EFFECT OF TDAE OIL ON PHASE DYNAMICS OF S-SBR/BR BLENDS FOR TREAD APPLICATION

A. Rathi1, M. Hernández2, C. Bergmann3, J. Trimbach3, W. Dierkes1, A. Blume1

1University of Twente, Enschede (NL)

2Delft University of Technology, Delft (NL)

3H&R Ölwerke Schindler GmbH, Hamburg (D)

OCTOBER 12, 2016

FALL 190TH TECHNICAL MEETING

ACS RUBBER DIVISION

PITTSBURGH, PA

• EC No 552/2009 - Shift to ‘safe’ process

oils with lower PAHs content such as

Treated Distillate Aromatic Extract

(TDAE), Mildly Extracted Solvate (MES).

• Effects on compound properties:

• Improvement in: Rolling Resistance

(RR).

• Negative effect on: Wet Skid

Resistance (WSR) and Abrasion

Resistance (AR).

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MOTIVATION‘SAFE’ PROCESS OIL

RR

AR WSR

Black- DAE

Purple- TDAE

Green- MES

MAGIC TRIANGLE*

*Roughly drawn for UHP tread compound; Source: ETRMA

• Tread of a PCT normally consists

of Styrene Butadiene Rubber

(SBR), Butadiene Rubber (BR)

and Natural Rubber (NR).

• Combination of two or more

rubbers forms the tread of a PCT.

• Can be miscible (SBR/BR) or

immiscible blends (SBR/NR or

NR/BR).

PASSENGER CAR TIRE TREAD (PCT)STRUCTURE AND COMPONENTS

Source of picture: www.planetillustration.co.uk 12-10-2016

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He

at flo

w

Temperature

Tg A

Tg BHeat flow

Temperature

Tg A

Tg B

Tg Blend Tg(A) Blend Tg(B) Blend

Tg Blend

Ta

n δ

Temperature

Tg A Tg B

Tg(A) Blend Tg(B) Blend

MISCIBLE BLENDS IMMISCIBLE BLENDS

Ta

n δ

Temperature

Tg ATg B

Callan et al., Rubber Chemistry and Technology, 1969.; Scale bar: 2 μ Kruse J., Rubber Chemistry and Technology, 1973.

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COMPONENT AMOUNT (phr)

Polymer 100

ZnO 4

Stearic Acid 3

CBS 2.5

Sulphur 1.6

TDAE 0/10/20

COMPOUND FORMULATION

• Compounds studied:

S-SBR_0/10/20

BR_0/10/20

S-SBR/BR_0/10/20

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BLEND DYNAMICS: TO QUANTIFY TDAE PARTITIONING IN BLEND COMPONENTS

WET SKID RESISTANCE (WSR): USING BDS TEMPERATURE DOMAIN CURVES

CHARACTERIZATIONCOMPARISON OF TG

EFF

Broadband Dielectric Spectroscopy (BDS)PhD Thesis, Kumar Kunal, University of Akron 2009

Dynamic Mechanical Analysis (DMA)www.paralab.pt

Differential Scanning Calorimetry (DSC)www.netzsch-thermal-analysis.com

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RESULTSDSC & DMA

Single, broad peak

associated with Tg.

Mathematical treatment

of data is not possible.

DMA

-120 -100 -80 -60 -40 -20 0 20 40 60 80 100

0,0

0,5

1,0

1,5

2,0

20 phr Oil

10 phr Oil

Ta

n

[]

Temperature [C]

BR

S-SBR

No Oil

S-SBR/ BR (50/50) Blend

DSC

-120 -100 -80 -60 -40 -20 0

20 phr Oil

He

at

flo

w [

a.u

.]

Temperature [C]

Exo

Crystallization

Glass transition: BR

S-SBR

No Oil

10 phr Oil

S-SBR/BR (50/50) Blend

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RESULTSBDS

Single, broad peak

associated with Tg.

Mathematical treatment of

data is possible.

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BDSSEGMENTAL DYNAMICS OF OIL-EXTENDED S-SBR AND BR

Local motions

<< 1 nm

Segmental mobility

1-2 nm

Chain dynamics

10 nm

Detectable only at very low

frequenciesSECONDARY RELAXATIONS

(For e.g. β)

GLASS TRANSITION (Tg)

[PhD Thesis, Marianella Hernández Santana Universidad Complutense de Madrid, 2012]

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BDSPRINCIPLE

Net dipole moment = 0[PhD Thesis, Kumar Kunal, University of Akron 2009]

Net dipole moment ≠ 𝟎

Gold electrodes

Polymer film

[PhD Thesis, Marianella Hernández Santana

Universidad Complutense de Madrid, 2012]

Reorientation of

dipoles on

application of an

electric field

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BDSFREQUENCY DOMAIN CURVES

Complex dielectric permittivity (ε ∗ = ε′ − iε″)

Real part

(Dielectric storage modulus)

