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Ionically cross-linked polyelectrolyte complex (PEC) membranes of cationic chitosan (CS) and anionic poly(acrylic acid) (PAAc) were synthesized and assessed for applicability in fuel cells. CS and PAAc were blended in different weight ratios and the resulting membranes were posttreated to enable the formation of the polyelectrolyte complex. The ionic cross-linking occurring on blending the polyelectrolytes excludes the need of using other cross-linking agents. These membranes were extensively characterized for morphology, their intermolecular interactions, thermal stability, and physicomechanical properties using SEM, FTIR, DSC, sorption studies, and tensile testing, respectively. Methanol permeability and proton conductivity were estimated and compared with respective values for Nafion 117. PEC membranes exhibited high ion exchange capacity (IEC), high proton conductivity, low methanol permeability, and adequate thermal and mechanical stability. Among the blends synthesized, the membrane blend with 50 wt...

Monomethylhydrazine (MMH) is a well-known liquid propellant used as fuel for launching of rockets and satellites. The desalted reaction liquor of MMH contains about 2 wt % of the propellant (balance water), which also forms an azeotrope with water at 35% MMH concentration. Removal of water to obtain pure MMH by conventional separation methods such as distillation is hazard prone and expensive. The potential of the membrane-based pervaporation technique has been investigated in this study for enriching aqueous solutions of MMH. Ethylcellulose membrane, which is selected on the basis of estimations of Flory−Huggins interaction parameters and Hansen's solubility parameter, gives promising results and is resistant to chemical attack by MMH. The effect of operating parameters such as feed concentration and membrane thickness on flux and selectivity are evaluated. Finally aging studies have been carried out to determine the life of the membrane in the propellant medium.

Specific interaction sites of ethylcellulose with water, hydrazine, and the mixtures of hydrazine hydrate and water have been studied by FTIR spectra. Measurements of diffusion and sorption coefficients of these materials in ethylcellulose were made to determine the overall selectivity. Aging studies of the membrane including an accelerated aging test have also been conducted. The influence of aging on physico-chemical and mechanical properties were assessed by FTIR studies and mechanical tests. These studies showed that the ethylcellulose membrane can be used for prolonged periods in hydrazine hydrate and as such is suitable for the separation of hydrazine−water mixtures.