Fatigue-resistant polyimide aerogels with hierarchical cellular structure for broadband frequency sound absorption and thermal insulation

Living in the noisy environment for long time would cause various diseases and seriously harm physical and mental health of mankind. In this work, water-soluble polyamide acid was used to prepare the polyimide-polyvinylpyrrolidone (PI-PVP) aerogels with hierarchical cellular structures by homogeneous mixing with pore modifier of PVP, freeze-drying, and thermal treatment. PVP could adjust pore structures, widen pore size distribution, and improve sound absorption performances for PI aerogels in wide frequency range. When the amount of PVP is 45 wt%, PI-PVP aerogels exhibit excellent sound absorption, mechanical, thermal insulation, and heat resistances performance. The noise reduction coefficient is 0.34 and average sound absorption coefficient is over 0.9 in the frequency range of 2000 similar to 6300 Hz. Young's modulus is 7.12 kPa. Stress loss and plastic deformation after 100 compression cycles (strain of 50%) are 14.7% and 3.2%, respectively. Meantime, the thermal conductivity coefficient and the initial thermal decomposition temperature in the air are 0.044 W/(m center dot K) and 420 degrees C, respectively. Our fabricated PI-PVP aerogels in this work own broad application prospects in the fields of engineering, construction, vehicle noise reduction, and personal protection.