HDPE (CM1) optical birefringence pattern in cross-slot flow, piston speed 0.88mm/s, 175C

Abstract

The optical birefringence pattern obtained from lightly branched high density polyethyene (HDPE - produced by metallocene catalysis polymerisation) flowing in a cross-slot multi-pass rheometer cell. Experiment carried out on the Cambridge Multi Pass Rheometer (MPR4) at a piston speed of 0.88 mm/s at 175C. The geometry generates a flow field with an extensional component at the centreline. If the no slip condition at a solid surface is satisfied, the side walls are high shear rate regions. The experiments were carried out to evaluate the material behaviour in extensional flow. At low extensional rates, an almost Newtonian stress profile is exhibited.