Mechanism of vulcanization promotion of thiazole zinc salts

- Aug 16, 2017-

1964, Coran et people according to the results of the analysis of Vulcanizate, the vulcanization mechanism of 2-mercapto-thiazole (MBT) Zinc salts was proposed: The Thiazole zinc salts reacted with the sulfur molecule, formed MS-SX-SY-SM, MS-SX-SY-SM and the rubber hydrocarbon r reaction, and formed the active intermediates. The active intermediate is a non cross-linked type of sulfide, with a vulcanizing promoter group at the end, and when it decomposes slowly to produce free radicals, the active free radicals react with the rubber hydrocarbons to obtain a vulcanized rubber.

In 1969, Manik and other people based on the introduction of fatty acids on the effect of Thiazole promoter, put forward different promotion mechanism. He believed that thiazole-like vulcanizing accelerator and fatty acid produced ionic active intermediates during vulcanization, rather than free radicals as Coran said. First, stearic acid reacts with ZnO to produce zinc stearate. Then, the reaction of zinc stearate with thiazole salt, by the coordination of O atoms in n atoms and zinc stearate in the thiazole zinc salts, to activate the Zn-s bond, form a transition state (a), and (a) react with the sulfur molecule (S8) to produce an active intermediate (B). (B) react with the rubber hydrocarbon r to produce a MSSXR. The MSSXR is unstable, the positive and negative ions are decomposed, and the ions are combined with the rubber hydrocarbon to produce vulcanized rubber.