Computer simulation of the film blowing process incorporating crystallization and viscoelasticity

A comprehensive two-dimensional simulation of the film blowing process is developed, based on a mathematical model that incorporates the Phan-Thien and Tanner (PTT) and the neo-Hookean constitutive equations with crystallization effects. The PTT constitutive equation is employed in the liquid-like region, whereas the neo-Hookean constitutive equation is employed in the solid-like region. The orientation-induced crystallization is accounted for by incorporating the Nakamura nonisothermal equation along with the Ziabicki equation. The proposed model provides predictions of the bubble shape and dimensions, the position of the freeze line, and evolution of the temperature, crystallinity, stress and deformation. The predictions of the model show good agreement with analytical and computational solutions for some limiting cases and with experimental results reported by various workers. (C) 2004 The Society of Rheology.