Heat shrinkable polymer blends based on grafted low density polyethylene and polyurethane elastomer - Part II

Heat shrinkability of a polymer, which depends on the elastic memory, can be introduced into the system in the form of an elastomeric phase. The present study deals with the measurement of heat shrinkability of a blend of grafted polyethylene and polyurethane elastomer. The grafting materials used are vinyl triacetoxy silane and maleic anhydride. The coupling agents used are ethane diol and 4,4'-diamino diphenyl sulphone. From Torque Rheometry it is found that the maximum amount of interchain crosslinking is obtained in the sample containing silane grafted LDPE. Shrinkability was measured at room temperature, 120 degreesC, 150 degreesC, and 180 degreesC. Shrinkability is greater in the high temperature stretched sample than in the room temperature stretched sample. Shrinkability depends on various factors such as orientation of the stretched sample, unrecoverable viscous flow, which occurs during stretching, and degree of interchain crosslinking. Interchain crosslinking between grafted polyethylene and elastomer improves the shrinkability. Probable interactions between the rubber and plastic phase are confirmed by IR spectroscopy. Extraction of the elastomeric phase is restricted due to interchain crosslinking as confirmed by scanning electron microscopy.