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electrophoretic porosimetry of sol-gelsIt has been hypothesized that gravity has an effect on the formation and resulting microstructure of sol-gels. In order to more clearly resolve the effect of gravity, pores may be non-destructively analyzed in the wet gel, circumventing the shrinkage and coarsening associated with the drying procedure. We discuss the development of an electrophoretic technique, analogous to affinity chromatography, for the determination of pore size distribution and its application to silica gels. Specifically a monodisperse charged dye is monitored by an optical densitometer as it moves through the wet gel under the influence of an electric field. The transmittance data (output) represents the convolution of the dye concentration profile at the beginning of the run (input) with the pore size distribution (transfer function), i.e. linear systems theory applies. Because of the practical difficulty in producing a delta function input dye profile we prefer instead to use a step function. Average pore size is then related to the velocity of this dye front, while the pore size distribution is related to the spreading of the front. Preliminary results of this electrophoretic porosimetry and its application to ground and space-grown samples will be discussed.
Document ID
20010021267
Document Type
Preprint (Draft being sent to journal)
Authors
Snow, L. A.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Smith, D. D.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Sibille, L.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Hunt, A. J.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Ng, J.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Rose, M. Franklin
Date Acquired
August 20, 2013
Publication Date
January 1, 2000
Subject Category
Inorganic, Organic and Physical Chemistry
Meeting Information
Aerogels(Albuquerque, NM)
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.