Thermal Conductivity of Monolithic Organic Aerogels

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Science  21 Feb 1992:
Vol. 255, Issue 5047, pp. 971-972
DOI: 10.1126/science.255.5047.971


The total thermal conductivity λ of resorcinol-formaldehyde aerogel monoliths has been measured as a function of density ρ in the range from ρ = 80 to 300 kilograms per cubic meter. A record-low conductivity value in air at 300 K of λ ≈ 0.012 watt per meter per kelvin was found for ρ ≈ 157 kilograms per cubic meter. Caloric measurements under variation of gas pressure as well as spectral infrared transmission measurements allowed the determination of solid conductivity, gaseous conductivity, and radiative conductivity as a function of density. The development of such low conductivity materials is of great interest with respect to the substitution of environmentally harmful insulating foams made from chlorofluorocarbons.