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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