Absorption diffusion coefficient

If absorption measurements are made on samples, which initially contain no water, by immersing them in salt solutions of different concentrations, the effective absorption diffusion coefficient can be calculated. These measurements are followed by desorption experiments in which the samples are dried by blowing air across both major surfaces and the effective desorption coefficient is calculated. The diffusion coefficients obtained from such absorption and desorption measurements are shown in Table II. It is evident that the ratio of the diffusion coefficient obtained from desorption to that from absorption measurements increases as the concentration of water in the rubber, C, Increases. The diffusion coefficient obtained from a desorption experiment can only be expected to be greater than that from an absorption experiment if D decreases with increasing liquid concentration (3). 

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