0) (b) PVC-PMMA-

Li2SO4-DBP-ZrO2 (15:15:10:50:10) (c) PVC-PMMA-Li2SO4-DBP-ZrO2

(15-15-10-45-15) (d) PVC-PMMA-Li2SO4-DBP-ZrO2 (15:15:10:40:20)

3.2.2.2 Preparation of PVC-PEO blend polymer electrolyte systems

Two different types of PVC-PEO blend polymer electrolyte systems (PVC-

PEO blend with plasticizer and PVC-PEO blend containing inorganic fillers)

were prepared

3.2.2.2(a) Samples of PVC-PEO blend polymer electrolyte system with & without plasticizer

o PVC-PEO-LiX (60-30-10) (X=ClO4-, BF4

-) solid polymer electrolyte

system

o PVC-PEO-LiClO4-EC solid polymer electrolyte system (a) PVC-

PEO-LiClO4-EC (30-15-5-50) (b) PVC-PEO-LiClO4-EC (30-10-10-

50) (c) PVC-PEO-LiClO4-EC (30-5-15-50)

o PVC-PEO:LiClO4 solid polymer electrolyte system (a) PVC-

PEO:LiClO4 (75:25) PVC-PEO:LiClO4 (80:20) (c) PVC-PEO:LiClO4

(85:15) (d) PVC-PEO:LiClO4 (90:10)

o PVC-PEO-LiBF4 (60-30-10)

3.2.2.2(b) Samples of PVC-PEO blend polymer electrolyte system containing inorganic filler

o PVC-PEO-LiClO4-TiO2 (50-30-10-10) solid polymer electrolyte system

o PVC-PEO-LiClO4-ZnO (50-30-10-10) solid polymer electrolyte system

o PVC-PEO-LiClO4-Al2O3 (50-30-10-10) polymer electrolyte system

o PVC-PEO-LiClO4-TiO2-EC (20-10-10-10-50) solid polymer electrolyte

system

o PVC-PEO-LiClO4-ZnO-EC (20-10-10-10-50) solid polymer electrolyte

system

o PVC-PEO-LiClO4-Al2O3-EC (20-10-10-10-50) solid polymer electrolyte

system

66

3.3 Sample Characterization

The prepared samples of solid polymer electrolyte systems were subjected to

a.c. impedance measurements at various temperatures. Conductivity of

polymer films was evaluated from impedance and admittance data. The

impedance and admittance data of these samples were obtained by using

LCR HITESTER ANALYZER, MODEL 3522-50 OF HIOKI, JAPAN. The

polymer electrolyte samples were cut into pieces with diameter of about 15

mm. The sample films of solid polymer electrolyte were sandwiched between

two polished stainless steel disk electrodes of diameter 10mm which acted as

blocking electrode for ions. The electrodes with sample were sealed in an air

tight container. The impedance and admittance data of these samples were

measured. The study was carried out in the frequency range of 1 mHz to 100

Khz. The temperature dependent conductivity of these samples was

performed at 5ºC intervals in the temperature range of 20ºC to 70ºC. For each

electrolyte three or more measurements were made.

Thermogravimetric analysis was carried out in order to evaluate the thermal

stability of the solid polymer electrolyte films in terms of percentage weight

loss. The films were subjected to thermogravimetry and differential thermal

analysis (TG/DTA) using PerkinElmer (pyres diamond) TG/DTA with a heating

rate of 10ºC/min in argon atmosphere and are discussed. The samples of

various compositions were heated from 5ºC to 250ºC. Thermogravimetric

analysis was carried out for thermal stability of the solid polymer electrolyte

system. The polymer electrolyte samples were subjected to phase analysis at

room temperature using X-ray diffractometer (XRD) [Bruker (D-8 Advance)].

67

Mechanical properties of the various polymer systems of different

compositions were measured by using an instron universal testing machine

(model 4202).

The thickness of all pieces of test material was almost same i.e. 2-3mm. The

pieces of the sample materials were designed according to ASTM

designation. Before testing, each sample was examined visually and no pores

were found in any sample of the test material. Crosshead speeds of 5mm/min

for all test samples of various compositions were maintained. All these tests,

of all the samples were carried out at room temperature. The reported data

were averages of at least 3 measurements.

Scanning electron microscopy was used to investigate the morphology of the

polymer electrolyte samples. The sample films were coated with gold after

fracturing at very low temperature using microtome. These sample films of

polymer electrolyte of various compositions were examined at 30 kV

accelerating voltage and 30° tilt angle using Japan Jeol,s SEM instrument

model JSM-6300. The plasticizers were removed from the sample films

without any change in their morphology by freeze drying. The sample films

were mounted in freeze dryer equipment after being quenched in liquid

nitrogen for 20 minutes and dried for 24 h under the pressure of 80 μHg.

The viscosity measurements were performed at room temperature using

Ubbelohde viscometer. The temperature was measured by thermometer.

Efflux time was measured for each sample by the serial dilution technique.

The specific viscosity, ηsp was calculated at different concentrations, from the

efflux time measurements.

68

CHAPTER # 4

CONDUCTANCE STUDIES

4.1 Conductance Studies of Pure PVC based Polymer Electrolyte

Systems

Three different types of pure PVC based polymer electrolyte systems

(systems without plasticizer, systems with plasticizer and systems containing

inorganic fillers) have been studied.

4.1.1 Conductance Studies of Pure PVC based Polymer Electrolyte

Systems without Plasticizer

Fig. 1.1 shows the effect of temperature on conductivity of PVC-NaClO4

polymer electrolyte system. These solid polymer electrolyte films have been

prepared using PVC polymer, NaClO4 salt, employing solvent casting method.

In order to understand the mechanism of conduction through polymer

electrolyte systems, the conductivity has been studied as a function of

temperature. It has been observed that with increase in temperature, ionic

conductivity also increases for all compositions but these polymer electrolytes

do not show any sudden change in conductivity with change in temperature.

Absence of any sudden change in conductivity with temperature shows that

these polymer electrolytes exhibit amorphous structure [170]. The continuous

increase in conductivity with temperature may be due to the increased

segmental motion of polymer chains caused by decrease in viscosity with

increase in temperature [171].

RESULTS AND DISCUSSION

69

It has been found that conductivity values shows enhancement with increase

in concentration of NaClO4 salt and reaches to its maximum value for the

system containing 15 wt% of NaClO4 salt. The maximum room temperature

conductivity is found to be 1.38 x 10-3 S cm-1 for PVC-NaClO4 (85-15) polymer

electrolyte system, while the ionic conductivity value of pure PVC is found to

be 3.1 x 10-5 S cm-1 [172].

These solid polymer electrolytes exhibit very low values of activation energy,

calculated from the conductivity plots which are shown in table 1.1. The low

values of activation energy may be due to the absence of crystallinity in

polymer electrolytes and so the mobility of sodium ion through polymer matrix

is facilitated [173]. Presence of amorphous phase causes increase in free

volume by increase in temperature which facilitates free motion of charge

carrier species into these free volumes, thereby increase in conductivity.

Fig. 1.2(a) shows variation of ionic conductivity with temperature for various

compositions of PVC-KClO3 complexes. It can be seen that variation of ionic

conductivity can be explained on the basis of Arrhenius relation. It has been

observed that conductivity values increases with temperature and followed

Arrhenius relation with two regions (region-I and region-II) with different

activation energies for all samples of various compositions. The maximum

ionic conductivity at room temperature has found to be 7.94 x 10-6 S cm-1 for

PVC-KClO3 (82-18) solid electrolyte system.

It is shown that all these polymer electrolyte films exhibit amorphous structure

because no abrupt variation of ionic conductivity occurs with temperature but all

samples shows smooth variation [174]. The improvement in ionic conductivity

with temperature can be explained on basis of the fact that when temperature is

70

increased then viscosity decreases which results in improved polymer chain

flexibility thereby enhanced ionic conductivity of the complex polymer electrolyte

films [175]. The increase in ionic conductivity is also due to the increase in

number of movable ions by dissociation of salts into its corresponding ions with

increase in temperature. It is found that mobility of cation in these polymer

composite systems is considered to be similar to that of ionic crystal in which

ionic conductivity is due to the motion of ions between vacant sites which are

available in the ionic crystals because the data exhibits Arrhenius behavior.

Fig. 1.2(b) shows that conductivity increases with increase in concentration of

KClO3 salt in the polymer electrolyte system. The enhancement in conductivity

may be due to the decrease in crystallinity [176]. The decrease in crystallinity

is due to complex formation between salt and polymer matrix.

Fig. 1.3(a) shows that PVC-Li2SO4 (85-15) polymer electrolyte complex,

exhibit much increase in ionic conductivity above 75°C compared to other

samples of PVC-Li2SO4 polymer electrolyte systems. The maximum room

temperature ionic conductivity is found to be 6.16 x 10-12 S cm-1 for the PVC-

Li2SO4 (80-20) polymer electrolyte system.

The increase in conductivity with temperature is nonlinear. The nonlinear

behavior may be due to the fact that ionic conduction depends on the

segmental motion of polymer electrolyte system [177]. It has been

investigated that polymer electrolytes expand with rise in temperature thereby

resulting in free volume. Therefore ions and polymer segments will move into

the free volume thereby contributing conductivity. The ionic conductivity

shows increase with rise in temperature due to availability of free volume

around polymer chains, which causes faster mobility of ions and polymer

71

segments. The above discussion shows that the polymer electrolytes

containing 85% or more PVC content cannot be described by Arrhenius

relationship, but can be explained on the basis of free volume concept.

Fig. 1.3(b) shows that conductivity increases with increase in concentration of

Li2SO4 salt in PVC-Li2SO4 polymer electrolyte system. The increase in

conductivity may be due to development of amorphous regions with

incorporation of Li2SO4 salt. These amorphous phase will allowed passage of

charge carrier species thereby increase in ionic conductivity.


Systems with Plasticizer

Fig. 1.4(a) shows the influence of temperature on ionic conductivity of PVC-

EC-LiClO4 polymer electrolyte system. The ionic conductivity of the polymer

electrolyte films has been increased considerably with increase in

temperature. The maximum ionic conductivity is found to be 1.41 x 10-7 S cm-1

for PVC:EC:LiClO4 (30:55:15) polymer electrolyte system at 303 K

temperature. Fig. 1.4(b) depicts the effect of concentration of salt on the ionic

conductivity of the films which shows that with increase in concentration of

salt ionic conductivity also increases which may be due to increase in the

number of mobile ions in the solid polymer electrolytes. It can be found from

Fig. 1.4(c) that ionic conductivity exhibit increase with decrease in PVC

content in the polyelectrolyte systems.

Fig. 1.5 shows variation of conductivity with temperature for PVC-EC-LiClO4

polymer electrolyte films containing EC as plasticizer and different weight

ratios of PVC. The maximum conductivity is found to be 1 x 10-7 S cm-1 for

PVC-EC-LiClO4 (.40PVC + .45EC + .15LiClO4) polymer electrolyte system at

303 K. It has been found that variation of conductivity with temperature is

72

parallel and the difference between conductivity of different polymer

electrolyte films depends on the weight ratio of PVC, showing VTF type

behavior.

Fig. 1.6 exhibits the effect of weight ratio of PVC on conductivity of PVC-

plasticizer-LiClO4 polymer electrolyte films containing EC and PC as

plasticizers. It can be seen that conductivity value shows decrease with

increase in the weight ratio of PVC and logarithm of the conductivity show

proportionally decrease with the increase in weight fraction of PVC. No

appreciable differences between conductivity of the films containing EC and

PC as plasticizer have found. It is also found that variation of conductivity as a

function of weight fraction of PVC is similar for both polymer electrolyte films

containing either EC or PC as plasticizer. The variation of conductivity is

mainly dependent on the amount of PVC instead of the nature of plasticizer.

The conductivity value shows decrease by addition of PVC because it

decreases the mobility of ions through polymer electrolyte films although it

has been investigated that addition of PVC increases the dissociation of salt.

The addition of PVC seems to decrease the mobility of ions but seems not to

increase the degree of dissociation.

Fig. 1.7(a) shows the effect of temperature on conductivity of PVC-Li2SO4-EC

polymer electrolytes. These solid polymer electrolyte films has been prepared

by using polymer PVC, Li2SO4 salt and EC as plasticizer, employing solvent

casting technique. Fig. 1.7(a) presents the variation of log of conductivity with

inverse absolute temperature for different solid polymer electrolyte films. The

maximum ionic conductivity at 303 K is found to be 4.78 x 10-10 S cm-1 for

PVC-Li2SO4-EC (10-10-80) polymer electrolyte system. It has been found that

73

conductivity-temperature plots shows linear behavior for the polymer

electrolyte system containing lower content of PVC, while the samples

containing higher content of PVC exhibit nonlinear variation. The nonlinear

behavior indicates that polymeric segmental motion influence ionic mobility in

polymer electrolytes. This non linear behavior of conductivity may be

effectively explained by emperical equation of Vogel-Tammann-Fulcher.

σ = AT-1/2exp [–B/T -Tg]

In this equation A and B are constants, T is the absolute temperature and Tg

is the glass transition temperature.The constant A is associated with the

number of charge carriers in polymer electrolyte systems, while B is

associated with the ionic transport. It reveals from temperature dependent

behavior that ion moves through that phase of polymer electrolyte films which

are rich with plasticizer.

It is also observed that with increase in temperature, ionic conductivity

increases for all polymer electrolyte systems containing different amounts of

PVC and EC as plasticizer. The increase in ionic conductivity may be due to

the fact that at higher temperature, salts can easily dissociated into ions and

thermal segmental motion of polymer chains also improves, while at low

temperature Li salt shows interaction with polymer chains due to which

cohesive energy of polymer chains increases and mobility of ions decreases

thereby shows decrease in ionic conductivity.

This behavior may be attributed to free volume model. According to this model,

with increase in temperature, free volume is produced due to expansion of

polymer. When free volume is produced then charge cariers can easily move

into these free volumes. In otherwords free volume determines conductivity.

74

By measurement of conductivity of the polymer electrolyte systems containing

different contents of plasticizer it can be observed that with increase in

plasticizer content the conductivity values also increases. The effect of

plasticizer on ionic conductivity can be observed from Fig. 1.7(b). The

increase in conductivity with increase in plasticizer content may be due to the

fact that plasticizers have very high dielectric constant which causes high

degree of dissolution of ionic species and resulting in greater number of

movable ions. The second reason of high ionic conductivity may be that

plasticized polymer electrolyte films have low viscosity so faster mobility of ions.

Different polymer electrolyte systems containing different proportions of PVC

has been prepared and their conductance behavior and mechanical

properties have been studied. Ionic conductivity of PVC-Li2SO4-EC solid

polymer electrolytes depends on concentration and mobility of ionic species.

Fig. 1.7(c) shows that with increase in concentration of PVC, conductivity

value of these solid polymer electrolytes decreases. The decrease in

conductivity values with increase in concentration of PVC may be due to

decrease in ionic mobility. It can be observed that conductivity decreases

while mechanical properties improved with increase in PVC content.

Fig. 1.8(a) presents the influence of temperature on the conductivity of PVC-

EC-KBrO3 complex polymer electrolyte system. It can be found that

conductivity shows increase with increase in temperature for pure PVC and

PVC containing KBrO3 and EC as plasticizer. The maximum conductivity at

room temperature is found to be 1 x 10-6 S cm-1 for PVC-EC-KBrO3 (60-25-15)

polymer electrolyte system. Similarly conductivity also exhibit increase with

increase in concentration of KBrO3 salt as shown in Fig. 1.8(b). The increase

75

in concentration of KBrO3 salt causes formation of charge transfer complexes

of salt with polymer matrix and decrease in the crystallinity of the polymer

matrix, thereby improvement in ionic conductivity. It has been observed that

the influence of incorporation of EC as plasticizer on conductivity values are

more compared to that of KBrO3 salt which may be due to smaller size of

plasticizer molecules compared to that of polymer molecules, on the basis of

which plasticizer molecules can easily penetrate into the polymer matrix and

exhibit interaction with polymer chains, while decrease intramolecular

interaction involved between polymer chains thereby improved ionic

conductivity due to increased segmental motion of polymer chains. The

mechanism of ionic conduction through complexed polymer electrolyte

systems has been investigated by calculating activation energies at different

region of the conductivity vs. temperature plot. It is found that conductivity-

temperature data can be explained on basis of Arrhenius relation, with two

regions (region-I and region-II). The activation energies of both these regions

have different values. The Arrhenius relation is given as

σ = σ0 exp (-Ea/KT)

where σ0 is proportionality constant, Ea is activation energy and K is the

Boltzmann constant. Conductivity-temperature studies shows that the nature

of cation transport through polymer electrolyte system may be similar to the

mobility of ions through the ionic crystals. The ions jump between available

sites in the ionic crystal.

It has been found that conductivity values of complex polymer electrolyte

show sharp variation just after 1st region in the plot. The sudden variation of

conductivity may be due to the transition of crystalline phase of polymer into

76

the amorphous phase thereby enhancement of conductivity due to improved

segmental motion.

It can be observed that activation energies show decrease with increase in

the concentration of KBrO3 salt in the complex polymer electrolyte system

thereby increase in conductivity. The decrease in ionic conductivity may be

due to the formation of charge transfer complexes in the complex polymer

electrolyte system by addition of dopant. These charge transfer complexes

provides additional charges in the lattices of the system [178].

Fig. 1.9(a) shows the influence of temperature on the log of conductivity of

PVC-EC-PC-LiClO4 polymer electrolyte systems containing double

plasticizers. It has been found that values of ionic conductivity increases with

increase in temperature but the difference between conductivity of three

different systems containing different content of salts and plasticizers is much

pronounced at lower temperature compared to the difference at higher

temperatures. The maximum room temperature ionic conductivity is found to

be 2.23 x 10-4 S cm-1 for PVC-EC-PC-LiClO4 (30-30-25-15) polymer

electrolyte system. It can also be observed from Fig. 1.9(b) that values of

conductivity shows increase with increase in the content of salt which may be

due to the increase in the number of movable ions by addition of salt into the


Fig. 1.10(a) shows variation of ionic conductivity with EC which are added to

the double salt system. It can be observed that addition of EC as plasticizer to

PVC-LiClO4-LiBF4-EC complexed polymer electrolytes exhibits very less

increase in conductivity. The insignificant increase in ionic conductivity by

addition of EC can be explained as that some content of the plasticizer are

77

involved in reducing coulombic attractive forces between oppositely charged

ions of the salts, while some EC are also utilized in minimizing interaction of

hydrogen and chlorine. Therefore the remaining content of EC is very small

which improve ionic conduction through polymer network. It can also be

observed that addition of EC into complex polymer electrolyte causes

increase in ionic conductivity to some limited extent beyond which addition of

any more EC results in the decrease of ionic conductivity. The reason is that

at higher concentration of EC, crystallization formation takes place due to

interaction between plasticizer molecules in the polymer electrolytes which

exhibit decrease in ionic conductivity. The maximum ionic conductivity at room

temperature is found to be 6.60 x 10-6 S cm-1 for the system containing 40

wt% EC as plasticizer.

