DSC and DMA studies on silane-grafted and water-crosslinked LDPE/LLDPE blends

Effects of silane grafting and water crosslinking reactions on crystallizat ions, melting behaviors, and dynamic mechanical properties of the LDPE/LLDP E blends are investigated using DSC and DMA. From DSC data, cocrystallizati on of LDPE and LLDPE does not occur, but cocrosslinking of these two polyme rs is evidenced at the experimental temperature of 100 degreesC, a temperat ure lower than melting temperatures of both polymers. The water crosslinkin g reactions of the LLDPE-rich blends enable development of a new phase havi ng a melting endotherm in between that of LDPE and LLDPE. From the thermal fractionation data, interaction between LDPE and LLDPE is observed, and com patibilization of the blends can be achieved by the crosslinking reactions. From DMA data, the storage moduli of the blends are not found to be consis tent with their degrees of crosslinking. The storage moduli of the blends a re not simply determined by the degree of crosslinking but determined by ve ry complicated but unclear factors. (C) 2001 John Wiley & Sons, Inc.