Silica aerogels

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Fig. XVII-29. Nitrogen isotherms the volume adsorbed is plotted on an arbitrary scale. The upper scale shows pore radii corresponding to various relative pressures. Samples A, Oulton catalyst B, bone char number 452 C, activated charcoal F, Alumina catalyst F12 G, porous glass S, silica aerogel. (From Ref. 196).

Table 2. Typical Values of Physical Properties of Silica Aerogels ...

Fig. 6. Schematic diagram showing the use of transparent silica aerogel in passive solar collection. Reproduced from Ref. 53.

Silica aerogels, a newly developing type of material, also have been produced as thermal insulations with superinsulation characteristics. The nanometer-size cells limit the gas phase conduction that can take place. The aerogels are transparent to visible light, so they have potential as window insulation. The use of superinsulations at present is limited by cost and the need to have a design that protects the evacuated packets or aerogels from mechanical damage. 

Hunt, A. J. (1992). Optical and Thermal Properties of Silica Aerogel. In Chemical Processing of Advanced Materials, ed. L. I. Hench and J. K. West. New York John Wiley Sons. 

Synthesis of Monolithic Titania-Silica Aerogel for PCO Reactions... 

Fig. 1. Crack-free monolithic titania-silica aerogel photos, (a) aerogel prepared by hi -temperature ethanol supercritical drying, (b) aerogel prepared by low-temperature CO2 supercritical drying.

Fig. 3. Photocatalytic oxidation test of titania-silica aerogels, (a) TCE (air 400 seem, TCE 113 ppm), (b) isopropanol (air 200 seem, isopropanol 268 ppm).

The components of VX2 are QL, which is designated chemically as 0-(2-diisopropylaminoethyl)-0 -ethyl methylphosphonite, and NE, which is powdered sulfur with a small amount of added silica aerogel prevent caking. 

The use of doped and undoped silica aerogels as multifunctional host materials for fluorescent dyes and other luminescent materials for display and imaging applications has been reported.278 Results have been presented on the PL spectra of undoped silica aerogels and aerogels doped with Er3+, rhodamine, and fluorescein.278... 

Maury, S., Buisson, P., Perrard, A. and Pierre, A.C. (2004) Influence of the sol-gel chemistry on the activity of a lipase encapsulated in a silica aerogel. Journal of Molecular Catalysis B-Enzymatic, 29, 133-148. 

Agents have also been micropulverized, encapsulated, or treated with flowing agents such as silica aerogel to facilitate their dispersal and increase their persistency. Color and other physical properties of the agent may be affected by these additives. 

CS2 o-Chlorobenzylmalononitrile and Silicon Treated Silica Aerogel Mixture C13-A009... 

NE Rhombic Sulfur and Silica Aerogel Mixture C01-C053... 

Figure 5.11 Entrapped in a silica aerogel, this manganese porphyrin is nine times more active than in solution. (Reproduced from ref. 22, with permission.)...

E. F. Murphy, L. Schmid, T. Burgi, M. Maciejewski, A. Baiker, D. Gunther and M. Schneider, Nondestructive Sol-Gel Immobilization of Metal (salen) Catalysts in Silica Aerogels and Xerogels, Chem. Mater., 2001, 13, 1296. 

Hybrid polymer-silica aerogels have exceptional insulating and mechanical properties and will soon be commercialized as high-performance, low-cost insulators.6 Inorganic-organic silica areogels are non-flammable... 

The brittle behaviour of the silica aerogel remains upon the introduction of TMS-modihed PNPs. However, even a low polymer content promotes a clear improvement of the mechanical properties of the material Young s modulus increases and the maximum compression strength and the corresponding strain become three to five times higher. Furthermore, the improvement in mechanical behaviour is noticeable... 

Passive heat-transfer enhancement techniques, retrofitted, 13 267 Passive mixers, in microfluidics, 26 966, 967 Passive noise detectors, 11 673 Passive nondestructive tests, 17 416, 425 Passive reactors, 17 555 Passive sensing materials, 22 706-707 Passive smart textiles, 24 625 Passive solar collection, silica aerogel application, 1 761-762 Pasta products, 26 278 Paste-extrusion process, 18 301-302 Paste forming, ceramics, 5 651 Paste inks, 14 315-316... 

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