investigation of thermal, mechanical, morphological and...

International Journal of Applied Engineering Research ISSN 0973-4562 Volume 14, Number 1 (2019) pp. 170-179

© Research India Publications. http://www.ripublication.com

170

Investigation of Thermal, Mechanical, Morphological and Optical

Properties of Polyvinyl alcohol Films Reinforced with Buddha Coconut

(Sterculia alata) Leaf Fiber

Kapil Gulati

Research Scholar, Department of Chemistry, Kurukshetra University, Kurukshetra-136119, India.

Sohan Lal

Assistant Professor, Department of Chemistry, Kurukshetra University, Kurukshetra-136119, India.

P.K. Diwan

Assistant Professor, Department of Applied Science, University Institute of Engineering & Technology (UIET), Kurukshetra University, Kurukshetra-136119. Haryana, India.

Sanjiv Arora*

Professor, Department of Chemistry, Kurukshetra University, Kurukshetra-136119, India.

Abstract

Polyvinyl alcohol (PVA) films reinforced with Buddha

Coconut (Sterculia alata) leaf fiber (SA) were synthesized by

solvent casting method. The influence of fiber addition (2.5-

15.0 %) on the resulted blended films was investigated by

thermogravimetric analysis, IR and UV/Vis spectra. The

kinetic parameters such as activation energy and degradation

temperature range for the first and second decomposition stage

based on thermogravimetric data were determined using single

heating rate models. The film containing 2.5 % fiber showed

the maximum weight loss percentage (41.2 ± 1.1) under soil

burial analysis. At the level of 12.5 % fiber, films showed the

lowest water uptake percentage (56.0 ± 1.9) and maximum

Ultimate Tensile Strength (38.1± 1.1) MPa.

Keywords: polyvinyl alcohol, sterculia alata fiber, buddha

coconut, thermal stability, tensile strength.

INTRODUCTION

The requirement to seek out the alternatives of materials

ensuing from non-renewable sources is strongly extending the

necessity for its replacement by renewable sources [1]. Among

the potential substitutes, the progress of composites using

lignocellulosic materials as strengthen filler and thermoplastic

polymer as the matrix is presently the focal point [2]. Natural

fiber polymer composites (NFPCs) have a class of renewable

and sustainable materials as they are created from natural fibers

set in a polymer matrix [3]. There are diverse categories of

natural fibers that are plentifully available from both naturally

and agricultural industries such as jute, banana, bamboo, rice

husk, bagasses etc. [4] In comparison to synthetic fibers,

natural fibers are cheap, light weight, biodegradable,

renewable, showing good mechanical properties, and non toxic

[5-7]. Jayaramudu et al. [8] documented a novel uniaxial bark

fabric obtained from the tree of Sterculiaurens (Roxb).

Mohanty et al. [9] made the use of pineapple leaf fibers by

implanting them with polyacrylonitrile to modify their

properties. The usage of pineapple leaf waste in the form of

short fiber for the synthesis of polypropylene composites was

also made by Nanthaya and Taweechai [10].

The creation of polymer composites by means of polymer

matrix that can offer high tensile strength and non-toxicity will

be appropriate for food packaging and biomedical applications

[11]. Polyvinyl alcohol (PVA) offers the property of

biocompatibility, non-toxicity, water solubility, superior tensile

strength and is gradually replacing other non-biocompatible

plastics like polyethylene, polypropylene, HDPE etc. in many

fields [12]. Certain drawbacks of PVA are its high hydrophilic

character [13] and slow degradation process particularly under

anaerobic conditions [14]. The possible solution to advance the

biodegradation rate and to lower the hydrophilic nature and cost

of PVA, demand the synthesis of its composites with

biodegradable fillers. The requirement of stronger interfacial

adhesion and superior mechanical strength is crucial when

synthesizing such type of composites which can be achieved

using some cross-linking agents such as boric acid, borax and

glutaraldehyde [15-17]. PVA/rice husk composites using boric

acid as cross linking agent [18], PVA fly ash composite cross-

linked with glutaraldehyde solution [19] and plasticized starch

PVA blends cross linked with epichlorohydrin [20] are some

examples, exhibiting the effect of cross-linking agents in

polymer composites. The aim of this work was to synthesize

the PVA based composite films reinforced with Buddha

Coconut (Sterculia alata) leaf fiber (SA). The tree from which

this fiber was extracted belongs to the sterculiacea family.

mailto:[email protected]



171

MATERIALS AND FABRICATION

Materials

Buddha Coconut (Sterculia alata) leaves were picked from its

plant (Kurukshetra University, Kurukshetra). Polyvinyl alcohol

(PVA) (Mw = 85,000-1,24,000, degree of hydrolysis = 86.0-

89.0 %) was supplied by SDFCL (s d fine-chem limited). Poly

(ethylene glycol) (PEG-6000) and boric acid were supplied by

Himedia (India). Deionised water was used for the preparation

of composite films.

