Abstract
Membranes for fuel cell applications were prepared using two polymer blends: poly(vinyl alcohol) (PVAL) and chitosan (CS), 80/20 (w/w) and 60/40 (w/w) with and without nylon. Sulfosuccinic acid (SSA) was used both as a crosslinking and a sulfonating agent. An increasing in the SSA content raised ionic exchange capacity and consequently proton conductivity in the membranes. The addition of nylon has improved membrane mechanical properties by decreasing stiffness. Membranes presented good proton conductivity (around 10-2 S cm-1) and lower H2 and methanol permeability rather than the standard membrane Nafion® 115. Membranes which showed to be stable under fuel cell operation were tested using hydrogen and methanol fuels. Membrane PVAL:CS, 80/20 (w/w), containing SSA crosslinker, (PVAL+CS)/SSA, of 4/1 (mol/mol), has shown the best performance under fuel cell environment. However, results have shown that an improvement is required in the adhesion between the membrane and the electrodes.
Highlights
Polymer electrolyte membrane (PEM) is an important component in many electrochemical devices
Such membranes presented good proton conductivity (0.218 S cm-1 at 70 °C) and low methanol permeability, suggesting that the membranes can be used in a direct methanol fuel cell (DMFC).[16]
Poly(vinyl alcohol) (PVAL) (99% hydrolysed with a molecular weight of 89,000 to 98,000 g mol-1), chitosan flakes with high molecular weight, Nylon 6,6 and sulfosuccinic acid (SSA, 70% aqueous solution) were supplied by Sigma Aldrich Chemical Co
Summary
Polymer electrolyte membrane (PEM) is an important component in many electrochemical devices. Polymer electrolyte membranes for fuel cell applications were prepared using sulfonated PVAL synthesized from 4-formylbenzene1,3-disulfonic acid and subsequently cross-linked with 1,3-bis(3-glycidyloxypropyl) tetramethyldisiloxane and 4,4’-oxydiphthalic anhydride. Such membranes presented good proton conductivity (0.218 S cm-1 at 70 °C) and low methanol permeability (at around 1.25x10-6 cm[2] s-1), suggesting that the membranes can be used in a direct methanol fuel cell (DMFC).[16] Ceramic-supported PVAL-CS composite membranes were prepared for pervaporation dehydration purposes. The prepared membranes were characterized by infrared spectroscopy, thermal gravimetric analysis (TGA), dynamical mechanical (DMA), water uptake and proton conductivity tests, followed by PEMFC and DMFC tests
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