Design and Development of Thermoplastic Polyurethane Based Composite Membranes

Polymer electrolyte membranes used in fuel cells are proton selective and hence allows only protons to pass through it. The electrolyte composition, morphology and water absorption properties of the membrane greatly influence the performance of the fuel cell. For example the membranes used in fuel cells should meet following requirements. • Good thermal stability above 250°C. • Proton conductivity greater than 10^-2 S/cm. • Good water absorption and water retaining capacity. • mechanical strength and flexibility. The present paper is focused on design and development of a membrane suitable for fuel cell application. The base polymer chosen in this present work has been thermoplastic polyurethane because of its high flexibility, temperature resistance and solubility in organic solvent such as DMF. Fabrication of the coating machine was done and thermoplastic polyurethane (TPU) based Composite membranes with an average thickness of 40 microns were cast. Sulphonation of polystyrene was carried out to get SPS with assay 98%. TPU based composite membranes with conducting resins of 25% SPEEK, 4%SPS and 10% PANI were cast and characterized by FTIR, DSC, four probe conductivity and SEM. The composite membranes were studied for fuel cell suitability. The studies show that a current in the range of 0.5×10⁻⁴ A to 0.8344×10⁻⁴ A and about 0.5V can be drawn out of these membranes. The results were compared with that of NAFION membrane.