Measurement of interfacial instabilities during coextrusion of LDPEs in flat dies

Abstract

In flat dies, measurement of interfacial instabilities during coextrusion process of low density polyethylenes (LDPEs) were discussed. Difference between zig-zag instabilities related to shear stress and wave instabilities related to the merge point of coextruded LPDEs were studied. The experiment was conducted on a standard multi-manifold coextrusion pilot plant line and with three LPDE materials. It was found that the shapes of the interfacial instabilities (zig-zag and wave) were same and also the origin of these instabilities was from the same part.