Effect of propylene carbonate on conductivity of PVC-LiClO4-LiBF4-PC

complex polymer electrolyte containing double salts has also been studied

which presents in Fig. 1.10(b). In this case different content of PC has been

added into fixed amount of PVC, salts and EC plasticizer. Results manifests

that PC shows more effect compared to EC on conductivity of PVC-based

polymer electrolyte containing double salt. This may be due to the reason that

PC-salts interaction shows higher specificity compared to EC-salts interaction

thereby PC plasticizer provides greater number of ions compare to the other

plasticizer present in polymer electrolyte. The maximum conductivity at room

temperature is found to be 6.68 x 10-6 S cm-1 for the system containing 40

wt% PC as plasticizer.

78


Systems containing Inorganic Filler

Fig. 1.11 shows the effect of temperature on conductivity of PVC-ZnO-LiClO4

polymer electrolyte. The maximum ionic conductivity is fond to be 4.78 x 10-8

S cm-1 at 303 K temperature for PVC-ZnO-LiClO4 (60-25-15) polymer

electrolyte system containing 25 wt% ZnO. It can be observed from

conductivity-temperature plot that conductivity increases with increase in

temperature and shows two regions (region-I and region-II) with different

activation energies for PVC-ZnO-LiClO4 (60-25-15) complexed polymer

electrolyte system. The effect of temperature on conductivity may be

explained on basis of cohesive energy of polymer chains. When temperature

of polymer electrolyte system is increased, then cohesive energy of polymer

chains decreases due to decrease in interaction involved between ionic

species and polymeric chains thereby improved conductivity of polymer

electrolyte system while conductivity exhibit decrease with decrease in

temperature, due to increase in cohesive energy of polymer chains. The

increase in cohesive energy of polymer chains may be due to stronger

interaction involved between ionic species and polymer chains thereby

decrease in conductivity of polymer electrolyte system. The variation of

conductivity with temperature may be associated with viscosity of the system

and dissociation of salt because when temperature increased then viscosity

shows decrease, due to which segmental motion of polymer chains increases

thereby improved ionic motion [179]. While with decrease in temperature

viscosity shows increase due to which segmental motion of polymer chains

become restricted thereby decrease in ionic motion. Similarly with increase in

temperature, salts can be easily dissociated into its corresponding ions

79

thereby improved ionic mobility, while at lower temperature, salts cannot

easily dissociated into its corresponding ions so decrease in conductivity.

Fig. 1.12(a) shows the effect of temperature on conductivity of PVC-Li2SO4-

EC-ZrO2 composite polymer electrolyte system. It is found from Fig. 1.12(a)

that conductivity values exhibit enhancement with increase in temperature

which can be explain on basis of free volume concept. According to free

volume theory, free volume is produced due to expansion of polymer, with

increase in temperature which results in enhancement of conductivity with the

improvement of ionic and segmental motion [180]. The variation of ionic

conductivity with temperature of composite polymer electrolyte systems with

various compositions seems to obey Vogel-Tammann-Fulcher (VTF) relation.

σ (T) = AT-1/2 exp[-B/(T-T g)]

In VTF equation A and B are constants and Tg is the reference temperature.

Constant A is related to the number of charge carriers in the electrolyte

system, while constant B is related to activation energy of ion transport

associated with configurational entropy of polymer chains. The maximum

room temperature conductivity is found to be 5.01 x 10-8 S cm-1 for PVC-

Li2SO4-EC-ZrO2 polymer electrolyte system containing 12 wt% of ZrO2.

Fig. 1.12(b) shows variation of ionic conductivity by incorporation of different

contents of ZrO2 to PVC-Li2SO4-EC composite polymer electrolyte systems.

The effect of inorganic filler particles have been studied at different

temperatures. It can be seen that initially there is increase in conductivity with

ZrO2 content, up to certain concentration which is approximately 12 wt% of

ZrO2 but beyond this, further increase in ZrO2 content decreases the

conductivity. This trend is for all temperatures studied. At higher

80

concentrations, formation of ZrO2 crystallites and the behavior of ZrO2

particles as insulators may be responsible for decrease in conductivity. It is

found that at low concentration of ZrO2, conductivity shows enhancement with

increase in concentration of ZrO2.

Fig. 1.13(a) presents the effect of temperature on the conductivity for PVC-

LiClO4-EC-ZrO2 polymer electrolytes of various compositions. It can be

observed that ionic conductivity show marked increase with increase in

temperature. Fig. 1.13(a) represents Arrhenius plots of ionic conductivity for

the complexed polymer electrolytes containing various content of ZrO2. It is

found that overall features of Arrhenius plot are similar for complexed polymer

electrolytes of various compositions containing different content of ZrO2. No

linear relationship could be observed for any sample of polymer electrolyte

containing ZrO2. Nonlinear relationship reveals that ionic conduction may be

associated with segmental motion of polymer chains. Therefore ionic

conduction may be based on Williams-Landel-Ferry mechanism thereby the

results may be effectively explained by Vogel-Tammann-Fulcher equation.

The influence of temperature on ionic conductivity reveals that charge carrier

species move through plasticizer rich phase of polymer electrolyte containing

PVC, salts and plasticizer according to VTF equation which describes ionic

transport through viscous matrix.

Fig. 1.13(b) reveals the effect of temperature on conductivity of PVC-LiClO4-

EC-ZrO2 polymer electrolyte systems containing different concentration of

ZrO2. It is observed that increase in concentration of ZrO2 exhibit improved

conductivity. This behavior is due to the reason that with increase in

temperature, softening point of polymer electrolytes is reduced while

81

segmental motion of polymer chains increases thereby conductivity also

increases. The increase in conductivity is shown up to 15 wt% of ZrO2,

beyond which there is decrease in conductivity. So this is optimum

conductivity of ZrO2, beyond which the formation of ZrO2 crystallite region are

possible and decrease in conductivity is observed. But increase in ionic

conductivity continues to an optimum concentration of ZrO2 beyond which it

starts decrease. The reason is that at high concentration of ZrO2 crystallite

region exists which causes decrease in conductivity. The maximum ionic

conductivity at 303 K temperature is found to be 7.24 x 10-6 S cm-1 for PVC-

LiClO4-EC-ZrO2 (30-5-50-15) polymer electrolyte system.

Fig. 1.14(a) shows the influence of temperature on conductivity of pure PVC

and PVC doped with different weight percent of activated charcoal. It has

been observed that conductivity values shows continuous increase with

increase in temperature which shows that PVC rendered semiconductive by

addition of activated charcoal. The increase in conductivity with temperature

of pure PVC may be due to the local motion of molecular groups e.g. internal

motions within the side groups or rotational motions of side groups which may

be occur at lower temperatures although various types of molecular relaxation

are possible in the polymeric systems at different temperatures but the

increase in the conductivity of pure PVC with temperature may be due to the

increase in the mobility of the main chain segment of the polymer [181].

It is investigated that conductivity exhibits increase with increase in

temperature by the following equation


82

In this equation σ is the conductivity, σ0 is the pre-exponential factor, Ea is the

activation energy and K is the Boltzmann constant. It has been observed that

conductivity of PVC shows much increase by addition of activated charcoal.

It is investigated that at low temperatures increase in conductivity may be due

to the charge carrier species which are injected in to the polymer electrolyte

films directly from the electrodes. There are two phases in the polymer

electrolyte systems i.e. filler phase and the polymer phase. It can be observed

that filler phase is very sensitive to temperature. The improvement in the

conductivity of the polymer electrolyte system may be due to the softening of

the polymer electrolyte films at higher temperatures thereby easy injection of

charge carrier species from electrodes into the films.

Fig. 1.14(b) shows that polymer electrolyte containing higher content of

carbon black exhibit higher values of ionic conductivity compared to the

systems containing lower concentration of carbon black.

4.2 Conductance Studies of PVC-PMMA Blend Polymer Electrolyte

Systems

Three different types of PVC-PMMA blend polymer electrolyte systems



4.2.1 Conductance Studies of PVC-PMMA Blend Polymer Electrolyte

System without Plasticizer

Fig. 1.15(a) shows variation of ionic conductivity with temperature for pure

PVC-PMMA blend polymer system and PVC-PMMA-NaClO4 blend polymer

electrolyte systems of various compositions. The conductivity has been

studied in the temperature range of 293 K to 373 K. The maximum room

temperature ionic conductivity is found to be 3.06 x 10-7 S cm-1 for PVC-

83

PMMA-LiClO4 (65-20-15) polymer electrolyte system. Fig. shows significant

enhancement in conductivity values at room temperature. The room

temperature conductivity has been increased approximately 10 times with

higher NaClO4 content. The increase in conductivity by addition of NaClO4 salt

may be due to formation of charge carrier species thereby increase in the

number of movable ions.

The variation of conductivity with temperature is according to Arrhenius

relation. The increase in conductivity with temperature may be due to the

improvement in segmental motion of polymer chains which leads to increase

in the free volume thereby increase in ionic mobility [182]. The variation of

conductivity with temperature can be explained according to Arrhenius

relation.


where Ea, K and σ0 represent activation energy, Boltzmann constant and pre

exponential factor, respectively.

It is found that activation energy shows decrease with increase in the

concentration of NaClO4 salt in complexed blend polymer electrolyte films

thereby increasing the ionic conductivity. The influence of incorporation of salt

on the activation energy values may be due to the formation of charge

transfer complexes in the polymer electrolyte system. These charge transfer

complexes provide movable ions to the system which result in improvement of

conductivity of the sample.

84


System with Plasticizer

In order to analyze the mechanism of ionic conduction through PVC-PMMA-

LiClO4 polymer electrolytes, variation of ionic conductivity have been

measured with temperature. Fig. 1.16(a) presents the variation of logarithm of

ionic conductivity with inverse absolute temperature for different complexed

polymer electrolytes of PVC-PMMA-LiClO4. No abrupt changes have been

observed, which indicates that all samples exhibit completely amorphous

structure. It can also be observed from conductivity-temperature plots that all

these samples follows Arrhenius rule. Therefore ion jumps from one site into

another site similar to that in ionic crystals. The maximum ionic conductivity at

303 K temperature is found to be 2.51 x 10-6 S cm-1 for PVC-PMMA-LiClO4

(45-15-40) complex polymer electrolyte system. Activation energy calculated

from Fig. 1.16(a) for all complexed plasticized films, are very low which have

been analyzed by measuring the temperature dependent ionic conductivity.

The temperature dependent ionic conductivity values suggest that all these

systems follows Arrhenius rule. These systems exhibit amorphous structure

because temperature dependent ionic conductivity data shows smooth

variation without any abrupt changes [183]. The nature of cation transport in

these systems seems to be very similar to that in ionic crystals, because

temperature dependent conductivity data follows Arrhenius behavior. These

polymer electrolytes show higher ionic conductivity and lower activation

energy Ea. The higher conductivity may be due to completely amorphous

nature of the electrolytes which provides higher free volume in the neighbour

of polymeric segments, thereby facilitating Li-ion conduction through the

polymeric system [184].

85

Fig. 1.16(b) shows that conductivity values exhibit continuous enhancement

with addition of LiClO4 salt. The trend of ionic conductivity variation is almost

similar at various temperatures.

Fig. 1.16(c) exhibits decrease with increase in PVC content in the polymer

electrolyte systems. The decrease in ionic conductivity at higher concentration

of PVC may be due to lower mobility of ions.

Fig. 1.17 depicts the effect of PVC/PMMA blend ratio containing fixed

contents of plasticizer on ionic conductivity of the system. It can be seen that

with increase in PVC/PMMA blend ratio, conductivity value decreases. The

films containing 100% PVC without any PMMA shows very lower values of

conductivity but the films obtained are free standing, showing very good

mechanical property. The highest conductivity is found for the blend which did

not contain PVC but the mechanical properties of such polymer electrolyte

films is not satisfactory at room temperature because 100% PMMA polymer

electrolyte exist in the form of gel instead of free standing films. It is clear from

the above discussion that the polymer electrolyte films contain both PVC and

PMMA shows intermediate behavior in which plasticizer rich phase provides

medium for transport of charge carrier species while PVC rich phase provides

mechanical support for film. PVC rich phase is a solid like medium through

which transportation of charge carrier species is difficult, while polymer

electrolyte films containing only PMMA provides medium through which

transfer of charge carrier species can easily takes place therefore exhibit

higher values of conductivity.

Fig. 1.18 depicts variation of ionic conductivity with plasticizer content of

polymer electrolyte containing fixed blend ratio of PVC/PMMA. It has been

86

observed that with increase in plasticizer content the ionic conductivity values

also show linear increase. It may be due to the increase in free volume of the

plasticizer rich phase and increase in degree of interconnections between

plasticizer rich phases by the addition of plasticizer in to polymer electrolyte. It

can be seen that at lower concentration of plasticizer, polymer electrolyte

shows lower values of conductivity due to poor linkage between plasticizer

rich phases. Therefore charge carrier species cannot transport through

plasticizer rich phases but it may be transported through PVC rich phase

which acts as solid like medium therefore ionic conductivity values are very

low [185]. While at higher concentration of plasticizer, polymer electrolyte

exhibit higher values of conductivity because charge carrier species can

easily transport through plasticizer rich phase. It can be said that free volume

becomes available for transportation of charge carrier species by addition of

plasticizer in to polymer electrolyte systems. When free volume is developed

in polymer electrolyte systems then segmental motion of polymer chains also

increases thereby improving ionic mobility.

Fig. 1.19 shows the effect of plasticizer contents on ionic conductivity of

polymer electrolyte films containing fixed PMMA/PVC blend ratios. The

maximum ionic conductivity is found to be 4.78 x 10-5 S cm-1 for PVC-PMMA-

EC-LiClO4 polymer electrolyte system containing 65% of ethylene carbonate

as plasticizer. It is found that at lower plasticizer content plots of ionic

conductivity of polymer blend electrolyte follow Arrhenius equation, while at

higher plasticizer content the effect of temperature on ionic conductivity

exhibits nonlinear trend which could be explain by VTF relation. The behavior

of ionic conductivity at lower plasticizer content is due to the poor linkage

87

between the plasticizer rich phases. Therefore transport of charge carrier

species may be through PVC rich phase. While in case of higher content of

plasticizer the transport of charge carrier species may be through the

plasticizer rich phase which is easier than through solid like PVC rich phase

so conductivity follow VTF relation.

Fig. 1.20 shows the influence of temperature on conductivity of PVC-PMMA

polymer electrolyte containing LiClO4 as salt. All these different polymer

electrolytes containing fixed content of polymers, while various contents of

salt and plasticizer. Ionic conductivity exhibits linear behavior with

temperature. It can be found that conductivity is similar to the gel electrolyte

based on PMMA, but PVC based gel electrolyte shows improved stability. Fig.

1.20(a) shows the effect of temperature on conductivity. It can be found that

conductivity increases with increase in temperature. This behavior may be

explained by free volume model. According to this model free volume

produces due to expansion of polymer network with increase in temperature.

Therefore charge carrier species, movable molecules and segments of

polymer chains freely move into these free volumes. In other words ionic

conductivity increases due to both ionic and segmental motion of polymer

chains. The segmental motion of polymer chains actually reduces the

retarding effect of the ions. The maximum ionic conductivity at 303 K

temperature is found to be 2.23 x 10-5 S cm-1 for PVC-PMMA-LiClO4-EC (20-

10-15-55) polymer electrolyte system.

It is also found from Fig. 1.20(b) that at lower concentration of salt,

conductivity shows increase with increase in concentration due to increase in

ionic species, while at higher concentration of salts conductivity is found to

88

decrease with increase in further concentration due to decrease in mobility

and number of ionic species. The decrease in ionic mobility may be due to

retarding effect of viscous medium caused by addition of further salt.

Plots of ionic conductivity vs. temperature for PVC-PMMA-LiClO4-EC polymer

electrolyte films of various compositions with fixed EC plasticizer content while

different PVC/PMMA blend ratios are depicts in Fig. 1.21(a). It is observed

that Arrhenius plots for all PVC/PMMA blends of various blend ratios of

polymer electrolytes shows similar features. No linear relationships are

exhibited by these polymer electrolytes. It is observed that as the temperature

increases, the conductivity value also increases for all different compositions

but nonlinearly. This behavior of polymer electrolytes can be explained on

basis of free volume model. According to this model with increase in

temperature free volume become produced due to expansion of polymer.

When free volume becomes available in polymer electrolytes then charge

carrier species can easily move into these regions. Therefore with increase in

temperature free volume increases which results in improved segmental

motion of polymer chains as well as ionic mobility thereby conductivity exhibit

improvement. The curvature of these plots indicates that ionic mobility through

these electrolytes could best explained by Williams-Landel-Ferry mechanism.

Ionic mobility through these polymer electrolyte films is associated with

segmental motion of polymer chains. Therefore the results may be more

effectively explained by empirical equation of Vogel-Tammann-Fulcher.

σ = AT-1/2exp [–B/T -Tg]

In this equation A and B are constants, T is the absolute temperature and Tg

is the glass transition temperature.The constant A is related with the number

89

of charge carriers in the polymer electrolyte systems while B is related with

the ionic transport. It reveals from temperature dependent behavior that ion

moves through that phase of polymer electrolyte films which are rich with

plasticizer. The maximum ionic conductivity at 303 K temperature is found to

be 1.44 x 10-4 S cm-1 for PVC-PMMA-LiClO4-EC (20-10-10-60) polymer

electrolyte system.

Fig. 1.21(b) shows that at lower concentration of PMMA the conductivity of the

polymer electrolytes increases with increase in concentration of PMMA, while

at higher concentration of PMMA the conductivity decreases with further

increase in concentration of PMMA.

Figs. 1.22(a) and (b) presents the effect of plasticizer content on conductivity

of complexed polymer electrolyte films of plasticized PVC-PMMA containing

LiClO4 and NaClO4 salts respectively. It can be observed from Figs. 1.22(a)

and (b) that with increase in plasticizer (EC) content, polymer electrolytes

exhibit linear increase in conductivity. It is also observed that the effect of

plasticizer content on enhancement of conductivity of polymer electrolyte

containing LiClO4 is higher compared to that containing NaClO4 salt. The

increase in conductivity may be due to the availability of larger free volume

and plasticizer rich phase thereby improving charge carrier mobility.

