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

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.