Experimental validation of two constitutive models for numerical simulation on the extrusion of rubber blends

Abstract Numerical simulation plays a crucial role in polymer processing. This paper analyzes the extrusion of two rubber blends using the Bird–Carreau viscous model and the Phan‐Thien–Tanner (PTT) viscoelastic model. The study found that wall slip phenomena occurred in both rubber blends when the apparent shear stress exceeded the critical value. Under these conditions, the physical parameters of the two constitutive models, along with the wall slip parameters that describe the degree of rubber sliding, were obtained. This information provided a theoretical basis for the numerical simulation of the extrusion process. The PTT model was found to be superior to the Bird–Carreau rheological model in predicting the rheological behavior of die swell, velocity field, and pressure field distribution in the extrusion process of the two rubber blends. Highlights Based on the numerical simulation analysis of the capillary extrusion process, we designed a more feasible method for fitting the physical parameters of the constitutive equation and parameters of the Navier slip model and established the foundation for the subsequent numerical simulation of extrusion processing. Phan‐Thien–Tanner model is proved to be the best candidate for predicting the extrusion of rubber blends with high Mooney viscosity, including die swell, velocity, and pressure distribution. Demonstrates that wall slip is an important factor in rubber extrusion. Combining simulation results with experimental data improves the accuracy and predictability of the simulation.