Figs. 1.22(c) and (d) exhibits the influence of PVC-PMMA blend ratio

containing fixed content of plasticizer (EC) on conductivity of complexed solid

polymer electrolyte containing LiClO4 and NaClO4 salts, respectively. It is

found that conductivity shows increase with increase in PMMA content

provided that temperature is kept constant. The conductivity of blend

electrolytes is very high compared to that of pure PMMA. It is found that these

90

polymer blend electrolytes mechanically become unstable at high content of

PMMA but exhibits improved conductivity.

It is clear from the above discussion that polymer blend electrolytes containing

PVC rich phase exhibits lower values of conductivity but higher mechanical

strength. This behavior may be due to the reason that polymer blend

electrolytes containing PVC rich phase show solid like behavior which

hindered mobility of charge carrier species thereby having lower conductivity.

While the polymer blend electrolyte containing PMMA rich phase exhibits

higher conductivity due to the reason that PMMA promotes the uptake of

liquid electrolyte to presents homogeneous medium which increases

conductivity since ions can move easily through it without any resistance to its

motion.

Figs. 1.22(e) and (f) reveal the variation of conductivity with temperature for

polymer electrolytes with different content of PMMA containing two different

salts. The maximum ionic conductivity at 303 K temperature is found to be

5.12 x 10-5 S cm-1 for PVC-PMMA-EC-LiClO4 (0-15-75-10) polymer electrolyte

system while the conductivity of PVC-PMMA-EC-NaClO4 (0-15-75-10)

polymer electrolyte system is found to be 3.23 x 10-6 S cm-1 at 303 K

temperature. It can be observed from Fig. 1.22(e) that the values of

conductivity of polymer electrolyte at higher temperature is much greater

compared to that at lower temperature in the presence of plasticizer. It may be

due to the reason that at lower temperatures plasticizer and salt mixture exist

in the form of crystals so conductivity is low while at higher temperatures,

these crystals of plasticizers becomes melt, thereby increase in conductivity

due to increase in number of charge carrier species by melting of crystals.

91

Fig. 1.23 represents conductivity versus temperature plots of PVC-PMMA-LiX-

PC polymer electrolyte films. All these Arrhenius plots for polymer electrolyte

films containing different Li salts show similar behavior. All these plots shows

linear behavior which indicates that ionic conduction through all these polymer

electrolyte films follows Arrhenius behavior throughout.

It has been found from conductivity plots of polymer electrolytes containing

different Li salts that LiBF4 salt shows highest ionic conductivity among the Li

salts. The highest ionic conductivity of LiBF4 may be due to the lowest lattice

energy of LiBF4 salt. The maximum ionic conductivity at 303 K temperature is

found to be 1.69 x 10-3 S cm-1 for PVC-PMMA-LiBF4-PC (20-10-10-60)

polymer electrolyte system.

Fig. 1.24(a) shows the influence of temperature on the conductivity of polymer

electrolyte system PVC-PMMA-LiClO4-PC containing different wt% of LiClO4

salt and fixed content of PC as plasticizer. The maximum ionic conductivity at

303 K temperature is found to be 2.29 x 10-5 S cm-1 for PVC-PMMA-LiClO4-

PC (28-14-8-50) polymer electrolyte system. The conductivity values shows

increase with increase in temperature for all systems containing various

content of salt. The improvement in conductivity of the films with rise in

temperature may be due to the availability of free volumes by expansion of

polymer because ions, solvated molecules and polymer segments can easily

move into these free volumes thereby increase in conductivity [186]. The

movement of these ions, solvated molecules and segments of polymers

become easier with rise in temperature into these free volumes due to

expansion of polymer. It has been found that variation of conductivity with

temperature is almost linear which shows that ion conduction through this

92

system is based on the Arrhenius relation. Therefore ionic mobility is

correlated mainly with the ionic motion in this system.

Fig. 1.24(b) shows the effect of salt concentration on the conductivity values

of polymer electrolyte systems at various temperatures. It is found that the

effect of addition of salt is pronounced at lower concentration of salt which

may be due to the build up of charge carriers which leads to the improvement

in the ionic conductivity of the polymer electrolyte systems, while at higher

concentrations of salt in the films ionic conductivity values shows decrease

due to the retarding effect of the ionic clouds thereby decrease in the ionic

conductivity. Therefore ionic conductivity decreases by further addition of salt

at higher concentration of salt due to the retarding effect of charge carrier

species in the polymer electrolyte system.

Fig. 1.24(c) shows that ionic conductivity values of polymer electrolyte

systems decreases with increase in PVC content. While mechanical strength

increases with incorporation of PVC in to polymer electrolyte systems.

Fig. 1.25 shows the variation of ionic conductivity with the PVC/PMMA blend

ratio containing fixed plasticizer content. It has been investigated from the plot

that conductivity of PVC-PMMA-EC-PC-LiClO4 system shows enhancement

with increase in PMMA content in the polymer electrolyte system. However

the mechanical strength of the system becomes affected with addition of

PMMA. The influence of addition of PMMA on conductivity of the system,

containing lower content of PMMA is higher compared to the system

containing higher content of PMMA. Table 1.6 shows that with increase in

concentration of PMMA, the Ea values of the system decreases so

conductivity increases. The maximum ionic conductivity at 303 K temperature

93

is found to be 5.24 x 10-4 S cm-1 for PVC-PMMA-EC-PC-LiClO4 (0-30-40-20-

10) polymer electrolyte system.


Systems containing Inorganic Filler

The influence of temperature on the ionic conductivity of PVC-PMMA-Li2SO4-

EC complex polymer electrolyte system containing various content of ZrO2 as

inorganic filler particles has been studied. Fig. 1.26(a) shows the variation of

ionic conductivity with temperature. The maximum ionic conductivity at room

temperature is found to be 1.33 x 10-7 S cm-1 for PVC-PMMA-Li2SO4-EC

polymer electrolyte system containing 5% of ZrO2. It can be observed that

ionic conductivity-temperature data exhibit nonlinear behavior which suggests

that ionic conduction of the system is based on Williams-Landel-Ferry

mechanism. The studies of incorporation of ZrO2 filler particles shows that

ionic conductivity improved by addition of ZrO2 into polymer electrolyte films

which may be due to the transition of crystalline phase of polymer into the

amorphous phase thereby improved ionic mobility. Fig. 1.26(a) shows that

conductivity data follows Vogel-Tammann-Fulcher relation.

Fig. 1.26(b) reveals that ionic conductivity increases with addition of ZrO2 filler

particles at lower concentration which may be due to the increase of mobile

ions by PVC-PMMA-Li2SO4-EC-ZrO2 system while decreases at higher

concentration by further incorporation of ZrO2. The decrease of conductivity at

higher concentration of ZrO2 may be due to the development of crystallite

regions and the ZrO2 particles may acts as insulators thereby resist mobility of

charge transfer complexes in the complex polymer electrolyte systems.

The increase in ionic conductivity of polymer electrolyte by incorporation of

inorganic filler particles may be due to the formation of charge transfer

94

complexes and reduction of softening point. The addition of filler particles may

causes formation of new kinetic path through the boundaries of polymer and

filler particles and similarly it may be involved in the development of

amorphous phases in the complex polymer electrolyte systems thereby

increased ionic motion. The incorporation of inorganic filler causes reduction

of softening point by transition of well ordered phase (crystalline phase) to

disordered phase (amorphous phase) which may lead to the improved

segmental motion due to the increased flexibility of polymer chains. It is

observed that conductivity values exhibit rise up to an optimum concentration

of ceramic particles beyond which it shows decrease by further incorporation

of ZrO2. The decrease in conductivity at high concentration of filler particles

may be due to the fact that well defined crystallite regions become develop at

such high concentration of filler which may lead to the decrease in

conductivity [187]. The lower conductivity of crystallites may be due to the

lower flexibility which results in slow segmental motion of polymer chains

thereby decrease conductivity. In addition of crystallite formation ZrO2

particles also acts as insulators at such high concentration which leads to

decrease in conductivity. The increase in ionic conductivity at low

concentration of filler may be due to the increase in the number of conductive

layers in the complex polymer electrolyte films, while at higher concentration

of filler particles ionic conductivity exhibit decrease due to the increase in

dilution effect and phase discontinuities caused by crystallinity.

Fig. 1.27(a) shows the effect of temperature on conductivity of polymer

electrolyte system PVC-PMMA-LiClO4-EC containing various content of TiO2

as filler. It is found that ionic conductivity increases with increase in

95

temperature. The maximum conductivity at 303 K temperature is found to be

3.98 x 10-4 S cm-1 for PVC-PMMA-EC-LiClO4 (20-5-65-10) polymer electrolyte

system containing 12 wt% of TiO2. Conductivity-temperature plot shows

almost linear behavior at lower concentration of TiO2 followed Arrhenius

behavior throughout. The variation of conductivity with temperature is not

linear at higher concentration of TiO2 but shows two regions (region-I and

region-II) with different activation energies Ea which can be explained

throughout on basis of Arrhenius relationship.

Fig. 1.27(b) reveals the influence of the TiO2 on the ionic conductivity of PVC-

PMMA-EC-LiClO4 polymer electrolytes containing various content of TiO2.

The effect of filler content on the ionic conductivity has been examined at

various temperatures. It can be found from the plots that ionic conductivity

exhibit increase by addition of TiO2 and reached a maximum value. By further

addition of TiO2 ionic conductivity shows decrease. Plots reveal that highest

conductivity obtained at 12 wt% of TiO2 in the polymer electrolyte films. The

increase in ionic conductivity may be due to the fact that addition of filler

particles causes development of the amorphous phase in the polymer

electrolyte systems. It may be possible that addition of filler particles provides

new kinetic path through boundaries of polymer and ceramic particles.

Addition of TiO2 also decreases the Tg of polymer and flexibility become

increase thereby ionic conductivity increases [188]. The decrease in the ionic

conductivity after addition of optimum concentration of filler may be due to the

reasons that further addition of filler would results in the development of

nonconductive phase. Development of electrically inert phase would increase

96

resistance to the ionic mobility and block up transportation of the Li ions

through the matrix thereby ionic conductivity exhibit decrease.

4.3 Conductance Studies of PVC-PEO Blend Polymer Electrolyte

Systems

Three different types of PVC-PEO blend polymer electrolyte systems



4.3.1 Conductance Studies of PVC-PEO Blend Polymer Electrolyte

System without Plasticizer

The variation of conductivity as a function of temperature is shown in Fig. 1.28

for PVC-PEO-LiX polymer blend electrolytes containing different salts (LiClO4,

LiBF4, NaClO4). Various factors can influence ionic conductivity of solid

polymer electrolytes. The most important of these factors are concentration of

conducting ions and their mobility. The mobility of ionic species decreases by

increase in degree of crystallization which causes low ionic conductivity. In the

present research work different solid polymer electrolytes have been prepared

by adding different Lithium salts into PVC/PEO blend electrolytes in different

amount, using solvent casting method. The polymer electrolytes obtained by

using this method are very translucent and free standing.

These solid polymer electrolytes have been subjected to ionic conductivity

measurement at different temperatures in order to find out the influence of

temperature on ionic conductivity of these electrolytes. From measurement of

ionic conductivity values at different temperatures it is found that ionic

conductivity values increases with increase in temperature but the increase in

ionic conductivity values are different for different salts depending on ionic

size and tendency of ionic association. The increase in ionic conductivity with

97

increase in temperature is due to the fact that at low temperature ionic

mobility and segmental motions of polymer chains are restricted due to strong

salt polymer association. While at higher temperature ionic conductivity

increases due to decrease in salt polymer association and increased thermal

segmental motion of polymer chains. It is found that ionic conductivity of

polymer electrolyte (PVC-PEO-LiBF4) containing LiBF4 salt is higher

compared to polymer electrolytes containing other salts. The reason is that

the anions of smaller radius shows greater increase in mobility with increase

in temperature as compared to that of larger sized anions. Studies of

association between Li ion and anions shows that ClO4-1 and BF4

-1 are weakly

associated with Li ions compared to other anion. Weak ion pairing of these

ions causes easy dissociation and greater mobility. The maximum

conductivity at 303 K temperature is found to be 1.07 x 10-5 S cm-1 for PVC-

PEO-LiBF4 (60-30-10) polymer electrolyte system.


System with Plasticizer

Fig. 1.29 shows the Arrhenius plots of PVC-PEO-EC-LiClO4 polymer

electrolyte samples containing various content of LiClO4 salt. Conductivity plot

shows a break around 60-70°C temperature which may be due to the

crystalline-amorphous transition of PEO present in the polymer electrolyte

films. It can be found that these films show maximum conductivity above

crystalline-amorphous temperature. Fig. 1.29 reveals that conductivity

increases by addition of salt. The maximum ionic conductivity at room

temperature is found to be 8.91 x 10-6 S cm-1 for PVC-PEO-EC-LiClO4 (30-5-

50-15) polymer electrolyte system.

98


System containing Inorganic Filler

Fig. 1.30 shows the effect of temperature on the conductivity behavior of

various composite polymer electrolyte systems with and without ethylene

carbonate plasticizer. It has been found that plasticized complex polymer

electrolyte systems exhibit higher conductivity compared to polymer

electrolyte without plasticizer. The higher conductivity of plasticized systems

may be due to its amorphous nature compared to unplasticized systems

[189]. The ionic conductivity of the plasticized complexed polymer electrolyte

containing Al2O3 as filler exhibit higher conductivity compared to other

electrolytes containing TiO2 or ZnO filler. The maximum ionic conductivity at

room temperature is found to be 3.98 x 10-6 S cm-1 for PVC-PEO-EC-LiClO4-

Al2O3 (20-10-50-10-10) polymer electrolyte system.

99

Table 1.1 Activation energies of pure PVC and PVC-NaClO4 polymer

electrolyte system

Polymer electrolyte Activation energy (Ea)

Region-I(eV) Region-II (eV)

PVC 0.70 0.85

PVC-NaClO4 (95-5) 0.58 0.65

PVC-NaClO4 (90-10) 0.40 0.52

PVC-NaClO4 (85-15) 0.25 0.40

Table 1.2 Activation energies of pure PVC and PVC-KClO3 polymer electrolyte

system (From fig. 1.2a)


Region-I (eV) Region-II (eV)

(a) PVC 0.75 0.90

(b) PVC-KClO3 (94-6) 0.60 0.70

(c) PVC-KClO3 (88-12) 0.49 0.55

(d) PVC-KClO3 (82-18) 0.39 0.44

Table 1.3 Activation energies of pure PVC-EC and PVC-EC-KBrO3 polymer

electrolyte system (From fig. 1.8a)



(a) PVC-EC 0.72 0.85

(b) PVC-EC-KBrO3 (70-25-5) 0.57 0.68

(c) PVC-EC-KBrO3 (65-25-10) 0.44 0.50

(d) PVC-EC-KBrO3 (60-25-15) 0.30 0.39

100

Table 1.4 Activation energies of PVC-PMMA and PVC-PMMA-NaClO4 polymer

electrolyte system (From fig. 1.15a)



(a) PVC-PMMA (70-30) 0.39 0.49

(b) PVC-PMMA-NaClO4 (70-25-5) 0.36 0.45

(c) PVC-PMMA-NaClO4 (67-27-10) 0.28 0.46

(d) PVC-PMMA-NaClO4 (65-20-15) 0.15 0.35

Table 1.5 Activation energies of PVC-PMMA-LiClO4 polymer electrolyte system

(From fig. 1.16a)



PVC-PMMA-LiClO4 (45-15-40) 0.66 0.88

PVC-PMMA-LiClO4 (50-20-30) 0.61 0.72

PVC-PMMA-LiClO4 (55-25-20) 0.50 0.60

PVC-PMMA-LiClO4 (60-30-10) 0.38 0.46

Table 1.6 Activation energies of PVC-PMMA-EC-PC-LiClO4 polymer electrolyte

system (From fig. 1.25)


(a) PVC-PMMA-EC-PC-LiClO4 (30-0-40-20-10) 0.39

(b) PVC-PMMA-EC-PC-LiClO4 (20-10-40-20-10) 0.33

(c) PVC-PMMA-EC-PC-LiClO4 (10-20-40-20-10) 0.29

(d) PVC-PMMA-EC-PC-LiClO4 (5-25-40-20-10) 0.20

(e) PVC-PMMA-EC-PC-LiClO4 (0-30-40-20-10) 0.10

101

Fig. 1.1 Arrhenius plots of conductivity for PVC-NaClO4 polymer

electrolytes.

-5

-4.5

-4

-3.5

-3

-2.5

-2

2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.51000/T (K-1)

Log σ

(S

cm

-1)

Pure PVC85-1590-1095-5

Fig. 1.2(a) Plot of log conductivity vs. reciprocal temperature for (a)

Pure PVC, (b) PVC-KClO3 (94-6), (c) PVC-KClO3 (88-12), (d) PVC-

KClO3 (82-18)

-8

-7.5

-7

-6.5

-6

-5.5

-5

-4.5

-4

-3.5

-3

2.7 2.8 2.9 3 3.1 3.2 3.3 3.4

1000/T (K-1)

Log σ

(S

cm

-1)

abcd

102

Fig. 1.2(b) Plots of log conductivity vs. composition for PVC-

KClO3 polymer electrolyte systems at various temperatures.

-8

-7.5

-7

-6.5

-6

-5.5

-5

-4.5

-4

-3.5

-3

0 5 10 15 20

KClO3 (wt%)

Lo

g σ

(S

cm

-1)

303313323333343348353

Fig. 1.3(a) Plots of log conductivity vs. 1000/T for PVC-Li2SO4


-14

-13.5

-13

-12.5

-12

-11.5

-11

-10.5

-10

-9.5

-9

2.7 2.8 2.9 3 3.1 3.2 3.3 3.41000/T (K-1)

Log σ

(S

cm

-1)

95-590:1085:1580:20

103

Fig. 1.3(b) Plots of log conductivity vs. composition of PVC-

Li2SO4 polymer electrolyte system at different

temperatures.

-14

-13.5

-13

-12.5

-12

-11.5

-11

-10.5

-10

-9.5

-9

5 7 9 11 13 15 17 19 21

Li2SO4 salt (w t%)

Log σ

(S

cm

-1)

303K313K323K333K343K348K353K

Fig. 1.4(a) Temperature dependence of ionic conductivity for

ternary polymer electrolyte system of PVC:EC:LiClO4.

-10

-9

-8

-7

-6

-5

-4

-3

-2

2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.51000/T (K-1)

Log σ

(S

cm

-1)

65:30:540:50:1030:55:15

104

Fig. 1.4(b) Log conductivity vs. salt concentration of PVC-EC-

LiClO4 polymer electrolyte system at various temperatures.

-12

-11

-10

-9

-8

-7

-6

-5

-4

-3

-2

5 7 9 11 13 15 17Salt concentration

Log

σ (

S c

m-1)

303K313K323K333K343K353K358K

Fig. 1.4(c) Log conductivity vs. PVC content of PVC-EC-LiClO4

polymer electrolyte system at various temperatures.

