Anomalous Diffusion of Vapors Through Solid Polymers. Part I: Irreversible Thermodynamics of Diffusion and Solution Processes

The solubility and diffusivity of vapors in polymers below and in the vicinity of glass transition temperature are known to be explicitly time-dependent. It is assumed here that the polymers are in nonequilibrium states, characterized by an internal order. the latter relaxes with time and moves towards equilibrium. the changes in the internal order bring about changes in the properties of the polymer-solute system. the time dependence of diffusivity and solubility has been derived for isothermal processes not far from equilibrium. Well-known procedures for analyzing relaxing systems are used to obtain the above results, and the knowledge of how the internal order is related to the molecular properties is not required