Heterogeneous Entanglement Distribution during Polymer Sintering and the Interplay of Entanglement with Crystallization: Molecular Dynamics Simulations

The entanglement distribution along a chain during re-entanglement and crystallization is investigated using large-scale molecular dynamics simulations. The dependence of the entanglement length, Ne, on the bead index is used to characterize the heterogeneity of the entanglement distribution. The results reveal that entanglements develop heterogeneously during re-entanglement. This is further supported by the broad bimodal distribution of the entanglement length. Furthermore, there is enhanced heterogeneity in the entanglement distribution along the chain during isothermal crystallization. This is ascribed to the heterogeneous disentanglement process, where chains prefer to disentangle and crystallize at chain-end segments. During crystallization, Ne decreases to a certain extent, followed by a significant increase. The initial reduction in Ne is attributed to increased chain rigidity and the continuous chain expansion and diffusion during crystallization. Additionally, the influence of entanglement reconstruction on crystal morphology is investigated.