Theoretically Self-Consistent Nonequilibrium Thermodynamics of Glassy Polymer Theory for the Solubility of Vapors and Liquids in Glassy Polymers
Bennett D. Marshall, Ronita Mathias, Ryan P. Lively, Benjamin A. McCool
Abstract
The nonequilibrium thermodynamics of glassy polymer (NETGP) theory provides a formalism to calculate solubilities of volatile species in glassy polymers using equilibrium free energies. The classic NETGP approach of Sarti and Doghieri assumes that the glassy polymer density of a solvent swollen polymer is known a priori. In the modified approach developed in this work, this density is calculated self-consistently. The self-consistent calculation of the swollen polymer density has profound implications on both the theoretical and practical aspects of the theory. This is accomplished by means of a new class of perturbation theory, which assumes that the sorption of volatile species in a glassy polymer can be treated as a perturbation to a dry polymer reference state. The new approach is then validated against sorption data in several glassy polymers.