Study On Modfication Of Solution-polymerized Styrene-butadiene Rubber By Olefin Metathesis

As important materials for tread of green tires,how to improve the interaction between solution-polymerized styrene butadiene(SSBR)and silica has always been the focus of tire industry.Silane coupling agent such as Si-69 is usually used to solve this problem.But the adding of Si-69 required more strictly to mixing temperature,lower temperature leads to inadequate salinization between silica and silane and higher temperature leads to scorch of the compounds.SSBR was modified through metathesis reaction.Groups which can interacted with silanols on the surface of silica was introduced onto SSBR,so as to improve the interaction between silica and SSBR and consequently the better dispersion of silica in SSBR matrix.The influence of solvent variety,reaction temperature,reaction time,rubber and catalyst concentration,olefin variety and concentration on modified SSBR was investigated in this thesis.NMR and GPC were used to characterize modified SSBR.The cure characteristic of silica filled modified SSBR,the interaction between silica and modified SSBR and the mechanical properties of vulcanizates were also studied.The results showed that the three kinds of olefin,vinyltrimethyoxysilane(VTMO),vinyltriethyoxysilane(VTEO)and methylacrylate(MA),were successfully introduced onto SSBR through metathesis.The optimum rection conditions were taken toluene as solvent,the reaction temperature was 40?,reaction time was 2 hours,concentration of SSBR and catalyst was 20% and 0.001%,respectively.Under the same reaction condition and at same olefin amount,modified SSBR got from MA had the lowest molecular weight(Mw)and bound rubber content of silica filled compound.Silica dispersion was poorest and consequently lowest tensilestrength.Compared with unmodified SSBR,modified SSBR got from VTEO and VTMO also had decreased molecular weight,but had higher bound rubber content and better silica dispersion,improved mechanical properties.Especially for VTEO modified SSBR,besides the improvement of strength,the loss factor at 0? increased and loss factor at 60? decreased,indicating improved wet skip resistance and rolling resistance when used as tire tread.SSBR modified with different amount of VTMO all showed increased bound rubber content and decreased Payne Effect,indicating better silica dispersion.Modified SSBR had longer scorch time,faster cure rate and higher crosslink degree and improved and static and dynamic mechanical properties.For SSBR modified with 0.1% VTMO,the tensile strength and elongation at break increased by 32.5% and 20%,respectively.Loss factor at 60? decreased by 16.3%,indicating lower rolling resistance for tire tread.