Multifunctional and recyclable aerogel/fiber building insulation composites with sandwich structure

Fire, electromagnetic (EM) pollution, and sustainability require building insulation with fire resistance, EM interference shielding, and recyclability. However, fewer building insulation materials can fulfill these multifunctional requirements. Here, we report a multifunctional building thermal insulation material with a sandwich structure that uses SiO 2 aerogel powder as the insulating filler phase, α-Al 2 O 3 fiber as the refractory reinforcing phase, and carbon fiber mat (CFF) as the electromagnetic interference shielding layer prepared by the mixing-pressing-drying method. The effects of different SiO 2 aerogel power contents on fire resistance, thermal insulation, and hydrophobicity, the effects of different carbon fiber contents on EMI performance, and the effects of CFF as an interlayer on compressive strength and recyclability were investigated. The results demonstrated exceptional fire resistance properties and low thermal conductivity (0.0529 W/m·K) with a SiO 2 aerogel powder content of 11.2 wt%. Specifically, the structure of the aerogel/fiber composite remains intact and the temperature of the non-heated surface is lower than 75.8 ℃ after 4 min of continuous flame combustion. It can achieve a commercial shielding standard of 20 dB at a carbon fiber content of 5 wt%. In addition, CFF as interlayers can effectively improve the compression strength of the material and solve the problem of difficult recycling of carbon fiber. In conclusion, this sandwich structure of multifunctional aerogel/fiber composites provides new ideas for the manufacture of fire resistance, energy-saving, EM-protection, and recyclable building insulation materials.