Thermal insulation performance of silicone rubber / silica aerogel composite

Silica aerogel (SA) is considered one of the most promising thermal insulation materials due to its nano-size open pore structure. In this study, one part room temperature vulcanized silicone rubber (RTV-SiR) composite with improved thermal performance has been produced simply by incorporating SA as filler. Hydrophobic SA particles of 0.5 mm with a surface area of ∼700 m2/g and density of 0.07 g/cm3 were prepared from rice husk ash via ambient pressure drying. The RTV-SiR composite of 5.0 mm thickness was prepared by blending with 9 wt% of SA particles using a mechanical mixer and kept for vulcanization at room temperature. The properties of the RTV-SiR composite were systematically investigated using scanning electron microscopy (SEM), tensile test, surface roughness, water contact angle measurement, Fourier transform infrared spectroscopy (FTIR), hot-disk thermal conductivity analyzer, thermogravimetric analysis (TGA) and flame penetration test. Compared to pristine RTV-SiR, composite reinforced with SA particles demonstrates low density, high strength and specific modulus, low thermal conductivity, high surface hydrophobicity and excellent resistance to flame penetration test. The composite can withstand the penetration of the butane flame torch for more than 800 s and keep the unexposed side temperature (plateau of 100 °C) below the decomposition temperature of the SiR. The results suggest that the thermal performance of the composite is strongly influenced by the physical properties of the SA and the structural integrity of the SA in the composite. The SA reinforced SiR composite has a potential application prospect in building insulation and fire protection.