Effect of styrene content on mechanical and rheological behavior of styrene butadiene rubber

Abstract

Styrene butadiene rubber(SBR) consists of two random polymerization units, styrene and butadiene. As a rigid segment, styrene chain provides strength and rigidity to the rubber. The content of styrene in SBR directly affects its strength and stiffness. In this paper, the effect of styrene content on the fatigue characteristics and rheological properties of SBR have been investigated. The stress relaxation of SBR was reduced and the cross-linking density of butadiene was increased with the increasing styrene content. Especially the dynamic fatigue life of precracked SBR samples was obviously prolonged via slow down crack growth rate when the styrene content increased, which was accompanied by an augment in the value of J-integral and tearing energy in the case of a same gap extension length. At the initial stage of crack growth, the growth of secondary crack played an important role in the growth of main crack, and when the main crack accelerates, the growth of main crack itself dominated. On the other hand, the glass transition temperature obviously increased with the increase of styrene content.