Structure and permeability of gels - Code: CP1

J. F. Quinson, M. Repellin Lacroix, M. Pauthe, A. Roche, George Scherer

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

The textures of silica gels made by two-step acid/base and acid/acid catalysis of TEOS have been examined by thermoporometry (TPM) and NMR, and their permeabilities (D) have been measured by a thermal expansion technique. Using the pore size distribution given by TPM, which includes a large proportion of macropores (≥30 nm), calculated values of D are seriously overestimated. We conclude that, consistent with a theoretical prediction, compliant materials such as gels undergo contraction during freezing in the calorimeter, so that most of the macropore volume reported by TPM is actually extracted from mesopores. The mesopore radius reported by TPM is underestimated by only ∼20%, even if 50% of the pore liquid is drained during crystallization, assuming that the change in pore radius is related to the cube root of the volume change. NMR does not distinguish macropores, because of diffusional averaging, but provides an apparent distribution that permits an accurate estimate of the permeability.

Original languageEnglish (US)
Pages (from-to)239-244
Number of pages6
JournalJournal of Sol-Gel Science and Technology
Volume2
Issue number1-3
DOIs
StatePublished - Jan 1 1994

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Chemistry(all)
  • Biomaterials
  • Condensed Matter Physics
  • Materials Chemistry

Keywords

  • permeability
  • texture of gels
  • thermoporometry

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