Study of thermal and humidity properties of SiO 2 aerogel composites with porous media

Building insulation improves the thermal environment of a building and significantly reduces energy consumption for heating and air conditioning. Traditional insulation materials are prone to moisture absorption and a significant reduction in thermal performance. Therefore, it is urgent to develop new building insulation materials to meet the high weather resistance, strong insulation and waterproof requirements of modern buildings. In this paper, the hydrophobic properties, pore size distribution and microstructure of SiO ₂ aerogel composite insulation materials with porous media were characterised. Its mass hygroscopicity at different humidity and thermal conductivity after hygroscopic equilibrium were tested. The results show that the increase in aerogel content complicates the microstructure of porous media SiO ₂ aerogel composites with wider pore size distribution and coarsening of pore structure. It optimises its physical properties and confers low water absorption with excellent hydrophobicity. The moisture absorption rate versus time curves of aerogel composites at different humidity levels were compared. It is found that the aerogel composites are highly applicable in wet or moisture-proof situations due to their low moisture absorption properties. Meanwhile, the thermal conductivity of porous media SiO ₂ aerogel composites is affected by both humidity and aerogel content. This indicates that increasing the aerogel content is an effective method to reduce the thermal conductivity of the composites. The Modified BET model used was able to verify this phenomenon. Therefore, porous media SiO ₂ aerogel composites can be widely used for building insulation in humid areas.