-12

-10

-8

-6

-4

-2

0

30 35 40 45 50 55 60 65 70PVC content

Log σ

(S

cm

-1)

303K313K323K333K343K353K358K

105

Fig. 1.5 Log conductivity vs. reciprocal temperature for ternary

system of PVC-EC-LiClO4

-9

-8

-7

-6

-5

-4

-3

2.85 2.9 2.95 3 3.05 3.1 3.15 3.2 3.25 3.3 3.351000/T (K-1)

Log σ

(S

cm

-1)

.60PVC+.35EC+.05LiClO4



Fig. 1.6 Variation of log conductivity vs.weight fraction of PVC

of ternary polymer electrolyte systems at 25oC.

-8

-7

-6

-5

-4

-3

-2

0 0.2 0.4 0.6 0.8 1

Wpvc/(Wpvc+Wplasticizer+WLiClO4)

Log σ

(S

cm

-1)

ECPC

106

Fig. 1.7(a) Arrhenius plots of ionic conductivity for PVC-Li2SO4-

EC polymer complexes.

-12

-11

-10

-9

-8

-7

-6

2.7 2.8 2.9 3 3.1 3.2 3.3 3.41000/T (K-1)

Log σ

(S

cm

-1)

10-10-8020-10-7030-10-6040-10-50

Fig. 1.7(b) Log conductivity vs. EC concentration of PVC-Li2SO4-

EC polymer electrolytes at different temperatures.

-12

-11

-10

-9

-8

-7

-6

50 55 60 65 70 75 80 85

EC content

Log σ

(S

cm

-1)

303K313K323K333K343K353K

107

Fig. 1.7(c) Log conductivity vs. PVC concentration of PVC-

Li2SO4-EC polymer electrolyte system at various temperatures.

-12

-11

-10

-9

-8

-7

-6

0 5 10 15 20 25 30 35 40 45

PVC concentration

Log σ

(S

cm

-1)

303K313K323K333K343K353K

Fig. 1.8(a) Plot of log conductivity vs. reciprocal temperature for

(a) Pure PVC-EC, (b) PVC-EC-KBrO3 (70-25-5), (c) PVC-EC-

KBrO3 (65-25-10), (d) PVC-EC-KBrO3 (60-25-15)

-8

-7.5

-7

-6.5

-6

-5.5

-5

-4.5

-4

-3.5

-3

-2.5

-2

2.6 2.8 3 3.2 3.4 3.61000/T (K-1)

Log σ

(S

cm

-1)

abcd

108

Fig. 1.8(b) Plots of Log conductivity vs composition for PVC-

KBrO3-EC plasticized polymer electrolyte system at various

temperatures.

-8

-7

-6

-5

-4

-3

-2

0 2 4 6 8 10 12 14 16

KBrO3 (w t%)

Log σ

(S

cm

-1)

303313323333343348353

Fig. 1.9(a) Temperature dependence of the conductivities of PVC-

EC-PC-LiClO4 plasticized polymer electrolyte systems.

-5

-4.5

-4

-3.5

-3

-2.5

-2

2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5

1000/T (K-1)

Log σ

(S

cm

-1)

30-35-30-530-32-28-1030-30-25-15

109

Fig. 1.9(b) Plots of log conductivity vs. reciprocal temperature of

PVC-EC-PC-LiClO4 polymer electrolyte system.

-5

-4.5

-4

-3.5

-3

-2.5

-2

5 7 9 11 13 15 17LiClO4 salt (%)

Log σ

(S

cm

-1)

303K313K323K333K343K348K353K

Fig. 1.10(a) Log conductivity vs. EC content of PVC-LiClO4-LiBF4

(70-15-15) system at room temperature.

-5.3

-5.26

-5.22

-5.18

-5.14

-5.1

0 10 20 30 40 50 60 70EC content (%)

Log σ

(S

cm

-1)

110

Fig. 1.10(b) Log conductivity vs. PC content of PVC-LiClO4-LiBF4

(70-15-15) system at room temperature.

-5.3

-5.26

-5.22

-5.18

-5.14

-5.1

0 10 20 30 40 50 60 70 80

PC content (%)

Lo

g σ

(S

cm

-1)

Fig. 1.11 Arrhenius plot of conductivity of PVC-ZnO-LiClO4 (60-25-

15) with 25 wt% ZnO.

-7.4

-7.2

-7

-6.8

-6.6

-6.4

-6.2

-6

2.8 2.9 3 3.1 3.2 3.3 3.4

1000/T (K-1)

Log σ

(S

cm

-1)

111

Fig. 1.12(a) Log conductivity vs. reciprocal temperature for PVC-

Li2SO4-EC-ZrO2 complex polymer electrolyte system with (a) 0% (b)

6% (c) 12% (d) 18% of ZrO2.

-10.2

-9.6

-9

-8.4

-7.8

-7.2

-6.6

-6

-5.4

-4.8

-4.2

2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.51000/T (K-1)

Log σ

(S

cm

-1)

abcd


Li2SO4-EC polymer electrolyte system at different

temperatures.

-11

-10

-9

-8

-7

-6

-5

0 5 10 15 20ZrO2 (w t%)

Log σ

(S

cm

-1)

303K313K323K333K343K348K353K

112

Fig. 1.13(a) Arrhenius plot of log conductivity against

reciprocal temperature for PVC-LiClO4-EC-ZrO2 polymer

complexes.

-9

-8

-7

-6

-5

-4

-3

-2

2.7 2.8 2.9 3 3.1 3.2 3.3 3.41000/T (K-1)

Log σ

(S

cm

-1)

30-5-65-030-5-60-530-5-55-1030-5-50-1530-5-45-20

Fig. 1.13(b) Plot of log conductivity vs. composition of PVC-LiClO4-EC-ZrO2 at various temperatures.

-9

-8

-7

-6

-5

-4

-3

-2

0 5 10 15 20 25ZrO2 (w t%)

Log σ

(S

cm

-1)

303K313K323K333K343K353K

113

Fig. 1.14(a) Plot of log conductivity against reciprocal temperature for pure PVC and PVC doped with activated

charcoal.

-15

-14

-13

-12

-11

-10

-9

-8

2.7 2.8 2.9 3 3.1 3.2 3.3 3.4

1000/T (K-1)

Log σ

(S

cm

-1)

Pure PVC0.6%CB1% CB1.5%CB

Fig. 1.14(b) Plots of log conductivity vs. composition of PVC doped with CB.

-15

-14

-13

-12

-11

-10

-9

-8

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6CB (%)

Log σ

(S

cm

-1)

303K313K323K333K343K348K353K

114

Fig. 1.15(a) Log conductivity vs. reciprocal temperature for (a)

Pure (PVC-PMMA), (b) PVC-PMMA-NaClO4 (70-25-5), (c) PVC-

PMMA-NaClO4 (67-23-10), (d) PVC-PMMA-NaClO4 (65-20-15)

-8

-7.5

-7

-6.5

-6

-5.5

-5

2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.51000/T (K-1)

Log

σ (

S c

m-1)

abcd


PMMA-NaClO4 polymer electrolyte system at various

temperatures.

-8

-7.5

-7

-6.5

-6

-5.5

-5

0 2 4 6 8 10 12 14 16

NaClO4 (w t%)

Log

σ (

S c

m-1)

303K313K323K333K343K348K353K

115

Fig. 1.16(a) Arrhenius plot of log conductivity against reciprocal

temperature for PVC-PMMA-LiClO4 polymer electrolyte

systems.

-9

-8

-7

-6

-5

-4

-3

2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.51000/T (K-1)

Log σ

(S

cm

-1)

60-30-1055-25-2050-20-3045-15-40

Fig. 1.16(b) Log conductivity vs. composition of PVC-PMMA-

LiClO4-EC polymer electrolyte system.

-9

-8

-7

-6

-5

-4

-3

10 15 20 25 30 35 40 45 50

Salt concentration

Log σ

(S

cm

-1)

303K313K323K333K343K353K

116

Fig. 1.16(c) Log conductivity vs. PVC content of PVC-

PMMA-LiClO4-EC polymer electrolyte system.

-9

-8

-7

-6

-5

-4

-3

40 45 50 55 60 65

PVC content

Log σ

(S

cm

-1)

303K313K323K333K343K353K

Fig. 1.17 Ionic Conductivity of the electrolytes as a function of PVC/PMMA blend ratio. (EC=70%)

-7

-6.5

-6

-5.5

-5

-4.5

-4

-3.5

-3

-2.5

-2

-20 0 20 40 60 80 100 120

PMMA blend content (%)

Log σ

(S

cm

-1)

20Ċ30Ċ40Ċ50Ċ60Ċ

117

Fig. 1.18 Ionic conductivity of the electrolytes as a function of plasticizer content for the blend of PVC/PMMA.

(PVC/PMMA=5/2)

-8

-7

-6

-5

-4

-3

-2

100 150 200 250 300 350 400

Plasticizer content

Log σ

(S

cm

-1)

20Ċ30Ċ40Ċ50Ċ60Ċ

Fig. 1.19 Arrhenious plot of ionic conductivity for various

plasticizer contents for the blend of PVC-PMMA-EC-LiClO4.

PVC/PMMA=5/2

-8

-7

-6

-5

-4

-3

-2

-1

2.8 2.9 3 3.1 3.2 3.3 3.4 3.51000/T (K-1)

Log σ

(S

cm

-1)

50%55%60%65%70%

118

Fig. 1.20(a) Arrhenius plot of log conductivity against reciprocal


systems.

-6.5

-6

-5.5

-5

-4.5

-4

-3.5

-3

2.7 2.8 2.9 3 3.1 3.2 3.3 3.4

1000/T (K-1)

Log σ

(S

/cm

)20-10-5-6520-10-10-6020-10-15-5520-10-20-50

Fig. 1.20(b) Log conductivity vs. composition of PVC-PMMA-

LiClO4-EC polymer electrolyte system.

-6

-5.5

-5

-4.5

-4

-3.5

5 7 9 11 13 15 17 19 21

Salt concentration

Log σ

(S

/cm

)

303K313K323K333K343K353K

119

Fig. 1.21(a) Arrhenius plot of log conductivity against

reciprocal temperature for PVC-PMMA-LiClO4-EC polymer

electrolyte system.

-8

-7

-6

-5

-4

-3

-2

-1

2.7 2.8 2.9 3 3.1 3.2 3.3 3.4

1000/T (K-1)

Log σ

(S

/cm

)0:30:10:6010:20:10:6020:10:10:6030:0:10:60

Fig. 1.21(b) Log conductivity vs. reciprocal temperature of PVC-

PMMA-LiClO4-EC polymer electrolyte system at various

temperature.

-8

-7

-6

-5

-4

-3

-2

0 5 10 15 20 25 30 35

PMMA (w t%)

Log

σ (

S/c

m)

303K313K323K333K343K353K

120

Fig. 1.22(a) Variation of conductivity with plasticizer content for

PVC-PMMA-EC-LiClO4 polymer electrolyte systems.

-6.5

-6

-5.5

-5

-4.5

-4

-3.5

-3

-2.5

-2

50 55 60 65 70 75 80Plasticizer content (wt%)

Lo

g σ

(S

/cm

)25Ċ35Ċ45Ċ65Ċ

Fig. 1.22(b) Variation of conductivity with plasticizer content for

PVC-PMMA-EC-NaClO4 polymer electrolyte systems.

-7

-6.5

-6

-5.5

-5

-4.5

-4

-3.5

-3

50 55 60 65 70 75 80

Plasticizer Content (w t%)

Log σ

(S

/cm

)

25Ċ35Ċ45Ċ65Ċ

121

Fig. 1.22(c) Variation of conductivity for PVC-PMMA-EC-LiClO4

polymer electrolyte with different polymer blend ratio.

-6.5

-6

-5.5

-5

-4.5

-4

-3.5

-3

-2.5

-20 0 20 40 60 80 100PMMA blend ratio (%)

Log σ

(S

/cm

)

25Ċ35Ċ45Ċ65Ċ

Fig. 1.22(d) Variation of conductivity with plasticizer content for

PVC-PMMA-EC-NaClO4 polymer electrolyte systems.

-10

-9

-8

-7

-6

-5

-4

-3

-2

-20 0 20 40 60 80 100

PMMA blend ratio (%)

Log σ

(S

/cm

)

25Ċ35Ċ45Ċ65Ċ

122

Fig. 1.22(e) Effect of temperature on ionic conductivity of PVC-

PMMA-EC-LiClO4 polymer electrolyte systems.

-7

-6.5

-6

-5.5

-5

-4.5

-4

-3.5

-3

-2.5

-2

2.9 3 3.1 3.2 3.3 3.4 3.51000/T (K-1)

Log σ

(S

/cm

)30-20-45-525-18-50-720-16-56-810-12-68-10 5-10-75-10 0-15-75-1010 - 5-75-1015 - 0-75-10

Fig. 1.22(f) Effect of temperature on ionic conductivity of PVC-

PMMA-EC-NaClO4 polymer electrolyte systems.

-8

-7

-6

-5

-4

-3

-2

2.95 3.05 3.15 3.25 3.35

1000/T (K-1)

Lo

g σ

(S

/cm

)

30-20-45-525-18-50-720-16-56-810-12-68-10 5-10-75-10 0-15-75-1010 - 5-75-10

123

Fig. 1.23 Arrhenius plot of PVC-PMMA-LiX-PC (20-10-10-60 wt%) complexes.

-3.5

-3.3

-3.1

-2.9

-2.7

-2.5

-2.3

-2.1

-1.9

2.85 2.9 2.95 3 3.05 3.1 3.15 3.2 3.25 3.3 3.35

1000/T (K-1)

Log σ

(S

/cm

)PVC-PMMA-NaClO4-PCPVC-PMMA-LiClO4-PCPVC-PMMA-LiBF4-PC

Fig. 1.24(a) Arrhenius plot of PVC-PMMA-LiClO4-PC complexes

for different concentrations.

-7

-6.5

-6

-5.5

-5

-4.5

-4

-3.5

-3

-2.5

-2

2.8 2.9 3 3.1 3.2 3.3 3.4

1000/T (K-1)

Log σ

(S

/cm

)

42-22 - 4-5026-18 - 6-5028-14 - 8-5030-10-10-50

124

Fig. 1.24(b) Log conductivity vs. salt concentration of PVC-

PMMA-LiClO4-PC polymer electrolyte systems at different

temperatures.

-7

-6.5

-6

-5.5

-5

-4.5

-4

-3.5

-3

4 5 6 7 8 9 10 11

Salt concentration

Log σ

(S

/cm

)

303313323333343

Fig. 1.24(c) Log conductivity vs. PVC content of PVC-PMMA-

LiClO4-PC polymer electrolyte systems at various temperatures.

-7

-6.5

-6

-5.5

-5

-4.5

-4

-3.5

-3

20 25 30 35 40 45

PVC content

Lo

g σ

(S

/cm

)

303K313K323K333K343K

125

Fig. 1.25 Arrhenius plot of ionic conductivity for various

PVC/PMMA blend ratio of PVC-PMMA-EC-PC-LiClO4 system.

-7

-6.5

-6

-5.5

-5

-4.5

-4

-3.5

-3

-2.5

-2

-1.5

-1

2.8 2.9 3 3.1 3.2 3.3 3.4

1000/T (K-1)

Lo

g σ

(S

/cm

) 30-0-40-20-10 20-10-40-20-10 10-20-40-20-10 5-25-40-20-10 0-30-40-20-10

Fig. 1.26(a) Plot of conductivity vs.reciprocal temperature for

PVC-PMMA-Li2SO4-EC for complex polymer electrolyte system

containing different content of ZrO2. (a) 0% (b) 5% (c) 10% (d)

15% ZrO2.

-8

-7.5

-7

-6.5

-6

-5.5

-5

2.6 2.8 3 3.2 3.4 3.61000/T (K-1)

Log σ

(S

cm-1)

abcd

126

Fig. 1.26(b) Log conductivity of the PVC-PMMA-Li2SO4-EC

polymer electrolyte system as a function of ZrO2 concentration

at different temperatures.

-8

-7.5

-7

-6.5

-6

-5.5

-5

0 2 4 6 8 10 12 14 16

ZrO2 (wt%)

Lo

g σ

(S

cm-1

)303 K313 K323 K333 K343 K346 K353 K

Fig. 1.27(a) Arrhenius plot of conductivity for PVC-PMMA-EC-

LiClO4 (20-5-65-10 wt%) polymer electrolytes with different

TiO2 concentrations.

-6

-5

-4

-3

-2

-1

0

2.8 2.9 3 3.1 3.2 3.3 3.41000/T (K-1)

Log σ

(S

/cm

)

TiO2(0%)TiO2(6%)TiO2(12%)TiO2(18%)TiO2(24%)

127

Fig. 1.27(b) Log conductivity vs. TiO2 concentration of PVC-

PMMA-EC-LiClO4 polymer electrolyte system at various

temperatures.

-6

-5.5

-5

-4.5

-4

-3.5

-3

-2.5

-2

-1.5

-1

0 5 10 15 20 25 30

TiO2 (w t%)

Log σ

(S

/cm

)

303K313K323K333K343K

Fig. 1.28 Arrhenius plot of log conductivity against reciprocal

temperature of PVC-PEO-LiX (60-30-10). (X=ClO4-, BF4

- )

-7

-6.5

-6

-5.5

-5

-4.5

-4

-3.5

-3

-2.5

-2

2.95 3 3.05 3.1 3.15 3.2 3.25 3.3 3.351000/T (K-1)

Log σ

(S

/cm

)

PVC-PEO-LiClO4PVC-PEO-LiBF4PVC-PEO-NaClO4

128

Fig. 1.29 Arrhenius plot of log of conductivity against reciprocal

temperature for PVC-PEO-EC-LiClO4 polymer electrolyte

systems.

-7

-6.5

-6

-5.5

-5

-4.5

-4

-3.5

-3

2.7 2.8 2.9 3 3.1 3.2 3.3 3.41000/T (K-1)

Log σ

(S

/cm

)30-15-50-530-10-50-1030 - 5-50-15

Fig. 1.30 Arrhenius plot of log conductivity against reciprocal temperature for polymer electrolyte systems containing various

inorganic fillers.

-9

-8

-7

-6

-5

-4

-3

-2

2.7 2.8 2.9 3 3.1 3.2 3.3 3.41000/T (K-1)

Log σ

(S

/cm

)

PVC-PEO-LiClO4-TiO2(50-30-10-10)PVC-PEO-LiClO4-ZnO(50-30-10-10)PVC-PEO-LiClO4-A2lO3(50-30-10-10)PVC-PEO-EC-LiClO4-TiO2(20-10-50-10-10)PVC-PEO-EC-LiClO4-ZnO(20-10-50-10-10)PVC-PEO-EC-LiClO4-Al2O3(20-10-50-10-10)

129

THERMOGRAVIMETRIC AND DIFFERENTIAL

THERMOGRAVIMETRIC ANALYSIS

Two different types of polymer electrolyte systems (systems without inorganic

fillers and systems containing inorganic fillers) have been studied.

