The effect of equivalent weight, temperature, cationic forms, sorbates, and nanoinorganic additives on the sorption behavior of Nafion®

A novel experimental technique, namely tapered element oscillating microbalance (TEOM) is utilized to study the effect of equivalent weights (960–1200), temperature (30–90 °C), various cationic forms (H+, Li+, Na+, K+ and Cs+), sorbates (water, methanol, ethanol and propanol), and inorganic additives on sorption behavior of Nafion® membrane. It is observed that water sorption increases with a decrease in EW and an increase in the sorption temperature. This is due to the increase in acid sites for sorption and a decrease in the Youngʹs modulus of the membrane with the increase in temperature. Further, sorption decreases with the increase in size of the counter ion due to a corresponding decrease in ion hydration capacity due to a decrease in the ionization equilibrium constant constant. Also, it is observed that the incorporation of acidic inorganic additives (ZrO2, TiO2 and SiO2) via sol gel methods provides higher water sorption amount at 90 °C, which is crucial for higher temperature operations of fuel cells.