Vapor-liquid equilibria behavior of binary and ternary polymer-polymer alcoholic solutions

•Soluting effect occurring in alcoholic systems composed of two polymers.•Ethanolic, propanolic, or butanolic solutions of two polymers were studied.•Iso-solvent activity lines of the systems were obtained by the isopiestic method.•The polymers PVP, PEG, PPG, and PEGDME were considered.•The mixtures of PVP with PEG, PPG and PEGDME show the soluting-in effect.•The mixtures of two polymers of PEG, PPG and PEGDME show the semi-ideal behavior.