Preparation of flexible fiber-reinforced aerogel composites for thermal insulation

Flexible fiber-reinforced SiO2 aerogel composites were prepared by forming SiO2 aerogel interstitially within a flexible fiber matrix, using tetraethoxysilane (TEOS) precursor by two-step acid-base catalyzed sol-gel process followed by soaking and supercritical drying. It has been observed that the tensile strength increased from 0.013 to 0.21 MPa at 600 degrees C with the increase in the aging time before drying the sol from 1 h to 7 d due to the various extent of hydrolyzation analyzed by FT-IR. The surface area of the aerogel was 209.6 m(2)/g and the average pore diameter was 18.8nm. Fiber-fiber contact was substantially avoided and the aerogel finely filled in the porous fiber matrix as shown by FE-SEM. So the flexible composites have a low thermal conductivity such as 0.019, 0.054 W/m(.)K at 120 degrees C and 500 degrees C, respectively.