TRANSPORT OF AROMATIC-HYDROCARBONS THROUGH POLY(ETHYLENE-CO-VINYL ACETATE) MEMBRANES

Solvent transport of aromatic hydrocarbons through both crosslinked an d uncrosslinked poly(ethylene-co-vinyl acetate) (EVA) membranes has be en studied using sorption gravimetric analysis. EVA was crosslinked by using dicumyl peroxide (DCP). Diffusion through membranes containing different loading of DCP was also carried out to follow the effect of crosslinking density on diffusion. It was found that as the extent of crosslinking increases the equilibrium uptake decreases. The dependenc e of transport process on the size of the penetrant and temperature wa s also investigated. Arrhenius activation parameters for the process o f diffusion, sorption and permeation have been estimated. Also, thermo dynamic quantities like enthalpy, entropy, and free energy change have been calculated. The molecular mass between crosslinks of the network polymer were calculated using Flory Rehner theory. Both first order a nd second order kinetics models were used to investigate the transport kinetics; A correlation between theoretical predictions and experimen tal results was also done. The transport phenomenon was found to follo w the anomalous mode at 28 degrees C and it approaches non-Fickian at higher temperatures. (C) 1997 Elsevier Science Ltd.