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Linear and Non Linear Rheological
Measurements on Rubber
Polymers and Compounds
Thomas Rauschmann
Copyright TA Instruments, USA
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Standard Test: Mooney
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0.0
16.0
32.0
48.0
64.0
80.0
0.0 1.6 3.2 4.8 6.4 8.0
Mo
on
ey-V
isko
sitä
t [M
U]
Zeit [min]
SCARABAEUS GMBH - info@scarabaeus-gmbh.de - Tel.:+49 (0) 6403/9034-0
Polymer C1
Polymer C1
Polymer B1
Polymer B1
Polymer A1
Polymer A1
SCARABAEUSMooneyprüfung
Entwicklung
• Mooney Viscosity• Mooney Relaxation• Mooney Scorch
Shear rate 1.6 s-1 (2 rpm)
0,01 0,1 1 10 100
0,01
0,1
1
.
η
shear rate, γ
vis
cosity
ML1+4
Standard Test: Mooney
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TA Instruments - RPA
Zeit
γ
-1.5
-1
-0.5
0
0.5
1
1.5
0 5 10 15 20 25 30 35 40
ω 1
ω 2
Zeit
γ1
-3
-2
-1
0
1
2
3
0 5 10 15 20 25 30 35 40
γ2
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Zeit
γ
-1.5
-1
-0.5
0
0.5
1
1.5
0 5 10 15 20 25 30 35 40
ω1
ω2
Frequency:
RPA 0.001…50.0 Hz
Step 0.001Hz
RPA Rheometer
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Effect of Branching on G’, G”, ηηηη* and tangent δδδδ
1000
10000
100000
1000000
10000000
0.01 0.1 1 10 100 1000
Frequency (Rad/s
Eta
* (P
a.s
)
Branched
Linear
Mooney shear rate
range
0.1
1
10
100
1000
0.01 0.1 1 10 100 1000
Frequency (Rad/s)
G' &
G"
(kP
a)
0
1
2
3
4
5
6
7
8
9
Tan
gen
t D
elt
a (
-)
∆δ or ∆Tan δ
“High performance EPDM polymers based on a new technology of controlled Long Chain Branching” H.J.H.
Beelen, IRC97, Nürnberg.
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LCB and MWD (linear) effect on Tangent δδδδ
0
0.5
1
1.5
2
2.5
3
0.01 0.1 1 10 100 1000
Frequency (Rad/s)
Ta
ng
en
t D
elt
a (
-)B50
B100
Star-IIR
Mix4
Weight % B15 B30 B50 B100 B200
Mix 1 90.7 0 0 0 9.3
Mix 4 10.9 21.9 36.4 22 8.8
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Correlation between ηηηη* and Mooney viscosity ML(1+4) – EPDM polymers
1000
10000
100000
1000000
10000000
0.01 0.1 1 10 100 1000
ηη ηη*
(Pa
.s)
Angular frequency (Rad/s)
Polymer 1-2
Polymer 2-2
Polymer 3-2
Polymer 4-2
Polymer 5-2
Polymer 6-2
Polymer 7-2
Mooney shear rate
range
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EPDM (ML(1+4)@125° C 65 ± 5 MU
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0.01 0.1 1 10 100 1000
Ta
ng
ne
tδ
δ
δ
δ
(-)
Angular frequency (Rad/s)
Polymer 1-2
Polymer 2-2
Polymer 3-2
Polymer 4-2
Polymer 5-2
Polymer 6-2
Polymer 7-2
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Zeit
γ1
-3
-2
-1
0
1
2
3
0 5 10 15 20 25 30 35 40
γ2
Strain:RPA 0.005…360.0 °
Step 0.01°
RPA Rheometer
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Why Non linear viscoelasticity ?
