SORPTION AND MIGRATION OF ALIPHATIC ORGANIC ESTERS INTO VITON FLUOROELASTOMER MEMBRANES

Sorption and migration of six aliphatic esters into four VITON fluoroe lastomers were studied by a gravimetric sorption method in the tempera ture interval of 30-60 degrees C. Fick's equation was used to obtain d iffusion coefficients. The dependence of fluorine contents and the pol ymer morphology on the sorption and diffusion characteristics of ester s was investigated. The permeability coefficients were obtained from t he sorption and diffusion data. Fick's equation was solved to compute the concentration profiles of liquids at various locations within the membrane materials using initial and boundary conditions. These profil es were compared with those obtained from the numerical method based o n finite difference technique. Activation parameters for diffusion and sorption were calculated using the Arrhenius relationship. These resu lts were discussed in terms of molecular size and shapes of the esters . For higher esters, namely, n- and iso-amyl acetates, a concentration dependency of the diffusion coefficient was investigated. (C) 1997 Jo hn Wiley & Sons, Inc.