Dimethylammonium dimethyldithiocarbamate‐accelerated sulfur vulcanization. I. Thermal stability and reactions with curatives

Abstract

AbstractTo investigate its thermal stability and reactivity towards other accelerators dimethylammonium dimethyldithiocarbamate ((dma)dmtc) was heated at programmed heating rates in sealed and open pans in a differential scanning calorimeter and on a thermobalance. (Dma)dmtc was heated on its own, in rubber compounds and in mixes with tetramethylthiuram disulfide, zinc dimethyldithiocarbamate, and ZnO. In open systems (dma)dmtc readily sublimes at temperatures well below its melting point, and it is almost as rapidly lost when compounded on its own with rubber. No decomposition is observed at vulcanization temperatures and (dma)dmtc is unreactive towards tetramethylthiuram disulfide and zinc dimethyldithiocarbamate. Moisture does not promote its decomposition. Reaction with ZnO to give zinc dimethyldithiocarbamate is restricted to the surface of ZnO particles. (Dma)dmtc is soluble in water in which it dissociates. It must be concluded that when its is included in formulations, (dma)dmtc, per se, would act as a vulcanization accelerator; it does not decompose to dimethyldithiocarbamic acid and dimethylamine, both of which are known accelerators. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3067–3073, 2001