Silica Aerogel composites are ultra-low density, highly porous foam-like materials that exhibit excellent thermal insulation and high strain recovery characteristics. In the present work, environment-friendly silica aerogel composites are fabricated using silica aerogel granules with bio based porcine-gelatin as the binding agent dissolved in water and by further drying the mix at sub-zero condition. This article focuses on improvement studies carried on the mold design and the manufacturing process to achieve better geometric compliance for the silica aerogel composites. It also presents contact angle measurements, compressive behavior under different cycles of loading, time dependent behavior and flexural response of the composites. The influence of additives, such as fumed silica and carbon nanotubes on mechanical properties of the composites is also deliberated. Water droplet contact angle experiments confirmed the ultra-hydrophobic nature of the composites. The mechanical properties were characterized under cyclic loading-unloading compression and three-point flexure tests. On successive compression in three consecutive load cycles, the strain and thickness recovery were found to decrease by around 30%. The flexural properties of the aerogel composites were investigated using it as the core covered by thin carbon composite face sheets. It was found that the flexural strength and the failure strain of this aerogel sandwich composites is approximately half of the conventional nomex honeycomb sandwich equivalent.
Keywords: aerogel composites; cyclic loading; mechanical characterization; sandwich design.