Fabrication of Polymer composite Films

Synthesis of polymer composite thin films of polyvinyl alcohol

(PVA) based matrix, reinforced with different loadings of 2.5,

5.0, 7.5, 10.0, 12.5 and 15.0 % of SA fiber was carried out by

solvent casting method. The plant leaves were washed with

water to remove any greasy materials, dried in the shade for 10

to 15 days and ground to powder. The fiber obtained was

treated with 5% aqueous NaOH solution to remove

hemicellulose and other greasy materials [21, 22]. The dried

fiber was passed through 18 mesh sieve. The calculated amount

of PVA [23] was added to hot deionised water at 80 °C and kept

under stirring for about an hour to dissolve it completely,

followed by the addition of polyethylene glycol (PEG-6000) as

plasticizer (33% of PVA) and cross-linking agent boric acid

(3% of PVA). The addition of homogenised solution of SA

fiber in water was carried out. When completely suspended, the

mixture was kept under stirring for 3h at 60 °C avoiding

frothing. The resultant mixture was sonicated in Ultra cleaner

sonicator for 15 min. and allowed to cool at room temperature.

Films were casted into clean and dry glass dishes 15cm x 5cm.

All the films were dried in vacuum oven at 65 °C for about 40

h to ensure the complete removal of absorbed moisture and

stored in airtight polyethylene bags until further testing. The

thickness of obtained films was 0.5 mm and named according

to the fiber loadings initiating from SA-0 to SA-6 (Table 1).

Table 1: Composition of PVA, PEG-6000, Boric acid and

SA-fiber

Sample

Index

PVA

(g)

PEG-6000

(g)

Boric acid

(g)

Fiber

content (g)

PVA 7.5 - - -

SA-0 7.5 2.5 0.225 -

SA-1 7.5 2.5 0.225 0.187

SA-2 7.5 2.5 0.225 0.375

SA-3 7.5 2.5 0.225 0.562

SA-4 7.5 2.5 0.225 0.750

SA-5 7.5 2.5 0.225 0.937

SA-6 7.5 2.5 0.225 1.125

Characterisation of Polymer Composite Films

FTIR Spectroscopy

FTIR spectra were used to characterize the presence of specific

groups in the neat PVA and composite films showing the

effectiveness of the developed method for different polymer

composites. FTIR spectra were recorded on a MB-3000 ABB

spectrophotometer in transmission mode over the frequency

range of 4000-600 cm-1.

Water Uptake Test

The film cuts (30 mm x 30 mm) dried to the constant weight

(wi) were submerged in the 50 ml water for 24 h at room

temperature which then were taken out and the final weight of

the absorbed films was recorded (wf) after removing the water

left at surface by absorbing it with filter paper. There were three

samples of each composition and the average readings were

taken. The water uptake (%) of each film was determined by

using the following formula [24]:

Water uptake (%) =[wf−wi

wi x 100 ]

Soil Burial Test

The soil collected from Kurukshetra University campus,

Haryana, India after drying in the shade for three days was

complemented with urea (6g/kg) to encourage an active

microbial flora. This blend of soil was then placed in a large

tray and kept wet by spraying water at the regular time interval

to keep the growth of microorganisms dynamic to degrade the

samples. Polymer films to be analyzed for biodegradation

dehydrated at 50 °C under vacuum to acquire constant weight

(wi) were covered in synthetic net and then buried fully into the

wet soil of test medium at 25 °C under aerobic conditions at

relative humidity of 50%. The degradation of the samples was

observed by withdrawing the samples from the soil on every 15

days for two months. Samples were then washed to get rid of

the soil particles. At each time interval atleast three samples of

the films were analyzed. The samples were dehydrated under

vacuum until they obtained a constant weight (wf). The %

degradation of the composite films was calculated using the

following equation [24-26]:

% degradation of the polymer film = [wi−wf

wi x 100 ].

Thermal Study

Thermogravimetry analysis (TGA) of composite films was

carried out using STAH instrument at the heating rate of 10 °C

min-1 from ambient temperature to 600 °C in the nitrogen

atmosphere. Non isothermal single heating rate methods used

for the computation of kinetic parameters are given in Table 2.



