opportunities for functionalized carbon blacks in …...rubber chem. technol., 1998 → reduce...
TRANSCRIPT
CHALLENGE
TESTED
BEYOND
DURABLE
MICRO
MATTERS
COMPOUND
KNOWLEDGE
FAMILIAR
BONDS
SHARE THE STRENGTH
Opportunities for Functionalized Carbon Blacks in Rubber Applications
Dr. Lewis B. Tunnicliffe, Dr. Charles R. Herd
IOM3 RIEG ATDM, London, March 22nd 2019
SHARE THE STRENGTH
Agenda
Rubber industry trends
Mechanics of carbon black reinforcement
Why do we need to functionalize carbon blacks?
Characterization of functionalized carbon black surface
Application examples
2
SHARE THE STRENGTH
Rubber Industry Trends
Sustainable mobility
➢Low rolling resistance tires without sacrifice to wear and grip
Anti-vibration devices for electric vehicles
Low heat buildup tracks, pads, belts and solid tires
3
Rolling
Resistance
Wet GripWear
SHARE THE STRENGTH
Reinforcing Fillers for Rubber
4
Carbon black
Precipitated silica-silane
Non-carbon nanofillers
➢ Layered/needle-like clays
Carbon-based nanofillers
➢ Fullerenes
➢ Graphenes
➢ Carbon nanotubes
➢ Nanocellulose
SHARE THE STRENGTH
Reinforcing Fillers for Rubber
5
Carbon black
Aggregates produced from incomplete combustion of oil feedstock
Classified by the structure of the aggregate and the primary particle size
Paracrystalline material with exposed graphitic regions at surface
100 Å
SHARE THE STRENGTH
Mechanics of Carbon Black Reinforcement
6
Dis
pe
rsiv
e M
ixin
g
Distributive Mixing
Agglomerate
Fractured Bead
Aggregate
Bead
Reinforcement and Dispersion
In order to realize full reinforcement potential, carbon black must be effectively dispersed
Inherent surface chemistry allows for easy incorporation vs e.g. silica
Once carbon black is dispersed the measured reinforcement follows certain rules…
SHARE THE STRENGTH 7
Mechanics of Carbon Black Reinforcement
At constant loading and dispersion state the surface area and structure of carbon black control parameters of the Payne Effect:
0.1 1 10
Dynam
ic M
odulu
s
Dynamic Strain %
Strain Amplification
Particle Networking
G'0
G'HS
DG' = (G'0 - G')
SHARE THE STRENGTH 8
Mechanics of Carbon Black Reinforcement
At constant loading and dispersion state the surface area and structure of carbon black control parameters of the Payne Effect:
0.1 1 10
Dynam
ic M
odulu
s
Dynamic Strain %
Strain Amplification
Particle Networking
G'0
G'HS
DG' = (G'0 - G')
-20 0 20 40 60 80 100 120 140
0
1
2
3
4
5
DG
' / M
Pa
Surface Area (STSA) / m2.g-1
0 20 40 60 80 100 120
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
G' H
S / M
Pa
Structure (COAN) / ml.100g-1
50phr/eSBR
60˚C, 10Hz
SHARE THE STRENGTH 9
Mechanics of Carbon Black Reinforcement
Example of surface area effect on filler networking:
➢Loading = 20% vol.
