ABSTRACT
Silicone rubber film has very high gas permeability among conventional commercially available polymers, but the selectivity is poor. If the selectivity is increased by a simple gas plasma treatment without sacrificing the flux, it could be used as a gas separation membrane. The permeability ratios for O2/N2 and CO2/CH4 gas pairs obtained from single-gas permeability measurements together with the permeation rate of the more permeable gas (O2, CO2) are plotted as a function of the argon plasma treatment time in Figures 34.4 and 34.5. The permeability ratios for both gas pairs increase rapidly in the first few minutes of plasma treatment and level off during prolonged periods of plasma exposure. In spite of the decrease of the permeability of the numerator gas (CO2), the permeability ratio increases indicating that the decreases of the denominator gas (N2 or CH4) are greater in these cases.
