Pressure Generation and Screw Design in Corotating Twin Screw Extruders

Abstract

In order to properly design the screws and to locate feed and devolatilization ports, it is necessary to determine the extent of filled zones and to evaluate the pumping and mixing efficiency of different kneading sections. This paper presents an experimental study of the pumping efficiency of forward and backward pumping screws and kneading sections. Results indicate that the pumping efficiency is generally greater than that predicted by 2D inelastic models and that left-handed elements do not necessarily fill entirely, especially at their downstream end where backward pumping and forward pumping flights meet.