Lab Electrospinning System| Sustainably designed SiO,/polyarylate nanofiber composite aerogels foradvanced thermo-acoustic insulation

Associate Professor Xiong Siwei from Wuhan Textile University: Sustainably Designed Silica/Polyarylate Nanofiber Composite Aerogels for Advanced Thermal and Acoustic Insulation

With the intensification of global energy crises and environmental issues, the application of thermal and acoustic insulation materials in building energy conservation, industrial equipment, and transportation has become particularly important. Such materials can not only effectively reduce the transmission of heat and sound but also significantly improve energy efficiency and environmental comfort. Traditional thermal and acoustic insulation materials (such as glass wool, mineral wool, and polyurethane foam) often suffer from high density, poor durability, or relatively high thermal conductivity, making them unable to meet the requirements of modern high-efficiency thermal insulation and noise reduction. Nanofiber aerogels, with their ultra-low density, high porosity, and excellent mechanical properties, hold great potential for applications in the field of thermal and acoustic insulation. However, existing nanofiber aerogels struggle to meet the demands due to their poor thermal-acoustic insulation synergy, complex preparation processes, and environmental unfriendliness. Therefore, the development of nanofiber aerogels that are simple to process, environmentally friendly, and exhibit excellent performance has become a key research direction in this field.

Figure 1: Schematic diagram of the preparation process of SiO₂/PAR NCAs.

Recently, Associate Professor Xiong Siwei from Wuhan Textile University published the latest research results, "Sustainably designed SiO₂/polyarylate nanofiber composite aerogels for advanced thermo-acoustic insulation," in the journal Composites Part A: Applied Science and Manufacturing. The first author of the paper is Cai Yuhan, a master's student at Wuhan Textile University. The research team facilely prepared a novel nanofiber composite aerogel (SiO₂/PAR NCAs) through freeze-drying and heat treatment methods. Polyarylate (PAR) nanofibers with a high aspect ratio construct a three-dimensional highly porous network, while silica hollow microspheres (SiO₂ HMs) reduce thermal conductivity and enhance sound wave dissipation through their hollow structure and interfacial damping effect, achieving excellent thermal-acoustic insulation synergy in the composite aerogel. Meanwhile, the thermoplastic processability of PAR enables the thermal welding of SiO₂ HMs to the fibers, improving structural stability and simplifying the recycling process.

Figure 2: Thermal insulation performance of SiO₂/PAR NCAs.

The three-dimensional porous network constructed by PAR nanofibers forms a low thermal conductivity path of "nanofiber-air-nanofiber." After the introduction of SiO₂ HMs, the modulus difference between the two phases induces significant interfacial phonon scattering. This multi-scale interfacial synergistic scattering mechanism leads to a continuous decrease in the thermal conductivity of the composite material when the SiO₂ HMs content is ≤30 wt%, reaching a minimum value of 0.018 W m⁻¹ K⁻¹ at 30 wt%, which is only 24% of the thermal conductivity of commercial polyurethane. When 30 wt% SiO₂/PAR NCAs were placed on a hot plate at 100 °C for 90 s, the temperature of the upper surface increased by only 22.5 °C compared to the room temperature state. When placed on a cold plate at -4.5 °C for 90 s, the upper surface temperature decreased by only 6.6 °C compared to the room temperature state.

Figure 3: Acoustic insulation performance of SiO₂/PAR NCAs.

When sound waves reach the surface of SiO₂/PAR NCAs, part of the sound waves is reflected, and the remaining part enters the material. On the one hand, the incident sound waves are reflected multiple times between the pores and generate viscosity and friction with the air, converting the sound wave energy into internal energy for dissipation. Meanwhile, part of the sound waves can penetrate into the hollow microspheres and undergo reflection and friction to dissipate the sound wave energy. On the other hand, the PAR nanofiber skeleton and dispersed SiO₂ hollow microspheres in SiO₂/PAR NCAs can vibrate with the incident sound waves, converting the sound wave energy into the mechanical energy of the vibration of PAR nanofibers and SiO₂ hollow microspheres, further dissipating the sound wave energy. When the SiO₂ HMs content is 30 wt%, the acoustic performance of SiO₂/PAR NCAs also reaches the optimal level, reducing the sound pressure level (SPL) from 67.3 dB to 53 dB, with an average sound absorption coefficient (SAC) of 0.7048 and a noise reduction coefficient (NRC) of 0.4276.

Figure 4: Recycling performance of SiO₂/PAR NCAs.