X-Message-Number: 6305
Date: Mon, 3 Jun 1996 05:51:29 -0700 (PDT)
From: Doug Skrecky <>
Subject: Xerogel Vacuum Insulation

    A new solid xerogel vacuum insulation is in development at Dow
 Chemical Company. Xerogels are microcellular solids prepared from a
 non-supercritical evaporation of solvents from a solvent/polymer gel. 
 They are potentially less expensive than aerogels since the later
 requires more expensive supercritical evaporation. Xerogels are somewhat
 denser than aerogels since surface tension causes some shrinkage during
 drying. Under a soft vacuum xerogels have a higher conductivity than
 silica vacuum powder insulation, but below 1.5 torr have a slightly
 lower conductivity. 
    Xerogels are a potential replacement for vacuum powders since their
 monolithic form might reduce the cost of building vacuum insulation
 panels. 

 Reference: "Microcellular Polyurea Xerogels for Use in Vacuum Panels" 
 Journal of Cellular Plastics Vol.32 172-190 March 1996

 For more information contact: 

 Rick L. Tabor
 The Dow Chemical Company
 Polyurethanes Products Research Laboratory
 Building B-1608
 Freeport, TX 77541


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