Essay --

Aerogel is a synthetic porous ultra-light material derived from a gel, in which the liquid component of the gel has been replaced with a gas, resulting in a solid with extremely low density and low thermal conductivity. Nicknames include "frozen smoke", "solid smoke", "solid air" or "blue smoke" owing to its translucent quality and the way light scatters in the material. However, it feels like Styrofoam to the touch. Aerogels are solid, rigid, dry materials that do not resemble a gel in their physical properties. Pressing softly on an aerogel usually does not leave even a minor mark; pressing more firmly will leave a permanent depression. Despite the fact that it is susceptible to to shattering, it is very strong structurally. Aerogels are good thermal insulators because they are adept at counteracting the three methods of heat transfer (convection, conduction, and radiation). They are good conductive insulators because they are composed almost entirely from a gas, and gases are very poor heat conductors. Silica aerogel is especially good because silica is also a poor conductor of heat (a metallic aerogel, on the other hand, would be less effective). Aerogels are poor radioactive insulators because infrared radiation passes right through silica aerogel. Aerogels by themselves are hydrophilic, but chemical treatment can make them hydrophobic. If they absorb moisture they usually suffer a structural change, such as contraction, and deteriorate, but this can be prevented by making them hydrophobic. Aerogel was discovered in the late 1930’s by chemist Samuel Stephens Kistler. He accomplished this by the process of supercritical fluid drying. A supercritical fluid is any substance at a temperature and pressure above its critical poi... ...st spacecraft. The particles vaporize on impact with solids and pass through gases, but can be trapped in aerogels. †¢ NASA used aerogel for thermal insulation of the Mars Rover and space suits. †¢ The US Navy is evaluating aerogel undergarments to be used as thermal protection for divers. †¢ Dunlop Sport uses aerogel in some of its racquets for tennis, squash and badminton. The production and use of silica aerogels is nonthreatening to the environment. No considerably hazardous wastes are created during their construction. The disposal of silica aerogels is harmless. In the environment, they quickly crush into a fine powder that is basically identical to sand. Additionally, silica aerogels are completely non-toxic and non-flammable. If they eventually find their way into widespread use, they could eradicate a very large amount of unwanted, hazardous plastic materials.