Fume silica improves the insulating and mechanical performance of silica aerogel/glass fiber composite

In this work, we prepared the mechanically strong and highly insulated composite of the silica aerogel/glass fiber by adding fumed silica. The composite was made by acid-base catalyzed tetraethyl orthosilicate sol-gel, to which the fumed silica was added, followed by supercritical CO₂ drying technique. The resultant composite possesses not only ultra-low thermal conductivity of 0.0194 W·(m·K)⁻¹ but also excellent flexural strength of 0.58 MPa stress and low bulk density of 0.239 g/cm³. These outstanding performances of the composite are related with its special dense mesoporous [tbnd]Si[sbnd]O[sbnd]Si[tbnd] network formed around the glass fiber by the silica aerogel, and fume silica merged matrix, in which the macrospores of the fumed silica turned to mesoporous and became a part of the silica aerogel which further helped in improving the pore structure. This technique paves a way to enable the silica aerogel/glass fiber pragmatic applications as insulation materials.