Relaxation and Crystallization of Oriented Polymer Melts with Anisotropic Filler Networks

Abstract

The coexistence of nanofillers and shear flow can influence crystallization of polymer melts. However, the microscopic mechanism of the effect is not completely revealed yet. Thus, dynamic Monte Carlo simulations were used to study the effect of the filler networks formed by one-dimensional nanofillers on relaxation and crystallization of oriented polymer melts. The filler networks restrict the relaxation of oriented polymers and impose confinement effect on the chains inside the filler networks, resulting in higher orientation and lower conformational entropy of the inside chains compared to those of the outside chains. Thus, the confined inside chains have stronger crystallizability. During crystallization, the confined chains are nucleated on the filler surface and then form nanohybrid shish-kebab structures. Furthermore, the effect of fillers and chain orientation closely depends on some factors, such as polymer-filler interaction, filler content, and filler spacing. Our simulation results are consistent with some experimental findings. Thus, these results can provide new insights into the mechanism of crystallization of filled polymers and also guide researchers to develop new polymer nanocomposites with high performance.

Blocked crystallization in capped ultrathin polymer films studied by molecular simulations

“…In addition, an increase of the interfacial interaction can also lead to a decrease of segmental mobility in the interfacial regions. The mean probability of segment movement “PSM” can be used to quantitatively reflect segmental mobility: where N 0 denotes the total number of segments. Higher values of “PSM” indicate stronger segmental mobility.…”

“…In other words, the finite size effect offsets the density effect, and thus the melting points do not depend on the interfacial interactions. In addition, the increase of interfacial interactions can also lead to a decrease of surface free energy of nuclei and thus a reduction of the free energy barrier for nucleation . In this way, the heterogeneous nucleation process can be enhanced.…”

“…In addition, due to the limitations of the experimental observation scale, the conformations of confined chains and the location of nuclei cannot be detected directly, somewhat hindering a complete understanding of the microscopic mechanism of polymer crystallization under confinement. Molecular simulations that can be used to directly probe molecular structure and motion have also been applied to study confined polymer crystallization behaviors . Using dynamic Monte Carlo (MC) simulations, Hu's group found that crystal orientations are affected by both the size of the confined space and the interaction between polymer and substrate .…”

The Effect of Grafting Density on the Crystallization Behaviors of Polymer Chains Grafted onto One-Dimensional Nanorod

“…Monte Carlo simulations [30,[32][33][34][35][36][40][41][42][43] were employed to investigate the crystallization behaviors of grafted polymer systems. It should be noted that dynamic Monte Carlo simulation is a proven method for studying polymer crystallization.…”

“…Luckily, computer simulations can supplement the shortcomings of experimental and theoretical work in the investigation of crystallization process for grafted polymers, which can be further used to solve many basic problems raised in the field of polymer materials and also the important technical problems related to the processing of new polymer materials [32][33][34][35][36]. Many groups studied the crystallization behaviors of polymer systems by simulations [37][38][39].…”