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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
chemistry
Free volume and permeabilities of O
2
and H
2
in Nafion membranes for polymer electrolyte fuel cells
Polymer, Volume 49, No. 13-14, Year 2008
Notification
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Description
The mechanism of gas permeation in Nafion membranes for polymer electrolyte fuel cells has been investigated from the viewpoint of free volume. Three different samples, a membrane with ionic exchange capacity (IEC) = 0.92 meq/g, and recast samples with IEC = 0.92 and 1.00 meq/g were used after drying. Free volume was quantified using the positron annihilation lifetime (PAL) technique and gas permeabilities were measured for O2 and H2 as functions of temperature and relative humidity. Good linear correlations between the logarithm of the permeabilities at different temperatures and reciprocal free volume indicate that gas permeation in dry Nafion is governed by the free volume. Nevertheless permeabilities are much smaller than the corresponding flexible chain polymer with a similar free volume size due to stiff chains of the perfluoroethylene backbone. In highly hydrated Nafion above 60% relative humidity, where the O2 permeability varies oppositely to the free volume, gas permeation proved to be controlled by the gradual increase in overall flexibility of the Nafion-water system. © 2008 Elsevier Ltd. All rights reserved.
Authors & Co-Authors
Mohamed, Hamdy F.M.
Japan, Tsukuba
National Metrology Institute of Japan
Egypt, Minya
Faculty of Science
Ito, K.
Japan, Tsukuba
National Metrology Institute of Japan
Kobayashi, Yoshinori
Japan, Tsukuba
National Metrology Institute of Japan
Takimoto, N.
Japan, Tsukuba
National Institute of Advanced Industrial Science and Technology
Takeoka, Y.
Japan, Tsukuba
National Institute of Advanced Industrial Science and Technology
Japan, Tokyo
Sophia University
Ohira, Akihiro
Japan, Tsukuba
National Institute of Advanced Industrial Science and Technology
Statistics
Citations: 95
Authors: 6
Affiliations: 4
Identifiers
Doi:
10.1016/j.polymer.2008.05.003
ISSN:
00323861
Research Areas
Environmental