Importance of heat transfer in membrane extrusion process involving flow-induced crystallization

In this work, a recently proposed viscoelastic non-isothermal extrusion film casting model, which accounts for flow-induced crystallization, was generalized by including heat transfer coefficient considering radiation, natural and forced convection. This variable heat transfer coefficient (HTC) based model was found to have the ability to predict the measured temperature, velocity, width and crystallization profile for process conditions typical for the production of polypropylene energy storage membranes. The difference between variable and constant HTC based models was investigated in more details by using systematic parametric study. The obtained results suggest that the use of the variable-HTC model should be preferred for polymer energy membrane production over the constant-HTC models, and flow-induced crystallization should always be included, otherwise the extrusion film casting model loses its ability to describe experimental reality. It is believed that the proposed model and the obtained results can help to understand the optimal process conditions for the production of polymer membranes for energy storage due to their use in rechargeable lithium-ion batteries and special energy storage.