The effect of temperature on the rheological response under elongation of two low density polyethylenes (LDPE 1 and LDPE 2), linear low density polyethylene (LLDPE) and their blends of different compositions was observed by using a constant strain rate elongational rheometer. In addition, blends were tested in the oscillatory shear test, and the data measured at 160, 190, and 230 degrees C indicate the larger level of intermolecular interactions in a blend than in the pure polymers. Elongational viscosity measured at temperatures of 140, 150, 170 ann 180 degrees C revealed a much greater sensitivity, for LLDPE (greater strain hardening with increasing temperature) to changing temperature than is observed for LDPE. This observation, coupled with the effect of melt morphology on elongational rheology. has been used to explain the synergism in elongational viscosity exhibited by LDPE-rich blends.