Effect of alkyl phthalate plasticizers on permeation of water vapour through PVC membranes

Abstract

PVC membranes plasticized with various concentrations of a di‐n‐alkylphthalate (methyl, ethyl, butyl or octyl) were studied for their water vapour permeation (WVP) properties. The rates of WVP through them were estimated under steady state by permeating the vapour through the membrane under the vapour pressure differential of approximately 100% to 0% relative humidities at 25°C. The rates of WVP were found to decrease with an increase in the size of the alkyl group of the phthalate but increased with its concentration. The maintenance of the property by the membranes being critical for their long‐term applications, the measurements were also repeated on the membranes aged for 250 days at intervals of 50 days. The WVP data indicate that membranes containing medium concentrations, i.e. 17.5‐20% of the plasticizers have better maintenance of the property during ageing and also in handling with good mechanical strength. Copyright © 1993 Society of Chemical Industry