1

Modern filler systems and efficient mixing

techniques for improved elastomers

U. Giese,, H. Chougule, T. Dilman, A. Jain

Deutsches Institut für Kautschuktechnologie e. V., Hannover

Innovation in Rubber Design 2016

December/7th – 8th/2016

London, UK

• Temperatur resistance• Life time• Media resistance• Lightweight construction• Strength• Elasticity

• Environmental exposure• REACH• Emissions• Smell• Fire behavior• Migration

Adapted specific elastomer materials

Requirements on elastomers for extrem conditions

Tools for improvement ofelastomer properties

Elastomers - Adapted Materials

Polymer

Additives/Plasticizers

Filler-Polymer systems

Polymer-Filler

-interaction

Dispersion

Crosslinking

J. L. Leblanc, Prog. Polym. Sci.

27 (2002) 627

Fillers - Reinforcement

20 – 50 nm

Silica

Graphene (exp. graphite)h = 5-8 nm

d = 2-25 nm

CarbonNanohorns

Polymerparticles

Nano-Clays(layered structure)

This image cannot currently be displayed.

Carbon –Nanotubes (CNT) aspect /ratio10 nm /µm

Carbon blacks (CB)200 nm

15 nm

TIE-GmbH

Carbon fillers - Carbon blacks

Heidenreich, 1975

Graphitic crystallites

WAXS-measurements

Turbostratic organisations

of graphitic layers

AFM-measurements show

roughness

Amorphous carbon

Raman spectroscopy

Carbon Fillers

• Bending of C -bonds • Pyramidalization angle• Miss-alignment of π-Orbitals• Higher electron density on

external surface of CNTs• Increasing surface activity

101.6°

Tube Curvature → Surface Activity

Rolled graphene sheetsSingle C-Polymer?C-molecule?

X. Lu, Z. Chen,

Chem. Rev. 105 (2005) 2343

MWCNTs:

• ∅ 1 – 50 nm• Length: appr. 100 nm – µm region

high aspect ratio

Carbon Nanotubes (CNT)

TEM-micrograph of MWCNTs, magnif. 50000x

(G. Schwerdt, DIK)

SWCNTs:

• Single cylinder ,

• Diameter: 0.7 to 1.5 nm

• Differencies in axial/radial

organization of C-atoms

O. Grady, J. Wiley 2011

Armchair, zigzag, chiralElectronic Properties

O. Grady, J. Wiley 2011

J. P. Solvetat et al. 1999

Main process:Catalytic Vapor

Deposition – metalcatalysts

Characterizaition of specific surface

Volumetric static gas adsorption:

BET-Isotherme using 1-butene (model substance)

Systems: N121, N347, EB 262, ES 204, Silica MP 1165,

VN 2, CNT-NC 7000

Equipment: BEL Sorp max.

Parameter: Temp. 267 K;

p < 100 kPa

V= volume adsorbed molecules

Vm= monolayer, volume adsorbed molecules

N = adsorbed molecules

Nm= monolayer, adsorbed molecules

00

11

)( p

p

Nc

c

cNNpp

p

mm

••

−+

•=

•−

BET:

10-6

10-5

10-4

10-3

10-2

10-1

100

10-5

10-4

10-3

10-2

10-1

100

101

V/ V

m

p/p0

MP1165 (151.53 m²/g)

VN2 (134.28 m²/g)

EB262 (100.75 m²/g)

N347 (63.23 m²/g)

ES204 (17.23 m²/g)

NC7000 (220.69 m²/g)

N121 (89.23 m²/g)Reduced activity

Distribution of surface energy Q - BET-Isotherm

Static gas adsorption: 1-butene

9

( ) ( ) ( )dQQfQTpN

NTp

m

⋅==Θ ∫∞

0

,,, θ

Langmuir isotherm

Energydistribution

Crystallite

Edges

Graphitic

Planes (sp²)

Amorphous

Carbon (sp3)

Slit Shaped

Cavities

I

II

III

IV

I II III IV

[S. Ross, J. P. Oliver, „On Physical Adsorption“,

J. Wiley & Sons, London (1964)]

[A. Schröder, M. Klüppel, R. H. Schuster,

Macromol. Mater. Eng, 292, (2007)]

N = adsorbed molecules

Nm= monolayer, adsorbed molecules

Systems: N121, N347, EB 262, ES 204,

Silica MP 1165, VN 2, CNT-NC 7000

Equipment: BEL Sorp max.

