AN INVESTIGATION OF THE LONG-TERM SORPTION KINETICS AND DIFFUSION ANOMALIES OF CHLOROALKANES INTO TETRAFLUOROETHYLENE PROPYLENE COPOLYMER MEMBRANES AT 30, 45 AND 60-DEGREES-C/

An investigation of the long-term sorption kinetics and diffusion anom alies of dichloromethane, chloroform, carbon tetrachloride, 1,2-dichlo roethane, l,l,l-trichloroethane, 1,1,2,2-tetrachloroethane, trichloroe thylene and tetrachloroethylene into the tetrafluoroethylene/propylene copolymer membranes has been carried out using gravimetric sorption t echnique at 30, 45 and 60 degrees C. Coefficients of diffusion and per meation have been calculated from Fick's equation. Analytical solution s of Fick's equation have been used to compute liquid concentration pr ofiles into polymeric sheet membranes at different times. Activation p arameters for diffusion and sorption have been evaluated and these res ults are discussed in terms of the molecular size of the liquids and t he temperature. The diffusion coefficient and activation energy for di ffusion do not exhibit any systematic dependence on the size of the pe netrant molecules, but these are mainly influenced by the nature of ch loroalkanes. (C) 1997 Elsevier Science Ltd. All rights reserved.