The interaction between tetramethyl thiuram disulphide and rubber and compounds containing an active hydrogen atom in the molecule

Abstract

IN our previous communication we put forward a number of ideas relating to vulcanization with thiuram in the presence of various metal oxides [l]. Opinion is divided on the mechanism underlying the vulcanizing action of thiuram-type accelerators. Some workers [2] maintain that these accelerators owe their vulcanizing action to the liberation of active sulphur and simultaneous decomposition into simpler compounds. Others [3] have elaborated the theory that vulcanization with thiuram operates via free radicals. Sehele et al. point out in their papers that when wdcanization is carried out in the presence of zinc oxide, the thiuram is converted to zinc dithiocarbamate (66.6 mole per cent) ; it forms no other conversion products. These, authors hold that an intermediate compound of thiuram and rubber is formed on the surface of the zinc oxide crystals which then decomposes to yield zinc dithiocarbamate and form chemical cross-links between the rubber molecules [4]. They fail to consider vulcanization in the absence of metal oxides and to su!)mit their experimental findings on the direct interaction between thiuram and rubber, t