General Model of Transport of Water and Low-Molecular Weight Solute in Swelling Polymer

A mathematical model of the simultaneous transport of water and low molecular weight solute in a swelling polymer film has been generalized by consideration of the expansion of the film area and their effect on the parameters involved. The character of the kinetic curves for water uptake and solute desorption were examined as a function of (i) mobility of the low molecular weight compound, (ii) concentration and stress dependence of the diffusion coefficient of the solvent, and (iii) mechanical properties of the polymer (whose dependence on the concentration of water and solute has also been considered). The correlation of the expansion area of the water sorption curves was examined briefly, mostly as a check of the validity of the model.