The Effect Of Dissociation Reagent Study In The Synthesis Of End-Functionalized Star-Shaped S-SBR

The rapid development of automobile industry, led the tire industry develop rapidly, while also rose demand for high-performance tires, especially on how to improve the high wet skid resistance and low rolling resistance. It was reported that 50% of rolling resistance is caused by hysteresis loss of the tread rubber. The hysteresis loss and heat generation can be reduced by modifying the macromolecular chain end. Moreover, rubber comprehensive performance can be improved as filler in the dispersion of matrix enhancement.Star-shaped solution polymerized styrene-butadiene rubber (S-SBR) was initiated by multifunctional lithium initiator self-made, THF as regulator, lithium sec-propoxide as dissociation reagent, then tert-butylchlorodiphenylsilane was added to react with the living polymer chain ends to obtain end-functionalized S-SBR. The influence of additives on polymerization was mainly measured. The results showed that only the lithium sec-propoxide joined polymerization system, the polymerization rate were improved, the vinyl contents were slightly improved, molecular weight, molecular weight distribution and sequential structures were less influenced, polymer for block structure. When two-component additives joined polymerization system, THF on regulating action of microstructures and sequential structures is more than lithium sec-propoxide which main play dissociation role. The influence of end-function efficiency (E) was measured. The results showed that 37.2% efficiency S-SBR was obtained by using the optimal reaction conditions as follows:to join dissociation reagent at the beginning of polymerization, the average molecular weight of 6.1×104, the lithium sec-propoxide/Li+(mole ratio) of 1.4:1, capping agent/Li+(mole ratio) of 2:1, end-capping reaction temperature of 60℃, end-capping reaction time of 60min. Physical properties and mechanical properties were measured. The results showed that compared with non-functionalized S-SBR, end-functionalized S-SBR exhibited better mechanical properties, lower Payne effect, balanced wet skid resistance and lower rolling resistance with higher 0℃tanδand lower 60℃tanδ.