Visualisation and analysis of polyolefin multilayer coextrusion flows

Abstract

Flow visualisation studies were preformed to determine process parameters initiating interfacial instability in the coextrusion of polyolefin melts. Slit coextrusion visualisation cells with 30° and 90° convergent streams were studied. Studies were performed using two different extruder arrangements. Stress fields, quantified using birefringence. Concomitant velocity and layer ratios leading to wave type interfacial instability in the polyolefin melts are presented.