ABSORPTION DESORPTION HISTORIES THROUGH A SPHERE WITH A CHANGE IN DIMENSIONS, WITH CONSTANT CONCENTRATION ON SURFACE DURING ABSORPTION, ANDFINITE-VOLUME OF SURROUNDING DURING DESORPTION

Liquids are transferred through nonporous polymers provoking a change in dimension. A mathematical treatment of the process of radial diffus ion through a sphere with consequent change in dimension is made, as w ell as a numerical treatment of the process. The case is considered wh en the concentration of the liquid on the surface is constant during a bsorption and then the surrounding fluid is of finite volume and stron gly stirred during the stage of desorption. The kinetics of absorption -desorption histories are calculated for various values of the volume expansion due to the presence of liquid. The profiles of concentration as well as the kinetics of change in dimension are also evaluated. Tw o parameters are introduced: the maximum of the volume expansion of th e polymer and the ratio between the amount of liquid in the polymer an d that contained in the surrounding at the final equilibrium of desorp tion. (C) 1995 John Wiley & Sons, Inc.