Research On End-Functionalized Star-Shaped Solution Polymerized Styrene-Butadiene Rubber

The rapid development of automobile industry, led the tire industry develop rapidly, while also rose demand for the use of high-performance tires. Balance of low rolling resistance tires and high wet skid resistance properties is development direction of high-performance tire.Half of rolling resistance is caused by hysteresis loss of the tread rubber. Synthesis of star-shaped polymer by reducing the free chain end can significantly reduce the hysteresis loss and heat generation. Silica filler used to replace part of carbon black can significantly improve the 0℃tanδvalue, improve wet skid resistance, but a poor dispersion in SBR matrix caused by serious agglomeration of silica. End groups on polymer modification can improve the interaction between chain ends with filler and the filler dispersion in the matrix, and improve over-all performance.Star-shaped solution polymerized styrene-butadiene rubber (S-SBR) was initiated by multifunctional lithium initiator self-made, then lithium sec-propoxide was added to decrease the solution viscosity, then 3-chloropropyl trimethoxy siloxane (CPTMO) was added to react with the living polymer chain ends to obtain end-alkoxysilane S-SBR. End-function efficiency (E) was measured. The effect of the lithium sec-propoxide/Li+ (mole ratio), (CPTMO)/Li+(mole ratio), end-capping reaction time, molecular weight on E was investigated. Physical properties and mechanical properties were measured. The results showed that 64.1% efficiency S-SBR was obtained by using the optimal reaction conditions as follows:the average molecular weight of 9.4×104, the lithium sec-propoxide/Li+(mole ratio) of 3:2, CPTMO/Li+(mole ratio) of 3:2, end-capping reaction time of 60min. Compared with unfunctionalized S-SBR and low efficiency of S-SBR lacking of, higher efficiency of end-functionalized S-SBR dissociated exhibited better filler dispersion, lower Payne effect, higher Tensile strength and modulus at a 300% elongation, lower Permanent set, balanced wet skid resistance and lower rolling resistance with higher 0℃tanδand lower 60℃tanδ.