Composite models for the calculation of the filling level profiles, the pressure profiles, the melting profiles, the residence time distributions, the temperature profiles, the shear stress profiles, and the power consumption in modular tightly intermeshing co-rotating twin screw extruders (ZSK) are developed. A complex systematic design procedure was compiled, which is explained in part in this paper. The simulation of the intermeshing co-rotating machine involves both screw and kneading disc elements, including left-and right-handed sections. Kneading blocks were approximated by a screw of "equivalent pitch" with making allowance for the leakage flow across the flights from one channel to the adjacent channel. The mathematical treatment of co-rotating twin screw extruders has been based up according to the theory of single screw extruders. There was seen to be a good correlation between calculated and experimental results.International Polymer Processing downloaded from www.hanser-elibrary.com by Kungliga Tekniska on August 25, 2015For personal use only.

This paper presents a mathematical-physical model for tightly intermeshing co-rotating twin screw extruders which describes the throughput and pressure characteristics of these extruders in the sections filled with molten plastic. With the equations that have been compiled, it is possible to calculate pressure profiles and back-pressure lengths for individual sections of isothermal and two-dimensional flow with non-Newtonian melts, making allowance for the screw geometry and for the parameters of relevance to the process. A comparison of the results supplied by the formulated theory and those obtained from the experiment shows that good computed results are obtained for various materials and different points of operation, although no allowance is made for the leakage flow that occurs in reality.