172

Table 2: Single heating rate methods for the activation energy evaluation

Method Considerations Expression Plots

Coats-Redfern [27] α =w0 − wt

w0 − w∞

is the fraction of

number of molecules

decomposed

ln [g(α)

T2] = −

Ea

RT+ constant

Here, g(α) = −ln(1 − α)

ln [g(α)

T2] vs

1

T

Horowitz-Metzger [28] α =w0 − wt

w0 − w∞

ln {ln (1

1 − α)} = −

Ea θ

RTs2

+ constant

Here Ts is the temperature at which

1

(1−α)=

1

exp= 0.368 and θ is the difference

between the peak temperature and temperature

at particular weight loss (θ =T-Ts)

ln {ln (1

1 − α)} vs θ

Mechanical Properties

The mechanical analysis of the films was studied by tensile

testing on Universal Testing Machine (UTM). The test samples

were according to ASTM D882 standards. The cross head

speed was 10 mm/min. Three samples were tested in each

category and the average value is reported.

Optical Property

Each film specimen was cut into a rectangular piece and placed

directly in a UV-Vis spectrophotometer (MODEL Shimadzu

Double Beam Double Monochromator, UV-2550) test cell and

measurements were made using air as the reference [29]. A

spectrum of each film was obtained at wavelength between 200

and 800 nm and expressed as absorbance.

Scanning Electron Microscopy (SEM) analysis

SEM analyses were performed on JEOL JSM-6510LV to

observe the morphology of composite films. Films were coated

with gold particles to prevent any damages by the electron

beam.

RESULTS AND DISCUSSION

FTIR Spectroscopy

FTIR spectra shown in Figure 1a correspond to the

characteristic peaks of SA fiber. The vibrational bands of SA

fiber observed at 3321 and 1627 cm-1 correspond to the OH

stretching and bending mode respectively. Peak obtained at

2916 cm-1 was due to the C-H stretching in cellulose and

hemicellulose present in fiber. The band observed at 1728 cm-

1 can be due to the C=O group present in hemicellulose.

Asymmetric C-O-C stretching band obtained at 1108 and 1034

cm-1 is an indication towards the presence of the chain of

anhydroglucose ring [25] i.e. cellulose.

FTIR spectra of pure PVA and SA-0 are shown in Figure 1b.

The broad absorption bands observed at 3310 in PVA and at

3350 cm-1 in SA-0 are assumed to arise from OH stretching

frequency of PVA and absorbed moisture. The vibration bands

observed at 2939, 2857 cm-1 (PVA) and 2939, 2830 cm-1 (SA-

0) correspond to the C-H stretching from alkyl groups. The

peaks at 1720 cm-1 are related to the C=O stretching of carbonyl

groups that remain after the synthesis of PVA by the hydrolysis

of polyvinyl acetate or oxidation during its synthesis [30]. A set of bands obtained at 1545-1330 cm-1 were due to the C-H/O-H

bending. The bands obtained at 1095 cm-1 (PVA) and 1102 cm-

1 (SA-0) corresponds to the C-O-H stretching.

The FTIR spectra of PVA composite films from SA-1 to SA-6

are shown in Figure 1c. The values of characteristic peaks

observed in PVA-SA composite films are almost similar to that

of PVA and SA-0. However, the intensity of the peak obtained

at 1111-1103 cm-1 was found to be more in comparison to that

of PVA and SA-0. The decrease in intensity of OH group with

fiber loading can be an indication towards the fact that OH

group of PVA is involved in intermolecular hydrogen bonding

giving rise to the polymeric association of OH group [25].



173

(A) (B)

(C)

Figure 1: FTIR spectra of: (A) SA powder and (B) PVA, SA-0 and (C) SA-1 to SA-6

Water Uptake Test

The water uptake percentage of PVA and its composite films

are shown in Figure 2. The virgin polyvinyl alcohol film due to

its high hydrophilic nature showed the highest percentage of

water uptake (79.9 ± 1.6). In case of SA-0, the addition of PEG

and cross linking agent boric acid [31] decreased the

hydrophilic nature of PVA film and hence decreased the water

uptake percentage. On the addition of fiber this value was

further decreased with the lowest value of 56.0 ± 1.9 for SA-5.



