Amidino Thiourea as a Secondary Accelerator in Rubber Vulcanization

Earlier studies5773 in our laboratory showed that when a nucleophile is used along with disulphide or sulphenamide accelerators the vulcanization is accelerated greatly and the reaction mechanism is generally nucleophilic in nature. However it was observed that it also changes with the systems under review. The present study, deals with the use of unsubstituted amidino thiourea i.e. aminoimino methyl thiourea(AMT) V in the vulcanization studies of different elastorners and their blends. One of the aims of this study was to get further proof with regard to the theory of nucleophilic reaction mechanism in such binary systems.Mixes containing thiourea are used as controls. AMT is more nucleophilic than TU and this is clear from the fact that the fonner can condense with isothiocynate even in the absence of alkali while TU cannot". Also the guanidinyl group in AMT can facilitate the polarization of the C=S bond favouring a nucleophilic reaction