Analysis Tool for Gas and Vapor Solubility in Glassy Polymers: The Dual Nonequilibrium Lattice Fluid (d-NELF)

In view of the physically sounding ideas it is founded on, as well of its simplicity and stand-alone character, the dual-mode sorption model (DMS) has been almost universally used in past decades to analyze and compare gas sorption data in polymeric matrixes below the glass transition temperature. The elements the DMS analysis is based on are here revised with the help of results developed within the nonequilibrium lattice fluid (NELF) model to derive meaningful relations between DMS model parameters and equilibrium and nonequilibrium structure property characteristics of the NELF approach. The result is a stand-alone and simple-to-use new tool for the analysis of solubility data in glassy polymers which allows for the use of a limited amount of data to retrieve the nonequilibrium structure property characteristic of the polymer matrix. The model can then be used to compare the solubility of different gases in the same glassy polymer, based just on equilibrium binary interaction parameters, or to distinguish the gas or vapor solubility properties of different nonequilibrium structures in the same polymer species, based on pertinent values of excess-free volume and compressibility.