174

It may be due to the fact that with the addition of SA fiber the

hydroxyl groups in PVA were involved in intermolecular

hydrogen bonding which led to decrease in number of hydroxyl

groups [32] ; responsible for the overall decrease in water

uptake percentage up to SA-5. However, in SA-6 due to the

super saturation of fiber the cross linking between fiber and

polymer matrix could not be made possible entirely; which led

to an increase in number of free hydroxyl groups and hence

increased the water uptake percentage (60.5 ± 0.7).

PVA SA-0 SA-1 SA-2 SA-3 SA-4 SA-5 SA-6

45

50

55

60

65

70

75

80

85

Wa

ter

Up

tak

e (

%)

Polymer Films

Figure 2: Water Uptake percentage of the polyvinyl

alcohol films

Soil Burial Test

The weight loss profile of the polymer films is shown in Figure

3. All the tested specimens had the same dimensions to avoid

the effect of films shape on the weight loss percentage and

hence biodegradability [24, 33]. The biodegradability of the

polymer films was analyzed by calculating the weight loss of

the films at regular interval of 15 days for two months. The soil

burial degradability of the polymer films found to show a slight

rise in its degradation rate with addition of fiber. The virgin

PVA film exhibited the highest resistance against degradation.

The possible reason can be due to the fact that the C-C

backbone linkage of PVA itself caused the low

biodegradability [34]. The maximum weight loss percentage

after 60 days for PVA and SA-0 films were 23.9 ± 1.1 and

28.1 ± 1.0 respectively. This value of weight loss percentage

was found to show a decrease from SA-1 to SA-5. The

maximum weight loss percentage at the end of 60 days was

observed in case of SA-1 (41.2 ± 1.1). This degradation pattern

can be explained on the basis of degree of cross linking. Highly

cross linked films do not favour the degradation, takes long

time to degrade and hence show the lower degradation rate

[35]. The low weight percentage observed for SA-5 (30.1

± 1.0) showed that maximum cross linking was obtained in it,

as established by tensile testing also (Maximum value of UTS

obtained in SA-5). The high degradation percentage observed

in SA-6 (35.0 ± 0.3) showing the presence of free volume/

voids [36] in composite film favouring the attack of

microorganisms and hence led to more degradation in

comparison to SA-5.


5

10

15

20

25

30

35

40

45

50

We

igh

t L

os

s %

Polymer Films

15 days

30 days

45 days

60 days

Figure 3: Plot of weight loss % as a function of polymer films

Thermal Study

Thermogravimetric Analysis (TGA)

The thermograms (TG and DTG) of some selected samples viz.

PVA, SA-0 and its composites (SA-2, SA-4 and SA-6) at the

heating rate of 10 °C/ min in the nitrogen atmosphere are shown

in Figure 4.

100 200 300 400 500 600

0

20

40

60

80

100

We

igh

t (%

)

Temperature (oC)

PVA

SA-0

SA-2

SA-4

SA-6

(a)

100 200 300 400 500 600

-14

-13

-12

-11

-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

1

dw

/dt

(% m

in-1

)

Temperature (oC)

PVA

SA-0

SA-2

SA-4

SA-6

(b)

Figure 4: (a) TGA thermograms and (b) DTG curves of

polymer films at the heating rate of 10 °C/ min



175

Table 3: Characteristic thermal decomposition data of PVA

and composite films

Sample First degradation stage Second degradation stage

To

(°C)

Tmax

(°C)

Tend

(°C)

MWLR

(%min-1)

To

(°C)

Tmax

(°C)

Tend

(°C)

MWLR

(%min-1)

PVA 268.8 325.6 368.8 7.24 388.9 427.6 448.9 7.24

SA-0 262.1 319.8 362.9 8.41 396.9 413.8 436.8 8.07

SA-2 282.1 323.7 362.8 7.80 392.9 415.9 442.9 10.45

SA-4 290.0 331.5 370.9 5.45 390.0 415.9 450.9 13.21

SA-6 288.1 325.6 368.8 6.78 398.9 411.8 438.9 9.90

where To, Tmax and Tend stands for onset, maximum

degradation and endset temperature respectively.