4.4 Thermal Studies of Polymer Electrolytes without Inorganic Fillers

Thermogravimetric and differential thermal analysis has been used to

investigate the thermal stability of PVC, PMMA, PVC-PMMA and PVC-PMMA-

EC blend electrolytes containing lithium salt. TG/DTA curves of PVC, PMMA,

blend films PVC/PMMA without plasticizer and films containing EC as

plasticizer is shown in Fig. 2.1(a-d) PVC shows thermal decomposition after

533 K temperature because endothermic peak appears after this temperature.

It is shown from Figs. 2.1 (a-d) that no weight loss is observed before 533 K

temperature for PVC which indicates thermal stability of PVC up to 533 K

temperature. TGA curve for PMMA manifests that no endothermic peak can

be observed before 513 K temperature which indicates that PMMA exhibit

stability up to 513 K beyond which it starts decomposition. On the other hand

decomposition starts earlier for the blend film without plasticizer because

endothermic peak is observed at 473 K which is much lower compared to

decomposition temperature of PVC and PMMA. It is found from TGA traces

that the decomposition temperature further decreases up to about 383 K with

the addition of EC as plasticizer into PVC-PMMA blend. The reason of

decrease in decomposition temperature may be that, glass transition

temperature decreases by addition of plasticizer into polymer electrolyte [190].

Fig. 2.2(a) exhibits the effect of Li2SO4 salt on the TG/DTA traces of

complexed polymer electrolyte system of PVC-PMMA-EC-Li2SO4. It is found

130

from Fig. 2.2(a) that very small weight loss is observed at 314-320 K

temperature. This weight loss or endothermic peak may be observed due to

evaporation of moisture absorbed during loading or presence of impurities in

the sample. No more weight loss can be observed from the TGA traces before

irreversible thermal decomposition at about 393 K. The irreversible thermal

decomposition temperature shows decrease by addition of lithium salts which

may be due to availability of Li ions in the polymer electrolyte film [191].

Fig. 2.2(b) shows the TG/DTA curve for the complexed polymer electrolyte

system of PVC-PMMA-EC containing LiClO3 salt. It is observed that TG curve

shows endothermic peak at 316-320 K with very small weight loss which

indicates evaporation of moisture from the polymer electrolyte system. No

other endothermic peak is observed until 388 K at which endothermic peak

indicates weight loss due to irreversible thermal degradation.

Fig. 2.2(c) shows TG/DTA curve for polymer electrolyte PVC-PMMA-EC

containing LiBF4 salt. It is found that an endothermic peak with weight loss of

about 0.6 is observed at 319 K and no other endothermic peak is observed

beyond 100°C because moisture completely evaporated out and thermal

degradation started at about 383 K which causes another endothermic peak.

Similarly Fig. 2.2(d) shows the TG/DTA traces for polymer electrolyte films

containing LiClO4 salt. Fig. 2.2(d) shows an endothermic peak with very small

weight loss at about 323 K. It is observed that endothermic peak starts at 380

K due to thermal decomposition of polymer electrolyte.

Therefore complexed polymer blend electrolytes containing LiClO4 salt are

suitable for battery operations up to 100°C while polymer electrolytes

complexed with LiBF4 can be used for battery operations only up to 85°C.

131

4.5 Thermal Studies of Polymer Electrolytes containing Inorganic Fillers

PVC-PMMA-LiClO4-EC-TiO2 System

Thermal stability is considered to be very essential property of polymer

electrolyte systems to make it useful in lithium batteries in order to ensure

safety when it is operated at elevated temperatures. TG/DTA analysis is used

to ascertain the thermal stability of polymer electrolyte systems containing

lithium salt. Figs. 2.3(a-e) show the effect of addition of TiO2 at various

concentrations on the thermogravimetric and differential thermal analysis.

Differential thermal analysis curves for all the samples observed a broad

endothermic peak around 325 K. These endothermic peaks may be observed

due to the evaporation of moisture at low temperatures which may be

absorbed due to the presence of impurities in these complexed polymer

electrolyte systems. Differential thermal analysis curves in Figs. 2.3(a-e) for

polymer electrolyte systems containing 0, 5, 10, 15 and 20 wt% of TiO2

manifests a broad exothermic peak at 503, 508, 513, 523 and 543 K,

respectively. Thermogravimetric analysis curves for these samples shows a

gradual weight loss up to 500, 505, 510, 520 and 540 K, while above these

temperatures TGA curves show rapid weight loss for these samples. This

rapid weight loss is due to the degradation of the polymer electrolyte system.

This rapid weight loss is found consistent with the result of differential thermal

analysis. It is found that degradation temperature exhibits increase with the

increase in concentration of TiO2 in complexed polymer electrolyte systems.

The increase in degradation temperature of these polymeric systems may be

due to the improvement in thermal stability with the addition of TiO2. It is found

that these polymer electrolyte systems exhibit stability up to about 510 K

temperature beyond which these samples shows degradation. It is found that

132

samples containing 15% and 20% wt of TiO2 exhibits maximum thermal

stability which may be due to the presence of high concentration of TiO2. The

temperature at which samples containing 15% and 20% TiO2 decomposes is

523 and 543 K respectively. Therefore it can be concluded that sample

containing 20% of TiO2 is superior compared to the other samples from the

thermal stability point of view.

PVC-PMMA-LiClO4-EC-Al2O3 System Figs. 2.4(a-d) show the influence of

variation of Al2O3 content on thermogravimetric and differential thermal

analysis of complexed polymer electrolyte system of PVC-PMMA-LiClO4-EC.

Differential thermal analysis of all different samples of these polymer

electrolyte systems shows broad endothermic peaks at low temperature.

These peaks may be appears due to the evaporation of moisture which may

be present in polymer electrolyte systems due to absorption by impurities in

polymer electrolytes or absorbed during sample loading [192]. Differential

thermal analysis traces in Figs. 2.4(a-d) shows a broad exothermic peak at

528, 538, 543, 548 and 566 K for samples of complexed solid polymer

electrolytes containing 0, 5, 10, 15 and 20% of Al2O3 respectively.

Thermogravimetric analysis traces in Figs. 2.4(a-d) for these complexed

polymer electrolyte systems exhibits a gradual weight loss up to 525, 533,

540, 543 and 560 K respectively. While above these temperatures TGA traces

show rapid weight loss for all different samples of the polymer electrolyte

system PVC-PMMA-LiClO4-EC. The sharp sudden variation in TG traces due

to rapid weight loss is found consistent with the result of DTA.

Thermogravimetric and differential thermal analysis curves in Figs. 2.5(a-e)

shows the effect of variation of concentration of ZrO2. It is found that at low

133

temperatures (350-470 K) Differential thermal analysis curves for all these

complexed polymer electrolyte systems exhibit two broad endothermic peaks.

These endothermic peaks may be observed due to the evaporation of

moisture at low temperatures which may be absorbed during loading of

samples or due to the presence of impurities in these complexed polymer

electrolyte systems. Differential thermal analysis curves in Figs. 2.5(a-e) for

polymer electrolyte systems containing 0, 5, 10, 15 and 20 wt% of ZrO2 shows

a broad exothermic peak at 535, 543, 548, 553 and 588 K, respectively.

Thermogravimetric analysis curves for these polymeric electrolyte system

shows a gradual weight loss up to 530, 540, 545, 550 and 580 K. while above

these temperatures TGA curves show rapid weight loss for these samples.

This rapid weight loss is due to the degradation of the polymer electrolyte

system. This rapid weight loss is found consistent with the result of differential

thermal analysis. Figs. 2.5(a-e) reveal that with the increase in content of ZrO2

in complexed polymer electrolyte systems degradation temperature also

increases. The increase in degradation temperature of these polymeric

systems may be due to the improvement in thermal stability with the addition

of ZrO2. It is investigated that these polymer electrolyte systems shows

stability up to about 515 K temperature while above this temperature these

polymer electrolyte samples shows thermal degradation.

134

Fig. 2.1(a) DTA and TGA scans of PVC

60

65

70

75

80

85

90

95

100

105

110

0 50 100 150 200 250 300 350

Temperature (°C)

Wei

ght%

-2

-1

0

1

2

3

4

5

6

7

8

Mic

roV

olt

TG

DTA

Fig. 2.1(b) DTA and TGA scans of PMMA

20

30

40

50

60

70

80

90

100

110

0 50 100 150 200 250 300 350

Temperature (°C)

We

igh

t%

-4

-2

0

2

4

6

8

10

12

Mic

roV

olt

TG

DTA

135

Fig. 2.1(c) DTA and TGA scans of PVC-PMMA

25

35

45

55

65

75

85

95

105

0 50 100 150 200 250 300 350 400 450

Temperature (°C)

We

igh

t%

-2

0

2

4

6

8

10

12

Mic

roV

olt

TG

DTA

Fig. 2.1(d) DTA and TGA scans of polymer complex PVC-PMMA-EC

40

50

60

70

80

90

100

110

0 50 100 150 200 250 300 350 400 450 500

Temperature (°C)

Wei

ght%

-1

1

3

5

7

9

11

Mic

roV

olt

TG

DTA

136

Fig. 2.2(a) DTA and TGA scans of polymer complex PVC-

PMMA-EC-LiSO4 (20-10-60-10 wt%)

75

80

85

90

95

100

105

0 50 100 150 200 250 300

Temperature (°C)

Wei

ght%

-1

-0.5

0

0.5

1

1.5

2

2.5

3

Mic

roV

olt

TG

DTA

Fig. 2.2(b) DTA and TGA scans of polymer complex PVC-

PMMA-EC-LiClO3 (20-10-60-10 wt%)

75

80

85

90

95

100

105

0 50 100 150 200 250 300

Temperature (°C)

Wei

ght%

0

0.5

1

1.5

2

2.5

3

Mic

roV

olt

TG

DTA

137

Fig. 2.2(c) DTA and TGA scans of polymer complex PVC-

PMMA-EC-LiBF4 (20-10-60-10 wt%)

70

75

80

85

90

95

100

105

0 50 100 150 200 250 300Temperature (°C)

Wei

ght%

0

0.5

1

1.5

2

2.5

3

Mic

roV

olt

TG

DTA

Fig. 2.2(d) DTA and TGA scans of polymer complex PVC-PMMA-EC-LiClO4 (20-10-60-10 wt%)

70

75

80

85

90

95

100

105

0 50 100 150 200 250 300

Temperature (°C)

Wei

ght%

0

0.5

1

1.5

2

2.5

3

Mic

roV

olt

TG

DTA

138

Fig. 2.3(a) DTA and TGA scans of polymer complex PVC-PMMA-

LiClO4-EC (20-5-10-65 wt%) with 0% TiO2.

30

40

50

60

70

80

90

100

110

30 130 230 330 430 530

Temperature (°C)

Wei

ght%

-20

-15

-10

-5

0

5

10

15

20

Mic

rovo

lt

TG

DTA

139

Fig. 2.3(b) DTA and TGA scans of polymer complex PVC-PMMA-


30

40

50

60

70

80

90

100

110

30 130 230 330 430 530

Temperature (°C)

Wei

ght%

-50

0

50

100

150

200

250

300

Mic

rovo

lt

TG

TDA

140

Fig. 2.3(c) DTA and TGA scans of polymer complex PVC-PMMA-

LiClO4-EC (20-5-10-65 wt%) with 10% TiO2.

35

45

55

65

75

85

95

105

30 130 230 330 430Temperature (°C)

Wei

ght%

-50

0

50

100

150

200

250

300

350

Mic

rovo

lt

TG

DTA

141

Fig. 2.3(d) DTA and TGA scans of polymer complex PVC-PMMA-


30

40

50

60

70

80

90

100

110

30 130 230 330 430 530

Temperature (°C)

We

igh

t%

-100

-50

0

50

100

150

200

250

300

350

400

Mic

rovo

lt

TG

DTA

142

Fig. 2.3(e) DTA and TGA scans of polymer complex PVC-PMMA-


25

35

45

55

65

75

85

95

105

30 130 230 330 430 530Temperature (°C)

Wei

ght%

-50

0

50

100

150

200

250

300

350

400

Mic

rovo

lt

TG

DTA

143

Fig. 2.4(a) DTA and TGA scans of polymer complex PVC-PMMA-

LiClO4-EC (20-5-10-65 wt%) with 0% Al2O3.

30

40

50

60

70

80

90

100

110

30 130 230 330 430 530Temperature (°C)

Wei

ght%

-15

-10

-5

0

5

10

15

Mic

rovo

lt

TG

DTA

144

Fig. 2.4(b) DTA and TGA scans of polymer complex PVC-PMMA-


35

45

55

65

75

85

95

105

30 130 230 330 430 530Temperature (°C)

We

igh

t%

-15

-10

-5

0

5

10

15

20

Mic

rovo

lt

TG

DTA

145

Fig. 2.4(c) DTA and TGA scans of polymer complex PVC-

PMMA-LiClO4-EC (20-5-10-65 wt%) with 10% Al2O3.

30

40

50

60

70

80

90

100

110

30 130 230 330 430 530

Temperature (°C)

Weg

ht%

-15

-10

-5

0

5

10

15

20

Mic

rovo

lt

TG

DTA

146

Fig. 2.4(d) DTA and TGA scans of polymer complex PVC-PMMA-


25

35

45

55

65

75

85

95

105

30 130 230 330 430 530

Temperature (°C)

Wei

ght%

-15

-10

-5

0

5

10

15

20

Mic

rovo

lt

TG

DTA

147

Fig. 2.4(e) DTA and TGA scans of polymer complex PVC-

PMMA-LiClO4-EC (20-5-10-65 wt%) with 20% Al2O3.

30

40

50

60

70

80

90

100

110

30 130 230 330 430 530Temperature (°C)

We

igh

t%

-15

-10

-5

0

5

10

15

20

Mic

rovo

lt

TG

DTA

Fig. 2.5(a) DTA and TGA scans of polymer complex PVC-

PMMA-LiClO4-EC (20-5-10-65 wt%) with 0% ZrO2.

30

40

50

60

70

80

90

100

110

30 130 230 330 430 530

Temperature (°C)

Wei

ght%

-15

-10

-5

0

5

10

15

Mic

rovo

ltTG

DTA

148

Fig. 2.5(b) DTA and TGA scans of polymer complex PVC-


25

35

45

55

65

75

85

95

105

30 130 230 330 430 530

Temperature (°C)

Wei

ght%

-15

-10

-5

0

5

10

15

Mic

rovo

lt

TG

DTA

Fig. 2.5(c) DTA and TGA scans of polymer complex PVC-PMMA-LiClO4-EC (20-5-10-65 wt%) with 10% ZrO2.

30

40

50

60

70

80

90

100

110

30 130 230 330 430 530

Temperature (°C)

Wei

ght%

-15

-10

-5

0

5

10

15

Mic

rovo

ltTG

DTA

149

Fig. 2.5(d) DTA and TGA scans of polymer complex PVC-


30

40

50

60

70

80

90

100

110

30 130 230 330 430 530

Temperature (°C)

Wei

ght%

-15

-10

-5

0

5

10

15

Mic

rovo

lt

TG

DTA

Fig. 2.5(e) DTA and TGA scans of polymer complex PVC-


35

45

55

65

75

85

95

105

30 130 230 330 430 530

Temperature (°C)

Weg

ht%

-15

-10

-5

0

5

10

15

20

Mic

ovol

tTG

DTA

150

X-RAY DIFFRACTION STUDIES

Three different polymer electrolyte systems (Pure PVC based systems, PVC-

PMMA blend systems and PVC-PEO blend systems) have been subjected to

X-ray Diffraction studies.

4.6 X-ray Diffraction Studies of Pure PVC based Polymer Electrolytes

XRD studies have been performed in order to investigate the effect of sodium

salt on the structure of PVC. Fig. 3.1 shows the XRD patterns of pure PVC,

NaClO4, and PVC complexed with NaClO4 salt. Comparative studies of the

XRD patterns of pure PVC, NaClO4 salt and PVC films complexed with

NaClO4 reveals that peaks observed for 2θ values in pure NaClO4 are more

intense as compared to that in PVC films complexed with NaClO4 salt. This

shows that PVC complexed with NaClO4 are less crystalline compared to that

of NaClO4 salt. The decrease in degree of crystallinity of PVC complexed with

salt is caused by complexation of NaClO4 salt with PVC. The absence of

crystalline peaks corresponding to NaClO4 for 2θ values, in PVC complexed

with NaClO4 shows the absence of any uncomplexed NaClO4 salt in the

complexed polymeric electrolyte system. From all these, it may be confirmed

that complexation of salt has taken place in the amorphous phase.

Fig. 3.1 shows that PVC is almost amorphous and pure NaClO4 is purely

crystalline. The incorporation of NaClO4 in PVC has shown to increase

crystallinity. As we increase salt contents from 10% to 30% NaClO4 in PVC,

the crystallinity is shown to be increasing. This reveals that NaClO4 has been

incorporated in PVC and is complexed with PVC.

X-ray diffraction analysis provides a wide range of information about

crystallinity, phase changes of materials and crystal structure. In the present

151

study X-ray diffraction analysis has been used to confirm amorphous,

crystalline nature and complex formation in the polymer electrolyte films. Fig.

3.2 shows X-ray diffraction pattern of pure PVC, KBrO3 salt and samples

containing different wt% of KBrO3 salt complexed with PVC. Peaks pertaining

to KBrO3 salt are not found in the complex of PVC and KBrO3 salts which

indicates that salt is completely dissolved in the polymer and it may be

confirmed that complexation has been taken place between polymer and salt

in the amorphous phase [193].

Fig. 3.3 presents the XRD patterns for pure PVC, Li2SO4 salt and samples of

PVC complexed with same amount of Li2SO4 salt and different amount of

ethylene carbonate as plasticizer. Fig. 3.3 shows that crystalline peaks for 2θ

values, pertaining to Li2SO4 is not observed in polymer electrolyte films

prepared by complexation of PVC with Li2SO4 salt and ethylene carbonate,

which indicates that any excess salt is not present in polymer electrolyte film

[194]. Therefore it is confirmed that complexation has taken place in the

amorphous phase in polymer electrolyte films.

Fig. 3.4(a-b and c-g) shows XRD patterns of TiO2, pure PVC and complex

polymer electrolytes containing various content of TiO2, respectively. These

complex polymer electrolytes contain 0, 5, 10, 15 and 20 wt% of TiO2. Fig.

3.4(b) shows that PVC exhibit amorphous phase. Fig. 3.4(a) shows that TiO2

exhibit crystalline nature. No sharp peaks can be observed in Fig. 3.4(c-d).

