opportunities for functionalized carbon blacks in …...rubber chem. technol., 1998 → reduce...

CHALLENGE

TESTED

BEYOND

DURABLE

MICRO

MATTERS

COMPOUND

KNOWLEDGE

FAMILIAR

BONDS

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Opportunities for Functionalized Carbon Blacks in Rubber Applications

Dr. Lewis B. Tunnicliffe, Dr. Charles R. Herd

IOM3 RIEG ATDM, London, March 22nd 2019

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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

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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

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwj0yc_-n5PhAhUM-YUKHS4mDDEQjRx6BAgBEAU&url=https://en.wikipedia.org/wiki/Tyre_label&psig=AOvVaw0FF7hhWw79xUrrdz3x8XE6&ust=1553258237788578

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwjx2KPItZThAhUIrp4KHWuWDcYQjRx6BAgBEAU&url=http://www.google.com/url?sa%3Di%26rct%3Dj%26q%3D%26esrc%3Ds%26source%3Dimages%26cd%3D%26ved%3D2ahUKEwjOoMq8tZThAhUCs54KHb3MAcQQjRx6BAgBEAU%26url%3Dhttp://www.jatma.or.jp/english/labeling/outline.html%26psig%3DAOvVaw3hVcocFmCZ3KYmHS7Ibv-Q%26ust%3D1553298364246973&psig=AOvVaw3hVcocFmCZ3KYmHS7Ibv-Q&ust=1553298364246973

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwjB8MrhtZThAhUX7J4KHR-UAbgQjRx6BAgBEAU&url=https://www.hankooktire.com/global/tires-services/technology/tire-labeling/overview.html&psig=AOvVaw2BYmnMjyGq1xRmDyJVX268&ust=1553298439474081

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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

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwivqa3-kOzZAhXKc98KHS-VCcMQjRwIBg&url=http://pubs.rsc.org/en/content/articlehtml/2016/nr/c5nr07855e&psig=AOvVaw0sh2fgi_gq3D6HWAnfHAi1&ust=1521127795609959

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwjMyb2ooJPhAhVFiRoKHU2MCusQjRx6BAgBEAU&url=http://www.european-coatings.com/Markets-companies/Raw-materials-market/New-market-study-about-the-world-market-for-carbon-black&psig=AOvVaw0bfHQtuwoOBF1zG5shibmf&ust=1553258323029937

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwjSz67IoJPhAhWXgM4BHddVAUgQjRx6BAgBEAU&url=https://www.indiamart.com/proddetail/precipitated-silica-8914220988.html&psig=AOvVaw1oHr-ko4fUxx77Q7o6LOTR&ust=1553258376862162

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwjHuNXYo5PhAhUPx4UKHc4kAvAQjRx6BAgBEAU&url=https://www.sigmaaldrich.com/catalog/product/aldrich/685445?lang%3Den%26region%3DUS&psig=AOvVaw3Fzx82-wvatKVDqRNu5Rhz&ust=1553259230591079

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwivqa3-kOzZAhXKc98KHS-VCcMQjRwIBg&url=http://pubs.rsc.org/en/content/articlehtml/2016/nr/c5nr07855e&psig=AOvVaw0sh2fgi_gq3D6HWAnfHAi1&ust=1521127795609959

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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

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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…

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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')



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



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



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

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwid67Lv8evYAhUChOAKHaLFCUoQjRwIBw&url=https://simple.wikipedia.org/wiki/Atomic_force_microscope&psig=AOvVaw3wTYgsAzwQ5Ll6ZscGZGXU&ust=1516721444738431

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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)



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

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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

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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


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

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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

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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

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➢Passenger car formulation

➢Compounds reactively mixed

17


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 ~400 -- 70 Ram Down Discharge

Mill: 70°C, 25:21 rpm, Gap 0.055-60"

2 30 80 70 Load: Masterbatch




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"

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➢Large increase in bound rubber for SM-CB/fxnSBR → polymer filler interaction

18


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 %

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➢Systematic increases in static modulus especially for SM-CB

19


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%

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➢Systematic reductions in Payne Effect

20


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 %

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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

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwi98PL73IvhAhWUj-YKHSBrDnIQjRx6BAgBEAU&url=http://polymerdatabase.com/Elastomers/ENR.html&psig=AOvVaw0DLeXDy7xaqcObV_EzRDVF&ust=1552999724001704

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwjt9qPdnJPhAhXBxoUKHZr8BQMQjRx6BAgBEAU&url=https://twitter.com/tarrcuk&psig=AOvVaw0wwsKMyIwPShyHckiFUiL3&ust=1553257361785100

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➢ 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


Manna, Ajoy K; De, P P; De, S K; Chatterjee, MK, Rubber

Chemistry and Technology; Sept/Oct 1997; 70, 4, p 624.

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwjt9qPdnJPhAhXBxoUKHZr8BQMQjRx6BAgBEAU&url=https://twitter.com/tarrcuk&psig=AOvVaw0wwsKMyIwPShyHckiFUiL3&ust=1553257361785100

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➢ 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


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

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➢CB phase distribution in ENR/NR blend is defined by affinity of SM-CB for the more polar rubber in the blend

24


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)

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➢Significant reductions in Payne Effect when ENR/SM-CB is co-continuous in phase blend

25


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



NR (100 phr), N234

0.1 1 10 100

0.05

0.10

0.15

0.20

0.25

tand

Shear Strain %

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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

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➢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


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"




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)

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➢Passenger car tread

28




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)

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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




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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

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Thank You

31

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32

opportunities for functionalized carbon blacks in …...rubber chem. technol., 1998 → reduce...

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