Investigation of ionomer structure through its dependence on ion exchange capacity (IEC)

► Comparison of properties between SSC and LSC-PFSA membranes over wide IEC range. ► New method for IEC determination-establishment of calibration curves. ► Thresholds for crystallinity and conductivity regardless of lateral chain length. ► Crystallinity and relaxation temperatures controlled by amount of TFE. ► Clarification of theoretical issues on conductivity, degradation and αβ relaxations.