Parameter: Temp. 267 K; p < 100 kPa

0 10 20 30 40 50

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

Q [kJ/mol]

N121 (89.23 m²/g)

EB262 (100.75 m²/g)

N347 (63.23 m²/g)

ES204 (17.23 m²/g)

NC7000 (220.69 m²/g)

MP1165 (151.53 m²/g)

VN2 (134.28 m²/g)

f(Q

) [m

ol/kJ]

10 20 30 40 500,000

0,002

0,004

0,006

0,008

0,010

CNT: Low surface energy,

10

Characterization of CNT/CB – Surface energy

Test component: e. g. pentaneRetention time (tr) = tr2 – tr1Retention volume (Vr) = tr * F * jSpec. retention volume (Vr

*) = Vr/m

tr = Retention Time (min), F = Carrier gas flow rate (ml/min),j = Pressure correction factor, m = mass of the filler (g),Pi = Inlet pressure (Bar), Po = Outlet pressure (Bar)

Inverse Gaschromatography (IGC)

11

Free sorption energy : ∆G = R * T * ln(Vr

*)

Test components:• Pentane

• Hexane• Heptane

• Acetone• Acetonitrile

Characterization of CNT and CB by IGC

Surface energy:γs = γs

d + γssp, with γs

d ,γssp disp. / polar part

γγγγsd = ∆∆∆∆G2

CH2 / 4N2 * a2CH2 * γγγγCH2

aCH2 : area covered by a –CH2– unit;

γCH2 :surface free energy of a surface composedentirely of –CH2– units; N = Avogadro's number

Surface energy for CNTs and CBs

Test component: pentane

Higher interaction

A. Jain, DIK/Universität Magdeburg

Reinforcement in elastomers

20 – 50 nm

S. Shiga, M. Furuta, RCT, 58, (1985), 1/22

A. R. Payne Rubber Chem. Technol. 39 (1966) 365

G = υ k T

υ = network density

φ = filler vol.- fraction)

Hydr. effect: η = ηo • (1+2,5 +φ+14,1 φ2)

Phys./chem. filler-rubber interaction

Payne effect

Agglomerates

Small Agglomerates

Combined

Aggregates

Separated

Aggregates

Mixing1. Internal mixer (Haake Rheomix),

Rotor speed. Var. (50; 75; 100 rpm)2. Two roll mill (Curing system)

Used materials and compounds

TAIC: Triallylisocyanurate (70 % active content)

DHBP: 2.5-Di-methylhexane-2.5-di-tert. butyl peroxide (45 % active content

phrNBR (28 % ACN) 100

CNT NC7000 0-10CB (N550)/N772) 0-60ZnO/st.-acid

S/CBS

Nanogummi Project, EU

phrFKM 100

CNT NC7000 0-10CB (N 990) 0-60Carnauba wax 1

ZnO 3DHBP /TAIC

phrEPDM (50 % ext. oil) 100

CNT NC7000 0-10CB (N550) 0-50Paraff. oil 10

ZnO/st.-acidS/ZBEC/TBzTD/MBT/CBS 1.2

EPDM: Keltan 9565 Q, high molecular type, 62.5 % ethylene

Hybrid systems:CB / CNT ratios in phr:

0 – 60 / 2 – 15depending on polymer

Mixing optimization

Equipment: Haake Rheomix 30000 2 4 6 8 10 12 14 16

0

50

100

150

200

250

300

10min, 100 rpm, 6CNT

10min, 75 rpm, 6CNT

15min, 50 rpm, 6CNT

15min, 50 rpm, 00

10min, 50 rpm, 6CNT

7min, 50 rpm, 6CNT

t [min]

