Vapor-Liquid Equilibrium of Copolymer+Solvent Systems: Experimental Data and Thermodynamic Modeling with New UNIFAC Groups

Vapor-liquid equilibrium (VLE) data for copolymer solutions are necessary for several chemical processes. However, VLE data for copolymer solutions in the published report are rare. In this study, experimental VLE data for binary systems copolymer+solvent were obtained using a gravimetric-sorption apparatus. The studied systems were hexane+poly (21% acrylonitrile-co-butadiene), hexane+poly (33% acrylonitrile-co-butadiene), hexane+poly (51% acrylonitrile-co-butadiene), hexane+poly (23% styrene-co-butadiene), hexane+poly (45% styrene-co-butadiene), and benzene+poly (44% styrene-co-methyl methacrylate) in the range 50–70°C. The experimental data were correlated with the UNIFAC and Elbro-FV group contribution models for the activity coefficient. Two sets of functional groups had been used to represent the monomers in copolymers: literature groups and new proposed groups. The mean deviations between experimental and calculated mass fractions about 2.4% with Elbro- FV and 13.3% with Zhong were observed when the groups proposed in this study were used, and of 3.5% for Elbro-FV and 13.2% for Zhong when literature groups were used.