Mechanical behavior of a semicrystalline polymer before necking. Part II: Modeling of uniaxial behavior

Based on the experimental mechanical characterization presented in Part I of this paper, a model allowing the prediction of the behavior of the studied semicrystalline polymer in the pre-necking domain was constructed. The modeling of the viscoelastoplastic behavior of polypropylene (PP) was described by partitioning the total strain into a viscoelastic strain and a viscoplastic strain. After being improved with experimental observations, the rheological model of Zener was used to model the viscoelastic behavior of PP. As for viscoplastic behavior modeling, it was based on the characterization of the mechanical behavior performed in the first part of the study. Attention was focused on the strain reversal in order to predict the unloading path. Experimental data from the performed mechanical tests were employed to determine the parameters of the viscoelastoplastic model.