Torq

ue [N

m]

50

100

150

200

TM

[°C

]

10 min./50 rpm

Laboratory Mixer (Polylab)

Chamber- Vol.: 300 ml

Filling: 70 %

Compound: 6 phr CNTs/NBR/ZnO/St.-acid

2 min.: filler

5-6 min.:ZnO/Stearic acid

Two roll mill:

4-5 min. CBS/S

Mixing sequence:

Parameters:

• mixing time

• rotor speed

Increasing rotor speed:

Increase in torque

and temperature

Mixing of Compounds - CNT vs. CB

Mixing steps1) 0 min. polymer2) 3 min. CNTs/CB N5503) 6 min. ZnO+ Stearic acid

(3 phr each)4) 15 min. Stop

Mixing conditionsTemp. 50 °CRotor speed 50 rpm

Mixing time 15 min.

Two-roll mill1) Sulfur (2 phr)

2) CBS (2phr)

0 2 4 6 8 10 12 14 16 18

0

50

100

150

200

250

300

CNT (phr)

10

6

4

2

00

Torq

ue [N

m]

t [min]

60

90

120

150

180

T [°C

]

0 2 4 6 8 10 12 14 16 18

0

50

100

150

200

250

300

CB(phr)

60

30

10

5

1

00

t [min]

To

rqu

e [N

m]

60

90

120

150

180

TM

[°C

]

• CNTs require higher torque than CB (higher energy input with CNTs) at same temperature• Temp. increases more with CNTs than with CB, 10 phr CNT: 150 °C vs. CB: 135 °C

CNT CB

NBR/CNT NBR/CB

Mixing optimization - Variable CNT-concentration

0 2 4 6 8 10 12 14 16 18

0

50

100

150

200

250

300

Torque

CNT (Vol. %)

5

3

2

1

00

To

rque

[N

m]

Mixing time [min]

Temp.

60

90

120

150

180

Mix

ing

tem

p. [°

C]

NBR/CNT at 50 rpm

FKM/CNT at 50 rpm

Laboratory Mixer (Polylab)Chamber- Vol.: 300 ml

Filling: 70 %Compound: 6 phr CNTs

Concerning temperature and torque profiles

best parameter: 15 min. and 50 rpm

17

mixed at 60 rpm

Morphological Characterization

mixed at 50 rpm

• TEM: Zeiss Libra 120 Acc. voltage:120 kV,

mixed at 40 rpm

System: FKM/1.5 Vol-% CNTs- nanocomposites, Prepared: Lab-Mixer

Preparation/Specimen:

• Ultramicrotome• Diamant knifes.

• Cryo-sections (100 nm).

• Magnification: 31,500 x

� Clusters of CNTs

� Some agglomerates

� No difference from 50 to 60 rpm

18

10-1

100

101

102

102

103

Strain Sweep 1 Hz 80°C CNT (phr)

10

08

05

03

01

00

G' [

KP

a]

Amplitude [%]10

-110

010

110

2

102

103

Strain Sweep 1 Hz 80°C N990 (phr)

50

30

20

10

05

00

G' [

KP

a]

Amplitude [%]

10-1

100

101

102

102

103

Strain Sweep 1 Hz 80°C CB:CNT (phr)

15 05

15 03

15 01

10 02

unfilled

G' [

KP

a]

Amplitude [%]

Rheological Properties of FKM-systems

Alpha Technologies RPA 2000Frequence: 1 HzAmplitude: 0.3 to 400 %Temperatur: 80 °CSample mass: app. 5 g.

Rubber Process Analysis (RPA)

FKM-CNT FKM-CB (N990) FKM-CB( N990)/CNT

10 phr CNT

Low additional content of CNT (hybrid systems):

15 / 5 for CB/CNT ~ 40 phr CB ~ 10 phr CNT

Rheological Properties – Payne effect

• CNTs affects higher increase of G’ than CB

• CNT shows higher Payne effect - anisotropy

(for example at 5 Vol.%)

Alpha Technologies RPA 2000Frequency: 1 HzAmplitude: 0.3 to 400 %Temperatur: 80 °CSample mass: app. 5 g.

