TERNARY PHASE-EQUILIBRIA OF TETRAHYDROFURAN-POLYSTYRENE-POLYTETRAHYDROFURAN

Phase diagrams including tie lines for three ternary solvent-polymer-p olymer systems consisting of tetrahydrofuran-polystyrene-polytetrahydr ofuran at 30-degrees-C have been obtained using size exclusion chromat ography. The effect of molecular weight on polymer-polymer compatibili ty has been investigated. A liquid-liquid equilibria (LLE) database ha s been used to compare UNIQUAC and a modified Flory-Huggins model with respect to their ability to correlate LLE data. Both models contain s ix adjustable parameters. As previously observed in the literature, th e estimation of the UNIQUAC parameters is troublesome due to the model 's complexity and the intercorrelation of the parameters. On the basis of better performance and ease of use, the Flory-Huggins model is rec ommended. The Flory-Huggins model is capable of accurately describing LLE of systems which exhibit quite complex tie line behavior. (C) 1993 John Wiley & Sons, Inc.