Sound absorption polyimide composite aerogels for ancient architectures’ protection

Ancient architectures are an important part of immovable cultural heritage and the largest surviving amount of tangible cultural heritage in the world. However, the increasingly serious noise pollution will not only affect the sanctity of ancient architectures, but also damage the internal structure caused by continuous mechanical vibration, and affect their lifetime. In this paper, diaminodiphenyl ether and pyromellitic dianhydride were used as monomers, modified by triethylamine to synthesize water-soluble polyamide acids, and calcium carbonate (CaCO3) was used as filler to prepare CaCO3/polyimide (CaCO3/PI) composite aerogels by homogeneous mixing, freeze-drying, and thermal imidization. CaCO3 can effectively adjust the pore wall roughness of CaCO3/PI composite aerogels, so as to improve their sound absorption performance. When the amount of CaCO3 is 4 wt%, CaCO3/PI composite aerogels exhibit optimal sound absorption performance, excellent mechanical properties, thermal insulation, and heat resistance. The corresponding noise reduction coefficient is 0.327, and the average sound absorption coefficient is 0.903 in the frequency range of 2000 ~ 6300 Hz. Young’s modulus is 4.03 kPa, stress loss and plastic deformation after 100 compression cycles with a maximum strain of 50% are 3.27% and 2.17%, respectively. The energy loss coefficient is 0.248, the thermal conductivity is 0.038 W/(m·K), and the heat resistance index is 334.1 °C. The CaCO3/PI composite aerogels show momentous application prospects in the field of ancient architectures protection. Above exhibited the sound absorption coefficient and noise reduction performance of CaCO3/PI composite aerogels