The absence of sharp peaks pertaining to TiO2 and salt in these figures shows

that complexation has taken place in these samples of complex polymer

electrolyte system. Fig. 3.4(e-g) exhibits crystalline peaks, indicating the

presence of undissolved TiO2 in the sample films. Some peaks pertaining to

152

TiO2 and salts are disappears, while some are shifted in Fig. 3.4(e-g) of

complex polymer electrolyte system. The absence and shifting of peaks

shows that some interactions has taken place between the different

constituents of sample films.

The XRD patterns of pure PVC, Li2SO4 salt, ZrO2 and PVC complexed with

different amounts of salt and ZrO2 are presents in Fig. 3.5. The degree of

crystallinity of pure PVC is reduced by the addition of Li2SO4 salt. The

crystalline peaks for 2θ values corresponding to Li2SO4 salt are not present in

complexed PVC polymer electrolyte films. Therefore it may be confirmed that

complexation of salt has taken place in the polymer electrolyte films.

4.7 X-ray Diffraction Studies of PVC-PMMA Blend Polymer Electrolytes

X-ray diffraction studies have been performed in order to investigate the effect

of sodium salt on the structure and confirmation of amorphous, crystalline

nature and complex formation of PVC-PMMA complexed solid polymer blend

electrolyte films. X-ray diffraction patterns for pure PVC, PMMA, NaClO4 salt

and PVC-PMMA solid polymer electrolytes films in which different wt% of

NaClO4 have been added are presents in Fig. 3.6. Amorphous nature of

PMMA and crystalline nature of NaClO4 has been confirmed by comparative

studies of PVC-PMMA solid polymer electrolyte and pure PVC, PMMA and

NaClO4. It is observed that complexed solid polymer blend electrolyte films

shows less intense and slightly displaced peaks for 2θ values as compared to

those in pure PVC films. The decrease in degree of crystallinity while increase

in amorphous nature of complexed solid polymer blend electrolyte films are

caused by addition of NaClO4 salt. It is confirmed by absence of crystalline

peaks for 2θ values that no excess (uncomplexed) NaClO4 salt are present in

153

the complexed solid polymer blend electrolyte films. At higher concentrations

there are no sharp peaks for 2θ values, which indicate presence of dominant

amorphous phase in the complexed solid polymer blend electrolyte films. Ionic

conductivity values are increased due to presence of amorphous phase which

causes increased ionic mobility [195].

X-ray diffraction studies have been performed in order to investigate the

influence of Li salts and ZrO2 on the structure of PVC blend electrolytes. X-ray

diffraction patterns of pure PVC, PMMA, Li2SO4, ZrO2 and complexed solid

polymer blend electrolyte films containing different wt% of ZrO2 are presents

in Fig. 3.7. Crystalline peaks obtained from X-ray diffraction studies manifests

crystalline phase of pure Li2SO4 salt. While complexed solid polymer blend

electrolyte films show complexation in the amorphous phase because no

sharp crystalline peaks pertaining to Li2SO4 are obtained in the X-ray

diffraction patterns of complexes. Absence of sharp crystalline peaks

pertaining to Li2SO4 reveals that no excess (uncomplexd) salts are present in

the polymer electrolyte films [196]. Therefore, it may be confirmed that

complexation between polymer and salt has taken place in the polymer

electrolytes in amorphous phase. X-ray diffraction patterns of complexes

containing ZrO2 reveals undissolved ZrO2 because these electrolyte films

observed sharp crystalline peaks pertaining to ZrO2. It is found from X-ray

diffraction pattern that with increase in wt% of ZrO2 in the polymer electrolyte

films, the crystalline peaks appears more intense. Therefore degree of

crystallinity increases with increase in ZrO2.

154

4.8 X-ray Diffraction Studies of PVC-PEO Blend Polymer Electrolytes

X-ray diffraction studies have been performed in order to investigate the

influence of Li salts on the structure of PVC-PEO blend, to provide information

about complex formation and presence of amorphous, crystalline or

semicrystalline phase in complexed solid polymer electrolyte films. Fig. 3.8

shows X-ray diffraction patterns of pure PVC, PEO, LiX and complex solid

polymer blend electrolyte films. Fig. 3.8 reveals that two distinct crystalline

peaks appear in X-ray diffraction pattern of pure PEO while intensities of

these crystalline peaks of 2θ values, pertaining to PEO, reduces in complex

solid polymer blend electrolyte films containing Li salts. Fig. 3.8 indicates

complete dissolution of Li salts in the polymer matrix because crystalline

peaks corresponding to Li salts are not found in the X-ray diffraction patterns

of complex solid polymer electrolyte films. The decrease in the intensities of

sharp crystalline peaks at higher concentrations of Li salts manifests presence

of amorphous phase in solid polymer electrolyte films which results in

increased ionic conductivity values due to increased ionic mobility in

amorphous phase [197]. It also indicates that no excess (uncomplexed) salts

are present in the solid polymer electrolyte films. Therefore it may be

confirmed that complexation has taken place in the amorphous phase

between polymer and salts.

155

Fig. 3.1 XRD patterns of (a) PVC (b) 10% PVC/NaClO4 (c) 20% PVC/NaClO4 (d) 30% PVC/NaClO4 (e) NaClO4

3 13 23 33 43 53 63 73

2 θ (degree)

Inte

nsity

(ar

b.un

it)

(e) NaClO4

(d) 30% PVC/NaClO4

(c) 20% PVC/NaClO4

(b) 10% PVC/NaClO4

(a) PVC

156

Fig. 3.2 XRD patterns of (a) Plasticized PVC (b) KBrO3 (c) Plasticized PVC-KBrO3

(95-5) (d) Plasticized PVC-KBrO3 (85:15) (e) Plasticized PVC-KBrO3 (75:25)

0 10 20 30 40 50 60 70 80 90

2 θ (degree)

Inte

nsity

(ar

b.un

it)

(a) Plasticized PVC

(b) KBrO3

(c) Plasticized PVC-KBrO3 (95-5)

(d) Plasticized PVC-KBrO3 (85:15)

(e) Plasticized PVC-KBrO3(75:25)

157

Fig. 3.3 XRD patterns of (a) Pure PVC (b) Li2SO4 (c) PVC-Li2SO4-EC (10-10-80) (d) PVC-Li2SO4-EC (20-10-70) (e) PVC-Li2SO4-EC (30-10-60) (f) PVC-Li2SO4-EC (40-

10-50)

2 θ (degree)

Inte

nsity

(ar

b.un

it)

a

b

d

c

e

f

158

Fig. 3.4 XRD patterns of (a) TiO2 (b) PVC (c) PVC-LiClO4-EC (20-10-70) (d) PVC-LiClO4-EC-TiO2 (20-10-65-5) (e) PVC-LiClO4-EC-TiO2 (20-10-60-10) (f) PVC-LiClO4-

EC-TiO2 (20-10-55-15) (g) PVC-LiClO4-EC-TiO2 (20-10-50-20)

0 10 20 30 40 50 60 70 80

2 θ (degree)

Inte

nsity

(ar

b.un

it)

(a) TiO2

(b) PVC

(c) PVC-LiClO4-EC (20-10-70)

(d) PVC-LiClO4-EC-TiO2 (20-10-65-5)

(e) PVC-LiClO4-EC-TiO2 (20-10-60-10)

(f) PVC-LiClO4-EC-TiO2 (20-10-55-15)

(g) PVC-LiClO4-EC-TiO2 (20-10-50-20)

159

Fig. 3.5 XRD patterns of (c) XRD pattern for ZrO2 (d) PVC-Li2SO4-DBP-ZrO2 (0) (e) PVC-Li2SO4-DBP-ZrO2 (6) (f) PVC-Li2SO4-DBP-ZrO2 (12) (g) PVC-Li2SO4-DBP-ZrO2

(18)

0 10 20 30 40 50 60 70 80 90

2 θ (degree)

Inte

nsity

(ar

b.un

it)

(c) XRD pattern for ZrO2.

(d) PVC-Li2SO4-DBP-ZrO2 (0)

(e) PVC-Li2SO4-DBP-ZrO2 (6)

(f) PVC-Li2SO4-DBP-ZrO2 (12)

(g) PVC-Li2SO4-DBP-ZrO2 (18)

160

Fig. 3.6 XRD patterns of PVC (b) Pure PMMA (c) PVC-PMMA-NaClO4 (60:35:5) (d) PVC-PMMA-NaClO4 (60:30:10) (e) PVC-PMMA-NaClO4 (60:25:15)

0 10 20 30 40 50 60 70 80 90

2 θ (degree)

Inte

nsity

(ar

b.un

it)

(c) PVC-PMMA-NaClO4 (60:35:5)

PVC

(b) Pure PMMA

(d) PVC-PMMA-NaClO4 (60:30:10)

(e) PVC-PMMA-NaClO4 (60:25:15)

161

Fig. 3.7 XRD patterns of (e) PVC-PMMA-Li2SO4-DBP-ZrO2 (15:15:10:60:0)

(f) PVC-PMMA-Li2SO4-DBP-ZrO2 (15:15:10:50:10) (g) PVC-PMMA-Li2SO4-

DBP-ZrO2 (15-15-10-45-15) (h) PVC-PMMA-Li2SO4-DBP-ZrO2

(15:15:10:40:20)

0 10 20 30 40 50 60 70 80 90

2 θ (degree)

Inte

nsity

(ar

b.un

it)

(e) PVC-PMMA-Li2SO4-DBP-ZrO2 (15:15:10:60:0)

(f) PVC-PMMA-Li2SO4-DBP-ZrO2 (15:15:10:50:10)

(g) PVC-PMMA-Li2SO4-DBP-ZrO2 (15-15-10-45-15)

(h) PVC-PMMA-Li2SO4-DBP-ZrO2 (15:15:10:40:20)

162

Fig. 3.8 XRD patterns (a) PVC (b) PEO (c) LiClO4 (d) LiBF4

(e) PVC-PEO-LiClO4 (60-30-10) (f) PVC-PEO-LiBF4 (60-30-10)

0 10 20 30 40 50 60 70 80

2 θ (degree)

Inte

nsity

(ar

b.un

it)

(a) PVC

(c) LiClO4

(d) LiBF4

(f) PVC-PEO-LiBF4 (60-30-10)

(e) PVC-PEO-LiClO4 (60-30-10)

163

MECHANICAL STUDIES

4.9 Mechanical Properties of PVC-PEO Blend System

Three different polymer electrolyte systems (PVC-PEO blend without

plasticizer, PVC-PEO blend with plasticizer, PVC-PEO blend containing

inorganic filler) have been subjected to mechanical studies.

4.9.1 Mechanical Properties of PVC-PEO System without Plasticizer

Figs. (4.1-4.3) exhibits stress versus strain traces for pure PVC, pure PEO

and PVC-PEO (75:25) blend respectively. Stress vs. strain traces for pure

PVC and PVC-PEO blend shows that values of maximum break strength

obtained for pure PVC are much higher compared to that of PVC-PEO blend

system.

It can be observed from Figs. (4.1-4.3) that both pure polymer and polymeric

blend system demonstrate high values of stress at peak, high values of

elongation but short elongation at peak. It is found that PVC having low values

of elongation at peak and high values of Young’s modulus exhibits more

brittleness and hardness as compared to PEO. Therefore harder and brittle

blends are obtained by addition of PVC into PEO due to increase in the

values of Young’s modulus. It is found that PVC blends containing different

content of PVC have different Young’s modulus values due to variation in

cross linking density between polymeric chains.

Figs. (4.4-4.8) shows Stress versus strain curves of PVC-PEO-LiClO4 polymer

electrolyte systems containing 10%, 15%, 20%, 25% and 30% Li salt

respectively. It is found from the stress-strain analysis that by addition of

LiClO4 salt the mechanical strength of polymer electrolyte system deteriorate.

It can be observed from stress-strain traces that polymer electrolyte

164

containing higher content of salt shows lower stress compared to polymer

electrolyte containing lesser content of salt for the same strain.

Figs. (4.9-4.11) exhibits the effect of LiClO4 salt content on the Young’s

modulus, stress at peak and elongation at peak in polymer blend electrolyte

system of PVC-PEO-LiClO4 respectively. It is observed from Figs. (4.9-4.10)

that incorporation of LiClO4 salt into polymer electrolyte system causes

decrease in the Young’s modulus and stress at peak values which may be

due to the intramolecular interaction of Li ions with polymer matrix instead of

intermolecular while elongation at peak values increase by incorporation of

salt. The content of salt in PVC-PEO polymer electrolyte controls the

mechanical strength by interaction with polymer chains.

It is found that incorporation of LiClO4 salt into PVC-PEO polymer electrolyte

system causes decrease in crystallinity because results reveals that addition

of salt decreases Young’s modulus and stress at peak values while increase

of elongation at peak values. Therefore amorphous behavior of polymer

electrolytes increases by addition of salt because polymers with lower

Young’s modulus lower stress at peak value and high elongation value

exhibits low degree of crystallinity and cross-linking [198].

4.9.2 Mechanical Properties of PVC-PEO Polymer Electrolytes with

Plasticizer

Figs. 4.12 and 4.13 present the influence of EC as single and EC-PC as

double plasticizers on the mechanical strength of PVC-PEO-LiClO4

complexed polymer electrolyte system. It is observed that Young’s modulus

and stress at peak values decreases by incorporation of low molecular weight

plasticizers into complexed polymer electrolyte system while elongation at

peak reveals that elasticity decreases by addition of plasticizer into complexed

165

polymer electrolyte system. Strong electrostatic attractive forces are involved

between chlorine and hydrogen atoms of different polymeric chains in PVC

which results its higher strength and hardness. Therefore incorporation of

plasticizers such as EC or PC acts to reduce its viscosity, Young’s modulus

and glass transition temperature thereby improved flexibility due to decrease

in intermolecular interactions of PVC. It is observed that plastic strain shows

increase by incorporation of plasticizer into polymer electrolyte systems

thereby these systems can easily stretched and exhibits plastic like behavior.

The improved plastic strain may be due to increase in flow rate and decrease

in viscosity by addition of plasticizers into polymer electrolyte systems.

Conclusion Mechanical strength of the complexed polymer electrolyte

systems deteriorate by addition of LiClO4 salt. By incorporation of LiClO4 salt

Young’s modulus values shows decrease which may be due to the

intramolecular interaction due to Li salt. While by addition of plasticizer such

as EC or PC flexibility of complexed polymer electrolyte system shows

increase due to decrease in intramolecular attraction involved between

polymer chains. The mechanical strength of plasticized polymer electrolyte

systems exhibits improvement by incorporation of silica as filler particles.

4.9.3 Mechanical Properties of PVC-PEO Polymer Electrolytes

containing Inorganic Filler

The influence of silica content on the Young’s modulus values is shown in Fig.

4.14. Mechanical properties of polymer electrolytes can be improved by

incorporation of small sized particles. Mechanical properties improved due to

chemical modification of the polymer. Chemical modification of the polymer

depends on the degree of polymer-filler interaction. Fig. 4.14 reveals that

mechanical strength of polymer electrolyte exhibit improvement with

166

incorporation of silica into complex polymer electrolyte system PVC-PEO-

LiClO4-EC-PC. The improvement in mechanical strength of complexed

polymer electrolyte system may be due to the reason that filler particles

dispersed uniformly and lodge themselves between the phases at the

interfaces of blend polymer electrolyte system [199] thereby reducing flexibility

of complexed polymer electrolytes.

4.10 Mechanical Properties of PVC-PMMA Blend Polymer Electrolyte

Systems with Plasticizer

Figs. 4.15 and 4.16 present variation of modulus and tensile strength of PVC-

PMMA bend polymer electrolyte system with PMMA content. It is found that

modulus and tensile strength of polymer electrolyte exhibit decrease with

initial increase in concentration of PMMA while beyond 15% concentration of

PMMA both these parameters shows increase. Variation of mechanical

properties with PMMA content can be explained on basis of interactions such

as Hydrogen bonding or dipole-dipole forces which are involved between

polymer chains of blend polymer electrolyte system. It is considered that the

improved mechanical properties may be due to the presence of hydrogen

bond which involved between α-hydrogen of vinyl chloride repeating unit of

PVC and ester carboxylate group of PMMA. The behavior of these

parameters is due to increase in plasticization of PVC polymer by

incorporation of rigid PMMA which enhances the function of plasticizer EC.

The increase in plasticization of PVC by incorporation of PMMA may be due

to be fact that PMMA throws apart polymeric chains of PVC because PMMA

is very rigid with bulky molecular structure. Therefore plasticizer EC are

comparatively more effective in the presence of PMMA thereby reducing the

intermolecular interactions involved between vinyl chloride repeating unit and

167

hydrogen of different PVC molecules. It is found that above 15% of PMMA

content further addition of PMMA exhibits reverse influences on PVC. When

PMMA content increases above 15%, then both these parameters show

increase. It is observed that initially the effect of PMMA on both these

parameters is more pronounced while gradually the effect of concentration of

PMMA decreases. The role of PMMA to improve the mechanical properties

may be attributed to its rigid behavior [200].

It is found from Fig. 4.17 that elongation at break shows increase up to about

15% of PMMA concentration while beyond which it become decreases. This

parameter always shows higher values compared to unmodified plasticized

PVC. PVC shows ductile response to loading due to its deformation after

addition of PMMA.

Conclusions It is found from Mechanical studies that mechanical properties

exhibit improvement by incorporation of PMMA in to PVC. The addition of

PMMA into matrix of PVC, have marked effect on the modulus and tensile

strength.

168

Fig. 4.1 Stress versus strain curve for pure PVC.

-1

0

1

2

3

4

5

0 1 2 3 4 5 6 7 8 9 10

% Strain

Str

ess

kgf/

mm

2

Fig. 4.2 Stress versus strain curve for pure PEO.

-0.1

0.1

0.3

0.5

0 2 4 6 8 10 12 14

% Strain

Str

ess

kgf/m

m2

169

Fig. 4.3 Stress versus strain curve for PVC:PEO (75:25) blend polymer system.

0

0.5

1

1.5

2

2.5

0 2 4 6 8 10 12% Strain

Str

ess

kgf/m

m2

Fig. 4.4 Stress-strain curve for PVC-PEO:LiClO4 (90:10) blend


0

0.2

0.4

0.6

0.8

1

1.2

0 5 10 15 20 25% Strain

Str

ess

kgf/m

m2

170

Fig. 4.5 Stress versus strain curve for PVC-PEO:LiClO4 (85:15)

blend polymer electrolyte system

-0.5

0.5

1.5

2.5

0 2 4 6 8 10 12 14 16 18 20 22 24

% Strain

Str

ess

kgf/m

m2



0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 5 10 15 20 25% Strain

Str

ess

kgf/m

m2

171



0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 5 10 15 20 25% Strain

Str

ess

kgf/m

m2

Fig. 4.8 Stress versus strain curve for PVC-PEO:LiClO4 (70:30)


-0.5

-0.3

-0.1

0.1

0.3

0.5

0.7

0.9

1.1

1.3

1.5

0 5 10 15 20 25 30

% Strain

Str

ess

kgf/m

m2

172

Fig. 4.9 Variation of Young,s modulus values in PVC-PEO blend

with respect to LiClO4 salt.

