Physical properties of silica aerogels prepared with polyethoxydisiloxanes

Silica aerogels were made by sol-gel techniques using industrial silicon derivatives (polyethoxydisiloxanes, E-40), followed by supercritical drying with ethanol. The morphology and microstructure of the silica aerogels were investigated by using specific surface area, S-BET, SEM, TEM and the pore size distribution techniques. The thermal conductivity was also measured as a function of air pressure. The results show that the diameter of the silica particles is about 13 nm and the pore size of the silica aerogels is 20-80 nm. The specific surface area of the silica aerogel is about 470 m(2)/g and the thermal conductivity of the silica aerogel prepared with E-40 is 0.014 w m(-1) K-1 at room temperature and 1 atm.