How to determine the parameters of polymer crystallization for modeling the injection-molding process?

To understand the relationship between ‘polymers-processing conditions-structures-properties’, crystallization is one of the major concerned phenomena. A general crystallization model derived from Avrami’s work has been developed at CEMEF and implemented into a 3D finite element code for injection-molding named Rem3D®. It gives a precise description of the crystallization event, allows the determination of morphological features, but it requires a reliable determination of the crystallization parameters. The experimental procedures adopted to capture relevant experimental parameters are presented. The determination of overall kinetics, density of potential nuclei with activation frequency of nuclei into crystalline entities, and growth rate is carried out with polarized optical microscopy (POM) and is supplemented by small angle light scattering (SALS). The treatment of data is performed by a classical method or using an inverse genetic algorithm method to extract the parameters necessary to our model. The 2D simulation of the crystallization, illustrated with Rem3D®, reproduces the experimental reality quite accurately, in the case of an isothermal and static crystallization. This is applied to two polymers, an isotactic homopolymer polypropylene iPP and a polyether-block amide PEBAX®.