The effect of temperature, molecular weight and structure of polymer on the vapor-liquid equilibrium behavior of aqueous polymer solutions were investigated. It was found that for a certain polymer mass fraction, water actvities of aqueous polymer solution increase by increasing molecular weight of polymer and temperatutre. Vapor pressure osmometery and isopiestic method are two well known technics for the determination of vapor-liquid equilibria of solutions. In this work, both technics have been used for the determination of vapor-liquid equilibria of the investigated polymer solutions and a comparison between the vapor-liquid equilibrium data such as water activity and vapor pressure obtained from these thechnics was investigated. A new molecular thermodynamics model has been used for the prediction of the vapor-liquid equilibrium data of the investigated polymer solutions. The model gives a good representation of water activities over wide concentration range.
