Journal of Membrane Science, Vol.162, No.1-2, 173-180, 1999
A study on pervaporation of aqueous ethanol solution by modified polyurethane membrane
In this study, the pervaporation performance of a hydroxyl terminated polybutadiene (HTPB) based polyurethane, synthesized by direct polycondensation was evaluated. Typical values of the permeation rate and the separation factor are 380 g/m(2) h and 60, respectively. The effects of the polyurethane composition, [hydroxyl terminated polybutadiene (HTPB)/4,4-dicyclohexylmethane diisocyanate (H12MDI)/1,4-butane diol (1,4BD)] and the molecular weight of PU on the pervaporation performances were investigated. It was found that 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 soft segment (H12MDI/HTPB). To improve the pervaporation performance, chemical-graft polymerization of 2,3-epoxypropylmethacrylate (EPMA) onto the HTPB-based-PU membrane was considered. The hydrophilicity and permeation rate of the chemically grafted PU membrane were improved due to the decrease in the crystallinity of membrane. It was also found that the hydrogen-bonding index (HBI) can be utilized to explain the permselectivity properties of the prepared membranes,