Crystallization of Crystalline/Crystalline Symmetric Polymer Blends Studied by Dynamic Monte Carlo Simulations

TL;DR

This study uses dynamic Monte Carlo simulations to explore how symmetric crystalline polymer blends crystallize, revealing the effects of segregation strength on morphology, crystallinity, and pathway-dependent behaviors.

Contribution

It provides new insights into the crystallization process of symmetric crystalline/crystalline polymer blends, highlighting the influence of segregation strength and crystallization pathways.

Findings

Higher segregation strength leads to smaller, less crystalline crystals.

A-polymer crystallizes before B-polymer during cooling.

Two-step crystallization produces better crystalline structures than one-step.

Abstract

In this paper, we report dynamic Monte Carlo simulation results on the crystallization of crystalline/crystalline (A/B) symmetric binary polymer blend, wherein the melting temperature of A-polymer is higher than B-polymer. Crystallization of A-polymer precedes the crystallization of B-polymer upon cooling from a homogeneous melt. The morphological development is controlled by the interplay between crystallization and macrophase separation. With increasing segregation strength, smaller and thinner crystals form with lesser crystallinity. During the process, A-polymer crystallizes first followed by the crystallization of B-polymer in the presence of already crystalline domains A-polymer. Thus, crystallization of B-polymer slows down influencing overall crystal morphology. With increasing segregation strength between two polymers, we observe a decreasing trend in mean square radius of gyration, reflecting the increased repulsive interaction between them. As a consequence, a large number of smaller size crystals form with lesser crystallinity. Isothermal crystallization reveals that the transition pathways strongly depend on segregation strength. We also observe a path-dependent crystallization behavior in isothermal crystallization: two-step (sequential) isothermal crystallization yields superior crystalline structure in both A- and B-polymers than one-step (coincident).