Interaction of Silica with Functionalized SBR

Abstract

Abstract In the absence of chemical interaction between precipitated silica and styrene-butadiene rubber, reticulation of silica particles occurs in the unvulcanized mixture and produces a stiffening effect. This process occurs gradually at room temperature and very rapidly at curing temperatures. The effect can be quantified conveniently by measuring the Young's modulus of raw compounds. SBR functionalized with a small concentration of hydroxyl groups, introduced by terpolymerization, can interact with precipitated silica particles by esterification. This reaction can be accelerated by catalysts. When carried out under conditions of combined heat and shear, this interaction prevents silica reticulation and produces vulcanizates with greatly altered and improved elastic properties. The present paper describes and illustrates these effects with reference to simplified compound recipes.