Numerical simulation of rheological behavior of polymer in three layer co-extrusion process

The two-dimensional rheological models of the three-layer co-extrusion process for the generalized Newtonian fluid were established. Meanwhile, the flow characteristics of melts in the die channels were numerically simulated using the finite element method to explain the influence of the structure change of flow channels in the die section on the rheological behavior of melts. The simulation results indicated that the changes in the convergence angle of flow channels have certain impacts on the shift of the confluence interface of the three-layer co-extruded melt flow while little effects on the interface shape at the outlet. The flow ratio of the melt in each layer at the entrance has a significant effect on the interface shift. The flowing pressure of melts in the die is mainly determined by the inclination angle of flow channels while less influenced by the fact whether the inlets of the flow channels in each layer are smoothed or not.