The effects of thermal annealing on commercial Nafion® membranes

✍ Scribed by Jesse E. Hensley; J. Douglas Way; Steven F. Dec; Kent D. Abney

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 817 KB
• Volume: 298
• Category: Article
• ISSN: 0376-7388
• DOI: 10.1016/j.memsci.2007.04.019

✦ Synopsis

The effect of thermal annealing as a pretreatment procedure for Nafion ® membranes was investigated. Commercial membranes with different thicknesses and ages (all melt extruded films) were considered. After a short heat treatment at 165 • C, the proton conductivity, water permeability, equilibrium water sorption, and self-diffusion coefficient of water and protons increased in all films, with the greatest improvements occurring in thin films (<50 m). Wide-angle X-ray measurements showed that the annealing procedure decreases the crystallinity of thick films and increases the crystallinity of thin films, in general. Small-angle X-ray measurements showed that annealing may alter the distribution of water within the films. Thermal annealing appears to 'normalize' the transport properties of different thicknesses and batches of Nafion ® , reducing the differences in values of measured transport properties between thin and thick membranes.