Rubber Process Analysis (RPA)

G`= Storage modulus

10-1

100

101

102

102

103

Strain Sweep 1 Hz 80°C CNT (Vol. %)

5

4

2.5

1.5

0.5

00

G' [

KP

a]

Amplitude [%]

FKM/CNT

0 5 10 15 20 25 300

50

100

150

200

250

300

350

G' 1

%-G

' 44

0%

[kP

a]

CB [Vol. %]

FKM/N990

NBR/N550

EPDM/N550

FKM/-, NBR/-and EPDM/CNT

0 1 2 3 4 5

40

80

120

160

200

240

G' 1

%-G

' 44

0%

[kP

a]

φ [Vol. %]

FKM

NBR

EPDM

CNT

Related storage modulusG’filled/G’unfilled - difference

at 1 % and 400 %strain

0 5 10 15 20 25 30 35

0

4

8

12

16

20

24

15min, 50rpm

10min, 50 rpm

7min, 50 rpm

10min, 100rpm

10min, 75rpmT

orq

ue

(dN

m)

Time (min.)

CNT

(6phr)

unfilled

No significant influenceof mixing parameters on crosslinking level

Equipment: Rheometer MDR 2000 E

Vulcanization behavior – Mixing parameters

Temp.: 160 °CDeformation-angle: +/-1,5 °Frequence: 1 Hz

System: NBR/CNT (6 phr)

∆S ≅ G = νe • R • T

Results:• Vulcanization time (t90 ) is reduced by CNTs,

(higher thermal conductivity)• ∆∆∆∆S is increased slightly by CNTs – different

behavior at perculation limit

(20 dNm vs. 17 dNm)

t90 and ∆S as f(cfiller),

-5 0 5 10 15 20 25 30 35 40 45 50 55 60 65

4,0

4,5

5,0

5,5

6,0

6,5

7,0

7,5

8,0

8,5

T90 (min)

S'max-S'min (dNm)

CB (phr)

T9

0(m

in.)

10

15

20

25

30

35

40

S'm

ax-S

'min

(d

Nm

)

NBR/CB N550

0 2 4 6 8 10

4,0

4,5

5,0

5,5

6,0

6,5

7,0

7,5

8,0

8,5

T90 (min)

S'max-S'min (dNm)

CNT (phr)

T9

0 (

min

)

10

15

20

25

30

35

40

S'm

ax-S

'min

(d

Nm

)NBR/CNT

Vulcanization behavior as f(cfiller)

Rheometer:Temp.: 160 °CDeformation-angle: +/-1,5 °Frequence: 1 Hz(DIN 53529)

22

FKM/CNT

0 5 10 15 20 25

0

5

10

15

20

25

30

35

N990 (Vol. %)

25

15

10

5

2.5

00

Torq

ue (dN

m)

Time (min.)

FKM/CB N990

Vulcanization behavior of FKM-systems as f(cfiller)

Rheometer:Temp.: 160 °CDeformation-angle: +/-1,5 °Frequence: 1 Hz(DIN 53529)

At 5 phr ∆S CNT = 27.0 dNm

∆S CB = 13.3 dNm

Higher cCNT : Increase in ∆S , higher as at NBR (reinforcing effect)

Mechanical Properties

0 100 200 300 4000

2

4

6

8

10

12

14

CNT(phr)

10

8

6

4

2

1

0,5

00

Strain [%]

Str

ess [

MP

a]

0 100 200 300 4000

4

8

12

16

20

24

CB(phr)

60

30

10

5

1

00

Strain [%]

Str

ess [

MP

a]

• CNTs reinforce at low concentrations much more than CB• Elongation at break decreases above percolation (2 to 4 phr)

