NONLINEAR VISCOELASTIC DISSIPATION IN VULCANIZATES CONTAINING CARBON BLACK AND SILANIZED SILICA HYBRID FILLERS

Abstract

ABSTRACT Different mechanisms of large-strain viscoelastic dissipation in vulcanizates containing carbon black or silanized silica and their synergistic effects in hybrid filler tread vulcanizates were investigated. In addition, the pure effects of fillers were examined while the degree of chemical cross-linking in the rubber matrix was similar in the vulcanizates. The results revealed that nonlinear viscoelastic loss modulus under strain-controlled dynamic tests, as a measure of dissipation mechanism, is high in both carbon black and silanized silica tread vulcanizates. However, a synergistic effect in reducing loss modulus was observed in the hybrid filler vulcanizates. Conversely, storage modulus in the vulcanizates containing more silanized silica is distinguishably higher and results in a lower loss factor representing load-controlled cyclic deformation of vulcanizates, such as in the heat buildup test. Both loss factor and heat build-up reduced nonlinearly as the amount of silanized silica increased in the vulcanizates, verifying the synergistic effect of hybrid carbon black–silanized silica filler in reducing dissipative mechanisms in large-strain dynamic loadings. This feature is highly favorable for the tire industry, where the lowering of viscoelastic dissipation in tread vulcanizates is of great importance.