PREDICTION OF VAPOR-LIQUID-EQUILIBRIA IN POLYMER-SOLUTIONS USING AN EQUATION OF STATE EXCESS GIBBS FREE-ENERGY MODEL

A new mixing rule has been developed, which is coupled with a translat ed and modified version of the Peng-Robinson equation of state (EoS) a nd the entropic-FV activity coefficient model. The resulting EoS/G(E) model is applied to the correlation and prediction of vapor-liquid equ ilibria (VLE) in solvent/polymer mixtures, after appropriate modificat ion of the cubic EoS to describe the volumetric behavior of the pure p olymer. The model yields very good correlation of experimental equilib rium pressures in concentrated polymer solutions, but more importantly , successful predictions of the same data are obtained. A comparison w ith other EoS-based models applicable to the prediction of VLE in poly mer solutions is also presented.