0

1

2

3

4

5

6

0 10 20 30 40 50% of Salt

You

ng,s

mod

ulus

Fig. 4.10 Variation of stress at peak values in PVC-PEO blend

with respect to LiClO4 salt.

0

5

10

15

20

25

0 10 20 30 40 50% of Salt

Str

ess

at p

ea

k(M

pa

)

173

Fig. 4.11 Variation of elongation at peak values in PVC-PEO

blend with respect to LiClO4 salt.

0

1

2

3

4

5

6

0 10 20 30 40 50% of Salt

Elo

ngat

ion

at p

eak

(m

m)

Fig. 4.12 Stress-strain curve for PVC-PEO-LiClO4-EC blend


-0.01

-0.005

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0 100 200 300 400 500

Percent strain

Str

ess

Kg

f/mm

2

174

Fig. 4.13 Stress-strain curve for PVC-PEO-LiClO4-EC-PC blend


-0.005

0

0.005

0.01

0.015

0 50 100 150 200 250

Percent Strain

Str

ess

kgf/m

m2

Fig. 4.14 Variation of Young,s modulus with respect to silica content in PVC-PEO complexes.

0

0.001

0.002

0.003

0.004

0 2 4 6 8 10 12 14% of SiO2

youn

g,s

mod

ulus

(M

Pa)

175

Fig. 4.15 Variation of modulus with blend composition of

PVC-PMMA-LiClO4-EC blend polymer electrolyte system.

0

10

20

30

40

50

60

0 10 20 30 40 50 60Composition (% PMMA)

Mo

du

lus

(MP

a)

Fig. 4.16 Variation of tensile strength with blend composition of PVC-

PMMA-LiClO4-EC blend polymer electrolyte system.

0

5

10

15

20

25

0 10 20 30 40 50 60

Composition (% PMMA)

Ten

sile

str

engt

h (M

Pa)

176

Fig. 4.17 Variation of percent elongation at break with

blend composition of PVC-PMMA-LiClO4-EC polymer

electrolyte system.

0

50

100

150

200

250

300

350

400

0 10 20 30 40 50 60

Composition (% PMMA)

Elo

ng

atio

n a

t bre

ak

177

SCANNING ELECTRON MICROSCOPY

Two types of polymer electrolyte systems (systems without inorganic fillers

and systems containing inorganic fillers) have been subjected to scanning

electron microscopy.

4.11 Scanning Electron Microscopy of Polymer Electrolytes without

Inorganic Filler

Figs. 5.1(a-e) shows the SEM micrographs of pure PVC and PVC blended

with PMMA. It is observed from SEM micrographs that surface morphology of

pure PVC is different compared from its blends with PMMA of various

composition. The microcharacteristics of surface of pure PVC are similar to

rigid and glassy surface. While blends of PVC with PMMA observe two phase

morphologies but no sharp boundary between these two phases. The

particles of PMMA in the PVC blend films manifests diffused outer surface

which may be due to the weak interaction of PMMA particles and the PVC

matrix. It means that blend consists of two phases but each of these phases

may be mixture of each other [201]. Partial phase mixing are found at the

surface of blends. Phase mixing is observed only at lower concentration of

PMMA while at higher concentration of PMMA we have not found any phase

mixing in the PVC blend. Polymer blends containing higher concentration of

PMMA observe regular structure results in higher values of modulus and

Tensile strength while lower values of elongation. Blend films containing lower

concentration of PMMA shows less denser distribution as compared to the

PVC blend containing higher concentration of PMMA in the PVC matrix.

Figs. 5.2(a-f) SEM image shows that PVC-PMMA blend film without plasticizer

are transparent. Transparent appearance of the film may be due to the reason

that PVC and PMMA are miscible with each other. While PVC-PMMA blend

178

film containing salt and EC as plasticizer are opaque in appearance which

may be due to the immiscibility of PVC with the plasticizer EC. The

immiscibility of PVC with plasticizer may result in the phase separation of

blend films [202]. It is observed that PMMA can be dissolved very easily in

plasticizer while PVC is not dissolves in the plasticizer.

The PVC-PMMA blend films have been immersed into the plasticizer EC for

24 h and phase structure of the films are studied in order to observe the effect

of plasticizer on the morphology of the blend films. The morphology of the

bend films containing plasticizer are compared to that of without plasticizer. It

is observed that homogeneous PVC-PMMA blends are obtained in the

absence of plasticizer. A clear phase change is found when PVC blended with

PMMA is observed before and after immersion in to the plasticizer EC which

are dried to evaporate the solvent. The plasticizer absorbed into the blend

films due to miscibility with the PMMA while PVC shows immiscibility with

plasticizer therefore it become coagulated from the blend which results in the

development of plasticizer rich phase and PVC rich phase. The pores in the

blend films are developed due to the evaporation of plasticizer by drying [203].

It is observed that morphology of the polymer electrolyte films prepared by

solvent casting method may be affected due to the immiscibility of plasticizer

with PVC [204]. The solvent casting solution becomes more concentrated by

solution casting because THF solvent dissolves all the components of the

casting solution and later evaporates. It is observed that PVC becomes

coagulated with evaporation of THF solvent due to immiscibility between PVC

and plasticizer which causes phase separation [205]. Therefore after

179

complete evaporation of THF solvent from solvent cast solution, two separate

phases, PVC rich-phase and plasticizer rich-phases have been obtained.

SEM images of the polymer electrolyte matrices with various compositions

which have been prepared by solvent casting method are shown in Fig. 5.2(a-

f). These polymer electrolyte films were dried and the incorporated solvent

THF were evaporated. The polymer electrolyte films containing lower

concentration of PMMA content shows large number of very small sized

pores. These small pores are homogeneously distributed. While the polymer

electrolyte films containing higher content of PMMA exhibits larger sized

pores which may be due to the coagulation of PVC during casting of blends

from its solvent [206]. It is found that two phase system consists of PVC

phase and plasticizer phase are obtained provided that PMMA are not

incorporated in to the solvent casting solution. SEM micrograph of these

complexed polymer electrolyte systems shows that large number of pore are

available in these films which may be due to the evaporation of plasticizer

because the sample is dried for SEM analysis [207]. These pores in the

samples may be the sites occupied by the plasticizer before evaporation. It is

found that composition of cast solution determines the rate of phase

separation. The rate of phase separation increases with decrease in PMMA

content and similarly reduces with increase in PMMA concentration due to the

compatibility of PMMA with both PVC and plasticizer [208]. When the driving

force for phase separation is reduced then the salt becomes mainly

distributed in the plasticizer phase due to the slow rate of coagulation of PVC

and phase separation. So it can be concluded that when polymer electrolyte

films are developed from the solutions containing PMMA content then such

180

films consists of plasticizer rich phase which appears in the form of pores in

the SEM micrograph of the samples obtained after drying. It is observed that

both PVC rich phase and plasticizer rich phase contain PMMA. The presence

of PMMA in both phases may be due to the miscibility of PMMA with both

PVC and plasticizer component of polymer electrolyte system [209]. So two

phases plasticizer rich phase and PVC rich phase are developed by solvent

cast method from cast solution containing PMMA and SEM image of the

polymer electrolyte films obtained after evaporation of plasticizer by drying

manifests plasticizer rich phase in the form of pores.

4.12 Scanning Electron Microscopy of Polymer Electrolytes containing

Inorganic Filler

SEM micrographs of PVC based polymer electrolyte with and without filler

particles containing LiClO4 salt is shown in Figs. (5.3-5.5). It can be observed

from micrograph of the PVC-LiClO4 polymer electrolyte without filler particles

(TiO2, Al2O3 or ZrO2) that PVC polymer and LiClO4 salt are smoothly

distributed in the sample. The formation of micro pores observed from cross-

sectional studies may be due to the interaction of polymer and solvent [210].

The SEM micrographs studies of PVC-LiClO4 polymer electrolyte containing

TiO2, Al2O3 and ZrO2 as inorganic filler particles shows various degree of

aggregation of particles depending on its content and the surface of the films

become rougher compare to the samples without any filler particles. The

surface region of these complexed polymer electrolyte films exhibits smooth

distribution of inorganic filler particles. SEM micrographs studies reveals that

spaces available between the polymer matrices is filled by the inorganic filler

particles which are added into these polymer electrolyte systems. It is found

that ionic conductivity increases by addition of inorganic filler particles which

181

are present in the form of micro aggregates in the pores available between

matrices of polymer because these aggregates of filler particles provide a

compensating effect to the transport properties by filling free spaces of

polymer matrices. But the samples of PVC based polymer electrolyte systems

containing more than 20% of inorganic filler particles shows decrease in

electrical conductivity due to the agglomeration of these inorganic filler

particles in polymer matrices which can be observed from SEM micrograph.

The conductivity PVC-LiClO4-EC-ZrO2 (30-5-50-15) polymer electrolyte

system is 7.24 x 10-6 Scm-1 while it decreases to 7.24 x 10-7 S cm-1 in PVC-

LiClO4-EC-ZrO2 (30-5-50-15) polymer electrolyte system. The decrease of

conductivity is only due to increase in concentration of ZrO2. It is found that

with increase in concentration of TiO2, the SEM show more incorporation of

filler. The shape is some what bead like.

Figs. (5.6-5.8) shows SEM photographs of PVC based complexed polymer

electrolyte films containing NaClO4 salt and various contents of inorganic

fillers. Several holes can be observed in the graph which may be either due to

the rapid evaporation of solvent THF which are used in the development of

polymer electrolyte films from the solution or due to rapid penetration of Na+

ions into the PVC matrix [211]. Figs. (5.6-5.8) shows that the surface

morphology of the polymer electrolyte film is similar to the interpenetrating

networks due to its fractured surface. The fractured surface of the sample

films may be due to the deformation of the PVC matrix [212]. Figs. (5.6-5.8)

manifests holes and strings of different sizes on the fractured surface of

complexed polymer electrolyte films containing NaClO4 salt. The formation of

such large number of holes, strings may be due to the deformation of PVC

182

matrix. It is found that polymer electrolyte film without NaClO4 exhibit higher

flexibility compared to the films containing NaClO4 salt. The higher flexibility of

the film may be due to the penetration of Na+ ions into the PVC matrix of

polymer electrolyte [213].

183

Fig. 5.1(a) SEM image of PVC.

Fig. 5.1(b) SEM image of PVC-PMMA-EC (30-5-65) system.

184

Fig. 5.1(c) SEM image of PVC-PMMA-LiClO4 (60-30-10) system.

Fig. 5.1(d) SEM image of PVC-PMMA-NaClO4 (60-30-10) system.

185

Fig. 5.1(e) SEM image of PVC-PMMA-Li2SO4 (60-30-10) system.

Fig. 5.2(a) SEM image of PVC-PMMA-LiBF4 (60-30-10) system.

186

Fig. 5.2(b) SEM image of PVC-PMMA-EC-Li2SO4 (20-10-60-10) system.

Fig. 5.2(c) SEM image of PVC-PMMA-NaClO4-EC (20-5-10-65) system.

187

Fig. 5.2(d) SEM image of PVC-PMMA-EC-LiClO4 (20-10-60-10) system.

Fig. 5.2(e) SEM image of PVC-PMMA-EC-LiClO3 (20-10-60-10) system.

188

Fig. 5.2(f) SEM image of PVC-EC-NaClO4 (30-60-10) system.

Fig. 5.3(a) SEM image of PVC-PMMA-LiClO4-EC (60-20-10-65) with 0% TiO2.

189

Fig. 5.3(b) SEM image of PVC-PMMA-LiClO4-EC (20-5-10-65) with 5% TiO2.

Fig. 5.3(c) SEM image of PVC-PMMA-LiClO4-EC (20-5-10-65) with 10% TiO2.

190

Fig. 5.3(d) SEM image of PVC-PMMA-LiClO4-EC (20-5-10-65) with 20% TiO2.

Fig. 5.4(a) SEM image of PVC-PMMA-LiClO4-EC (20-5-10-65) with 5% Al2O3.

191

Fig. 5.4(b) SEM image of PVC-PMMA-LiClO4-EC (20-5-10-65) with 10%

Al2O3.

Fig. 5.4(c) SEM image of PVC-PMMA-LiClO4-EC (20-5-10-65) with 15%

Al2O3.

192

Fig. 5.4(d) SEM image of PVC-PMMA-LiClO4-EC (20-5-10-65) with 20%

Al2O3.

Fig. 5.5(a) SEM image of PVC-PMMA-LiClO4-EC (20-5-10-65) with 10% ZnO.

193

Fig. 5.5(b) SEM image of PVC-PMMA-LiClO4-EC (20-5-10-65) with 20% ZnO.

Fig. 5.5(c) SEM image of PVC-PMMA-LiClO4-EC (20-5-10-65) with 10% ZrO2.

194

Fig. 5.5(d) SEM image of PVC-PMMA-LiClO4-EC (20-5-10-65) with 20% ZrO2.

Fig. 5.6(a) SEM image of PVC-PMMA-NaClO4-EC (20-5-10-65) with 10%

ZnO.

195

Fig. 5.6(b) SEM image of PVC-PMMA-NaClO4-EC (20-5-10-65) with 20%

ZnO.


TiO2.

196


TiO2.


Al2O3.

197


Al2O3.

Fig. 5.8(c) SEM image of PVC-PMMA-NaClO4-EC (20-5-10-65) with 20%

Al2O3.

198

VISCOMETRIC STUDIES

4.13 Viscometric Studies of PVC and PVC Blend with other Polymers

Figs. (6.1-6.2) shows Huggins plots for two different polymeric systems

PVC/PMMA and PVC/PEO respectively. Relative and reduced viscosities

were obtained for pure and polymer blends from viscometric measurement.

The miscibility of the polymeric systems has been found by using the equation

α = Kblend-K1

where Kblend is the Huggins constant obtained experimentally while K1 is

calculated by using the equation.

kA[η]A2WA

2+kB[η]WB2+2(kAkB)1/2[η]WAWB

k1 = ____________________________________ (WA[η]A+WB[η]B)2

It is found that both polymeric system exhibits positive α values. Positive α

value indicate miscibility due to strong attractive forces, while negative α

values reveals immiscibility due to repulsive forces involved between

polymers [214]. Positive α value of polymeric systems may be due to

attractive forces involved between chlorine atom of PVC and oxygen atoms of

PEO and PMMA, in which oxygen atoms of PEO and PMMA acts as donor

species of non bonded electrons [215].

Fig. 6.3 shows the Huggins plots for PVC/PMMA polymeric system. Relative

and reduced viscosities of pure polymer and their blends have been obtained

from viscometric measurement. By extrapolation to infinite dilution of the

Huggin,s plots the values of [η] have been determined, while b are the slopes

of the plots. Thermodynamic parameter α has been calculated in order to

observe the miscibility of polymer blends.

199

The values of thermodynamic parameter α indicate miscibility due to attractive

forces involved between polymers [216]. Miscible polymers in which attractive

forces are involved shows higher α values (α > 0, while immiscible polymers

in which repulsive forces are involved shows lower α values (α < 0).

It is found that PVC/PMMA polymer blend exhibit miscibility because it shows

positive α value due to interaction between polymers while PS/PMMA

polymeric system exhibits immiscibility because it shows negative α value

which may be due to repulsive forces involved between PS and PMMA [217].

Fig. 6.4 exhibit plots of reduced viscosity against concentration at room

temperature for pure PVC in pure solvent THF and in polymer solvent (PVAc

+ THF), PVC in pure solvent of MEK and in polymer solvent (PVAc + MEK),

PVC in pure solvent of DMF and in (PVAc + DMF). It is found that all plots at

all concentrations shows linearity. The value of intrinsic viscosity has been

found by extrapolating the plots to zero concentration. The value of intrinsic

viscosity for PVC in THF solvent is higher than in polymer solvent (PVAc +

THF). The higher value of intrinsic viscosity for PVC in THF than in polymer

solvent may be explained as that attractive forces are involved between PVC

and THF while in case of PVC and polymer solvent, repulsive forces are

involved between PVC and PVAc in polymer solvent (PVAc + THF) which

increased the intermolecular excluded volume thereby decrease in intrinsic

viscosity due to the contraction of PVC coils [218].

It can be observed from the plots that the intrinsic viscosity of PVC in MEK is

lower compared to that of PVC in polymer solvent (PVAc + MEK). The reason

of higher intrinsic viscosity of PVC in polymer solvent may be explained as

that stronger attractive forces involved between PVC and PVAc of polymer

200

solvent (PVAc + MEK) which decreased the intermolecular excluded volume

thereby increase in intrinsic viscosity due to the expansion of PVC coils [219].

Fig. 6.4 shows that the intrinsic viscosity of PVC in DMF is higher than PVC in

polymer solvent (PVAc + DMF). The lower value of intrinsic viscosity of PVC

in polymer solvent (PVAc + DMF) compared to that of PVC in DMF may be

due to the reason that repulsive forces are involved between PVC and PVAc

present in the solution of DMF which causes increased intermolecular

excluded volume. Therefore the intrinsic viscosity of PVC in polymer solvent

exhibit lower value due to contraction of PVC coils [220]. From the above

discussion it is obvious that the interaction of PVC with PVAc depends on the

solvent of the solution.

Fig. 6.5, 6.6 and 6.7 shows the plots of reduced viscosity against

concentration at room temperature for PVC, PVAc and PVC/PVAc blends in

solvents THF, MEK and DMF. It is found that all the plots show linear

behavior at all concentrations. The values of intrinsic viscosity and slope can

be found by extrapolating the plots to zero concentration.

Figs. 6.8, 6.10 show the plots of reduced viscosity vs. concentration at room

temperature for PVC and PS in THF and DMF solvents. It is found that all

plots show linear behavior at all concentrations. THF is the best solvent for

both PVC as well as PS because the intrinsic viscosity value for both

polymers is higher in THF compared to that in DMF. The higher value of

intrinsic viscosity in THF may be due to the reason that the polymer-solvent

interaction in THF solvent is stronger compared to the polymer-solvent

interaction in DMF, therefore coils of polymer exhibits higher degree of

swelling which results in higher intrinsic viscosity [221].

