A PREDICTIVE MELTING MODEL FOR POLYMER PARTICULATES IN CO-ROTATING TWIN SCREW EXTRUDERS

摘要

A predictive melting model for polymer particulates in co-rotating twin screw extruders (Co-TSEs) is proposed. The proposed model starts with the solids conveying section where discrete mechanics is used to describe the movement and deformation of solid particulate assemblies. The interparticle forces can be estimated based on the screw geometry, processing conditions, and material properties. These forces are the sources of two important melting mechanisms: the Frictional Energy Dissipation (FED) and the Plastic Energy Dissipation (PED). The model also considers the role of barrel heating in creating a layer of "preformed melt". The existence of preformed melt changes the conveying properties of solid particulates dramatically. Finally the model considers the important heat generating term, the Viscous Energy Dissipation (VED), whose onset coincides with the creation of a fraction of molten polymer generated by any of the above mechanisms.