Development of Modified Solution SBR for the Reduction of Rolling Resistance of Tire

In recent years, to reduce CO₂ emission, improvement of fuel efficiency has become an urgent task in the automobile industry. An important factor for improvement of automobile fuel efficiency is reduction of rolling resistance of tire. Rolling resistance is primarily related to hysteresis loss of the tire tread compounds. From previous studies, it is recognized that improvement of filler dispersibility in the compounds and reduction of free chain ends of polymer are effective for the reduction in hysteresis loss.  To achieve those goals, that is, better filler dispersibility and less free chain ends, solution SBRs modified with functional groups, reactive with silica filler, at polymer chain ends have been developed. We investigated the relationship between hysteresis loss and dispersion of silica filler by observation and measurement of various modified solution SBRs using TEM (transmission electron microscopy) and USAXS (ultra small angle X-ray scattering). Results have shown appropriate direction for molecular design of solution SBR for reduction of hysteresis loss.