ENTRY PRESSURE AND ELASTIC BEHAVIOR OF A BRANCHED POLYETHYLENE

摘要

Die entry pressures and elastic parameters derived from these have been determined for one low-density polyethylene (LDPE) at four temperatures using three dies having different entry angles. The elongational viscosity shows a somewhat different behavior with respect to temperature than the shear viscosity. Mostly the elastic parameters show a temperature-independent relation to the shear stress but only if the data at the lowest temperature used (130 degrees C) are ignored. The latter data show that the material is much more elastic at this temperature than at higher ones; this is so even when the temperature is increased by only 20 degrees C, after which any further increase gives negligible difference in elasticity. This behavior is probably due to a structural difference which may be a result of increased crosslink sites created by flow-induced crystallization. (C) 1995 John Wiley & Sons, Inc. [References: 11]