• At 10 phr σCNT = 12.0 MPa, εCNT = 209 %σCB = 8.5 MPa, εCB = 363 %

Stress Strain –measurements acc. to DIN 53504

NBR/CB N550NBR/CNT

S2-specimen

Speed: 200 mm/min

Zwick-testmachine

24

0 20 40 60 80 100 120 140 1600,0

0,3

0,6

0,9

1,2

1,5

1,8

2,1

CNT (phr)

10

07

05

03

01

00

Strain [%]

Str

ess [M

Pa]

Mechanical Properties

Stress Strain –measurements acc. to DIN 53504

S2-specimen

Speed: 200 mm/min

Zwick-testmachine

0 10 20 30 40 50 600

3

6

9

12

15

18

21

Tensile strength

Elongation at break

CB [phr]

Ten

sile

str

en

gth

[M

Pa

]

160

200

240

280

320

360

400

440 E

lon

ga

tion

at

bre

ak [%

]

0 2 4 6 8 100,0

0,3

0,6

0,9

1,2

1,5

1,8

Tensile strength

Elongation at break

CNT [phr]

Te

nsile

str

eng

th [M

Pa

]

100

120

140

160

180

200

Elo

ng

ation

at b

rea

k [%

]

00:00 15:01 15:03 15:05 20:07

1,0

1,5

2,0

2,5

3,0

3,5

4,0

Tensile strength

Elongation at break

CB:CNT [phr]

Tensile

str

ength

[M

Pa]

170

180

190

200

210

220

230

Elo

ngation a

t bre

ak [%

]

EPDM-CB/CNT

EPDM/CNT

EPDM/CB

EPDM/CNT

Filler –conc.

From stress-strain measurements:

Related modulus at 100 % Reinforcing Factor = (σF/σ0)100%

Reinforcing Factor CNT vs. CB

0 5 10 15 20 25 300

2

4

6

8

10 FKM/CNT

NBR/CNT

EPDM/CNT

FKM/CB

NBR/CB

EPDM/CB

RF

@ 1

00

% s

tra

in

Filler [Vol. %]

RF FKM: 4 : 1.5 Vol.% CNT/17 Vol. % CB

RF NBR: 4 : 3.2 Vol.% CNT/19 Vol. % CB

RF EPDM: 2 : 5.0 Vol.% CNT/15 Vol. % CB

For the same reinforcing effectThe loading of CB has to be factor

5-6 higher than for CNT

Polymer-Filler Interaction

0,0 0,1 0,2 0,3 0,4 0,5

0,4

0,5

0,6

0,7

0,8

0,9

1,0

QF

ille

d/Q

un

fille

d

φ/(1−φ)

CNT CB

−−=

φ

φ

11 m

V

V

rf

ro

Swelling experiments: Kraus Equation

V = equilibrium volume fraction,

filled/unfilled

m = polymer-filler interaction parameter

C= Kraus constant

φ = filler volume fraction

Specimen: 2 mm discs, 1 g

Swelling medium: MEK

Temperature: 20 °CEqulibrium: 24 h

0,00 0,01 0,02 0,03 0,04 0,05 0,06

0,88

0,90

0,92

0,94

0,96

0,98

1,00

EPDM/CNT

NBR/CNT

FKM/CNT

φ/(1−φ)

Vr0

/Vrf

NBR CNT vs. NBR CB

1)EPDM-values are corrected by the extender oil content

Interaction

parameter

FKM/CNT NBR/CNT NBR/CB EPDM/CNT

m 2.3 1.6 0.3 0.71)

C 12.2 3.8 1.5 2.51)

