An analysis of flow fields, pressure fields and screw pumping characteristics is presented for non-Newtonian fluids in various types of screw elements of an intermeshing counter-rotating twin screw extruder. These elements are in turn considered modules of a modular intermeshing counter-rotating twin screw extruder and an analysis of non-isothermal starved flow in such a machine is presented. Pressure profiles, fill factor profiles and temperature profiles have been calculated for various modular screw designs of a Leistritz GG modular intermeshing counter-rotating twin screw extruder.