Non-isothermal viscoelastic simulations of extrusion through dies and prediction of the bending phenomenon

Non-isothermal simulations are carried out for the flow of an IUPAC low-density polyethylene melt. Extrusion flow from an infinitely long capillary die is considered with isothermal walls and different thermal boundary conditions on the extrudate surface. The flow through flat dies is then studied with the walls kept at various temperatures to create a non-isothermal flow. The viscoelasticity of the polymer melt is described by an integral constitutive equation of the K-BKZ type with a relaxation spectrum. The non-isothermal computations are based on a pseudotime method by applying the Morland-Lee hypothesis.