SOME THERMAL AND OPTICAL-PROPERTIES OF A NEW TRANSPARENT SILICA XEROGEL MATERIAL WITH LOW-DENSITY

In this work we have studied a new type of monolithic silica aerogels (xerogels) made without supercritical drying. The xerogels are produce d by performing washing and ageing treatments on the alcogel before dr ying at ambient pressure. Densities as low as 0.26 g/cm3 have so far b een obtained and the thermal conductivity of air-filled xerogels has b een measured down to 18 mW/mK. Properties of this new type of silica x erogels have been compared to the properties of silica aerogel made by supercritical drying. Density, pore size, thermal conductivity and op tical transmittance are reported, and some application advantages are discussed.