A blend of sulfonated polyether ether ketone and polyether ether sulfone for direct methanol fuel cell

Fuel cells are considered to be the promising alternatives to conventional power engines. In our investigation, we have synthesized blend membranes of sulfonated poly(ether ether ketone) (SPEEK) and poly(ether ethersulfone) (PEES) for electrochemical and especially Direct Methanol Fuel Cell applications (DMFC). The ion exchange capacity, water and alcohol absorption, durability were found to be promising for its application. When compared to SPEEK, since the methanol absorption is low, the methanol permeability was also found and it was suitable for applications in DMFC. The membranes were characterized by means of FT-IR, TGA, DMA, UTM, SEM and XRD. From the FT-IR studies, the sulfonic acid grouping of SPEEK was found to interact with PEES. TGA gave an idea about the thermal stability of the membrane. The membranes were stable up to 200°C which is very well suitable for DMFC. The Tg values were obtained from DMA. The UTM studies clearly revealed an appreciable mechanical behaviour. The tensile strength of the blend with 10% PEES exhibited the maximum tensile strength of 19.25 MPa. From the XRD studies, the crystalline nature was studied. The proton conductivity of the membranes was found to be in the order of 10-3 S/cm which is optimum for application in DMFC. The performances of the membrane-electrode assembly (MEA), in DMFC, using the blend membranes at room temperature and 60 °C were evaluated by single cell test and are found to be 350 and 590 mA/cm2, respectively.