High polymer filler interaction for CNTsHigh spec. surface and high aspect ratio

� =� − ��� + 1

3 1 − ����/

Electrical Conductivity

High Resolution Dielectric AnalyzerBDS 40 (Novocontrol GmbH)f = 10-1 – 107 Hz

Undispersed CNT-Agglomerates

CNT-Network

''ε

ω

relaxationD −

relaxationD−β

α

Glass

Transition

onpolarisatielectrode

tyconductivi

Segment

movements

''ε

ω

relaxationD −

relaxationD−β

α

Glass

Transition

onpolarisatielectrode

tyconductivi

onpolarisatielectrode

tyconductivi

Segment

movements

ε’’ reaches maximum values at Tg

''εi'ε*ε -=

Principle: Orientation of dipolesin presence of altering current (AC)

A

Dipoles

Polar Molecules

Dielectric Constant e

A

Free Charge Carriers

Electrons , Ions

Conductivity s

A

Dipoles

Polar Molecules

Dielectric Constant e

A

Dipoles

Polar Molecules

Dielectric Constant e

A

Free Charge Carriers

Electrons , Ions

Conductivity s

A

Free Charge Carriers

Electrons , Ions

Conductivity s

Dielectric spectroscopy

Permittivity

1

I

dE

I

U

F

dR

•===

σ

σ'=ε0 ε'' ω

σ''=ε0 ε' ω

σ= conductivityω= angular freq.

E= electricfieldd= distanceF= areaε= permittivity

Conductivity

Electric Conductivity – NBR-systems

10-2

100

102

104

106

108

10-11

10-9

10-7

10-5

10-3

10-1

CNT(phr)

10

8

6

4

2

1

0.5

00

Ele

ct. c

ond

uctivity σ

' [S

/cm

]

Frequency [Hz]

10-2

100

102

104

106

108

10-11

10-9

10-7

10-5

10-3

10-1

CB(phr)

60

30

10

05

01

00

Ele

ct. c

onductivity σ

' [S

/cm

]

Frequency [Hz]

• Electrical saturation above elect. percolation threshold• At 10 phr σ’CNT = 0.01 S/cm

σ’CB = 2.5*10-10 S/cm

NBR/CB N550NBR/CNT

Method: High Resolution Dielectric Analyzer

BDS 40 (Novocontrol GmbH)f = 10-1 – 107 Hz Parameter: filler content

filler type

29

Electric Conductivity –FKM-systems

10-2

100

102

104

106

108

10-14

10-12

10-10

10-8

10-6

10-4

10-2

100

CNT [phr]

10

08

05

03

01

00

Ele

ct. c

onductivity σ

' [S

/cm

]

Frequency [Hz]10

-210

010

210

410

610

810

-14

10-12

10-10

10-8

10-6

10-4

10-2

100

N990 [phr]

50

30

20

10

05

00

Ele

ct. c

on

du

ctivity σ

' [S

/cm

]

Frequency [Hz]10

-210

010

210

410

610

810

-15

10-13

10-11

10-9

10-7

10-5

10-3

CB:CNT(phr)

15 05

15 03

10 02

15 01

unfilled

Ele

ct. c

onductivity σ

' [S

/cm

]

Frequency [Hz]

FKM/CNT FKM/CB FKM-CB/CNT-hybrid

Method: High Resolution Dielectric Analyzer

BDS 40 (Novocontrol GmbH)f = 10-1 – 107 Hz

• CNT: high conductivity, sp2 - structure of C-atoms

• Continuous filler-filler contact network

• High aspect ratio of the CNTs, substitution of CB by small amounts of CNT (hybrid)

saturation

Parameter: Filler content

Filler type and combination

0 2 4 6 8 101E-11

1E-9

1E-7

1E-5

1E-3

0,1

Co

nd

uctivity s

' [S

/cm

] a

t 1

Hz

CNT (phr)

Percolation

• Electrical Percolation Threshold: CNTs = 1-2 phr rangefor NBR-systems (at 1 Hz) CB = 10-15 phr range , Factor : < 5 to 6

• Depending on polymer type: Perculation threshold is < appr. 5 phr (0.6 to 2.8 vol-%

Electric Conductivity

Method: High Resolution Dielectric AnalyzerBDS 40 (Novocontrol GmbH)f = 10-1 – 107 Hz

