VAPOR-LIQUID-EQUILIBRIUM OF POLYMER-SOLUTIONS USING A CUBIC EQUATION OF STATE

A recently proposed mixing rule has been combined with a cubic equatio n of state to correlate the vapor-liquid equilibria of various polymer + solvent and solvent + long chain hydrocarbon mixtures. We find that the two-parameter version of this model can correlate the solvent par tial pressure in concentrated polymer solutions with high accuracy ove r a range of temperatures and pressures with temperature-independent p arameters. For the solvent + long chain hydrocarbon systems, for which accurate vapor-phase concentrations are also important, the model is best used as a three-parameter correlation. Advantages of this approac h are that it extends the application of cubic equations of state to p olymer + solvent systems in a simple fashion and that generally only t emperature-independent parameters are required which allow for accurat e interpolation and extrapolation of available data.