PIPKIN Diagram
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RPA Rheometer
0
100
100
200
200
300
300
400
400
1 10 100
Schubmodul G' [kPa]
Amplitude [%]
SCARABAEUS GMBH - info@scarabaeus-gmbh.de - Tel.:+49 (0) 6403/9034-0
Scarabaeus GmbHMeß- und Produktionstechnik
SIS V 50
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Physical description of PolymersStrain Sweep - LAOS
0.0π 0.5π 1.0π 1.5π 2.0π
-8000
-6000
-4000
-2000
0
2000
4000
6000
8000
-1200
-1000
-800
-600
-400
-200
0
200
400
600
800
1000
1200
PIB, ω=0.1 Hz, γ0=1000%, T=140°C
τ [P
a]
t×ω [Pa]
γ [%
]
•" S
tad
ler
FJ,
Le
yg
ue
A,
Bu
rhin
H,
Ba
illy
C (
20
08
) T
he
po
ten
tia
l o
f la
rge
am
plitu
de
osc
illa
tory
sh
ea
r to
ga
in a
n in
sig
ht
into
th
e
lon
g-c
ha
in b
ran
chin
g s
tru
ctu
re o
f p
oly
me
rs.
•In
: T
he
23
5th
AC
S n
ati
on
al
me
eti
ng
, p
oly
me
r p
rep
rin
ts A
CS
, vo
l4
9. N
ew
Orl
ea
ns,
LA
, U
SA
, p
p 1
21
–1
22
"
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Physical description of PolymersStrain Sweep - LAOS
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Henri Burhin, Polymer Process Consult, 2012
Physical description of PolymersStrain Sweep - LAOS
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LAOS – Sensitivity to branching content
A (Branched) 2.5% branched in linear H (Linear)
G'1/G'5 6,91 6,09 3,74
A3/A5 -2,97 -3,44 -3,00
E1 3,91 5,32 4,00
E2 -3,97 -4,44 -4,00
E3 4,94 5,93 5,00
G'1/G'5-E3 1,97 0,16 -1,27
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EPDM polymers ML(1+4), 125° C 65 ± 5 MU
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0.01 0.1 1 10 100 1000
Ta
ng
ne
tδ
δ
δ
δ
(-)
Angular frequency (Rad/s)
Polymer 1-2
Polymer 2-2
Polymer 3-2
Polymer 4-2
Polymer 5-2
Polymer 6-2
Polymer 7-2
-300000
-200000
-100000
0
100000
200000
300000
-8 -6 -4 -2 0 2 4 6 8
Sh
ea
r st
ress
(P
a)
Shear rate (s-1)
Polymer 6-2
Polymer 7-2
Polymer 5-2
Polymer 4-2
Polymer 3-2
Polymer 2-2
Polymer 1-2
-2
0
2
4
6
8
10
12
Polymer 7-2 Polymer 6-2 Polymer 5-2 Polymer 4-2 Polymer 3-2 Polymer 2-2 Polymer 1-2
mean
LCB
In
de
x (
G'1
/G'5
-E
3)
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RPA Rheometer – Tan Delta
LCB Index:BR1: 3.7BR2: 2.2
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Strain-Sweep / tan δ δ δ δ @ 1000%aging @ 150°C, 400%
2.7
4
53.7
6
0
10
20
30
40
50
60
BR 1 BR 2
Tan Delta
percentage differencesbefore and after aging
0.000
0.500
1.000
1.500
2.000
2.500
3.000
3.500
4.000
4.500
BR 1 BR 2
Tan Delta
before aging
after aging
2 types of BR with:45MUcis-1,4 Content % > 96
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Strain-Sweep / LCB @ 1000%
aging @ 150°C, 400%
14.45
101.74
0
20
40
60
80
100
120
BR 1 BR 2
LCB Index
percentage differencebefore and after aging
0
1
2
3
4
5
6
7
8
BR 1 BR 2
LCB Index
before aging
after aging
2 types of BR with:45MUcis-1,4 Content % > 96
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Strain-Sweep / tan δ δ δ δ @ 1000% aging @ 150°C, 400%
2.74
53.76
14.45
101.74
0
20
40
60
80
100
120
BR 1 BR 2
dif
fere
nce b
efo
re/a
fter
ag
ing
[%
]significant differences in LCB Index
Tan Delta
LCB Index
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Practical example, linear and branched Polymer
Keltan 6950 Nordel 5565
Mooney ML 1+4 [MU] 65 65
Ethylen [%] 48 50
ENB content [%] 9 7.5
Distribution medium medium
Degree of branching Branched Linear
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Practical example, linear and branched Polymer
Frequency Sweep
Shear - thinning
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Practical example, linear and branched Polymer
Frequency Sweep
Mooney
Low
Frequency
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Physical description of Polymers
Strain Sweep - LAOS
High Strain
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Physical description of PolymersStrain Sweep - LAOS
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Recipe of Compounds
Keltancompound
Nordelcompound
