This paper presents an extended application of the recently developed FV-UNIQUAC segmental interaction model especially suited for correlation and prediction of liquid-liquid equilibrium (LEE) of polymer solutions. The accuracy and the range of applicability of the model is determined by the available number of reliable segmental parameters. In this paper new parameters are reported for 13 different binary interactions between polystyrene and different solvents, and the three previously published sets of binary segmental interaction parameters have been revised. The parameters were estimated to achieve the best possible representation of the reported experimental equilibrium compositions. The absolute mean deviation between experimental and predicted equilibrium compositions of polymer is 4.8 wt.%.