The weight loss in all the samples, up to about 150 °C results

from the evaporation of absorbed water. Degradation of PVA

occurs in two steps [37]. For pure PVA and SA-0, weight loss

during first degradation stage can be due to the formation of

polyethylene resulting from the dehydration and

depolymerization of PVA. During the second step after 385 °C

the residue resulting from the first stage undergoes the process

of intramolecular cyclization and producing some organic

volatiles [38]. After 500 °C weight loss percentage was

constant (Figure 4a) due to the carbonaceous mass formed

during the degradation of polymer which creates layer on the

polymer surface and hence prevents its further decomposition

[39]. The SA reinforced PVA composites exhibited two stage

decomposition like PVA and SA-0. The onset temperature for

PVA-SA composites was found to increase with incorporation

of fiber in the matrix. A shift of around 20 °C was realized in

the first degradation stage of SA-4 with the highest value of

onset degradation temperature (To) around 290 °C in

comparison to PVA. The maximum degradation temperature

(Tmax) and maximum weight loss rate (MWLR) for

PVA/composites showed a slight variation during the first

degradation stage (Figure 4b). However, these values were

found to be significant in the second degradation stage (Table

3).

All the observations apparently showing that the mechanism of

thermal decomposition differs for PVA, SA-0 and its

composites. The improvement in thermal stability of SA-0 with

the addition of fiber is indicated by a shift in its onset

degradation temperature to the higher side. The increase in

thermal stability can be explained in terms of interaction of

fiber with the hydroxyl group of PVA forming a complex as

confirmed from the IR spectra of PVA/SA composite films.

Moreover, boric acid played an important role as a cross linking

agent between PVA and fiber, resulting in the high thermal

stability of PVA/SA composite films [31]. Among the

composite films, SA-4 showed the highest thermal stability;

followed by SA-6 and SA-2. The reason for observing a

decrease in thermal stability from SA-4 to SA-6 can be

explained in such a way that at high fiber loading the

homogeneous dispersion of fiber could not take place and

resulting adhesion between fiber and matrix reduced and hence

decreased the thermal stability. The above statement can be

generalized by saying that with increase in the fiber loading

thermal stability increases up to 10% and the order is SA-4 >

SA-6 >SA-2.

Kinetic Study

Kinetic parameters comprising of degradation temperature

range and activation energy (Ea) for both the stages were

calculated and are summarized in Table 4. It can be inferred

that in case of most thermally stable composite SA-4, the

activation energy value was less during first degradation stage

and high during second degradation stage in comparison to SA-

0. This shows that although the degradation of SA-4 occurs at

high temperature but once it starts, it degrades much faster in

comparison to SA-0 during first degradation stage.

Table 4: Kinetic parameters in the thermal decomposition of

PVA and composite films

Sample

index

Degradation

temperature

range (°C)

Activation Energy (kJ/mol)

and Regression Coefficient

Coats-

Redfern

R2 Horowitz-

Metzger

R2

PVA 268-368 53.94 0.984 62.79 0.986

388-448 41.78 0.987 37.10 0.995

SA-0 262-362 67.48 0.979 76.80 0.976

396-436 54.12 0.980 45.51 0.985

SA-2

282-362 63.46 0.983 66.60 0.967

392-442 57.20 0.968 49.23 0.976

SA-4 290-370 60.65 0.995 66.99 0.986

390-450 77.92 0.975 73.08 0.986

SA-6 288-368 58.52 0.981 64.37 0.977

398-438 58.87 0.973 49.74 0.978

Optical Property

The light absorbance of composite films at wavelengths from

200 and 800 nm were recorded [40] and shown in Figure 5.

Virgin PVA and composite films showed the absorbance in the

range of 200-300 nm with maximum at 248 for pure PVA and

252 for SA-0. On increasing the fiber loading the absorption

region shifted towards the higher wavelengths. At the same

wavelength, SA-5 showed the highest absorbance with



176

maximum obtained at 272 nm. An increase in

absorbance/intensity of absorption with addition of fiber is an

evidence of occurring electronic interactions in composite films

[41]. The enhancement in intensity of composite films showed

the localization of SA fiber between PVA chains [13].

However, no significant changes were observed in the

absorption spectrum of SA-6 showing that with further loading

of fiber homogeneous dispersion could not take place and

hence not any observable change in its absorbance value.

300 400 500 600 700 800

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Ab

so

rba

nc

e (

a.u

.)

