Aerogels are a relatively new class of ultralight, porous materials, typically derived from a gel. In an aerogel, the liquid component of the gel has been replaced by a gas (typically air). Owing to the very light nature of most aerogels, most aerogel samples have a transluscent, blueish appearance. Porosity of aerogels is generally in excess of 98% (meaning that, per unit volume, >98% of an aerogel’s volume is pore volume). Aerogels can be made of a variety of chemical compounds.
Image Source: NASA/JPL-Caltech
Aerogels (above) are known for their extremely low thermal conductivity, which is often lower than that of air. In this respect, the thermal conductivity of an aerogel material is typically identified as a critical performance specification. This low thermal conductivity makes aerogel materials exciting in the field of insulation research, where engineers are continually looking to improve energy efficiency without adding excessive weight.
Three commercially-available aerogel samples were recently provided by a client seeking performance data on them in comparison to the specification sheet. The samples were analyzed with the C-Therm TCi Thermal Conductivity Analyzer using the Modified Transient Plane Source (MTPS) technique. The results are displayed below:
It can be seen that the thermal conductivity performance measured is in good agreement with the specified thermal conductivity of these commercially-available aerogel samples. Agreement with the specified value in all three cases was better than 4%.