Nafion β-Relaxation Dependence on Temperature and Relative Humidity Studied by Dielectric Spectroscopy
| Autor: | D.Z. de Florio, Marcelo Linardi, Mauro André Dresch, Elisabete I. Santiago, Fabio C. Fonseca, Bruno R. Matos |
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| Rok vydání: | 2012 |
| Předmět: |
Materials science
Renewable Energy Sustainability and the Environment Scattering Relaxation (NMR) Analytical chemistry Ionic bonding Condensed Matter Physics Surfaces Coatings and Films Electronic Optical and Magnetic Materials Dielectric spectroscopy chemistry.chemical_compound chemistry Nafion Materials Chemistry Electrochemistry Side chain Relative humidity Ionomer |
| Zdroj: | Journal of The Electrochemical Society. 160:F43-F48 |
| ISSN: | 1945-7111 0013-4651 |
| Popis: | Nafion β-relaxation was studied by detailed dielectric spectroscopy measurements carried out over a wide range of both temperature and relative humidity. Both cast and extruded Nafion were compared in the H+, Na+, and Cs+ forms to evaluate contributions arising from membrane morphology and ionic interactions. The combined data indicated that β-relaxation is related to the motion of the polymer side chains. The shift to lower frequencies of the β-relaxation was shown to be more pronounced for samples containing high water content at temperatures above the α-relaxation, evidencing that the electrostatic repulsions between bare sulfonic groups reduce the side chain mobility. An abrupt change of relaxation time was observed at relative humidity > 60% and associated with a change of morphology of the ionomer from an inverted micellar structure to a rodlike network. |
| Databáze: | OpenAIRE |
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