This paper describes a numerical study on the extrudate swell of polymer melts in extrusion from various kinds of dies in shape, namely parallel plate, capillary, annular and converging dies. The Oldroyd-B, the Giesekus type and the Phan Thien-Tanner type models were used as the constitutive equations of polymer melts. Swelling ratio, shape of the free surface, and distributions of velocity, stress and pressure were calculated by the ordinary Galerkin's finite element method and the streamline-upwind finite element method. The calculated results for three kinds of viscoelastic models and the Newtonian fluid showed that the swelling phenomenon is closely related to the magnitude of the primary normal stress difference and the shear-thinning effect of shear viscosity. It was also found that the swelling mechanism can be understood mainly from the viewpoint of stress. From the results for annular dies, the difference of shape of free surface between annular extrudate and parallel plate or capillary extrudate was clarified. Furthermore the entrance effect on extrudate swell was found in the low deformation rate from the results for converging dies.
|Number of pages||18|
|Journal||Memoirs of the Kyushu University, Faculty of Engineering|
|Publication status||Published - Sep 1 1991|
All Science Journal Classification (ASJC) codes
- Atmospheric Science
- Earth and Planetary Sciences(all)
- Management of Technology and Innovation