Water vapor sorption thermodynamics of the Nafion ionomer membrane

Research output: Contribution to journalArticle

Abstract

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.

Details

Authors
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Chemical Sciences

Keywords

  • Ionomer, Nafion, water vapor, sorption, sorption isotherm, sorption enthalpy
Original languageEnglish
Pages (from-to)8561-8570
JournalThe Journal of Physical Chemistry Part B
Volume117
Issue number28
Publication statusPublished - 2013
Publication categoryResearch
Peer-reviewedYes

Bibliographic note

Publication Date (Web): June 18, 2013