PERMEABILITY FUNCTIONS FOR PURE AND MIXTURE GASES IN SILICONE-RUBBER AND POLYSULFONE MEMBRANES - DEPENDENCE ON PRESSURE AND COMPOSITION

Permeability functions are developed for pure gases and mixtures of N- 2, CH4, CO2, and O-2 as a function of driving pressure for polysulfone and silicone rubber membranes. The gas mixtures used in the measureme nts include N-2-O-2, CO2-N-2-O-2, and CH4-N-2-CO2. The functions are e xpressed in a Linear form in terms of species partial pressures. The f unctions are in good agreement with the measured data. Positive and la rge weights for the fastest permeating species, CO2, are obtained in t he permeability functions for all species in polysulfone. The opposite is obtained for the slower permeating species in the polysulfone perm eability functions. This result is consistent with the membrane behavi our, where permeability of faster species is reduced by presence of sl ower species. The species weights in the silicone rubber permeability functions are 1-5 orders of magnitudes smaller than the function const ant. This behaviour is dictated by limited Variations in species perme ability in silicone rubber.