Effect of Substituted Dithiobiurets—Tetramethyl Thiuram Disulfide (TMTD) Binary Accelerator Systems in the Vulcanization of NR-SBR Blends

Abstract

Abstract 1-Phenyl 2,4-dithiobiuret and 1,5-diphenyl 2,4-dithiobiuret were studied as secondary accelerators along with tetramethyl thiuram disulfide (TMTD) in the vulcanization of a blend of natural rubber (NR) and styrene-butadiene rubber (SBR). These binary systems were found to be very effective and reduced the optimum vulcanization time considerably. 1-Phenyl 2,4-dithiobiuret, which is more nucleophilic than 1,5-diphenyl 2,4-dithiobiuret, reduced the vulcanization time more, indicating a nucleophilic reaction mechanism in the vulcanization reactions under review. In both cases the optimum dosage of the secondary accelerator was derived. Physical properties such as modulus, tensile strength, elongation at break, hardness, compression set, heat buildup, resilience, etc., of the vulcanizates were studied before and after heat aging and compared with a reference mix. There is substantial increase in many of these properties compared with TMTD alone or with the reference mix. Chemical characterization of t...