1 The effect of filling on water uptake has been studied for coatings based on aqueous dispersion Acronal-290D and pigment part consisting of titanium dioxide and calcium carbonate. It was found that an increase in the pigment volume concentration is accompanied by an increase in the rate of water absorption, but the maximum value of water uptake is characterized by a minimum near the critical pigment volume concentration. It was shown that at a low degree of filling of the films, water absorption is a long-term process, the kinetics of which can be described by superposition of two functions that take into account both the Fickian character of water diffusion and the relaxation process, associated with structural changes in the samples.

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A model is discussed which explains reported complex effects of feed composition and pressure on component permeabilities in high‐pressure gas separators based on glassy polymer membranes. A special form of Fick's law which accounts for the fact that penetrants in glassy polymers sorb into and diffuse through two different molecular environments provides the basis for the analysis of gas mixture permeation. Potential deviations from the theory are discussed in terms of separable solubility‐and mobility‐related effects.

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