Structure–shrinkability correlation in polymer blends of ethylene vinyl acetate and chlorosulfonated polyethylene

Heat shrinkability, which is a collective property of polymers, is being utilized in various applications, mainly in the field of encapsulation. Elastic memory is introduced into the system in the form of an elastomeric phase. Here the blends of ethylene vinyl acetate and chlorosulfonated rubber were studied with reference to their shrinkability. It was found that an increase in the elastomer content increased the shrinkage and an increase in cure time also increased the shrinkage. It was seen that high temperature (H-T) stretched samples showed higher shrinkage than the low (room) temperature (R-T) stretched one. Generally, the crystallinity of the H-T stretched sample was higher than that of the low temperature stretched sample, which was again higher than that of the original unstretched sample; but for the low elastomer content blend the crystallinity of the R-T stretched sample was found to be greater than the corresponding H-T stretched one. The H-T differential scanning calorimetry showed that an increase in the CSM content caused the stability toward oxygen to increase. The first decomposition temperatures were found to be higher and the second decomposition temperatures appeared to be lower for the H-T shrunk sample than the corresponding unstretched sample. The rate of degradation appeared to be enhanced initially, then after 50% decomposition the rate started going down compared to the usual unstretched sample. From SEM it was seen that the H-T stretched sample was more elongated than the R-T stretched one. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 707–715, 2000