Molecular migration of hazardous liquids into thermoplastic ethylene-propylene random copolymer and isotactic polypropylene membranes

The molecular migration of hazardous organic halocarbons into thermoplastic polymer blend membranes has been studied using a gravimetric technique. From the sorption results, the diffusion and permeation of liquids have been calculated. Molecular migration depends on the nature of the halocarbons, membrane-solvent interactions, temperature, and availability of free volume within the membrane matrix. The size and the polarity of liquids do not show any systematic effect on sorption and desorption phenomena. The liquid migration results have been analyzed using a Fickian mechanism of sorption and diffusion. A numerical method based on the finite difference approach has been used to compute the liquid concentration profiles in the membrane materials. The estimated Arrhenius activation energy for diffusion and the heat of sorption are indicative of the nature of the liquids and their interactions with the membrane. The rate of evaporation of liquids has been calculated for sorption and desorption runs, and these results depend on the volatility of the halocarbons.