A lattice-based activity coefficient model for gas sorption in glassy polymers

Abstract

The glassy polymer lattice sorption model (GPLSM) is a lattice-based activity coefficient model that has been developed for gas sorption in glassy polymers. The model recognizes the presence of holes on the lattice and determines how the number of holes changes by taking into account swelling due to penetrant gas molecules. The GPLSM equation has a composition-dependent energy term similar to that in the Flory-Huggins theory and an entropic term based on the mixing of gas molecules and holes. The utilization of sorptive dilation data for the determination of the number of holes gives a physically realistic interpretation of the local free volume in a glassy polymer. A good representation of the experimental data is obtained for the carbon dioxideand methane-polycarbonate systems.

Entropic nanothermodynamic potential from molecular trapping within photon induced nano-voids in photon processed PDMS layers

“…hydrogen polar interactions, where the order of magnitude of free energy difference from physisorption in thin layers is in the pJ range and the associated strained field does not exceed a few Angstroms, is the theoretical description of the energy transfer and the experimental verification of the internal energy differences. Any description should take into account both the molecular interactions 22 and the conformational configuration of the combined specific system, 23,24 as well as any additional constraint that might be important, such as the size and the concentration of nanocomposites. 25 Finally, the key theme is the interplay between the combinatorial entropic change, including any possible restriction of the translational symmetry of molecules at the nanoscale and the molecular interaction between the polymeric matrix (matrix) and the adsorbed molecules (analytes).…”

Gas‐separation Membrane Applications

“…Polymer free-volume, the void space between polymer molecules, plays a major role in permeation of gases through membranes [6,7]. Sorption can be so complete as to block the transport of otherwise highly permeable species [12,13]. Others have sought to alter the free-volume and modify the surface by various chemical treatments [10,11].…”

Sorption and permeation in elastic solids: applicability to gas transport in glassy polymeric materials

“…Conforti ef al. [15] developed an extension of this lattice fluid theory for glassy polymers. An expression for the gas activity coefficient was derived assuming the entropy of mixing of the polymer is negligible.…”