A study on pervaporation of aqueous ethanol solution by modified polyurethane membrane

In this study, the pervaporation performance of a hydroxyl terminated polyb utadiene (HTPB) based polyurethane, synthesized by direct polycondensation was evaluated. Typical values of the permeation rate and the separation fac tor are 380 g/m(2) h and 60, respectively. The effects of the polyurethane composition, [hydroxyl terminated polybutadiene (HTPB)/4,4-dicyclohexylmeth ane diisocyanate (H12MDI)/1,4-butane diol (1,4BD)] and the molecular weight of PU on the pervaporation performances were investigated. It was found th at the permeation rate and the water/ethanol separation factor are strongly dependent on the molecular weight of PU and the ratio of hard segment to s oft segment (H12MDI/HTPB). To improve the pervaporation performance, chemic al-graft polymerization of 2,3-epoxypropylmethacrylate (EPMA) onto the HTPB -based-PU membrane was considered. The hydrophilicity and permeation rate o f the chemically grafted PU membrane were improved due to the decrease in t he crystallinity of membrane. It was also found that the hydrogen-bonding i ndex (HBI) can be utilized to explain the permselectivity properties of the prepared membranes, (C) 1999 Elsevier Science B.V. All rights reserved.