Simulation of non-linear viscoelastic flow behavior in the Buss Kneader

We seek to simulate the non-linear viscoelastic characteristics of molten thermoplastics in the Buss Kneader in which the screw has both rotating and oscillating motions. Non-linear viscoelastic effects are considered using a convected Maxwell model. Calculations are made first in a basic screw element and subsequently in the special Kneader screw modules where we consider leakage flows by drag and pressure flows through the interrupted screw flights. Our study predicts screw pumping characteristics of Kneader screw elements which vary with material properties such as viscosity and relaxation time. It also considers pressure and fill factor profiles along the screw axis in the modular Kneader machine.