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 b e introduced into the system in the form of an elastomeric phase. The prese nt study deals with the measurement of heat shrinkability of a blend of gra fted polyethylene and polyurethane elastomer. The grafting materials used a re vinyl triacetoxy silane and maleic anhydride. The coupling agents used a re 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 r oom temperature, 120 degreesC, 150 degreesC, and 180 degreesC. Shrinkabilit y is greater in the high temperature stretched sample than in the room temp erature stretched sample. Shrinkability depends on various factors such as orientation of the stretched sample, unrecoverable viscous flow, which occu rs during stretching, and degree of interchain crosslinking. Interchain cro sslinking between grafted polyethylene and elastomer improves the shrinkabi lity. Probable interactions between the rubber and plastic phase are confir med by IR spectroscopy. Extraction of the elastomeric phase is restricted d ue to interchain crosslinking as confirmed by scanning electron microscopy.