Constitutive Modeling of Polymer Films From Viscoelasticity to Viscoplasticity

A unified constitutive model for polymer films is proposed with viscoelastic characterization at small deformation and viscoplastic characterization at large deformation, based on molecular chain deformation mechanisms. The evolution equations and the temperature dependence of drag stress and back stress are well established from molecular network theories. The material constants are then determined by master curves and a consistent procedure. The excellent agreement between experimental data of polycarbonate film tests and model predictions is achieved.