Synthesis and characterization of ambient-dried microglass fibers/silica aerogel nanocomposites with low thermal conductivity

Abstract

A new ambient-dried silica aerogel nanocomposites reinforced by smaller diameter microglass fiber mat were synthesized. Effects of gel treatment and drying temperature, molar ratio of modification agent and volume content of microglass fiber on the composites’ structure and properties were investigated. Increasing the gel treatment temperature with a gradient multi-segment drying process, the aerogel density and volume shrinkage decreased rapidly. Homogeneous and translucent bulk aerogel could be obtained with the density of 0.129 g/cm3, specific surface area of 731.76 m2/g and average pore size of 20 nm. Fewer cracks, more silica matrix and stronger fiber/silica interface, which significantly improves the mechanical performance of the nanocomposites with a high bending strength of 1.4 MPa. The thermal conductivity of the ambient-dried nanocomposites decreased and the bending strength increased with increasing fibers’ volume content. The retrieved nanocomposites is an excellent thermal insulation material with lower thermal conductivity (0.022 W/m K, 650 °C) and high mechanical performance.