10 m2/g
~N990160 m2/g
UHP grade
80 m2/g
~N330
40 m2/g
~N550
20 m2/g
~N772
All simulations
at φ = 0.20
1μm3 box volume
Decreasing nearest neighbor distance
Increasing networking
SHARE THE STRENGTH 10
Mechanics of Carbon Black Reinforcement
Direct correlation of inter-aggregate distances with dynamic properties via AFM
𝑁𝑁𝐷 =σ𝑖=1𝑛 𝑑𝑖𝑛
(5 x 5 μm scan size)0.030 0.035 0.040 0.045 0.050 0.055 0.060
2
3
4
5
6
7
DG
' / M
Pa
NND / mm
0.030 0.035 0.040 0.045 0.050 0.055 0.060
0.16
0.18
0.20
0.22
0.24
0.26
0.28
0.30
0.32
tand
NND / mm
Passenger tire treads
60˚C strain sweep data
SHARE THE STRENGTH
Mechanics of Carbon Black Reinforcement
Despite best efforts to disperse carbon black, aggregates have tendency to re-agglomerate
11
Surface energy approach:MJ Wang, Rubber Chem. Technol., 1998
→ reduce difference between polymer and filler surface energies
Differences in surface energy and chemistry drive
flocculation (networking of particles) in rubber
Polymer-filler interaction also influences Payne Effect
time
temperature
(dispersed) (flocculated)
SHARE THE STRENGTH 12
Mechanics of Carbon Black Reinforcement
Stiffness-hysteresis tradeoff controlled by surface area and polymer-filler interaction:
R2 = 0.97
N990
N660
N330
N134
How do we break the relationship?
Functionalization of filler / elastomer systems
to suppress flocculation effects
SHARE THE STRENGTH
Surface Modification of Carbon Blacks
• Graphitization
• Plasma treatment
• Amine treatment
• Polymer grafting
• Nano-particle deposition
• …..
• Oxidation
• Peroxide
• Acid
• Ozone
13
Wet processes
Gas phase
Increases in surface volatile content1
2
3
4
5
6
7
8
9
10
Vola
tile
Conte
nt %
Treatment TIme
Ozone oxidized N234
SHARE THE STRENGTH
Increase in oxygen content and surface species as function of treatment time by XPS
Resulting in increasing acidity of the carbon black
Increases in –OH and –COOH groups on the carbon black surface
Most likely regions of oxidation are at the crystallite edges
Surface Modification of Carbon Blacks
14
0.00E+00
1.00E+04
2.00E+04
3.00E+04
4.00E+04
5.00E+04
6.00E+04
7.00E+04
8.00E+04
9.00E+04
280282284286288290292294296298
Cou
nts
/ s
(R
esid
ua
ls ×
5)
Binding Energy (eV)
C1s Scan
10 Scans, 1 m 35.5 s, 400µm, CAE 50.0, 0.10 eV
C1s Scan A
C1s Scan B
C1s Scan C
C1s Scan DC1s Scan E
XPS Atomic Percent
Sample C-C O-C=O C=O C-O O Total
N234 98.2 0 0.2 0 0.9
Incre
asin
g o
xid
atio
n tim
e
←
96.0 0.5 0 0.4 2.6
94.7 0.6 0.3 0.5 3.4
94.2 0.7 0.5 0.6 3.6
91.9 1.1 0.1 1.2 5
90.7 1.3 0.8 0.9 5.7
88.8 1.9 0.7 1.5 6.6
86.3 2.3 0.9 1.7 8.3
SHARE THE STRENGTH
Surface Modification of Carbon Blacks
How to implement oxidized carbon blacks in rubber formulations?
➢ Use the polar surface to interact with a functionalized elastomer➢ In-chain functionalized sSRB for passenger tire
➢Epoxidized NR for commercial tire
➢ Use polar surface to perform coupling chemistry reactions➢Use sulphur donor as coupling chemical
15
SHARE THE STRENGTH
Implementation Example: SBR passenger tire
In-Chain Functionalized sSBR (carboxylic functionality)
➢Varied degrees of in-chain functionalization of sSBR
➢Carboxylic group functionality
➢ Intermolecular hydrogen bonding?
