Degradation of Polymer Electrolyte Membranes

Premature failure of polymer electrolyte membranes used in proton exchange membrane fuel cells result in short life and degradation of performance of the fuel cell stack. Changes in the humidity and temperature cause swelling and shrinking of the membrane which result is stresses in the membrane. Stress relaxation and changes in conductivity will occur in the membrane. A novel experimental facility which allows the control of humidity, temperature, load or strain and the simultaneous measurement of the proton impedance has been developed and used to measure the stress relaxation and associated changes in conductivity of Nafion membranes. It was found that at constant strain, both stress relaxation and a drop in the conductivity of the membrane occurs.