On the mechanism of radiation-induced crosslinking of poly(vinyl chloride) in the presence of some polyfunctional monomers

Abstract

Some features of low-temperature radiolysis of poly (vinyl chloride) and the effect of added polyfunctional monomers such as triallyl cyanurate have been studied using the technique of infrared spectrophotometry. It has been found that the radiation yield of HCl formed in the radiolysis of poly(vinyl chloride) alone at 100°K is equal to 2.5. Additives form a complex with radiolytically produced HCl. The structure of this complex corresponds to on oxonium compound. The radiation yield of the complex reaches 50–80 per 100 eV of energy absorbed by additives. At the same time, the addition of triallyl cyanurate in poly (vinyl chloride) decreases the radiation yield of HCl associated with polymeric matrix by 2–3 times. The reaction of the allyl groups of the additive with the polymer free radicals already occurs at low temperatures. On heating, the irraditated at low temperature samples, the complex of additive with HCl decomposes, the remaining allyl groups disappear, and triazine rings are partly transformed to the isocyanurate form. These results are interpreted in terms of a mechanism which postulates the localization of the dehydrochlorination process of poly(vinyl chloride) in the vicinity of the additive molecules and the promotion of crosslinking efficiency by the formation of complex of additive with HCl.