N.m.r. relaxation in Nafion—the low temperature regime

The dynamical characteristics of water absorbed in Nafion are investigated using n.m.r. At temperatures below the dynamical transition temperature, T t, relaxation rates indicate mobility associated with a fluid but the derived motional activation energies are similar to those of ice. This indicates...

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Bibliographic Details
Published in:Polymer (Guilford) 1999-05, Vol.40 (10), p.2481-2485
Main Authors: MacMillan, Bryce, Sharp, Allan R., Armstrong, Robin L.
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
Exchange resins and membranes
Forms of application and semi-finished materials
n.m.r
Nafion
Polymer industry, paints, wood
Relaxation
Technology of polymers
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Summary:The dynamical characteristics of water absorbed in Nafion are investigated using n.m.r. At temperatures below the dynamical transition temperature, T t, relaxation rates indicate mobility associated with a fluid but the derived motional activation energies are similar to those of ice. This indicates a well ordered supercooled fluid consisting of hydrogen bonded water structures. The correlation time τ c is found to have a Gaussian dependence on the surface area to volume ratio, unlike simple porous systems. We have shown that the surface area depends on r 2.5. We feel that this is due to the irregular nature of the surfaces of the clusters.
ISSN:0032-3861
1873-2291
DOI:10.1016/S0032-3861(98)00483-2