PREPARATION AND CHARACTERIZATION OF SOLUTION SIBR VIA ANIONIC POLYMERIZATION Adel F. Halasa The Goodyear Tire & Rubber Company, 142 Goodyear Blvd., Akron, OH 44305 CONTENTS Page I. Introduction ............................................................. 295 II. Discussion ............................................................... 295 A. Solution prepared terpolymers: styrene–isoprene–butadiene ........... 297 B. Methodology ......................................................... 297 C. Synthesis ............................................................ 297 D. Viscoelasticity ....................................................... 303 E. Morphology .......................................................... 305 III. Conclusion ............................................................... 307 I. INTRODUCTION The development of emulsion styrene–butadiene rubber (E-SBR) in the early 1940s was hailed as a new era in synthetic elastomers for tire applications. Its uses, in blends with natural rubber, and later with polybutadiene, as a tread rubber was a technical breakthrough. In the 1960s, E- SBR and its blends played a very important role in bias-belted tire applications. The demand by the car manufacturers for improved tire mileage with better wear and traction put constraints on the tire industry. Such demand focused research on tire construction rather than on improved materials. The introduction of the radial tire construction in the 1970s definitely improved tire performance and resulted in better traction and wear properties over that of the bias belted tire. More recently, tire technologists have been looking to materials for next generation improvements in tire performance. This led to the introduction of solution SBR, (vs. E-SBR) as the new rubber for the 20th century. The development and commercialization of solution SBR in the 1960s as a replacement for E-SBR in tires was seen as a modern innovation in the synthetic rubber field. The demand by the car manufacturers for further improvement in fuel economy with no sacrifice in wear or traction paved the way for the synthetic chemist to prepare various elastomers with unique viscoelastic properties. In the early 1980s these concepts were put into practice by the Shell Oil Co. when they intro- duced two new solution SBRs: CARAFLEX  901 and 902. These two elastomers displayed glass transition temperatures in the range of −40 to −45 ◦ C with varying composition of styrene and vinyl units. At the same time Shell introduced a low vinyl, tin coupled solution SBR with a glass transition temperature (Tg ) of −75 ◦ C similar to that of Phillips Petroleum Co’s. SOLPRENE  and Firestone Tire & Rubber Co’s. DURADENE  . All these new elastomers, when compounded in tread tire application, performed better than E-SBR. However, all these solution SBRs showed deficiencies and some compromises were necessary in certain applications. II. DISCUSSION The problem of physical property compromise (i.e. between wear, traction, rolling resistance and handling) is related to elastomer viscoelasticity and dynamic properties. Figure 1 shows that polymer architecture plays a key role in the viscoelastic properties of any tire elastomer as related to the overall tire performance. We identified that certain polymer features such as 295