Acoustic Properties of Aerogels: Current Status and Prospects

Abstract

Noise pollution has been aptly described as one of the modern plagues. [1] Due to many adverse health effects of loud environments, ranging from sleep disturbances to cardiovascular diseases, reducing the exposure of humans to excess noise is essential to the public health of large populations living in the cities. Regarding sound absorption materials, the optimal choice depends on the intended sound frequency range; solutions of damping high-frequency sound waves rely on totally different absorption mechanism than the solutions for very low-frequency noise. Indoors, the most commonly used sound absorption materials are porous by nature due to their ability to efficiently absorb sound at mid to high frequencies with relatively thin layers. Common porous absorption materials in the market, targeting to over 90% absorption above 350 Hz, are glass and mineral wools and acoustic foams made, e.g., from melamine or polyurethane. Here, we review the acoustic properties of aerogels and demonstrate their high potential to challenge and exceed the absorption properties of the current market standards, whether we talk about the performance in

Highly Efficient Thermo-Acoustic Insulating Aerogels Enabled by Resonant Cavity Engineering

“…In general, in fibrous and porous materials, the acoustic attenuating mechanism can be divided into three categories: , (i) vibration and friction of air molecules with the cavity walls or fibers, (ii) periodic compression and release of air inside cavities, and (iii) resonance between sound wave and cavity walls and fibers. Among the commonly used prediction models of porous sound absorption materials, the Johnson–Champoux–Allard model is the most widely used prediction model of porous fiber materials (see Supporting Information Methods).…”

“…3,13 Compared with commercial products with similar thickness, TNF aerogels are simultaneously endowed with low density and better acoustic attenuating properties, which distinguish them for many critical industrial applications where lightweight materials are required. In general, in fibrous and porous materials, the acoustic attenuating mechanism can be divided into three categories: 36,37 (i) vibration and friction of air molecules with the cavity walls or fibers, (ii) periodic compression and release of air inside cavities, and (iii) resonance between sound wave and cavity walls and fibers. Among the commonly used prediction models of porous sound absorption materials, the Johnson− Champoux−Allard model is the most widely used prediction model of porous fiber materials (see Supporting Information Methods).…”

Direct ink writing of polyimide aerogels for battery thermal mitigation

“…Aerogels are a key material in advanced applications because of their unique combination of extremely low density (ranging from 1 to as low as 0.001 g cm −3 ), 1 high porosity (up to and sometimes exceeding 99%), [1][2][3] high specific surface area (500-1000 m 2 g −1 ), 1 and mechanical strength. 4,5 Since their introduction in 1931, 6 aerogels have found application across a variety of disciplines, including energy storage devices, 7 acoustic insulators, 8,9 thermal insulators, [10][11][12][13][14][15] vibration mitigation systems, 16 catalysts and catalyst supports, [17][18][19] and Cherenkov detectors. 20 The light weight of aerogels makes them appealing for space applications, where each kilogram of mass can cost tens of thousands of dollars to launch.…”

Effects of Freeze-Drying Processes on the Acoustic Absorption Performance of Sustainable Cellulose Nanocrystal Aerogels

“…Due to their unique physical properties, such as ultra-high porosity, ultra-low density, and Gels 2024, 10, 141 2 of 13 sound propagation speed, aerogels are also excellent acoustic absorption materials to efficiently suppress noise [1,12,13]. Cellulose aerogels, as a new type of bio-based porous material, not only inherit the superior porous structures of traditional aerogels, but also possess extremely high sustainable value, showing good prospect in the field of noise reduction [14][15][16].…”

“…The absorption of sound energy by porous materials occurs through their interconnected pores due to viscous, thermal, and inertial effects caused by the interaction of air molecules at the interfaces of the gas and the solid phases [15]. Hence, the design and regulation of the pore structures of cellulose aerogels play an important role in optimizing their acoustic absorption performance.…”