Silica aerogel/epoxy composites with preserved aerogel pores and low thermal conductivity

The thermal conductivity of aerogel/epoxy composite based on the inexpensive powder form of silica aerogels by using water glass under ambient drying conditions was evaluated to investigate the relationship between the internal structure and the thermal conductivity of the composite. A high thermal conductivity was obtained for the composite fabricated by the typical liquid epoxy processing because the pores of the aerogels became filled with the epoxy resin during the processing of the composite. A new processing method for preserving the aerogel pores was then developed using ethanol evaporation, which lowered the thermal conductivity of the composite. The lowest thermal conductivity of 0.04 W/m K was obtained for the composite containing the as-received aerogel of 75 vol% with preserved pores. The preserved aerogel pores in the composite were the most significant physical factor in determining the thermal conductivity of the composite.