Sustainable cellulose-based aerogels fabricated by directional freeze-drying as excellent sound-absorption materials

With noise pollution and environmental pollution becoming more and more serious, it is very urgent to develop a kind of green, recyclable and degradable sound-absorbing material. In this study, the cellulose hydrogels were obtained by dissolving cotton staple as the main material, and the cellulose hydrogel was treated with directional freezing to solve the problem of irregular distribution and coexistence of open and closed pore structures in the traditional cellulose aerogels (CAs). CAs with regularly distributed and axially open porous structure were prepared to improve the sound-absorbing performance to meet application requirements. The sound absorption coefficient of directional cellulose aerogel reached 0.88 at 4500 Hz. In addition, CAs prepared in this study have low density (0.0554 g·cm−3), high porosity (89.32%) and good thermal stability. More importantly, directional cellulose aerogel in this study has good mechanical properties, with a compressive stress of 0.35 MPa at 70% strain. Therefore, the CAs treated with directional freezing has good prospects for application in the field of sound absorption.