A general non‐isothermal model for one‐dimensional multilayer coextrusion flows

Abstract

A general computation of multilayer coextrusion flow in a flat die geometry is presented. For any given number of layers of different polymers, characterized by their thermal and rheological behaviors, the model permits computation of velocity and temperature fields along the flow in constant or slightly varying geometries. The influence of different operating parameters (wall regulation temperature, flow rate, initial temperatures) on the interface positions and temperature evolutions is evaluated. Theoretical predictions of interface positions are in agreement with experiments carried out on an industrial multimanifold flat die.

Visualisation and analysis of interfacial instability in coextrusion of LDPE melt

“…20 An adjustable flow restriction plate was placed in the bottom channel. The plate was used to alter the relative stream velocities in the two channels.…”

Imaging and analysis of wave type interfacial instability in the coextrusion of low-density polyethylene melts

“…The long die land is intended to promote temperature uniformity in the final stratified melt stream. Temperature uniformity is predicted to take place over relatively short distances for such narrow channels [31]. A further borosilicate window was strategically placed beneath the confluent region thus forming the base wall of the die.…”

Pressure Variation during Interfacial Instability in the Coextrusion of Low Density Polyethylene Melts

“…Several experimental and numerical studies (Yu and Han, 1973;Malkin et al, 1975;Han and Shetty, 1976;1979;Shrenk et al, 1978;Mavridis et al, 1987;Mitsoulis and Heng, 1987;Dooley and Ramanathan, 1994;Puissant et al, 1992) have been undertaken over the past four decades to develop understanding of layer distributions in multilayer flows of melts. Ad ifficulty lies in accurately determining the interface position so as to predict stress fields in these complex flows.…”