A FINITE STRAIN THERMO-MECHANICALLY COUPLED MATERIAL MODEL FOR SEMI-CRYSTALLINE POLYMERS

In this work, a thermo-mechanically coupled constitutive model for semi crystalline polymers is derived in a thermodynamically consistent manner. In general, the macroscopic material behaviour of this class of materials is dictated by the underlying microstructure, i.e. by the distribution and structure of crystalline regimes, which form up after cooling from the amorphous melt. In order to account for the latter, the total degree of crystallinity is incorporated as an internal variable and its evolution is prescribed by means of a non-isothermal crystallisation kinetics model. The numerically efficient and robust framework is characterised based on experimental data for Polyamide 6 and shows a promising potential to predict the hyperelastic, visco-plastic material behaviour at various temperatures.