Accession Number : ADA261505
Title : Studies of Water in Nafion Membranes: Dielectric Relaxation and Deuteron and Oxygen-17 NMR
Descriptive Note : Interim technical rept.
Corporate Author : HUNTER COLL NEW YORK DEPT OF PHYSICS AND ASTRONOMY
Personal Author(s) : Chen, R S ; Jayakody, J R ; Greenbaum, S G ; Pak, Y S ; Xu, G ; McLin, M G ; Fontanella, J J
Report Date : 25 Jan 1993
Pagination or Media Count : 38
Abstract : Dielectric relaxation and both deuteron and oxygen-17 nuclear magnetic resonance measurements on NAFION-117 membranes with variable water content (approx. 5 - 18 % by weight) are reported. Glassy behavior of the water domains at low T (below approx. 200 K) is evidenced by the specific nature of the observed dielectric loss peaks and 2 H NMR lineshapes. Activation energies extracted from 2 H spin-lattice relaxation data on the high T side of the T sub one minimum exhibit a steady increase with increasing water content. In spite of a high degree of water molecular mobility, angular-dependent spectra in both as- received and stretched samples reflect considerable anisotropy of the host polymer. A dielectric loss peak is observed which has previously been attributed to the glass transition of the aqueous domains.
Descriptors : *WATER , *OXYGEN , *DEUTERONS , MEASUREMENT , MOBILITY , CRYSTAL LATTICES , MOTION , SPECTRA , IONOMERS , RELAXATION , ACTIVATION ENERGY , SULFONIC ACIDS , SPIN STATES , FUEL CELLS , TRANSITIONS , MEMBRANES , ANISOTROPY , VARIABLES , GLASS , DIELECTRICS , POLYMERS , NUCLEAR MAGNETIC RESONANCE
Subject Categories : Physical Chemistry
Atomic and Molecular Physics and Spectroscopy
Distribution Statement : APPROVED FOR PUBLIC RELEASE