16
Use of Surface Treated Carbon Blacks in an Elastomer to Reduce Compound Hysteresis and Tire Rolling Resistance and improve Wet Traction, PCT/US2010/043384
Sample
CodeType
Degree of in-chain
functionalization
Vinyl
(wt% on SBR)
Styrene
(wt%)Tg (°C)
ML1+4 @
100 °C
(MU)
sSBR A
high vinyl
unfct. 41.0 26.2 -27.5 68
sSBR B ~3 mol% 40.0 26.1 -27.5 71
sSBR C ~6 mol% 44.2 24.8 -24.5 82
Carbon Black SBR
SHARE THE STRENGTH
Implementation Example: SBR passenger tire
In-Chain Functionalized sSBR (carboxylic functionality)
➢Passenger car formulation
➢Compounds reactively mixed
17
Use of Surface Treated Carbon Blacks in an Elastomer to Reduce Compound Hysteresis and Tire Rolling Resistance and improve Wet Traction, PCT/US2010/043384
Component Loading
sSBR 70
BR 30
SM-CB / N234 75
TDAE (32), ZnO (4), strearic acid (2), 6PPD (2), TMQ
(2), sulfur (1.9), TBBS (1.5), DPG (1.5 – with SM-CB)
PassTime
(sec)
Temp
(°C)RPM Process
1 30 80 70 Load: Polymer
1 60 -- 70 Load: 2/3 Carbon Black, Sweep
1 90 120 Var. Load: 1/3 Carbon Black, Oil (Blended)
1 15 -- 70 Load: Chemicals, Sweep
1 30 150 Var. Mixing - Reactive Feedback to 150°C
1 120 160 Var. Mixing - Reactive Feedback to 160°C
1 ~400 -- 70 Ram Down Discharge
Mill: 70°C, 25:21 rpm, Gap 0.055-60"
2 30 80 70 Load: Masterbatch
2 30 150 Var. Mixing - Reactive Feedback to 150°C
2 120 160 Var. Mixing - Reactive Feedback to 160°C
2 ~190 -- 70 Ram Down Discharge
Mill: 70°C, 25:21 rpm, Gap 0.055-60"
3 180 25 60 Load: 1/2 MB, Cures. 1/2 MB
3 ~190 -- 45 Discharge (100°C Max)
Mill: 70°C, 25:21 rpm, Gap 0.055-60"
SHARE THE STRENGTH
Implementation Example: SBR passenger tire
In-Chain Functionalized sSBR (carboxylic functionality)
➢Large increase in bound rubber for SM-CB/fxnSBR → polymer filler interaction
18
Use of Surface Treated Carbon Blacks in an Elastomer to Reduce Compound Hysteresis and Tire Rolling Resistance and improve Wet Traction, PCT/US2010/043384
SBR A
/ N23
4
SBR A
/ SM
-CB
SBR B
/ N23
4
SBR B
/ SM
-CB
SBR C
/ N23
4
SBR C
/ SM
-CB
0
10
20
30
40
50
60
70
80
90
Bo
und
Rub
be
r %
SHARE THE STRENGTH
Implementation Example: SBR passenger tire
In-Chain Functionalized sSBR (carboxylic functionality)
➢Systematic increases in static modulus especially for SM-CB
19
Use of Surface Treated Carbon Blacks in an Elastomer to Reduce Compound Hysteresis and Tire Rolling Resistance and improve Wet Traction, PCT/US2010/043384
SBR A
/ N23
4
SBR A
/ SM
-CB
SBR B
/ N23
4
SBR B
/ SM
-CB
SBR C
/ N23
4
SBR C
/ SM
-CB
0
2
4
6
8
10
12
14
16
18
Modulu
s / M
Pa
100%
200%
300%
SHARE THE STRENGTH
Implementation Example: SBR passenger tire
In-Chain Functionalized sSBR (carboxylic functionality)
➢Systematic reductions in Payne Effect
20
Use of Surface Treated Carbon Blacks in an Elastomer to Reduce Compound Hysteresis and Tire Rolling Resistance and improve Wet Traction, PCT/US2010/043384
0.1 1 10 100
0
2
4
6
8
10
12
G' /
MP
a
Shear Strain %
SBR A / N234
SBR A / SM-CB
SBR B / N234
SBR B / SM-CB
SBR C / N234
SBR C / SM-CB
0.1 1 10 100
0.05
0.10
0.15
0.20
0.25
0.30
tand
Shear Strain %
SHARE THE STRENGTH
Implementation Example: ENR commercial tire
Epoxidized Natural Rubber (ENR-25)
➢ In-chain functionalized cis poly-isoprene
➢Epoxy functionality has potentially high affinity to acidic functional groups on SM-CB
21
From ‘Low Rolling Resistance TBR Tread Compounds Based on Epoxidized Natural rubber and a Surface Modified Carbon Black’, Tire Technology Expo 2018
SHARE THE STRENGTH
Implementation Example: ENR commercial tire
Epoxidized Natural Rubber (ENR-25)
➢ In-chain functionalized cis poly-isoprene
➢Epoxy functionality has potentially high affinity to acidic functional groups on SM-CB
Pheonolic linkage (via –OH)
Benzoate-ester linkage (via –COOH)
22
From ‘Low Rolling Resistance TBR Tread Compounds Based on Epoxidized Natural rubber and a Surface Modified Carbon Black’, Tire Technology Expo 2018
Manna, Ajoy K; De, P P; De, S K; Chatterjee, MK, Rubber
Chemistry and Technology; Sept/Oct 1997; 70, 4, p 624.
