Gas permeation properties of polyvinylchloride/polyethyleneglycol blend membranes

Abstract In this study, the effect of the molecular weight of polyethyleneglycol (PEG) on the gas permeability and selectivity of a series of polyvinylchloride/polyethyleneglycol (PVC/PEG) blend membranes was investigated. The molecular weight of polyethylene glycol ranged from 400 to 4000. PVC/PEG blend membranes were prepared via thermal phase inversion of PVC/PEG/dimethylformamide solution at 60°C. The permeabilities of pure CO2, CH4, O2, and N2 gases through prepared membranes were determined at room temperature (25°C) and 20 bar feed pressure. The blend membranes having PEG with 4000 molecular weight showed higher values of CO2 permeability, and CO2/CH4 and CO2/N2 ideal selectivities (the ratio of pair gas permeabilities) compared with other blend membranes containing PEGs of lower molecular weights. It was also found that the gas permeabilities of PVC/PEG4000 blend membrane rapidly increased with an increase in PEG concentration (weight fraction). The PVC/PEG blends containing 10, 20, and 30 wt % of PEG4000 showed CO2 permeabilities equal to 0.84, 2.38, and 5.82 Barrer (1 Barrer = 10−10 cm3 (STP) cm/cm2 s cmHg), respectively. The CO2/N2 ideal selectivities of 10, 20, and 30 wt % of PEG4000/PVC blend membranes were 49, 70, and 109, respectively. This is a great improvement compared with the pure PVC membrane, which showed CO2 permeability and CO2/N2 ideal selectivity of 0.13 Barrer and 14.5, respectively. These results and comparison of CH4 and N2 permeabilities of PVC membrane and PVC/PEG blend membranes indicated that the gas solubility is dominant in the permeation of gases through abovementioned blend membranes. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008