Shrinkability of poly(ethylene vinyl acetate) - Epichlorohydrin blends andtheir characterisation

The heat shrinkability of polymers is utilised in Various applications-main ly in the field of encapsulation. Elastic memory is introduced into the sys tem by means of an elastomeric phase. Here, blends of ethylene vinyl acetat e (EVA) and epichlorohydrin were studied with reference to their shrinkabil ity, by introducing crosslinking in the elastomer phase. It was found that an increase in elastomer content and cure time caused the shrinkage to incr ease. High temperature (H-T) stretched samples showed higher shrinkage than room temperature (R-T) stretched ones. Generally the crystallinity of high temperature (H-T) stretched samples was higher than that of low temperatur e stretched ones which was again higher than that of the original unstretch ed samples. From high temperature DSC it was found that with increase in ep ichlorohydrin content, stability towards oxygen was decreased and for high temperature stretched samples, the stability was increased compared to the original unstretched and high temperature shrunk samples. But for H-T shrun k samples the first and second decomposition temperatures were lower and th e rate of degradation was enhanced compared to unstretched samples and H-T stretched ones. SEM showed that H-T stretched samples were more elongated t han R-T stretched ones.