Fiber Reinforced Polyimide Aerogel Composites with High Mechanical Strength for High Temperature Insulation

Glass fiber/polyimide aerogel composites are prepared by adding glass fiber mat to a polyimide sol derived from diamine, 4,4-oxydianiline, p-phenylene diamine, and dianhydride, 3,3,4,4-biphenyltetracarboxylic dianhydride. The fiber felt acts as a skeleton for support and shaping, reduces aerogel shrinkage during the preparation process, and improves the mechanical strength and thermal stability of the composite materials. These composites possess a mesoporous structure with densities as low as 0.143-0.177 gcm(-3), with the glass fiber functioning to improve the overall mechanical properties of the polyimide aerogel, which results in its Young's modulus increasing from 42.7 to 113.5MPa. These composites are found to retain their structure after heating at 500 degrees C, in contrast to pure aerogels which decompose into shrunken ball-like structures. These composites maintain their thermal stability in air and N-2 atmospheres, exhibiting a low thermal conductivity range of 0.023 to 0.029 Wm(-1)K(-1) at room temperature and 0.057to 0.082 Wm(-1)K(-1) at 500 degrees C. The high mechanical strengths, excellent thermal stabilities, and low thermal conductivities of these aerogel composites should ensure that they are potentially useful materials for insulation applications at high temperature.