Physical properties of silica aerogels prepared with polyethoxydisiloxanes

Silica aerogels were made by sol-gel techniques using industrial silicon de rivatives (polyethoxydisiloxanes, E-40), followed by supercritical drying w ith ethanol. The morphology and microstructure of the silica aerogels were investigated by using specific surface area, S-BET, SEM, TEM and the pore s ize distribution techniques. The thermal conductivity was also measured as a function of air pressure. The results show that the diameter of the silic a particles is about 13 nm and the pore size of the silica aerogels is 20-8 0 nm. The specific surface area of the silica aerogel is about 470 m(2)/g a nd the thermal conductivity of the silica aerogel prepared with E-40 is 0.0 14 w m(-1) K-1 at room temperature and 1 atm.