Using olefin metathesis reaction to modify solution polymerized styrene-butadiene rubber (SSBR) by for a more stable “green tire”

Nowadays, silica is used to make green tire, as silica improve the wet skid resistance and rolling resistance of rubber. The key point is that the poor compatibility and interface adhesion between silica and solution polymerized styrene-butadiene rubber, which results in poor dispersibility of silica and hinders its application in tire industry. In this study, using vinyl trimethoxysilane as polar monomer modified the solution polymerized styrene-butadiene rubber by olefin metathesis reaction with metal complexes as catalysts, which the condition was the temperature at 40℃ and the time was 4 h. In particular, the amount of metal complexes was only 0.01‰ of the rubber matrix. Successful olefin metathesis reaction was proved by the following tests. The structure of the modified solution polymerized styrene-butadiene rubber was confirmed by nuclear magnetic resonance spectrometer analyses demonstrated that the existence of methoxy about the rubber chains. The incorporation of polar monomer in the solution polymerized styrene-butadiene rubber chains by olefin metathesis reaction resulted a significant change of the molecular weight about polymer after modification, which were analyzed and verified in detail by gel permeation chromatography. The modified rubber /silica composites were compared with the compositions where silane coupling agent was separately added in rubber before modification during mixing. Bound rubber content increased 18.3% demonstrated strong polymer-filler interaction after modification of the rubber. Payne effect was measured by rubber process analyzer, which decreased 60% compared with silica/rubber composites before modification showed that polar groups of rubber after modification improved the dispersity of silica effectively. In addition, with the agglomeration of silica was reduced which help to accelerate the cure rate and improve the cross-link density in sulfur-cured system. Moreover, we also researched on the mechanical properties and the dynamic viscoelastic properties of silica/rubber after modification, which demonstrated that using vinyl trimethoxysilane modified solution polymerized styrene-butadiene rubber by olefin metathesis reaction was a favorable strategy for “green tires” with lower energy loss, better wet skid resistance and mechanical properties without silane coupling agent.