Aerogels insulating foams

Erik, B., M. Joseph, and P. David. 2006. Thermal resistance and compressive strain of underwater aerogel-syntactic foam hybrid insulation at atmospheric and elevated hydrostatic pressure. Journal of Physics. D. Applied Physics 39(9) 1908. 

Fidler, C. (W. S., PA), and C.S. Thomas (Willow Street, PA). 1996. Aerogel-in-foam thermal insulation and its preparation. United States Armstrong World Industries, Inc. (Lancaster, PA). 

Fidler, C., and T.C. Simonton. 1996. Aerogel-in-foam Thermal Insulation and its Preparation. 

FIGURE 14.46 An aerogel is a ceramic foam. Its low density and low thermal conductivity, combined with great strength, make it an ideal insulating material. Here a thin piece protects three wax crayons from the heat of a fiame. Aerogels were used to insulate the Mars Rover. 

Aerogels are solid foams prepared by removing the liquid from the gel during a sol-gel process at high temperatures and low pressures. Because aerogels are good insulators, have very low densities, and do not melt at high temperatures, they are attractive for use in spacecraft. 

Although the aerogel loses its optical transparency by this measure, its thermal insulation is strongly enhanced. Total conductivities for nonevacuated aerogels of the order of 0.014 W/(m K) are achievable. This is considerably lower than in CFC-blown polyurethane (PU) foams, the best nonevacuated thermal insulators available today [48]. 

Aerogels are particularly well suited for insulation applications because of their exceptionally low density, thermal stability, and high transparency. In fact, they can have a thermal conductivity only one-third that of polyurethane or polystyrene foam, and with recent process improvements that reduce the cost of manufacmre by an order of magnitude their practical use in certain construction applications is now feasible [31]. The insulating properties can be enhanced through the addition of IR opacifiers [32]. The high transparency of aerogels makes them suitable as insulation in windows or translucent panels. 

Polyurethane and, to a lesser extent, cellulose-based aerogels, were initially developed for applications in thermal insulation [15, 16]. However, they have been studied for other applications as well [17]. For example, they have been considered as precursors of nanos-tructured carbons [18,19] but, contrary to cellulose-based carbon aerogels (Figure 10.2) that appear promising [20, 21], no clear evidence of superior performance exists relative to resorcinol-formaldehyde-based carbon aerogels, mainly because of foaming during... 

By focusing on customer-driven development, American Aerogel has successfully commercialized a form of aerogel materials. Aerocore, a black organic monohthic open cellular rigid foam, can be produced with a wide range of properties and sizes. It can be used as a thermal insulator, acoustic attenuator, chemical support media, electrical conductor, and mechanical shock absorber. 

---