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Effects of Branch Content and Branch Length on Polyethylene Crystallization: Molecular Dynamics Simulation
Authors:Rui Gao  Xuelian He  Yunqi Shao  Yanling Hu  Haiyang Zhang  Zhen Liu  Boping Liu
Abstract:Influences of branch content (BC) and branch length (BL) on isothermal crystallization of precisely branched polyethylene are studied by molecular dynamics simulation. Branch acts as a defect both in nucleation and crystal growth process. BC affects not only crystallization kinetics but also final morphologies. Crystallization rate and crystallinity decrease as BC increases. Morphology Regimes change from lamellae crystal to bundle crystal at critical BC (20/1000 C) because of different folding pattern. 50 CH2 is the critical methyl sequence length to form lamellae crystal. Lamellae thicknesses of final morphologies decrease in gradient corresponding to Morphologies Regimes. BL has no influence on the crystallization kinetics, and only affects the final morphologies when more branches inclusion happens with BL increasing. Trans‐rich phenomenon in pre‐crystalline state is observed. Crystallization process begins at the end of induction stage when trans state population reaches a critical value, and this value is independent of BC and BL.
Keywords:branch content  branch length  molecular dynamics simulation  polyethylene  trans‐rich state
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