Influence of filler type and content on properties of styrene-butadiene rubber (SBR) compound reinforced with carbon black or silica

Rubber compounds are filled with reinforcing fillers to improve their physical properties. Carbon black and silica have different surface chemistries to each other. Differences in properties of carbon black- and silica-reinforced styrene-butadiene rubber (SBR) compounds were studied. Variation of properties of carbon black- or silica-filled compounds with the filler content was also investigated. The silica-filled compounds without any coupling agent and dispering agent were prepared to investigate the influence of polar materials-adsorption on the silica surface. Viscosity and crosslink density increased with increase of the filler content. Hardness, modulus, tensile strength, and wear property were improved more and more by increasing the filler content. Viscosity of the silica-filled compound was higher than that of the carbon black-filled one. Cure rate of the silica-filled compound became slower as the filler content increased, while that of the carbon black-filled one became faster. Difference in properties between the carbon black- and silica-filled compounds were explained by the poor silica dispersion and the adsorption of cure accelerator on the silica surface. Copyright (C) 2004 John Wiley Sons, Ltd.