Fire-resistant polyimide-silica aerogel composite aerogels with low shrinkage, low density and high hydrophobicity for aerospace applications

Polyimide (PI)-silica aerogel composite aerogels with low shrinkage (3.7%), low density (0.061 g/cm3), low thermal conductivity (0.0216 W m−1 K−1), high hydrophobicity (146°) and good fire resistance were prepared by incorporating silica aerogel powders into PI matrix. The properties of the aerogels are affected by the type and content of silica aerogel powders. The samples show high compressibility, and the stress at 80% strain increases with the increase of silica aerogel powder content. The addition of inorganic silica aerogel powders (ISAp) can improve the thermal stability of the aerogel and the fire resistance and structural integrity of the sample under flame, but has adverse effect on moisture resistance. While the addition of polyvinylpolymethylsiloxane aerogel powders (PAp) improves the moisture resistance of the aerogel but weakens the thermal stability and fire resistance. The introduction of both ISAp and PAp can reduce the thermal conductivity of the aerogel, and the samples exhibit good thermal insulation performance. Furthermore, ground equivalent simulation tests were carried out to verify the adaptability of these aerogels in the space environment. The sample meets the standard requirements and shows stable structure and performance during the tests, which proves its potential application in the aerospace field.