1. COPOLYMERIZATION USING nBuLi/SDBS SYSTEM
Adel Halasa PhD
Jim Prentis, Bill Hsu, Chad Jasiunas, Ronald Kovalak,
The Goodyear Tire & Rubber Company

2. AGENDA Background SDBS/nBuLi RATIO STUDY (@ 40/60 SBR comp.)
SBR COMPOSITION STUDY (styrene randomization)
SDBS/TMEDA SYSTEMS (Tg control)
Conclusions

3. What are the Critical Tire Needs?
Better Fuel Economy
Improved Wet Traction
Better Handling
Better Durability
Improved Treadwear
Improved Flex Fatigue (Sidewall Applications)
Better Component Adhesion
Improved Belt Package
New Polymers for Run Flat Operation
Improved Air Permeability

4. What are the Polymer Structural Features that Contribute?
Better fuel economy related to microstructure, chain-end concentration, and glass transition temperature
Treadwear related to macrostructures, and glass transition temperature
Durability and handling related to filler-polymer interaction, macrostructure, crosslink density, and crosslink type

5. Energy Loss in a Motor Vehicle
The technical literature claims that fuel provides 100% of the energy needed in a motor car
About 78% is used in the exhaust and chassis, whereas 22% energy available is consumed by the engine
About 7 to 9% of the energy losses is attributed to the tire
aerodynamics
ground interface
hysteresis

6. Tire Hysteresis
The literature has credited the tire tread to control about 60 to 70% of the tire hysteresis and any improvement in the tread compound could result in significant savings in fuel economy
Tire tread compounds are typically comprised of NR, E-SBR, and cis-BR. The cis-BR, IR, & NR are good for low hysteresis while the E-SBR is good for traction

7. Frequency
Rolling resistance (RR) caused by tire contact on the road, has a frequency of 10 to 100 Hz at 50-70°C
Wet traction (WT) is caused by road friction resistance generated by tires at the road surface or near the surface at a very high frequency of deformation near or between kHz
Rolling resistance and wet grip are governed by different frequencies

8. Conversion of Frequency to Temperature
In polymer science, it is understood that frequency is equivalent to temperature
This conversion is suggested by the WLF equation
The following conclusions have been reported:
Wet traction/grip has a correlation to tan delta -30 to °C
RR has correlation with tan delta +50°C

9. Rolling Resistance
RR is the result of energy loss caused by the following factors:
Moment of compression
Bending and shearing
It can be affected by Loss Compliance (J”) and Loss Modulus (E”)

10. Viscoelastic Properties
Tire properties can be predicted from:
Viscoelastic dynamic measurements of G`, G`` and Tan Delta
Rolling resistance measured at 10 to 16 Hz in the temperature range of 50 to 70°C
Wet skid resistance can be improved by high Tan Delta at -30 to -50ºC
Polymers with high Tg show improvement in wet skid, while polymers with low Tg show wear improvements

11. Conclusions The most preferred polymers are those which have:
High Tan Delta at temperatures in the range of -30 to ºC for WT
Low Tan Delta at temperatures in the range of +50 to +70ºC for RR
Polymers which improve both RR/WT are made by an anionic catalyst system in which:
polymer composition, Mw, Mwt Distribution, Tg, macrostructure, etc. are all carefully controlled

12. Building a Macromolecular Structure
Our approach to this technical challenge is called Anionic Polymerization
Anionic Polymerization is also referred to as Living Polymerization
It is interesting that anionic polymerization was first discovered in early 1935 by Carl Ziegler

13. BACKGROUND
Random S-SBRs offer improvements in traction, while offering relatively low hysteresis
Typically, modifiers that randomize styrene also increase the vinyl content of the diene phase

14. BACKGROUND
sodium t-amylate (STA), has been used to produce random high styrene S-SBRs with relatively low vinyl contents and long-chain branched macrostructures
other polar modifiers utilizing the cation-exchange mechanism inherent to Li/Na polymerization systems are in development
P-Li + NaOR P-Li/NaOR P-Na/LiOR
(soluble in presence of TMEDA)

15. MODIFIER STRUCTURE (C12H25)C6H4SO3-Na
sodium salt of dodecylbenzenesulfonic acid (SDBS)
inexpensive compound
is an emulsifier similar to active ingredients in detergents (eg. sodium lauryl sulfate)
this “soap” is water soluble, yet forms a homogenous mixture in some hydrocarbon solvents
(C12H25)C6H4SO3-Na
SDBS prepared in-house (Halasa) and sodium concentration in solution determined by Atomic Absorption Spectroscopy

16. POLYMERIZATION SYSTEMS
40/60-18/82 wt% styrene/butadiene feed ratios
hexane solvent
90°C polymerization temp
20% monomer concentration
conditions similar to Beaumont operations

17. SDBS/nBuLi RATIO STUDY
40/60 SBR highest styrene content generally used
SDBS/Li molar ratios:
0.25/1, 0.35/1, 0.5/1, 0.75/1
determine optimum ratio for lowest vinyl, random styrene incorporation

18. CONVERSION vs. TIME
0.25/1
0.75/1
polymerization time increases w/ increased SDBS ratio

19. CONVERSION vs. TOTAL CONVERSION
0.25/1
0.75/1
styrene reactivity increases as SDBS ratio increases

20. NMR RESULTS BLOCK STYRENE DECREASES W/ INCREASE IN SDBS AMT
* STA/Li ratio
BLOCK STYRENE DECREASES W/ INCREASE IN SDBS AMT
VINYL CONTENT, NORMALIZED TO PBd, REMAINS LOW (12-15%)

21. SBR COMPOSITION STUDY
rate decreases dramatically at SDBS/Li ratios > 0.5/1
0.5/1 ratio should randomize lower styrene composition materials (10/90-30/70) at fast rate
scale-up to continuous operation also enhances styrene incorporation

22. CONVERSION vs. TIME

23. NMR RESULTS
POLYMERIZED WITH 0.5:1 SDBS/nBuLi

24. COMONOMER REACTIVITY butadiene monomer appears to be more reactive to
both butadienyl- and styryl-Li chain ends

25. SDBS/TMEDA SYSTEM Tg can be controlled by TMEDA addition
rate affected by TMEDA
molecular weight appears to be affected by TMEDA level (initiator activity)
30/70 SBR system utilized for study

26. EFFECT OF TMEDA LEVEL
30/70 1/0.5/X Li/SDBS/TMEDA

27. RATE EFFECTS
addition of TMEDA increases rate

28. TMEDA LEVEL / INITIATOR ACTIVITY
target molecular weight is 100,000 g/mol
calculated molecular weight reduced as TMEDA level increases

29. MACROSTRUCTURE ANALYSIS
SDBS/TMEDA
batch
STA/TMEDA
continuous
SBDS materials (batch pzn.) appear to be linear

30. SUMMARY very fast rates at SDBS levels <0.5
low vinyl, random S-SBRs at proper SDBS/Li ratio
Tg controlled by TMEDA addition
polymerization rate enhanced further by TMEDA addition
TMEDA apparently aids initiator activity (solubility)

31. Sodium Alkoxide

32. SDBS

33. SDBS with TMEDA