SHARE THE STRENGTH
Implementation Example: ENR commercial tire
Epoxidized Natural Rubber (ENR-25)
➢ Strong (covalent?) interaction between SM-CB and ENR limits dispersibility of SM-CB
➢ Blending with of ENR with NR is required
➢ Significant build in high strain modulus resulting from strong interactions
23
From ‘Low Rolling Resistance TBR Tread Compounds Based on Epoxidized Natural rubber and a Surface Modified Carbon Black’, Tire Technology Expo 2018
Component Loading
NR CV60 Varied
ENR 25 Varied
SM-CB (N234) 55
TDAE (5), calcium strearate (1), ZnO (3),
strearic acid (3), 6PPD (1), TMQ (1), sulfur
(1.8), TBBS (2.4), DPG (1.5)
100phr 75phr 50phr 25phr 0phr
0
5
10
15
20
25
300
% m
od
ulu
s in r
e-m
ille
d c
om
pun
ds /
MP
a
ENR phr in ENR/NR blend
100phr 75phr 50phr 25phr 0phr
0
20
40
60
80
100
IFM
Dis
pers
ion
ENR phr in ENR/NR blend
Re
-mill
ing
SHARE THE STRENGTH
Implementation Example: ENR commercial tire
Epoxidized Natural Rubber (ENR-25)
➢CB phase distribution in ENR/NR blend is defined by affinity of SM-CB for the more polar rubber in the blend
24
From ‘Low Rolling Resistance TBR Tread Compounds Based on Epoxidized Natural rubber and a Surface Modified Carbon Black’, Tire Technology Expo 2018
SM-CB in 75/25 ENR-25/NRSM-CB in 50/50 ENR-25/NRSM-CB in 25/75 ENR-25/NR
(Red = NR, Blue = ENR, Green = SM-CB)
SHARE THE STRENGTH
Implementation Example: ENR commercial tire
Epoxidized Natural Rubber (ENR-25)
➢Significant reductions in Payne Effect when ENR/SM-CB is co-continuous in phase blend
25
From ‘Low Rolling Resistance TBR Tread Compounds Based on Epoxidized Natural rubber and a Surface Modified Carbon Black’, Tire Technology Expo 2018
0.1 1 10 100
0
2
4
6
8
10
12
14
G' /
MP
a
Shear Strain %
NR (100 phr), SM-CB
ENR (100 phr), SM-CB
ENR/NR (25/75), SM-CB
ENR/NR (50/50), SM-CB
ENR/NR (75/25), SM-CB
NR (100 phr), N234
0.1 1 10 100
0.05
0.10
0.15
0.20
0.25
tand
Shear Strain %
SHARE THE STRENGTH
Implementation Example: coupling agent
Sulphur Donor Approach
➢SDT/S (Rhein Chemie) dithiophosphate with sulphur bridge
➢Analogy with TESPT coupling agent used in silica systems
26
From ‘Novel Approach to Coupling Functionalized Carbon Black in Non-Functionalized Elastomer Systems’, ACS Rubber Division Fall Meeting, 2017
From ‘ New Approach to Couple Functionalized Carbon Black’ Rubber & Plastics News, April, 2018
Carbon Black Composition with Sulfur Donor, PCT/US2016/066920
➢ Phosphoryl transfer reaction between sulphur donor
and –OH or –COOH present on SM-CB surface
➢ Sulphur groups then available for coupling with diene
rubber
➢ Through this mechanism SDT acts as a coupling
chemical rather than a sulphur donor
SHARE THE STRENGTH
Implementation Example: coupling agent
Sulphur Donor Approach
➢Passenger car tread