201

Fig. 6.9 presents the variation of reduced viscosity vs. concentration at room

temperature of PVC/PS. At low concentration of PVC/PS there is positive

deviation is observed from linear behavior. It can be observed that polymer-

solvent interaction increases with the increase of volume ratio of THF/DMF

because polymer-solvent interaction in solvent DMF is weaker than that in

THF. Therefore with increase in THF/DMF volume ratio polymer-polymer

interaction becomes weakened due to the increase in polymer-solvent

interaction. While with decrease in THF/DMF volume ratio polymer-polymer

interactions become stronger due to the decrease in polymer-solvent

interaction. With increase in content of THF in mixed solvent system negative

deviation from linear relationship is obtained which is due to stronger polymer-

solvent interaction compared to that of polymer-polymer interaction [222].

Fig. 6.11 presents viscometric plots for PVC-solvent and PS-solvent. The

values of intrinsic viscosity has been observed for both polymers and found

that DMF is poor solvent while THF and DCE are good solvents for both PVC

and PS polymers. Fig shows that at lower concentration reduced viscosity

decreased with increase in concentration. This behavior may be due to the

reason that chemical structure of PVC and DCE are very similar which results

in strong interaction between polymer and solvent [223].

Fig. 6.12 presents the plots of reduced viscosity vs. concentration for PVC/PS

blends in solvents THF, DCE and DMF. Viscometric study is a simple and

effective tool for determination of interactions involved in dilute solution of

polymer blends [224]. Fig. 6.12 reveals that PVC-PS-THF polymeric system

exhibits crossover and slope decreases. The sudden decrease in slope of plot

may be due to decrease in hydrodynamic volume.

202

Fig. 6.12 shows the plots of reduced viscosity vs. concentration for PVC, PS

and PVC/PS polymer system in DMF solvent. It is found that all these plots

show linear behavior. Therefore crossover in plots of reduced viscosity vs.

concentration of polymer depends on the nature of solvents because same

polymers show different behavior in THF and DMF solvents [225]. In case of

THF solvent crossover in the plots is observed while when DMF is used as

solvent then linear behavior is observed instead of crossover.

It is found that polymers become expand in a good solvent e.g. PVC in THF

and PS in THF due to repulsive forces involved between segments of polymer

chains. While in case of ternary polymeric system PVC-PS-THF, polymer

chain exhibit shrinkage due to incompatibility of PVC and PS polymers. In

case of unfavorable polymer-solvent interactions segments of a single

polymer shows shrinkage [226]. The decrease in hydrodynamic volume

caused by mutual repulsion between PVC and PS can be neglected

compared to that of originally shrinking chain of polymer.

Fig. 6.12 shows that the plots of reduced viscosity for PVC and blend of

PVC/PS in DCE solvent shows no marked differences. This may be due to the

reason that no marked effect of repulsion involved between PVC and PS on

the interaction between PVC and DCE [227].

It is found that in ternary polymeric system i.e. polymer-polymer-solvent, the

interaction between polymer-polymer may be influenced by changing polymer

and similarly polymer-solvent interaction may also be affected by changing

solvent [228]. Different types of interactions e.g. thermodynamic and

hydrodynamic can influenced the viscometric behavior of ternary polymeric

systems. It is found that in ternary polymeric systems, polymer coils may

203

show either contraction or expansion depending upon the power of solvent.

Contraction of polymer coils may results due to intermolecular excluded

volume effect which includes the intermolecular repulsion and polymeric

segmental attraction in a poor solvent, while expansion of polymer coil results

due to intramolecular excluded volume effect which includes intermolecular

attraction and polymeric segmental repulsion in a good solvent [229].

204

Fig. 6.1 Variation of reduced viscosity with concentration in PVC/PMMA in THF at room temperature.

0

1

2

3

4

5

6

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

C (g/dl)

ηs

p/C

(dl

/g)

PVC:PMMA(60:40)PVC:PMMA(80:20)PVC

Fig. 6.2 Variation of reduced viscosity with concentratipon in PVC/PEO in THF at room temperature.

0

1

2

3

4

5

0 1 2 3 4 5C (g/dl)

η sp/C

(dl

/g)

PVC:PEO(60:40)PVC:PEO(80:20)PVC

205

Fig. 6.3 Plot of reduced viscosity against concentration for PVC-PMMA-THF polymer electrolyte systems.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0.2 0.4 0.6 0.8 1 1.2 1.4

C (g/dl)

ηs

p /C

(d

l/g)

PVC-PMMA(40-60)PVC-PMMA(50-50)PVC:PMMA(70:30)PVC:PMMA(80:20)PVC:PMMA(90:10)

Fig. 6.4 Plot of reduced viscosity against concentration for pure PVC-based polymer electrolyte systems.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0 0.2 0.4 0.6 0.8 1 1.2 1.4

C (g/dl)

η sp/C

(dl

/g)

PVC(MEK)PVC(MEK+PVAc)PVC(DMF+PVAc)PVC(DMF)PVC(THF+PVAc)PVC(THF)

206

Fig. 6.5 Plots of reduced viscosity vs. concentration for PVC, PVAc, and PVC/PVAc at room temperature in THF.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 0.2 0.4 0.6 0.8 1 1.2 1.4C (g/dl)

η sp/C

(dl

/g)

PVAcPVC-PVAc(40-60)PVC-PVAc(60-40)PVC-PVAc(80-40)PVC

Fig. 6.6 Plots of reduced viscosity vs. concentration for PVC, PVAc and PVC/PVAc at room temperature in MEK.

0

0.2

0.4

0.6

0.8

1

1.2

0 0.2 0.4 0.6 0.8 1 1.2 1.4C (g/dl)

ηs

p/C

(dl

/g)


207

Fig. 6.7 Plots of reduced viscosity vs.concentration for PVC, PVAc and PVC/PVAc at room temperature in DMF.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 0.2 0.4 0.6 0.8 1 1.2 1.4C (g/dl)

η sp/C

(dl

/g)


Fig. 6.8 Plots of reduced viscosity vs.concentration for PVC in THF, DMF and MEK at 25°C.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0 0.2 0.4 0.6 0.8 1 1.2 1.4

C (g/dl)

η sp/C

(dl

/g)

THFDMFMEK

208

Fig. 6.9 Plots of reduced viscosity vs. concentration for PVC/PS (1:1) in different volume ratios of THF/DMF at room temperature.

0

0.2

0.4

0.6

0.8

1

1.2

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

C (g/dl)

η sp/C

(dl

/g)

10:010:310:710:10 0:10

Fig. 6.10 Plots of reduced viscosity vs. concentration for PS in THF and DMF at room temperature.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 0.2 0.4 0.6 0.8 1 1.2 1.4

C (g/dl)

η sp/C

(dl

/g)

THF

DMF

209

Fig. 6.11 Plots of reduced viscosity vs. concentration for PVC and PS in three different solvents at room temperature.

0

0.5

1

1.5

2

2.5

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

C (g/dl)

η sp/C

(dl

/g)

PVC in THFPS in THFPVC in DCEPS in DCEPVC in DMFPS in DMF

210

Fig. 6.12 Plots of reduced viscosity vs. concentration for PVC, PS and (1:1) blend in three different solvents THF, DCE and

DMF at room temperature.

0

0.5

1

1.5

2

2.5

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

C (g/dl)

η sp/C

(dl

/g)

PVC in THFBlend of PVC/PS in THF(1:1)PS in THFPVC in DCEBlend of PVC/PS in DCE(1:1)PS in DCEPVC in DMFBlend of PVC/PS in DMF(1:1)PS in DMF

211

CONCLUSIONS

o The conductivity exhibits enhancement with increasing concentration of

PMMA in PVC-PMMA blend electrolytes.

o The complex formation has been confirmed in PVC-PMMA-LiClO4-EC


o The ionic conductivity of PVC-based polymer electrolytes has been

found to be affected by the salt content.

o It has been found that ionic conductivity of pure PVC and PVC-KClO3

systems shows improvement with increase in temperature and

concentration of dopant.

o The variation of ionic conductivity with temperature shows that PVC-

based polymer electrolytes obey the Arrhenius relationship.

o It is found that polymer electrolytes with lower degree of crystallinity

shows higher ionic conductivity which has been proved by XRD

studies.

o The ionic conductivity of the polymer electrolytes shows enhancement

at ambient temperatures by introduction of plasticizers. The mechanical

property of the polymer electrolyte systems has affected by variation of

polymer composition, depending on salt/plasticizer ratio.

o The maximum value of ionic conductivity for the PVC-PMMA-LiClO4-

EC (20-10-15-55) polymer electrolyte system is 2.23 x 10-5 S cm-1 at

room temperature.

o The polymer electrolyte consists of PVC-PMMA (30:70) polymer blend

containing 70% plasticizer content is found to be most suitable due to

electrochemical and thermal stability.

212

o The activation energy exhibit decrease with increase in the ionic

conductivity of the PVC-based polymer electrolyte. The ionic

conductivity of the system affected by the content of both salt and

plasticizer.

o The ionic conductivity shows enhancement with addition of ZrO2 in the

PVC-based polymer electrolyte.

o It has been observed that ionic conductivity is influenced by both

temperature and incorporation of activated charcoal. The filled PVC is

good for low cost semiconducting devices.

o A new composite polymer electrolyte material PVC-LiClO4-EC with

various insoluble insulating dispersed oxide particles (ZnO, Al2O3,

TiO2) has been prepared. Various techniques such as XRD, SEM have

been employed to characterize the resulting material.

o The conductivity studies of the polymer electrolytes show that ionic

conductivity increase with increase in the concentration of the

dispersed oxide particles in the system. The enhancement in ionic

conductivity for all system is with same activation energy as that of

polymer electrolyte containing pure salt. This suggests that the

dispersed oxide filler generates an excess of cation vacancies at the

interface.

o Polymer electrolytes containing LiClO4 salt exhibit appreciable

conductivities above room temperature such as PVC-PMMA-EC-LiClO4

(0-15-75-10) shows 5.5 x 10-4 S cm-1 value of conductivity.

o The incorporation of PMMA in the polymer electrolyte considerably

reduces the interfacial resistance.

213

o The composite polymer electrolytes containing TiO2 exhibit better

compatibility with lithium electrode compared to the polymer electrolyte

containing liquid plasticizer such as ethylene carbonate (EC) or

propylene carbonate (PC).

o The lower ionic conductivity of the PVC-PMMA-Li2SO4-EC solid

polymer electrolytes containing 15% ZrO2 is due to the crystallinity of

the polymer and low segmental motion of the polymeric chains.

o It has been observed from the conductivity-temperature relationships

that the transportation of ions in solid polymer electrolytes is similar to

that in ionic crystals.

o The activation energy of polymer electrolyte exhibit decrease with

enhancement of ionic conductivity.

o The effect of plasticizer in optimizing polymer electrolyte has been

proved through AC impedance analysis.

o The higher uptake of the liquid electrolyte by the polymer matrix

containing silica may be originated due to the interaction between the

liquid electrolyte and silica.

o The solid polymer electrolyte comprising of PVC-ZnO-LiClO4 exhibit

enhancement in ionic conductivity in a range of temperature (303-343

K) and then do not shows any further increase with temperature.

o The conductivity-temperature relationships of the PVC-ZnO-LiClO4

polymer electrolyte do not follow Arhennian behavior.

o The ionic conductivity of PVC-based polymer electrolyte system

containing Li2SO4 salt exhibit decrease with increase in concentration

of PVC due to the decrease of ionic mobility.

214

o It has been observes that ionic conductivity of PVC-Li2SO4 polymer

electrolyte with any concentration of PVC and EC shows enhancement

with increase in temperature due to dissociation of salt and improved

thermal segmental motion of the polymer chains.

o The conductivity of polymer electrolyte shows increase with

incorporation of plasticizer due to dissolution of ionic species.

o The ionic conductivity of PVC-LiClO4 polymer electrolyte shows

continuous increase with temperature due to increased segmental

motion of polymer chains.

o The conductivity-temperature relationships of PVC-PMMA-LiClO4-EC

polymer electrolyte system can be explained on basis of Williams-

Landel-Ferry mechanism.

o The nature of cation transport in polymer electrolyte may be similar to

the ionic transportation in ionic crystal. The increase of ionic

conductivity in ionic crystals is due to jumping of ions in to vacant sites

by increase in temperature.

o The incorporation of PC shows more affect on ionic conductivity

compared to EC in to PVC-LiClO4-LiBF4 (70-15-15) PVC-based

polymer electrolyte containing double salt.

o The polymer electrolyte containing ZrO2 shows non linear conductivity-

temperature relationship for any sample. The increase in ionic

conductivity continues to an optimum concentration of ZrO2, beyond

which it starts decreasing due to the development of crystallite regions

at high concentrations of ZrO2.

215

o The ionic conductivity of PVC-ZnO-LiClO4 polymer electrolyte

increases with increase in temperature at lower temperature while at

higher temperatures there is no more increase in conductivity with

further increase in temperature.

o The conductivity of the PVC-PMMA-LiBF4 shows increase with

increase in concentration at lower concentration of salt due to increase

in ionic species while at higher concentration of salt, the ionic

conductivity is found to decrease with further increase in concentration

due to decrease in the mobility and number of ionic species. The

decrease in mobility ions may be due to retarding effect while the

decrease in the number of ionic species is due to pairing of ions at

higher concentration of salt.

o The ionic conductivity of PVC-PMMA polymer electrolyte containing

silica exhibit improvement by addition of PMMA but the mechanical

stability of the system deteriorated at higher concentration of PMMA.

o The conductivity of the plasticized PVC-PMMA system containing Li

salts shows improvement with increase in plasticizer content linearly.

The improvement in ionic conductivity by addition of plasticizer may be

due to the improved charge carrier mobility.

o The effect of plasticizer content on enhancement of ionic conductivity

of the system containing LiClO4 is higher compared to that containing

LiBF4 salt.

o The value of ionic conductivity of the plasticized PVC-PMMA polymer

electrolyte containing salts is much greater at higher temperature

216

compared to that at lower temperature due to the presence of crystals

of plasticizer and salts mixture at lower temperature.

o The addition of salt in to PVC-PMMA containing ethylene carbonate

and propylene carbonate as plasticizer, causes enhancement in ionic

conductivity to a limited extent due to dissociation of salt and then

decreases due to decrease in number of charge carrier species by

further increase in concentration of salt.

o The conductivity value decreases with increase in PVC/PMMA blend

ratio in polymer electrolyte system.

o The plasticized PVC-PMMA blend exhibit higher values of electrical

conductivity at higher concentration of plasticizer due to increase in

interconnections between plasticizer rich phases which facilitate ionic

transportation.

o The incorporation of ZrO2 causes increase in ionic conductivity of PVC-

Li2SO4-EC-ZrO2 polymer electrolyte system at lower concentration of

ZrO2 while exhibit decrease in ionic conductivity at some higher

concentration of ZrO2.

o The incorporation of NaClO4 salt in to PVC-PMMA-NaClO4 polymer

electrolyte system is much effective at lower concentration of salt.

o The incorporation of KBrO3 salt in to complex polymer electrolyte PVC-

KBrO3-EC resulting in improved ionic conductivity due to decrease in

crystallinity of the polymer electrolyte system. The activation energy of

the system shows decrease with increase in concentration of KBrO3

salt.

217

o The addition of ZrO2 filler particles in to PVC-PMMA-Li2SO4-EC

polymer electrolyte system causes enhancement in ionic conductivity

due to the transition of crystalline phase of polymer in to the

amorphous phase.

o The ionic conductivity of PVC-PMMA-EC-LiClO4 (20-5-65-10) polymer

electrolyte containing TiO2 shows decrease at higher concentrations of

filler particles due to the development of crystallite regions.

o The variation of conductivity as a function of weight fraction of PVC is

similar for both polymer electrolyte containing either EC or PC as

plasticizer.

o The variation of conductivity depends on the amount of PVC instead of

the nature of plasticizer.

o The addition of PVC in to the polymer electrolyte systems shows

decrease in ionic conductivity due to decrease in the mobility of ions

through polymer electrolyte films although addition of PVC increases

the dissociation of salt.

o The difference in the ionic conductivity of the PVC-EC-PC-LiClO4

systems containing different content of salt and plasticizers is much

pronounced at lower temperature compared to the difference at higher

temperatures.

o The increase in ionic conductivity of pure PVC with temperature may

be due to the local motion of molecular groups.

o The addition of TiO2 causes increase in ionic conductivity due to the

development of amorphous phase in the PVC-PMMA-EC-LiClO4


218

o The ionic conductivity of the PVC-PMMA-LiX-PC (20-10-10-60)

polymer electrolyte system containing LiBF4 salt shows highest ionic

conductivity (1.69 x 10-3 S cm-1) compared to the polymer electrolyte

containing other Li salts.

o It has been found from the X-ray diffraction studies that degree of

crystallinity of PVC shows decrease by complexation with NaClO4 salt.

o The crystalline peaks in the X-ray diffraction pattern of PVC-PMMA-

Li2SO4-ZrO2 polymer electrolyte system become more intense with

increase in the wt% of ZrO2.

o X-ray diffraction studies show that polymer electrolyte system

containing EC/PC as plasticizer are more amorphous compared to that

of polymer electrolyte system containing DBP as plasticizer.

o The degradation temperature exhibit increase with increase in

concentration of TiO2 in the complexed polymer electrolyte system. The

increase in degradation temperature may be due to the improvement in

thermal stability with the addition of TiO2.

o The TGA traces of the PVC-PMMA blend shows that decomposition

temperature decreases with the addition of EC as plasticizer.

o The thermal decomposition temperature of the PVC-PMMA-EC-Li2SO4

complexed polymer electrolyte system shows decrease with addition of

salt which may be due to the availability of Li ions in the polymer

electrolyte film.

o The complexed polymer electrolyte system PVC-PMMA-EC containing

LiClO4 salt are suitable for battery operation up to 100°C while the

219

polymer electrolyte complexed with LiBF4 can be used for battery

operations only up to 85°C.

o PVC-based polymer blend containing higher concentration of PMMA

observe regular structure resulting in higher values of modulus and

tensile strength while lower values of elongation.

o SEM micrograph studies shows that PVC-based polymer electrolyte

systems containing TiO2, Al2O3 or ZrO2 exhibit smooth distribution of

inorganic filler particles.

o SEM image shows that PVC-PMMA blend films without plasticizer are

transparent which may be due to miscibility of PVC and PMMA. While

the films containing salt and EC as plasticizer are opaque in

appearance due to immiscibility of PVC with plasticizer EC.

o The polymer electrolyte films containing lower concentration of PMMA

content shows large number of very small sized homogeneously

distributed pores. While the systems containing higher content of

PMMA exhibit large sized pores which may be due to the coagulation

of PVC during casting of blends.

o The polymer electrolyte system without NaClO4 exhibit higher flexibility

compared to the films containing NaClO4 salt. The higher flexibility of

the films may be due to the penetration of Na+ ion into the PVC matrix

of polymer electrolyte.

220

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