Simulation of Polymer Crystal Growth with Various Morphologies Using a Phase-field Model

A finite element-based phase-field model was developed to simulate crystal growth in semi-crystalline polymers with various crystal morphologies. The original Kobayashi’s phase-field model for solidification of pure materials was adopted to account for polymer crystallization. Evolution of a nonconserved phase-field variable was considered to track the interface between the melt and the crystalline phases. A local free energy density was used to account for the meta-stable states in polymer solidification. The developed model was successfully applied for simulation of two and three dimensional, singleand polycrystalline morphologies (hexagonal and spherulitic) in isotactic polypropylene (iPP). These morphologies were compared based on different super-cooling conditions and interface anisotropy. The unique aspect of this work is that the employed model is capable of simulating multiple arbitrarily oriented crystals and has no limitations with respect to the crystal morphology. The results show significant thermal effects on the shape and growth rate of iPP crystals.