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

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

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

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

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

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

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 10-100 kHz Rolling resistance and wet grip are governed by different frequencies

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 -50°C RR has correlation with tan delta +50°C

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”)

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

Conclusions The most preferred polymers are those which have: High Tan Delta at temperatures in the range of -30 to -50ºC 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

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

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

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)

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

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

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

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

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

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%)

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

CONVERSION vs. TIME

NMR RESULTS POLYMERIZED WITH 0.5:1 SDBS/nBuLi

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

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

EFFECT OF TMEDA LEVEL 30/70 SBR @ 1/0.5/X Li/SDBS/TMEDA

RATE EFFECTS addition of TMEDA increases rate

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

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

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)

Sodium Alkoxide

SDBS

SDBS with TMEDA