Modeling of spherulite microstructures in semicrystalline polymers

Oktay, H. Emre
Gürses, Ercan
Semicrystalline polymers are composed of crystalline structures together with amorphous polymer chain networks and therefore they exhibit deformation mechanisms of both crystalline materials and amorphous polymers. One of the most common microstructures observed in semicrystalline polymers is the spherulite microstructure in which crystalline lamellae are embedded in a matrix of amorphous material and grow out from a common central nucleus in radial directions. The mechanical behavior of semicrystalline polymers is strongly dependent on the underlying spherulite microstructure. Therefore, characterization of the deformation of spherulites is very important to understand the mechanical behavior of semicrystalline polymers. In this work, we propose a new FEM-based model for semicrystalline polymers which explicitly discretizes the spherulite microstructure consisting of crystalline and amorphous phases. In the model, a viscoplastic crystal plasticity model is employed for the crystalline phase, whereas 8-chain model is employed for the amorphous phase. The model captures the evolution of inhomogeneous plastic deformation activity in a spherulite microstructure, as well as the important features of the spherulite deformation reported in the literature.