Wavelength (nm)

PVA

SA-0

SA-1

SA-2

SA-3

SA-4

SA-5

SA-6

Figure 5: Absorbance spectra of composite films as a

function of wavelength (nm)

Mechanical Properties

Table 5: Mechanical Properties of Polymer Composite Films

Sample

Index

Percentage

Elongation

Ultimate Tensile

Strength (MPa)

Young’s

Modulus (MPa)

PVA 161.6± 2.0 30.2 ± 1.0 98.2± 3.8

SA-0 168.0± 2.3 25.1 ± 1.1 79.2± 3.2

SA-1 164.6± 2.6 27.2± 1.2 133.6± 4.1

SA-2 162.3± 2.6 29.9± 1.2 149.6± 4.9

SA-3 148.3± 2.3 31.8± 1.0 154.8± 3.6

SA-4 111.6± 1.8 35.0± 1.2 179.8± 4.9

SA-5 82.0± 2.0 38.1± 1.1 204.6± 5.1

SA-6 72.6± 2.6 30.9± 1.1 285.4± 6.6

The Elongation (%), Ultimate Tensile Strength (UTS) and

Young’s Modulus calculated from the stress-strain (%)

relationship diagrams are reported in Table 5. Tensile strength

of polymer composite films was found to improve in

comparison to virgin. An addition of SA fiber increased the

tensile strength of the films up to 12.5% loading (Figure 6a).


0

5

10

15

20

25

30

35

40

Te

ns

ile

Str

en

gth

(M

Pa

)

Polymer Films

(a)


0

50

100

150

200

250

300

Yo

un

g's

Mo

du

lus

(M

Pa

)

Polymer Films

(b)

Figure 6: (a) Tensile strength (MPa) and (b) Young’s

modulus (MPa) of polymer composite films

This implies that PVA-SA composites can withstand much

greater stress without undergoing any irreversible deformation.

The reason for obtaining high tensile strength can be due to the

hydrophilic nature of PVA which results in a strong interface

bonding between hydroxyl groups of fiber with PVA [42]. A

further addition of fiber (SA-6) led to the significant decrease

in UTS. The decrease in tensile strength was due to the super-

saturation of particles in the composite films, due to which the

enhancement of particle-particle interfacial interaction takes

place rather than particle-PVA interaction [43]. It can also be

said that with increase in further loading of fiber the nature of

adhesion resulted between fiber and matrix was poor which led

to an increase in number of void formation in composite film.

Due to which enhancement in the formation of micro cracks at

the interface of composite film took place and reducing the

tensile strength [44]. The decrease in elongation was also

observed continuously with an increase in the loading. Young’s

modulus of the natural fiber reinforced polymer composites

generally increases with increasing the fiber amount [6, 45]. In



177

the present study also, Young’s modulus was found to increase

continuously up to fiber loading of 15% (Figure 6b) and is an

indication of difficulty obtained during stretching the films in

an elastic way. It can be inferred that 12.5% loading of SA fiber

reinforced in PVA matrix gives the optimum results of tensile

strength.

Scanning Electron Microscopy (SEM) Analyses

The SEM photographs of the cross-sections of PVA, SA-0,

SA-3 and SA-5 are shown in Figure 7. It was observed that

surface of pure PVA film was smooth [46] (Figure 7a). An

obvious aggregation of PEG was observed in SEM photograph

of SA-0 (Figure 7b). On the introduction of fiber, contraction

in the surface of the produced film (SA-5) was observed as

shown in Figure 7c. Surface roughness was increased with high

fiber content. It was also observed that fiber dispersed more

homogeneously with its loading up to 12.5% in PVA matrix.

On further addition of fiber (SA-6), roughness level and

cracking of surface was enhanced, showing that the

homogeneous dispersion of fiber can’t take place further with

high loading (Figure 7d).

(a)

(b)

(c)

(d)

Figure 7: SEM photographs of (a) PVA and (b) SA-0 and

(c) SA-5 and (d) SA- 6

CONCLUSIONS

In this work, PVA has been blended with PEG-6000

(plasticizer), boric acid (cross-linking agent) and Sterculia alata leaf fiber to form the polymer composite films and were

characterized by different techniques. FTIR studies confirmed

the presence of interactions involved in PVA matrix with SA

fiber. Polymer films exhibited decrease in water uptake

percentage with fiber loading. Soil burial test confirmed fairly

good biodegradability of PVA/SA composites in comparison of

PVA and SA-0. Addition of fiber enhanced the thermal

stability. Tensile strength with 12.5 % loading was found to be

maximum. Light absorbance of the composite films against UV

light was also found to be improved.

ACKNOWLEDGEMENT

Financial support from the University Grant Commission

(UGC), New Delhi as Junior Research Fellowship, award letter

no. 21/06/2015 (i) EU-V to Kapil Gulati is gratefully

acknowledged. Acknowledgement is also due to Chairman,

Chemistry department, Kurukshetra University, Kurukshetra

for providing necessary laboratory facilities.



178

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