Fabrication of Polytetrafluoroethylene Aerogels with Excellent Sound Absorption and Thermal Insulation

Abstract

As the application scenarios of aerogels expand, higher requirements are put forward for the materials used to prepare aerogels. Due to the unique chemical structure, polytetrafluoroethylene (PTFE) has excellent properties such as high-temperature resistance, hydrophobicity, and chemical stability. However, the PTFE aerogels are difficult to be molded due to the weak interaction between resin particles. In this work, poly(ethylene oxide) (PEO) was selected as the carrier to assist the PTFE aerogels molding. The pure PTFE aerogels were prepared by homogeneously mixing PTFE aqueous dispersion and PEO, freeze-drying, and high-temperature sintering. When the mass fraction of PTFE and PEO were appropriate, the porosity of PTFE aerogels exceeded 90% and had a hierarchical honeycomb structure. Results showed that the PTFE aerogels not only had excellent hydrophobicity but also possessed superior acoustic insulation, mechanical strength, thermal insulation, and heat resistance properties. Specifically, the water contact angle is about 140°. The noise reduction coefficient is 0.34 and the average sound absorption coefficient is greater than 88% in the frequency range of 2000–6400 Hz. Meanwhile, the thermal conductivity in the air is about 0.045 W/(m·K), and the initial thermal decomposition temperature is 450 °C. More importantly, the PTFE aerogels had excellent temperature and corrosion resistance. Even after extremely thermal and chemical treatment, they remained unchanged porous structure as well as acoustic and thermal insulation properties, which exhibits great potential for application in many harsh environments.