Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Tracer-desorption H-1 NMR measurement of diffusion coefficients in polyphosphazene ion-exchange membranes
Autore:
Carter, R; Evilia, RF; Pintauro, PN;
Indirizzi:
Tulane Univ, Dept Chem Engn, New Orleans, LA 70118 USA Tulane Univ New Orleans LA USA 70118 Chem Engn, New Orleans, LA 70118 USA Univ New Orleans, Dept Chem, New Orleans, LA 70148 USA Univ New Orleans New Orleans LA USA 70148 Chem, New Orleans, LA 70148 USA
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 12, volume: 105, anno: 2001,
pagine: 2351 - 2355
SICI:
1520-6106(20010329)105:12<2351:THNMOD>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
STUDYING TRANSLATIONAL DIFFUSION; NUCLEAR-MAGNETIC-RESONANCE; PHOTO-CROSS-LINKING; TRANSPORT; TOOL;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
17
Recensione:
Indirizzi per estratti:
Indirizzo: Pintauro, PN Tulane Univ, Dept Chem Engn, New Orleans, LA 70118 USA TulaneUniv New Orleans LA USA 70118 w Orleans, LA 70118 USA
Citazione:
R. Carter et al., "Tracer-desorption H-1 NMR measurement of diffusion coefficients in polyphosphazene ion-exchange membranes", J PHYS CH B, 105(12), 2001, pp. 2351-2355

Abstract

The growth of an NMR signal due to diffusion of solute out of a thin membrane has been investigated for the measurement of diffusion rates under conditions that are not suitable for accurate application of pulsed field gradient methods. Such conditions include those where the internal solute signalis either too small or too broad to be utilized or where the diffusion rate is too slow to yield observable attenuation of the NMR signal with commonly available gradient strengths or possible gradient application times. Themethod was used to measure the mutual diffusion coefficient of methanol ina series of polyphosphazene-based cation-exchange membranes, which are currently being examined for possible use in direct liquid methanol fuel cells. Diffusion coefficients at 25 degreesC were in the range of 8.0 x 10(-8) to 4.0 x 10(-7) cm(2)/s for methanol concentrations of 1.0-5.0 M and were significantly smaller than those reported for a Nafion perfluorosulfonic acidmembrane. Successful application of the tracer-desorption NMR approach requires that the external solute signal be observable in a single pulse and that the membrane desorption rate not be too fast (the diffusion coefficientshould be < 10(-6) cm(2)/s).

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 02/06/20 alle ore 02:03:23