Preparation and properties of ultra-lightweight,low-drying-shrinkage nano-aerogel for thermal insulation

Abstract

Aerogels are renowned for their ultra-low density and exceptional thermal insulation. However, high drying shrinkage during preparation often leads to pore collapse and inadequate mechanical strength, severely limiting their aerospace applications. This work innovatively proposes a molecular bonding engineering strategy by introducing trace-aminated glass fiber (GF-NH₂) into a polyimide (PI) matrix. This approach leverages strong hydrogen bonding between the –NH₂ groups on the fiber and the electronegative N and O atoms in PI, creating robust reinforcement nodes. Combined with supercritical drying, this technique yielded a high-performance nanocomposite aerogel. The results demonstrate a dramatically reduced drying shrinkage of only 3.2% (a 57% reduction compared to PI aerogel), while retaining an ultra-low density of 0.049 g/cm³ and a predominant pore size distribution of 30-60 nm. Remarkably, the composite achieves a compressive strength of 2.79 MPa and a modulus of 19.34 MPa. Its thermal diffusivity remains impressively low at 0.158 mm²/s, attributable to the Knudsen effect, and its thermal decomposition temperature (Td5%) exceeds 548°C. Infrared thermography confirmed that its thermal insulation performance substantially surpasses that of commercial silica aerogel (CSA). This strategy, leveraging the synergy of molecular bonding and supercritical drying, provides an excellent solution for developing aerospace thermal protection materials with high integral forming capability.