In-Situ Synthesis of Layered Double Hydroxide/Silica Aerogel Composite and Its Thermal Safety Characteristics

To adjust the thermal safety of hydrophobic silica aerogel, layered double hydroxide (LDH)/silica aerogel (SA) composites were prepared by an in-situ sol-gel process at ambient pressure. This study found the physical combination of SA and MgAl-LDH based on the FTIR spectra and phase composition of LDH/SA. The N2 sorption analysis confirms that the introduction of MgAl-LDH does not change the mesoporous attribution of LDH/SA significantly. With the increase in MgAl-LDH addictive content, the low density (0.12–0.13 g/cm3), low thermal conductivity (24.28–26.38 mW/m/K), and large specific surface area (730.7–903.7 m2g) of LDH/SA are still maintained, which can satisfy the requirements of thermal insulation. The TG-DSC analysis demonstrates that the endothermic effects and metal oxides formed during the MgAl-LDH decomposition are beneficial to the improvement of the thermal stability of LDH/SA composites. In addition, it was found that the gross calorific values of LDH/SA composites decrease with an increase in MgAl-LDH addictive content, all of which are lower than that of the pure SA. The research outcomes indicate that the thermal safety of LDH/SA composites is enhanced significantly by doping MgAl-LDH without impairing too many of the excellent properties, which benefits their expansion in the thermal insulation field.