A two-phase model for the mechanical behaviour of semicrystalline polymers. Part II – Modelling of the time-dependent mechanical behaviour of an isotropic and a highly oriented HDPE grade

Abstract This paper presents an application of the model presented in Part I for the prediction of the mechanical response of two semicrystalline polymers. This Part II particularly emphasises the capacity of the model to predict the time-dependent behaviour of semicrystalline polymers, whereas Part I illustrates the potentiality of the model to predict their multiaxial and large strains behaviour. The two studied materials consist of an initially isotropic HDPE, studied up to the beginning of the tensile hardening, and of any highly oriented HDPE bands, so that their mesostructure state can be considered constant in the studied strains domains. This paper shows that the large strains model can be simplify to predict the mechanical behaviour of SCPs, as well isotropic as anisotropic. The model is validated for the two studied HDPE materials under uniaxial tension on the basis of experimental data, which evidence the sensitivity to the strain rate, and the short-time and long-time viscous behaviour.