Fig. 3. Water uptake and proton conductivity.

Humidity dependence at 80°C of (A) water uptake and (B) proton conductivity of PEMs. The IEC values (mmol g⁻¹) in parentheses were determined by acid base titration. Fenton’s test was conducted by immersing the membrane in Fenton’s solution (aqueous solution containing 3% H₂O₂ and 2 ppm Fe²⁺) at 80°C for 1 hour. The solid lines are guides for the eye.