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Self-diffusion in two- and three-dimensional powders of anisotropic domains: An NMR study of the diffusion of water in cellulose and starch

Topgaard, Daniel LU and Söderman, Olle LU (2002) In The Journal of Physical Chemistry Part B 106(46). p.11887-11892
Abstract
The pulsed field gradient stimulated echo NMR technique is applied to the study of water diffusion in biological porous materials (a sheet of wood cellulose fibers and a packed bed of potato starch granules) consisting of randomly oriented domains with an anisotropic supermolecular organization. Expressions are presented for the probability distribution of apparent diffusion coefficients due to two- and three-dimensional powder distributions of domain orientations. The distributions are converted to echo attenuation curves with a method taking cross relaxation between the water and the solid matrix into account, Using a model in agreement with the structure and domain orientation known from other experimental techniques, it is found that... (More)
The pulsed field gradient stimulated echo NMR technique is applied to the study of water diffusion in biological porous materials (a sheet of wood cellulose fibers and a packed bed of potato starch granules) consisting of randomly oriented domains with an anisotropic supermolecular organization. Expressions are presented for the probability distribution of apparent diffusion coefficients due to two- and three-dimensional powder distributions of domain orientations. The distributions are converted to echo attenuation curves with a method taking cross relaxation between the water and the solid matrix into account, Using a model in agreement with the structure and domain orientation known from other experimental techniques, it is found that the mean diffusion coefficient and degree of anisotropy (ratio between water diffusivity parallel and perpendicular to the structure director) at a level of hydration corresponding to approximately 90%, relative humidity are (1.68 +/- 0.03) x 10(-11) m(2)/s and 6.4 +/- 0.9 for cellulose and (7.8 +/- 0.1) x 10(-12) m(2)/s and 2.5 +/- 0.3 for starch, respectively. A systematic examination of different models for the diffusion coefficient distribution shows that the chosen models are not unique in describing the data. For the estimation of anisotropy, a physically correct model is required. The average diffusion coefficient can be determined with any reasonable model. not necessarily physically correct. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Part B
volume
106
issue
46
pages
11887 - 11892
publisher
The American Chemical Society
external identifiers
  • wos:000179336200001
  • scopus:0037153274
ISSN
1520-5207
DOI
10.1021/jp020130p
language
English
LU publication?
yes
id
8135e027-9700-4beb-b552-137f6f855c52 (old id 322792)
date added to LUP
2007-10-11 07:40:21
date last changed
2017-11-05 04:39:31
@article{8135e027-9700-4beb-b552-137f6f855c52,
  abstract     = {The pulsed field gradient stimulated echo NMR technique is applied to the study of water diffusion in biological porous materials (a sheet of wood cellulose fibers and a packed bed of potato starch granules) consisting of randomly oriented domains with an anisotropic supermolecular organization. Expressions are presented for the probability distribution of apparent diffusion coefficients due to two- and three-dimensional powder distributions of domain orientations. The distributions are converted to echo attenuation curves with a method taking cross relaxation between the water and the solid matrix into account, Using a model in agreement with the structure and domain orientation known from other experimental techniques, it is found that the mean diffusion coefficient and degree of anisotropy (ratio between water diffusivity parallel and perpendicular to the structure director) at a level of hydration corresponding to approximately 90%, relative humidity are (1.68 +/- 0.03) x 10(-11) m(2)/s and 6.4 +/- 0.9 for cellulose and (7.8 +/- 0.1) x 10(-12) m(2)/s and 2.5 +/- 0.3 for starch, respectively. A systematic examination of different models for the diffusion coefficient distribution shows that the chosen models are not unique in describing the data. For the estimation of anisotropy, a physically correct model is required. The average diffusion coefficient can be determined with any reasonable model. not necessarily physically correct.},
  author       = {Topgaard, Daniel and Söderman, Olle},
  issn         = {1520-5207},
  language     = {eng},
  number       = {46},
  pages        = {11887--11892},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part B},
  title        = {Self-diffusion in two- and three-dimensional powders of anisotropic domains: An NMR study of the diffusion of water in cellulose and starch},
  url          = {http://dx.doi.org/10.1021/jp020130p},
  volume       = {106},
  year         = {2002},
}