Rapid Synthesis Of Silica Aerogel And Its Composite Heat Insulation Materials

Silica aerogel is a kind of light nanoporous material. Owing to its unique nanoporous network structure, silica aerogel has many advantages such as high porosity, high specific surface area, low density and low thermal conductivity etc., and it has a broad application prospect in many fields such as thermal insulation materials, sound insulation and filter material etc..In this paper, using industrial water glass as silicon source, SiO2aerogel was prepared by surface modification and ambient pressure drying method. On the base of the preparation method of a small amount of SiO2aerogel in the laboratory, the rapid manufacturing method and process with large volume for preparing SiO2aerogel was investigated, and preparation of SiO2aerogel/glass wool and SiO2aerogel/polyvinyl butyral (PVB) composite insulation material was studied. The micro morphology of SiO2aerogel and its composite thermal insulation materials was investigated using scanning electron microscopy (SEM). The specific surface area and pore volume of the obtained aerogels were analyzed by BET (Brunauer-Emmett-Teller) method with N2as carrier gas. The thermal conductivity of SiO2aerogel/glass wool and SiO2aerogel/PVB composite thermal insulation material was measured by thermal conductivity meter.The research results indicate that the density of SiO2aerogel prepared by rapid large volume ambient pressure drying method was0.1～0.2g/cm2, which is similar to that of SiO2aerogel by laboratory small amount preparation method. Moreover, there is no obvious difference on the surface morphology and surface microstructure between the two kinds of SiO2aerogels prepared by larger volume preparation method and laboratory small amount method. The specific surface area of the prepared SiO2aerogel was600～700m2/g, pore volume was greater than2.5cc/g, even up to3.4cc/g, and the average pore radius is larger than4nm. It is a kind of SiO2aerogel with excellent properties.The surface morphology of SiO2aerogel/glass wool composite materials were observed, the results showed that SiO2aerogel was well attached to the glass fiber in the glass cotton. The glass cotton played a very good framework and a supporting role, which can ease the disadvantages of SiO2aerogel that is fragile and easily broken when used alone. Moreover, the prepared SiO2aerogel/glass cotton composite material has excellent hydrophobicity, and it will not produce a great impact on the thermal insulation material when it is used in a humid environment. The thermal conductivity of the prepared SiO2aerogel/glass cotton composite materials was measured to be1.12×10-2W· M-1·-1℃.SiO2aerogel/PVB composite material also has good hydrophobicity, and moist environment would not affect its thermal insulation performance and life. The thermal conductivity of the prepared SiO2aerogel/PVB composite material was measured to be2.0×10-2W·M-1·℃-1.