Vapor−Liquid Equilibrium for Polymer−Diluent Systems from Melting Point Depression

Abstract

A novel approach for determining vapor−liquid equilibrium (VLE) for polymer−diluent systems is described. The concentration- and temperature-dependence of diluent−polymer Flory−Huggins interaction parameter χij is first estimated from depression in polymer melting point as a function of monomer (diluent) concentration. VLE for the polymer−diluent binary system is then obtained using an activity coefficient model and equation of state model with Aspen Polymer Plus. The technique is validated for the syndiotactic polystyrene−toluene and syndiotactic polystyrene−methyl ethyl ketone and is extended to polybutylene terephthalate − with various diluents such as butanediol, tetrahydrofuran, isophorone, 1-methylnaphthalene, and benzonitrile, systems hitherto not reported in the literature.

Molecular Mechanism of Plasticizer Exudation from Polyvinyl Chloride

“…Miscibility-related parameters, such as the Flory–Huggins interaction parameter, between the polymer and solvent can be estimated from the measurements of thermodynamic interactions using various techniques such as melting point depression, inverse gas chromatography, differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and dielectric spectroscopy. − We used the melting point depression method with an optical microscope based on the technique described by Anagnostopoulos et al While this may not be the most sophisticated method, it has been shown that it can effectively capture the effect of solvent-on-polymer melting point as a function of the solvent concentration and the nature of polymer–solvent interactions . A Flory–Huggins interaction parameter was derived from the apparent melting temperature ( t m ) of a PVC particle (OxyVinyls 240F, K = 70) heated in the plasticizer and Anagnostopoulos et al.’s equation 1/ t m = 0.002226 + 0.1351­(1 – χ)/ V 1 , where χ is the Flory–Huggins interaction parameter and V 1 is a molar volume of the plasticizer .…”

“…31−34 We used the melting point depression method with an optical microscope based on the technique described by Anagnostopoulos et al 35 While this may not be the most sophisticated method, it has been shown that it can effectively capture the effect of solvent-on-polymer melting point as a function of the solvent concentration and the nature of polymer−solvent interactions. 31 A Flory−Huggins interaction parameter was derived from the apparent melting temperature (t m ) of a PVC particle (OxyVinyls 240F, K = 70) heated in the plasticizer and Anagnostopoulos et al's equation 1/t m = 0.002226 + 0.1351(1 − χ)/ V 1 , where χ is the Flory−Huggins interaction parameter and V 1 is a molar volume of the plasticizer. 35 Supplementary method information is included in Section S1, and reference data are included in Table S1.…”