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Thermodynamic model for the permeability of light gases in glassy polymers
Author(s) -
Minelli Matteo,
Sarti Giulio C.
Publication year - 2015
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.14858
Subject(s) - penetrant (biochemical) , thermodynamics , polymer , thermal diffusivity , non equilibrium thermodynamics , solubility , chemistry , permeability (electromagnetism) , materials science , physics , organic chemistry , biochemistry , membrane
The permeability of light gases in a series of different glassy polymers is analyzed through a thermodynamic‐based approach for solubility and diffusivity. The nonequilibrium thermodynamic model for glassy polymers describes the solubility of the different penetrants; diffusivity is given as the product of a mobility factor and a thermodynamic factor. The latter is predicted by the nonequilibrium lattice fluid thermodynamic model, while the mobility coefficient is determined using the experimental permeability data. For rather soluble penetrants (e.g., CO 2 ), a plasticization factor is also accounted for, considering the mobility to depend exponentially on penetrant concentration, as often observed experimentally. The model is able to describe accurately the experimental behavior in a simple and effective way, considering only two adjustable parameters. The mobility coefficient is found to depend on the penetrant size (critical volume) and on the fractional free volume of the polymer matrix, following rather general and reasonable correlations. © 2015 American Institute of Chemical Engineers AIChE J , 61: 2776–2788, 2015