THE MODELING OF CONTINUOUS MIXERS .1. THE COROTATING TWIN-SCREW EXTRUDER

A simple model is developed for the hot melt closely intermeshing corotating twin-screw extruder. With this model, and more specifically with its extension to the complete nonisothermal, non-Newtonian situation, it is possible to understand the extrusion process and to calculate the energy, specific energy, and temperature rise during the process with respect not only to viscosity of the melt, but also to the screw geometry (location and number of transport elements, kneading sections and blisters, pitch, positive or negative, screw clearance, and flight width) and screw speed. To support the theoretical analysis, model experiments with a Plexiglas-walled twin-screw extruder were performed, in addition to practical experiments with melts on small-and large-scale extruders, with very reasonable results.