NBR/CNT

FKM/-, EPDM/-,NBR/CNT

31

High conductivity silicon-CNT composites for electrodes

+

ObjectiveObjectiveObjectiveObjective::::• Material development for an electrode as

implantate to the brain measuring and stimulationof neuronal signals

• Treatment of neurological diseases like Alzheimer's, Morbus Parkinson

MaterialsMaterialsMaterialsMaterials• Biological compatible soft silicone rubber PDMS (product Sylgard 184)

- crosslinking: Pt- catalysed curing system- dyn. viscosity : 3500 mPa*s (liquid silicone)

• Highly electrical conductive filler – CNT Nanocyl 7000 (MWCNT)(volume resistivity on powder = 10-4 Ω*cm or conductivity of 106 S/m comparable to

Cu or Au)

32

Mixing of low viscous silicone/CNT-compounds

Using an internal mixer

or laboratory stirring system

for low-viscosity mixture

Difficulties• shear thickening while

compounding• motor strength too low• Bad dispersion

Planetary mixer• different geometry and principle of mixing• two mixing tools

• additional scraper (10 rpm)• High shear forces• up to 620 rpm

• vacuum bell jar

PC-Laborsystem Dissolver - LPV 1A40Source: http://www.pc-laborsystem.ch TEM micrographs: 2 phr CNT in silicone, DIK

33

Mixing Optimization

10-2

10-1

100

101

102

103

104

105

106

10-15

10-13

10-11

10-9

10-2

10-1

100

σ' [

S/c

m]

f [Hz]

100rpm

200rpm

250rpm

300rpm

350rpm

400rpm

500rpm

Sylgard 184

4,0 wt% CNTbest result with 300 rpm at 10 min. : σ' = 1,1*10-1 [S/cm]

at 1Hz conductivity of silicone: σ' = 3,3*10-15 [S/cm]

50 100 150 200 250 300 350 400 450 500 550

1E-3

0,01

0,1

σ' [

S/c

m]

rotor speed [rpm]

4,0 wt% CNT at 1Hz

Rotor speed

10-2

10-1

100

101

102

103

104

105

106

107

108

10-15

10-14

10-13

10-12

10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

σ' [

S/c

m]

f [Hz]

0.5 wt% CNT

1.0 wt% CNT

2.0 wt% CNT

3.0 wt% CNT

4.0 wt% CNT

5.0 wt% CNT

Sylgard 184

CNT-concentration

• Highest conductivity with 5 wt% CNT: σ' = 9,4 x 10-2 [S/cm]• Percolation threshold ϕ* at ~0.9 wt% CNT

Summary

� Carbon fillers – CB, CNTs, fullerenes, graphenes

� CNT : Low surface energy, high aspect ratio and high specific surface of CNTs - reason of

advantage for mechanical and electric properties of composites

� Effective incorporation and dispersion of CNTs in NBR, FKM and EPDM- rubber (TEM, RPA)

by melt mixing technology

� High increase in viscosity of uncured compounds by CNT

� Swelling: Filler /polymer interaction: FKM/CNT >> NBR/CNT > EPDM/CNT > NBR/CB N550)

� High reinforcing factors for CNT in comparison to CB, appr. factor 6 to 10 for all systems

� Electrical percolation for CNTs around 1-2 phr range (factor < 5 lower than CB) for melt

mixing

� Mixing of low viscous silicone for electrode applications: Special mixing methodology

� Perculation threshold at appr. 0.9 wt. -% , conductivity at 5 wt.-%: 0.1 S/cm

Acknowledgement:

Funded by EU- Eurostar

and DLR, !E!7836 NanoGummi

Federeal Ministry of Education

and Reasearch (BMBF),

KMU innovativ - FlowTrode 13GW0050C

Partners:

• KKT, Osterode

• Nanocyl, Sambreville

www.DIKautschuk.de

• Competence in rubber• Tailor made solutions

• Confidential• Accreditation: ISO/DIN 17025• Staff: 80 colleagues

• Non profit organizationThank you for your attention