Thiosalicylic acid as a devulcanizing agent for mechano-chemical devulcanization

Abstract

A mechano-chemical devulcanization process for vulcanized natural rubber (NV) was investigated. Thiosalicylic acid was used as a test devulcanizing agent in comparison to diphenyl disulfide as the reference. The optimum condition for devulcanization of NR vulcanizates (NVs) was found to be grinding of the NV and subsequent mixing with a selected devulcanizing agent at 140°C for 30 min. The degree of devulcanization was indicated by using sol-gel fractions of the devulcanized rubber (DVR). Revulcanized rubber was made by using virgin natural rubber (NR) containing DVR at different ratios. The tensile strength of the DVR/NV composite, after revulcanization, decreased by 5-10%, while the elongation at brake was improved by 5-10% at a DVR content of 5-15%. Devulcanization of industrial truck tires, as a typical sample of industrial products, was also demonstrated for the practical application of this technique. © 2010 Korean Institute of Chemical Engineers, Seoul, Korea.