Precursor formation and crystal nucleation in stretched polyethylene/carbon nanotube nanocomposites

YJ Nie and J Yang and ZF Liu and ZP Zhou and YQ Ming and TF Hao, POLYMER, 239, 124438 (2022).

DOI: 10.1016/j.polymer.2021.124438

Based on molecular dynamics simulations, we focused on the stretch- induced precursor formation and nucleation process in carbon nanotube (CNT) filled polyethylene. During stretching, in addition to polymer segments, CNTs can also orient along the stretching direction. In this condition, the segments in interfacial regions are subject to two orientation effects: CNT-induced segment orientation and stretch-induced segment orientation, which then can exhibit higher degree of orientation and higher content of segments with trans-conformation, compared with the segments in non-interfacial regions. Finally, these interfacial segments are easier to evolve into precursors and oriented crystallites. Based on the theoretical analysis, it was demonstrated that the crystallization rate at the early stage of crystallization is codetermined by the difference in the nucleation modes (homogeneous nucleation or heterogeneous nucleation), the stretch-induced conformational entropy reduction and the orientation entropy reduction.

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