An Analysis of Die Swell with Rolie-Poly Model

Abstract

Previous efforts on die swell issues mainly focus on linear models such as Oldroyd-B, Linear PTT. However, the characteristic of Rouse Linear Entangled Polymers (Rolie-Poly) model, as a simple model derived from tube-based molecular theory, is rarely discussed before. Compared with other constitutive models, the Rolie-Poly model did a better job in predicting the dynamics of entangled polymer melts problems. In this paper, we analyzed the role of parameters in Rolie-Poly model when determining the behavior of die swell in 2D cases. Results show that the velocity in the die and the shape of the free surface are both totally different from Oldroyd-B model. It seems that the reptation relaxation time plays a dominant role in determining the final result of the extrusion. Moreover, the input velocity might have different influences under different conditions.