Mechanical and Water Sorption Properties of Nafion® and Nafion® /Titanium Dioxide Membranes for Polymer Electrolyte membrane Fuel Cells

The mechanical properties of the membranes used in polymer electrolyte membrane fuel cells are important to the performance and longevity of the cell. The speed and extent of membrane water uptake depend on the membrane’s viscoelastic mechanical properties, which are themselves dependent on membrane hydration, and increased hydration improves membrane proton conductivity and fuel cell performance. Membrane mechanical properties also affect durability and cell longevity, preventing membrane failure from stresses induced by changing temperature and water content during operational cycling. Further, membrane creep and stress-relaxation can change the extent of membrane/electrode contact, also changing cell behavior. New composite membrane materials have exhibited superior performance in fuel cells, and it is suspected that improved mechanical properties are responsible. Studies of polymer electrolyte membrane (PEM) fuel cell dynamics using Nafion membranes have demonstrated the importance of membrane mechanical properties