Computer simulation of rubber extrusion in the capillary die using viscoelastic models

Rubber compounds have high viscoelastic property. The viscoelastic behaviors shown in die extrusion are an extrudate swell and circulation flow at the entrance of die. Application of viscoelastic models to a capillary extrusion has been investigated in this study. Experiment and simulation have been performed using fluidity tester and commercial CFD code, Polyflow respectively. Die swells of rubber compounds through a capillary die have been predicted using various viscoelastic models, such as PTT, Giesekus, and POMPOM models. Simulation results of die swell were compared with the experiment. Pressure drops, velocity distributions and circulation flows at the corner of reservoir have been analyzed through computer simulations.