Modeling the morphology development of ethylene copolymers in rotational molding

A model is proposed to describe the solidification and crystallization phenomena in rotational molding. To capture the morphology development with crystallization behavior, a two‐dimensional theoretical simulation was carried out, consisting of a phase‐field model emphasizing the metastability of polymer crystallization and a heat‐transfer model describing the molding cycle. The model parameters were experimentally evaluated with differential scanning calorimetry and isothermal crystallization tests. Molding trials were also conducted with bench‐scale rotational molding equipment, and the cross sections of the molded products were examined under polarized light optical microscopy. The model predictions capture the formation of transcrystalline structures near the mold surface, which is more apparent under moderate cooling conditions. Our results show that the model predictions are in general agreement with the experimental results obtained in our laboratory as well as those presented in the literature. Because morphological features are important contributing factors to product performance, the model will be useful for the formulation of new materials and process optimization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5903–5917, 2006