Computer simulation of the flow of a thermoplastic elastomer vulcanizate melt through an axisymmetric extrusion die using an augmented Navier's slip equation

The pressure flows of a thermoplastic elastomer vulcanizate (TPV) melt through the die region of a single-screw extruder were simulated using the finite-element method. The COMSOL software was utilized to develop the finite-element model of the die and solve the working equations. ACross-WLF rheological equation of state was used for the description of the rheological behavior of the polymer melt. The numerical results were compared with their associated experimental data. The novel aspect of the present work is the development of a new augmented Navier's slip equation to take the effect of wall slip on solution variables into account. The proposed model consists of a power-law equation, which relates the slip coefficient to the shear rate at wall. It is implemented in the COMSOL code through a simple script. The distribution of the velocity, pressure, and temperature as well as the profile of the fluid velocity at exit region and slip velocity along the flow directions were presented and discussed. It has been shown that using the no-slip condition at wall or employing the Navier's slip equation with a constant slip coefficient leads to notable error in the prediction of mass flow rates and pressure. [GRAPHICS] .