27
N234 and SM-CB Mixing Protocol
PassTime
(sec)
Temp
(°C)RPM Process
1 30 80 70 Load: Polymer
1 60 80 70 Load: 2/3 Carbon Black
1 120 80 70 Load: Oil, 1/3 CB (blended)
1 180 150 Var.Load: Chemicals and SDT -
Reactive Feedback to 150°C
1 ~400 -- 70 Ram Down Discharge
Mill: 70°C, 25:21 rpm, Gap 0.055-60"
2 180 25 60 Load: 1/2 MB, Cures, 1/2 MB
2 ~190 -- 45 Discharge (100°C Max)
Mill: 70°C, 25:21 rpm, Gap 0.055-60"
From ‘Novel Approach to Coupling Functionalized Carbon Black in Non-Functionalized Elastomer Systems’, ACS Rubber Division Fall Meeting, 2017
From ‘ New Approach to Couple Functionalized Carbon Black’ Rubber & Plastics News, April, 2018
Carbon Black Composition with Sulfur Donor, PCT/US2016/066920
Component Loading
sSBR 96.25 (OE)
BR 30
SM-CB (N234) 75
ZnO (4), strearic acid (2), 6PPD (2), TMQ (2), SDT/S
(8.4), sulfur (varied), TBBS (varied), DPG (1.5)
SHARE THE STRENGTH
Implementation Example: coupling agent
Sulphur Donor Approach
➢Passenger car tread
28
From ‘Novel Approach to Coupling Functionalized Carbon Black in Non-Functionalized Elastomer Systems’, ACS Rubber Division Fall Meeting, 2017
From ‘ New Approach to Couple Functionalized Carbon Black’ Rubber & Plastics News, April, 2018
Carbon Black Composition with Sulfur Donor, PCT/US2016/066920
PCR N234 PCR SM-CB PCR SM-CB + Coupling
0
2
4
6
8
10
12
14
16
Mod
ulu
s /
MP
a
100%
200%
300%
➢ Poor affinity of the SM-CB for standard diene
elastomer is manifested as low build in modulus
➢ Modulus is recovered (excessively) when
coupling chemistry is used
➢ Tensile strength is maintained
➢ Crosslink density equivalent (measured by NMR)
SHARE THE STRENGTH
Implementation Example: coupling agent
Sulphur Donor Approach
29
0
2
4
6
8
10
0.1 1 10 100 1000
G' (
MP
a)
Strain - % ptp
Non-Coupled N234
Non-Coupled SM-CB
Coupled SM-CB
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.1 1 10 100 1000
Tan
gen
t D
elt
a
Strain - % ptp
From ‘Novel Approach to Coupling Functionalized Carbon Black in Non-Functionalized Elastomer Systems’, ACS Rubber Division Fall Meeting, 2017
From ‘ New Approach to Couple Functionalized Carbon Black’ Rubber & Plastics News, April, 2018
Carbon Black Composition with Sulfur Donor, PCT/US2016/066920
SHARE THE STRENGTH
Summary
➢Overcoming intrinsic reinforcement relationships with carbon black can be achieved via surface modification (in this case gas phase oxidation)
➢Surface oxidation leads to a number of key changes in the chemistry and energetics of the carbon black surface
➢Use of oxidized carbon blacks with functionalized synthetic rubbers to lower hysteresis
➢Use of oxidized carbon blacks with epoxidized natural rubbers to lower hysteresis
➢Coupling agent approaches
30
SHARE THE STRENGTH
Thank You
31
SHARE THE STRENGTH
32