A new apparatus and procedure for gas permeability measurements on water-swollen gel membranes

An improved apparatus for the measurement of gas permeability through water-swollen gel membranes is described. The apparatus is fitted with a water bubble chamber and a water reservoir to prevent evaporation of water from the swollen membranes. Permeabilities to O₂ and N₂ of two kinds of poly (vinyl alcohol) (PVA) membranes and cationically modified PVA membranes with a swelling ratio of 0.3–0.8 were measured. It was found that the introduction of charged groups at 3.5 mol/100 mol monomer units into the PVA membranes with the above swelling ratio range does not significantly alter the permeability of the membranes to the gases. The permeability values are independent of the upstream pressure up to 4.6 atm.