EFFECT OF PHYSICOCHEMICAL MICROSTRUCTURE ON THE THERMAL-STABILITY OF ETHYLENE-VINYL CHLORIDE COPOLYMER

In this study, we investigated the relationship between the thermal st ability and physicochemical microstructure of EV (ethylene-vinyl chlor ide) copolymer prepared by reductive dechlorination of PVC with tribut yltin hydride. The EV copolymer grades varied in both molecular weight and ethylene content, the latter being in the range of 21-61 mol% eth ylene. The thermal stability of EV copolymer was studied by thermograv imetic analysis (TGA). It was found that the rate of dehydrochlorinati on decreased with increase in degree of alternation of comonomer units in the copolymer and the homogeneity of its physical morphology. This study appears to substantiate the explanation put forward by Braun et al. and Naqvi for the thermal stability of this copolymer.