Vapor-Liquid Equilibrium in Diluted Polymer plus Solvent Systems

Vapor-liquid equilibrium data were determined for five polymer + methylbenzene systems under isothermal conditions between (333.15 and 373.15) K. The polymers studied include copolymers and terpolymers of octadecyl propenoate, propenoic acid, ethenylbenzene, and 1-vinyl-2-pyrrolidone because of their practical importance as flow improvers for crude oil and/or derivatives. An all-glass microebulliometer with circulation of the liquid phase was used for measurements of total pressure over polymer + methylbenzene mixtures. Two predictive group-contribution models (entropic-free volume and group contribution-Flory) were applied to estimate the phase behaviors of two polymer solutions; good agreement with the experimental data was achieved.