This paper reviews some theories and models which are employed in analysis, interpretation, simulation, and prediction of equilibrium and unsteady-state sorption behavior of gases and vapors in nonporous polymer membranes. Applicability of 2- and 3-parameter adsorption isotherms to treat quantitatively the equilibrium sorption behavior is discussed. Sorption isotherms of organic vapors in a disubstituted polyacetylene, poly [1- (trimethylsilyl) -1-propyne], membrane is quoted. It has been shown that a treatment, which takes account of both adsorption on the internal and external polymer surfaces with lateral penetrant-penetrant interaction and dissolution into the polymer network, reproduces satisfactorily the complex shape of the sorption isotherms. The limitations of the dual-mode sorption model are discussed in light of recent results of spectroscopic measurements of systems of gases and glassy polymers. The analysis and the interpretation of nonsteady-state sorption behavior of gases and vapors in rubbery polymer membranes are discussed in terms of the free volume models developed by Fujita and by Vrentas and Duda.
