DIFFUSION AND SORPTION OF ORGANIC LIQUIDS THROUGH POLYMER MEMBRANES .9. BROMOBUTYL RUBBER, CHLOROSULFONATED POLYETHYLENE, AND EPICHLOROHYDRIN VERSUS SUBSTITUTED MONOCYCLIC AROMATIC LIQUIDS

Sorption and diffusion of four monocyclic aromatic liquids-namely, chlorobenzene, o-dichlorobenzene, bromobenzene, and nitrobenzene into bromobutyl rubber, chlorosulfonated polyethylene, and epichlorohydrin-have been investigated in the temperature interval of 25-60-degrees-C by using a gravimetric technique. The transport results have been analyzed by using the Fickian model of diffusion. The dependence of transport coefficients on the size and shape of the penetrant molecules has been discussed. Transport coefficients have not shown any systematic variation with the penetrant size, but the results are greatly influenced by the polymer-solvent interactions. The Arrhenius activation parameters have been estimated from a temperature dependence of sorption, diffusion, and permeation coefficients. The first-order kinetic rate constants have been obtained from the time-dependent sorption data. Enthalpy and entropy of sorption for the polymer-solvent systems have been studied. The molar mass between network crosslinks was calculated from the Flory-Rehner theory. Computed parameters and experimental results are used to discuss the transport mechanism in terms of the type and nature of the polymer membranes and solvent molecules. None of the polymer membranes studied have shown any degradative reactions and significant swelling in the presence of the chosen solvents. The present results would have applications in areas such as those including the studies on barrier properties, separation science, and chemical pond lining, etc.