ANALYSIS OF SWELLING BEHAVIOR OF POLYMERIC MEMBRANES IN SOLUTIONS USING UNIFAC-FV-HB ACTIVITY COEFFICIENT MODEL

摘要

The chemical potential of species i in liquid phase equal that in polymer when sorption-desorption equilibrium was reached in the solvent/polymer mixture system. A simple activity coefficient model in conjunction with the free volume theory was used to estimate the swelling behavior of poly vinyl alcohol (PVA) in water/glycol (EG) mixture over a wide range of concentrations. The activity of solvents in the liquid was calculated by the modified UNIQUAC model equations with temperature-dependent binary interaction parameters, while that in the polymer was predicted by the UNIFAC-FV-HB activity coefficient model involving hydrogen bonds effects. The estimations consist with experimental data at three temperatures of 60℃, 70℃ and 80℃. It is proved that the model is a suitable alternative to the Flory-Huggins equation for analysis of the swelling behaviors of polymeric membranes in solutions.