Imaginary part

(Dielectric loss modulus)

Log (Frequency)

[P. Lunkenheimer, A. Loidl J. Phys.: Condens. Matter 27 (2015)]

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BDSFREQUENCY DOMAIN CURVES

Frequency

T1 T2 T3 T4 T5

𝛕 = Τ𝟏 𝟐𝛑𝐅𝐦𝐚𝐱

𝝉 is the relaxation time at frequency of maximum loss

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HAVRILIAK-NEGAMI EQUATION(S) BASED FITTING50/50_NO OIL AT T = -300C

Δεα 0.226

𝜏HN (α) 1.384 × 10-4

b 0.609

c 0.131

Δεα′ 0.089

𝜏HN (α′) 5.317 × 10-4

b′ 0.429

c′ 1

εHN∗ (ω) = ε∞+

∆ε

1 + iωτHN b c

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ACTIVATION PLOTVOGEL-FÜLCHER-TAMMAN (VFT) EQUATION 𝛕𝐦𝐚𝐱 = 𝛕𝟎𝐞𝐱𝐩 Τ𝐁 𝐓 − 𝐓𝟎

BR

S-SBR VFT Fitting line

MOBILITY (segmental motion)

RESTRICTION (segmental motion)

Tg: Temperature at which

𝜏max = 100 s

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ACTIVATION PLOTEFFECT OF ADDITION OF TDAE ON PURE POLYMERS

-28 °C

-50 °C

-76

°C

-30 °C

-31 °C

-90 °C

-99 °C

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ACTIVATION PLOTEFFECT OF ADDITION OF TDAE ON COMPONENT Tg IN SBR/BR BLENDS

-69 °C

-54 °C

-58 °C

-43 °C

-38 °C

-36 °C

• Decoupling of individual S-SBR and BR phases via BDS.

• Effect of TDAE on the individual phases by observing the change in Tgeff.

• Greater effect of the TDAE is observable on the BR phase (50/50).

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BLEND DYNAMICSCONCLUSIONS FROM COMPONENT Tg ESTIMATION IN BLENDS

1st step towards the final

goal i.e., quantification of

the partitioning of TDAE.

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BLEND DYNAMICS: TO QUANTIFY TDAE

PARTITIONING IN BLENDS

WET SKID RESISTANCE (WSR): USING BDS

TEMPERATURE DOMAIN CURVES

• Affected by the properties of the tire tread compound.

• High-frequency phenomenon, which makes it difficult to be predicted

accurately using DMA.

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WET SKID RESISTANCE (WSR)

At high frequencies,

the glass-to-rubber

transition separates

into two peaks:

i) S-SBR rich,

ii) BR rich phase

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PREDICTION OF WSR USING BDS TEMPERATURE DOMAIN CURVES

-150 -100 -50 0 50 100

-3,0

-2,5

-2,0

-1,5

-1,0

-0,5

0,0

0,5

log

Temperature [C]

1 Hz

BR

S-SBR

S-SBR/BR Blends

30/70 50/50 70/30

-120 -100 -80 -60 -40 -20 0 20 40 60 80

-3,5

-3,0

-2,5

-2,0

-1,5

-1,0

log

Temperature [C]

104 HzT

g of BR

Crystallization of BR

Tg of S-SBR

-120 -100 -80 -60 -40 -20 0 20 40 60 80

-2,4

-2,2

-2,0

-1,8

-1,6

-1,4

log

Temperature [C]

106 HzBR component

S-SBR component

WSR

Reversible phase change in

the ambient temperature

region.

Closer look at

70/30 blend

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-120 -100 -80 -60 -40 -20 0 20 40 60 80

-2,6

-2,4

-2,2

-2,0

-1,8

-1,6

-1,4

20 phr Oil

log

Temperature [C]

104 Hz

No Oil

10 phr Oil

-120 -100 -80 -60 -40 -20 0 20 40 60 80

-2,4

-2,2

-2,0

-1,8

-1,6

-1,4

log

Temperature [C]

106 Hz

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Why 70/30 blend?

• WSR: Polymer with higher Tg is

preferredHigher the Tg, higher is

the possibility of a

reversible phase change

happening at R.T.

• Tire testing has shown that 70/30

blend shows the best WSR.

70% S-SBR 30% BR

• 70/30 blend shows the best WSR.

• The scientific proof for the best WSR for 70/30 blend can be seen with

the temperature domain curves from BDS.

• More research with this concept is necessary.

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WSRCONCLUSIONS

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FUTURE OUTLOOK

• Calculation of partitioning coefficient of the TDAE oil in the S-

SBR/BR blends.

• Testing the concept of prediction of WSR using BDS temperature

domain curves in detail.

I am thankful to H&R Ölwerke Schindler GmbH (Hamburg, Germany) for the

scientific, financial and materials support as well as the permission to

present this work.

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ACKNOWLEDGEMENT

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THANK YOU FOR YOUR ATTENTION!