Stress Contribution in the Relaxation of Linear Polymer Melts under Extensional Flow

Abstract

The elongational rheological behaviour of polymer melts is of great importance for most of industrial processes. The extensional kinematics may change during the process, like in film blowing and blow moulding. Rheological properties appear to be sensitive on the type of extensional flow (single, biaxial or planar elongation). Predicting both shear and elongational viscosity of polymer melts requires therefore an objective constitutive equation, taking into account the differences between extension modes.