Deformation of aerogels during characterization

George Scherer, Douglas M. Smith, David Stein

Research output: Contribution to journalArticle

62 Scopus citations

Abstract

Aerogels have such low moduli that they can exhibit large strains under very small loads, and this leads to errors in measurements of porosity and pore size. The use of porosimetry, thermoporometry and nitrogen sorption on aerogels is examined and it is shown that all of these techniques underestimate the pore volume and pore size of typical aerogels. Even at the highest pressures there may be no intrusion of mercury at all, so porosimetry serves only to measure the bulk modulus of the aerogel network, not its pore size distribution; an analysis of the conditions for intrusion as a function of modulus and pore size of the gel is presented. Direct experimental observation of a silica aerogel indicates that its volume shrinks by ⋍ 50% as liquid nitrogen condenses in its pores. Consequently, it is likely that the quantity of macropores in aerogels has been seriously overestimated in the past.

Original languageEnglish (US)
Pages (from-to)309-315
Number of pages7
JournalJournal of Non-Crystalline Solids
Volume186
DOIs
StatePublished - Jan 1 1995

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Materials Chemistry

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