The end pressure losses during short die extrusion of LLDPE melt

Abstract

The end pressure losses and the factors affecting them during short die extrusion of a linear low density polyethylene (LLDPE) melt have been investigated under the experimental conditions of temperatures from 230 to 260°C and apparent shear rates of 12 to 120s−1, by employing a capillary rheometer and a set of dies with different diameter and length. The results show that the entry pressure loss, ΔPen, increases non-linearly with increasing shear rate, and is an index function of the wall shear stress; the dependence of ΔPen on temperature accords with a formula such as the Arrhenius equation; ΔPen decreases with increasing die diameter; ΔPen is more than 80% of the end pressure losses.