Studies on the Diisocyanate-Modified Polyvinyl Alcohol Reverse Osmosis Membranes

The hydroxyl group in polyvinyl alcohol (PVA) membranes had been partially reacted with diisocyanates such as 4,4′-diphenylmethane diisocyanate (MDI) or the prepolymers containing different functional groups. The transport properties toward water and salt and the stress-strain properties of these modified membranes were investigated. The results showed an improvement in salt rejection and a considerable increase in the wet strength of the modified membrane. The water absorption and permeabilities of these modified membranes depended largely upon the functional groups introduced into them.