Prediction of miscibility in chlorinated polyethylene/poly(vinyl chloride) blends via atomistic molecular dynamics simulations

Abstract

The miscibility of chlorinated polyethylene (CPE)/polyvinyl chloride (PVC) blends is intricately influenced by both chemical structures and environmental conditions. This study employs all-atom molecular dynamics simulations to systematically investigate the effects of CPE chlorine content and molecular architecture, blend composition, and temperature on CPE/PVC miscibility behavior. Analysis of solubility parameters (δ) suggests that the compatibility of CPE/PVC blends improves with increasing chlorine content within the examined range. Random-chlorinated polyethylene (r-CPE) demonstrates superior miscibility with PVC compared to block-chlorinated polyethylene (b-CPE), attributed to enhanced electrostatic contributions arising from intensified polar Cl–Cl interactions. CPE/PVC blends containing approximately 20–80 wt% CPE are found to be thermodynamically immiscible at 300 K. Furthermore, a quantitative relationship between the Flory–Huggins interaction parameter (χ₁₂) and temperature (T) is established, revealing an increase in χ₁₂ with T, indicative of reduced miscibility at higher temperatures. The phase diagram exhibits a low critical solution temperature (LCST) behavior, consistent with the χ₁₂–T relationships. Notably, r-CPE/PVC binary systems exhibit a higher LCST critical temperature (T_cr) than b-CPE/PVC systems. In general, this simulation study provides better understandings of CPE/PVC miscibility and offers valuable guidance for the design and optimization of CPE/PVC composite materials.