Numerical examination of the dual‐mode model for permeation, sorption, and desorption rate curves

Abstract

SYNOPSISNumerical solutions were applied to the dual-mode sorption and transport model for gas permeation, sorption, and desorption rate curves allowing for mobility of the Langmuir component. Satisfactory agreement is obtained between integral diffusion coefficient from sorption and desorption rate curves and apparent diffusion coefficient from permeation rate curves (time lag method). These rate curves were also compared to the curves predicted by Fickian-type diffusion equations.

Sorption and diffusion of water vapor in poly(ethylene terephthalate) film

“…It is assumed that the water vapor sorption occurs simultaneously. It gives initial and boundary conditions as5 where x is the coordinate in the direction of the film thickness and C is the concentration of water vapor. The origin of the coordinate is fixed at the center of the film.…”

Molecular Interactions in and Transport Properties of Densely Cross-Linked Networks: A Time-Resolved FT-IR Spectroscopy Investigation of the Epoxy/H2O System

“…Also the kinetic aspects of water diffusion have been investigated in detail. ,− In particular, the role played by excess free volume elements (microvoids) has been evidenced by several investigators. − …”

“…Also the kinetic aspects of water diffusion have been investigated in detail. 5,[28][29][30][31] In particular, the role played by excess free volume elements (microvoids) has been evidenced by several investigators. [29][30][31] In the present contribution the sorption-desorption kinetics of water in a typical TGDDM/DDS formulation are investigated at different water vapor activities by means of in situ, time-resolved FT-IR spectroscopy measurements, in the transmission mode.…”

“…5,[28][29][30][31] In particular, the role played by excess free volume elements (microvoids) has been evidenced by several investigators. [29][30][31] In the present contribution the sorption-desorption kinetics of water in a typical TGDDM/DDS formulation are investigated at different water vapor activities by means of in situ, time-resolved FT-IR spectroscopy measurements, in the transmission mode. We present the results obtained by analysis of the frequency range relative to the O-H stretching fundamental (3700-2800 cm -1 ) and the bending mode of water (1650-1590 cm -1 ).…”

The effect of mass transfer resistance and nonuniform initial solvent concentration on permeation through polymer membranes

“…Permeation through polymers has been investigated analytically by modified time‐lag analyses and with various diffusion models, within finite volume systems and at various experimental conditions . Application of time‐lag analysis has been applied to extract diffusion information along with permeation data and both dual sorption and free volume theories have been proposed to understand the transport mechanism within polymer membranes.…”