Flow Behavior of High Molecular Weight Polyethylene

Flow behaviors of a high molecular weight polyethylene were studied by using a parallel plate plastometer and a capillary extrusion rheometer of a constant load. The flow curve at 175°C covering the shear rate range from 3×10-6 to 108 sec-1 was obtained. The flow was non-Newtonian even at the shear rate as low as 3×10-6 sec-1. The activation energy for flow was 5.9kcal/mole. The flow curve showed a remarkable discontinuity in the shear stress region from 106 to 2.5×106dyne/cm2. The zero shear viscosity η0, the weight average molecular weight and the ratio of weight average molecular weight to number average molecular weight Mw/Mn were estimated by using relations reported in literatures. The results were as follows:η0(175°C)=1010 poises, Mw, =2.5×1010, and Mw/Mn=18.6.