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A theoretical model of the dynamics, heat transfer and crystallization processes in tubular film extrusion is presented. It is presumed that the polymer melts flow behavior is dominated by the temperature dependence of its rheological properties, as opposed to the specific rheological model used to represent it. Specifically we presume the melt is a Newtonian fluid with a temperature dependent viscosity, characterized by an activation energy of viscous flow E. The shape of the bubble and radius and film thickness profiles are primarily influenced by E. Crystallization makes a second order correction. Detailed comparisons are made to experimental investigations for low density polyethylene, linear low density polyethylene and high density polyethylene and generally good agreement is found.

Dynamics, heat transfer and structure development in tubular film extrusion of polymer melts: a mathematical model and predictions