Manifestation of accelerator type and vulcanization system on the properties of silica-reinforced SBR/devulcanize SBR blend vulcanizates

Abstract

Mechanochemically devulcanized styrene-butadiene rubber, prepared by bis[3-(triethoxysilyl)propyl]-tetrasulfide, was blended with fresh styrene-butadiene rubber. The ultimate properties of the blend vulcanizate depend on a three-dimensional network structure formed during vulcanization which relies mainly on the accelerator and the vulcanizing system used during compounding. The effect of monosulfide, disulfide, and poly sulfide cross-links, which primarily gets controlled by different accelerators such as N-cyclohexyl-benzothiazyl-sulfenamide (CBS), tetramethylthiuram disulfide, 2-mercaptobenzothiazol, and N-tert-butyl-2-benzothiazyl-sulfonamide on mechanical, thermal, and dielectric behavior of the blend vulcanizates, was studied. The results indicate that the semi-efficient CBS vulcanizate has superior mechanical and thermal properties. Therefore, the effect of accelerator to sulfur ratio, that is, (accelerator/sulfur) on the properties of the blend vulcanizates was determined. It is to highlight that a distinctive correlation is observed between the cross-link types and the fraction of immobilized polymer chains of the blend vulcanizates. Further, the effect of cross-link types on segmental dynamics of the blend vulcanizates was studied through broadband dielectric spectroscopy. The SEM micrographs indicate the homogeneity of the blend vulcanizates.