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

To investigate its thermal stability and reactivity towards other accelerat ors dimethylammonium dimethyldithiocarbamate ((dma)dmte) was heated at prog rammed heating rates in sealed and open pans in a differential scanning cal orimeter and on a thermobalance. (Dma)dmte was heated on its own, in rubber compounds and in mixes with tetramethylthiuram disulfide, zinc dimethyldit hiocarbamate, and ZnO. In open systems (dma)dmtc readily sublimes at temper atures well below its melting point, and it is almost as rapidly lost when compounded on its own with rubber. No decomposition is observed at vulcaniz ation temperatures and (dma)dmte is unreactive towards tetramethylthiuram. disulfide and zinc dimethyldithiocarbamate. Moisture does not promote its d ecomposition, Reaction with ZnO to give zinc dimethyldithiocarbamate is res tricted to the surface of ZnO particles. (Dma)dmtc is soluble in water in w hich it dissociates. It must be concluded that when its is included in form ulations, (dma)dmtc, per se, would act as a vulcanization accelerator; it d oes not decompose to dimethyldithiocarbamic acid and dimethylamine, both of which are known accelerators. (C) 2001 John Wiley & Sons, Inc.