Porous lyocell powders as sound absorbers

Abstract: Environmentally friendly insulation materials based on renewable resources come more and more to the fore, replacing less sustainable materials, such as mineral wool or polystyrene foams. In this study, we present a straight-forward avenue to a highly porous cellulose II powder for application as sound absorber. The material was prepared from a lyocell-derived cellulose II gel by a freeze-drying approach. The powder has a porosity of 98% and a specific surface area of 177 m²/g. It featured a sound absorption maximum in the frequency range of one-third-octave bands of 400–800 Hz (65 mm thickness) and was significantly more efficient as acoustic insulation material than commercial alternatives. The high performance makes the cellulose II sound absorber especially attractive for a use in loudspeakers for small electronics. Graphical Abstract: [Figure not available: see fulltext.].