(187c) Preparation and Characterization of Polyurethane Membranes and Pervaporation / Swelling Properties

Two kinds of polyurethane (PU) membranes were prepared by a two-step method using Hydroxyl-terminated polybutadiene (HTPB) as soft segment and the 4, 4'-diaminodiphenyl methane (MDA) and b-cyclodextrins (b-CDs) as chain extenders, respectively. Firstly, HTPB reacted with 2, 4-toluene diisocyanate (TDI) with the molar ratio of 1/2, and then the NCO-terminated prepolyurethane was obtained. Secondly, MDA or MDA+b-CDs was added to the prepolyurethane, and the membranes of PU were prepared by solution casting. The structures and properties of PU thus obtained were characterized by means of FT-IR, DSC. And the swelling characteristics of the obtained membranes were studied in ethanol/water mixtures with various concentrations at 30°C. Furthermore, the pervaporation (PV) performances were investigated for separating ethanol/water aqueous solution with 90wt% ethanol content at different temperatures. The results showed that the swelling degrees of PU membrane with MDA+b-CDs were higher than that with MDA. The permeation fluxes of both membranes increased with the increased feed temperature from 40 to 70°C, while the separation factors of PU membrane with MDA decreased. But the separation factor of PU membrane with MDA+b-CDs decreased and then increased.