Mechanical, thermal and flammability properties of glass fiber film/silica aerogel composites

Aerogels are the best thermal insulating materials ever known because of their extremely low thermal conductivity. However, their applications are limited because of their brittleness and low strength. For maintaining the integrity, we prepared glass fiber film reinforced silica aerogel composites have been prepared by the sol-gel method via ambient pressure drying. The composites were characterized by scanning electron microscopy, bulk density analysis, Brunauer-Emmett-Teller method, thermal constant analysis, and compression and cone calorimeter tests. The H2O: TEOS molar ratio of the silica aerogels was found to affect the properties of the composites significantly. As the H2O: TEOS molar ratio increased from 2 to 6, the density of the composites first decreased dramatically and then increased slightly. The thermal conductivity also showed the same trend. The mechanical properties of the composites were improved greatly compared to the pure aerogels without compromising their thermal insulation properties. Moreover, the composites prepared in this work exhibited more elasticity and flexibility than the conventional thermal insulating materials. The data obtained from the cone calorimeter test showed that with an increase in the H2O: TEOS molar ratio, the fire hazard of the composites decreased.