Chitosan/polyvinyl alcohol aerogels with improved structure for thermal insulation and noise reduction

As modern industry continues to advance, noise pollution is becoming increasingly severe, posing a significant threat to the global economy and human health. Given their porous structure and lightweight properties, aerogels exhibit substantial potential in the field of acoustics. Concurrently, the use of environmentally-friendly, biodegradable materials such as chitosan (CS) and polyvinyl alcohol (PVA) not only helps address environmental challenges but also contributes to reducing pollution. This study investigates the microstructural evolution of CS/PVA aerogels through compositional tuning, aiming to significantly enhance their acoustic properties. Through meticulous adjustment of the CS and PVA concentrations during the sol-gel process, we successfully fabricated aerogels with a remarkable low density of 0.0240 g·cm^-3 and a high porosity of 98 %. The resulting aerogels demonstrate exceptional acoustic performance, with a sound transmission loss (STL) exceeding 20 dB in the frequency ranges of 450 to 1000 Hz and greater than 3000 Hz, and a noise reduction coefficient (NRC) of 0.428 at a thickness of only 18 mm. In addition, CS/PVA aerogel also exhibits certain thermal insulation properties, with a minimum thermal conductivity of 0.0387 W·m^-1·K^-1. These findings underscore the potential of CS/PVA aerogels as low-density and environment friendly acoustic materials.