Vulcanization of Latex Films

In the sulphur vulcanization of latex films, the formation of cross-links proceeds only on the surface of the latex globules. The rate of reaction of vulcanization is determined by content of rubber in the surface layer of globules. The rate of reaction of vulcanization is zero order with respect to sulphur. Therefore it is possible, by regulating the amount of vulcanizing agents in the latex, to define the quantity of rubber taking part in the vulcanization reaction, and to calculate the average thickness of the surface reaction zone. The peculiar mechanical characteristics of these films are explained by their unusual network structure. 

At the same time, the curve of the change of free sulphur content during vulcanization of latex films obtained from blends 1-5 is rather accurately described by a straight line in semilogarithm coordinates (Figure 3). Thus, depending on the sulphur content in the blend, vulcanization can proceed with 1-st order kinetics with respect to sulphur - as occurs for blends 1-5 - if the sulphur content is 2 pph or less or with zero order if the sulphur content is 2.5 pph or more. 

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