Kinetics and equilibria associated with the absorption and desorption of water and lithium chloride in an ethylene—vinyl alcohol copolymer

doi:10.1016/S0376-7388(00)80182-9

Journal of Membrane Science

Volume 12, Issue 2, December 1982, Pages 195-205

https://doi.org/10.1016/S0376-7388(00)80182-9 Get rights and content

Abstract

Sorption and desorption equilibria and kinetics for LiCl and H₂O in an ethylene—vinyl alcohol copolymer film containing 70 mole percent vinyl alcohol were investigated at 25°C. The swelling behavior of water in the polymer was characterized by vapor and liquid sorption experiments over a range of water activities. p]The effects of LiCl content on the water sorption kinetics and equilibria in the films are presented and discussed. The kinetics and mechanism of LiCl sorption have also been studied. The amount of salt sorbed into the polymeric films increases linearly with the salt concentration in the external aqueous solutions. Both the rate and the amount of sorbed water increase significantly as the LiCl content increases. p]The desorption of LiCl, previously sorbed into the polymer, was characterized for different salt loadings. The rate of fractional salt release is independent of LiCl concentration in the film. Initially, the salt release is controlled by the nearly constant-rate absorption of water. The salt release, at long times, lags behind the swelling-controlled water uptake, indicating that the salt release is not completely controlled by the water sorption and that diffusion in the swollen polymer matrix contributes significantly to the long term elution of LiCl. Independent thermal analysis experiments suggest the formation of a metal salt—poly(ethylene—vinyl alcohol) complex.

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¹: Present address: American Can Co., Barrington Technical Center, Barrington, IL 60010 (U.S.A.).

²: Present address: Istituto di Principi di Ingegneria Chimica, Università di Napoli, Piazzale Tecchio, Naples (Italy).

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Kinetics and equilibria associated with the absorption and desorption of water and lithium chloride in an ethylene—vinyl alcohol copolymer

Abstract

J. Membr. Sci.

Polym.

Swelling-controlled, constant rate delivery systems

Polym. Eng. Sci.

Diffusion in glassy polymers

J. Polym. Sci.

Vapor and liquid equilibria in glassy polyblends of polystyrene and poly(2,6-dimethyl-1,4-phenylene oxide)

Polym. Eng. Sci.