phr phr
EPDM (LCB) 100
EPDM, linear 100
Fast Extrusion Furnace (FEF) carbon black 95 95
Chalk 50 50
Paraffinic Oil 65 65
ZnO 6 6
Stearic acid 1 1
Drying agent 9 9
Antiaging agent 0,5 0,5
Sulfur and accelerator 4,5 4,5
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Physical description of filled Polymers
Strain Sweep - PAYNE
Tensile Strength [Mpa]
Keltan cmp. 9.25
Nordel cmp. 8.32
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Kinetic description of filled PolymersVulcanisation
Keltan compound
Nordelcompound
S' Min [dNm] 1.21 1.4
S' Max [dNm] 20.44 23.17
ENB content [%] 9 7.5
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Physical description of filled PolymersFrequency Sweep
Shear thinning
15%
5%
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Extrusion – Machine parameters
Extrusion Keltan compound Nordel compound
Temp. extruder [°C]70 70
Pressure die [bar]91.3 102
Current [A]111.5 124
Speed [m/min]10.5 10.5
Temp. Mass [°C]
114 114-125
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Rubber compound process troubleshooting
Rubber compound extrusion.
Serious processing problem in production
Summary of observations:
• All batches passed standard QC tests.
• QC test involves rheometer only (MDR).
• One batch gave higher extrusion head pressure and temperature,
higher swell and surface defect (“Orange skin”) suggesting possible
scorch in the extruder.
• The faulty batch was compared to a trouble free batch.
Good
Bad
160° C
GoodBad
Both compounds have identical or almost identical ML and
MH.
The faulty compound exhibits a lower cure rate (?)
The faulty compound exhibits a significantly LONGER
scorch time (??????)
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Rubber compound process troubleshooting
Good
Bad
Non isothermal cure test (80° C – 180° C)
Some differences in
the uncured state
Non isothermal cure test confirms
identical ML and MH and longer
cure time for the faulty batch
Some differences are observed on
G’ and Tangent δ before cure
suggesting that viscoelastic
properties of uncured compounds
being different.
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Rubber compound process troubleshooting
Good
Bad
RPA testing “Payne” diagram – 100° C
Bad compound shows higher
modulus at both low and high
strain.
This suggest that filler
dispersion is not the cause of
the problem.
The problem therefore stays
in either polymer quality of
filler content.
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Rubber compound process troubleshooting
Frequency sweep at 100° C Strain sweep at 100° C
Bad and good batches show almost
identical viscoelastic properties in both
frequency and strain sweep.
Only some significant difference is
observed at very low shear rate
(frequency) on Tangent δ.
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Rubber compound process troubleshooting
W disp.
(J)
Good 168.94
Bad 177.11
ISO Standard method 4664-1
Where ε is the ellipse area or the energy lost per
oscillation
γ0 is the maximum strain
σ0 is the maximum stressε = π.γ0.σ0.sin δ
The bad compound has been
found to dissipate almost
10% higher energy per cycle
in non-linear conditions.
Premature scorch for this
compound is produced by
large heat generation in the
extruder.
LAOS test 100° C, 90° arc, 0.2 Hz
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Summary and Conclusion
• The combination of linear and non linear
viscoelasticity measurements offers a unique tool for
polymer characterization.
• It clearly differentiates between MWD effect from
LCB effect
• It proved itself the fastest and most sensitive test for
detection of ultra low LCB content in polymers.
• This technique was successfully demonstrated on
SBR, BR, IIR, EPDM, NR, PE, PP, FKM, PC etc.
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Thank You
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Rheology, and Microcalorimetry
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