Water vapor sorption thermodynamics of the Nafion ionomer membrane
Research output: Contribution to journal › Article
The water interactions of polymer electrolyte membranes are of significant interest when these materials are used in for example fuel cells. We have therefore studied the sorption thermodynamics of Nafion 117 with a sorption calorimeter that simultaneously measures the sorption isotherm and the mixing (sorption) enthalpy. This unique method is suitable for investigating the sorption thermodynamics of ionic polymers. The measurements were made at 25 °C on a series of samples dried at different temperatures from 25 to 120 °C. The sorption isotherms indicate that the samples dried at 120 °C lost about 0.8 more water molecules per sulfonic group during the drying than did the samples dried at 25 °C, and this result was verified gravimetrically. The mixing enthalpies showed several peaks or plateaus for the samples dried at 60-120 °C. This behavior was seen up to about 2 water molecules per sulfonic group. As these peaks were not directly related to any feature in the sorption isotherm they probably have their origin in a secondary process, such as a reorganization of the polymer.
|Research areas and keywords||
Subject classification (UKÄ) – MANDATORY
|Journal||The Journal of Physical Chemistry Part B|
|Publication status||Published - 2013|
Publication Date (Web): June 18, 2013