“Skin-Core-Skin” Structure of Polymer Crystallization Investigated by Multiscale Simulation

• Main Author: Chunlei Ruan
• Format: Article
• Language: English
• Published: MDPI AG 2018-04-01
• Series: Materials
• Subjects: “skin-core-skin” structure; flow-induced crystallization; multiscale simulation; crystal morphology
• Online Access: http://www.mdpi.com/1996-1944/11/4/610

“Skin-core-skin” structure is a typical crystal morphology in injection products. Previous numerical works have rarely focused on crystal evolution; rather, they have mostly been based on the prediction of temperature distribution or crystallization kinetics. The aim of this work was to achieve the “skin-core-skin” structure and investigate the role of external flow and temperature fields on crystal morphology. Therefore, the multiscale algorithm was extended to the simulation of polymer crystallization in a pipe flow. The multiscale algorithm contains two parts: a collocated finite volume method at the macroscopic level and a morphological Monte Carlo method at the microscopic level. The SIMPLE (semi-implicit method for pressure linked equations) algorithm was used to calculate the polymeric model at the macroscopic level, while the Monte Carlo method with stochastic birth-growth process of spherulites and shish-kebabs was used at the microscopic level. Results show that our algorithm is valid to predict “skin-core-skin” structure, and the initial melt temperature and the maximum velocity of melt at the inlet mainly affects the morphology of shish-kebabs.