In-situ synthesis of silica aerogel in polyethylene terephthalate fibre nonwovens and their composite properties on acoustical absorption behavior

In this research work we focus on engineering the silica aerogel/polyethylene terephthalate (PET) fibre nonwoven fabric composites with various silica content during in-situ synthesis of silica aerogels in the nonwovens and their composite properties on sound absorption. The silica content was varied by varying the molar ratio of methanol (MeOH)/tetraethyl orthosilicate (TEOS) from 110 to 28. The gelation of silica alcogel took place inside the fabric followed by silylation and atmospheric pressure drying. The aerogel/PET nonwoven composites were characterized by FTIR, TGA and contact angle to explain the aerogel content and its behavior. Moreover, the physical properties such as thickness, bulk density, specific airflow resistance, and mean flow pore size have been investigated. The two microphone transfer function method was used to test the sound absorption coefficient (SAC) of aerogel composites at 1/3rd octave frequencies of 50–6300 Hz. The aerogel/PET nonwoven composites have exhibited higher SAC than the untreated or control PET nonwoven for the entire frequency range. The suitable solvent molar ratio of 55 has been recommended for synthesis of silica aerogels by considering not only the silica content to have high sound absorption but also based on hydrophobic characteristics of aerogel/PET nonwoven composites.