Characterization of. blended polymeric membranes for pervaporation of hydrazine hydrate

Pervaporation of commercial hydrazine hydrate (at 64 wt.% hydrazine) was carried out to obtain hydrazine, which in anhydrous form is an important inorganic fuel. Experimental studies were made using various laboratory prepared polymeric membranes, primarily through blending of polymers and the results are analyzed through the measurements of flux and selectivity. Acrylonitrile-butadiene-styrene (ABS) and ethyl cellulose (EC) polymers, in different ratios, were blended to prepare membranes in order to vary the ratios of hydrophilic-hydrophobic characteristics. The objective was to characterize blended membranes in terms of measurement of contact angle, X-ray diffraction (XRD), positron annihilation techniques (PAL), thermo-gravimetric analysis (TGA) and tensile strength. Sorption studies helped in estimating equilibrium sorption, which further enhanced understanding towards pervaporation selectivity. It was evident from the results that blended polymers could be useful to develop newer membranes with improved perm-selectivity. Further, adjusting blend composition pervaporation properties could be varied. Analysis of results is based on normalizing the values of flux with respect to thickness, in order to develop better understanding of blended properties of membranes. Values of sorption and diffusion selectivity were also obtained from thermodynamic treatment which is based on Flory-Huggins theory. (C) 2007 Elsevier B.V. All rights reserved.