Preparation of Fully Bio-based Sound Absorbers from Waste Wood and Pulp Fibers by Foam Forming

Building materials that are bio-based and produced from waste streams have a substantial effect on the carbon footprint of buildings. In this study, the authors prepared fully bio-based sound absorbers from waste wood and other cellulosic materials. Cutter shavings (CSs), softwood pulp, and cellulose powder (CP) were used as raw materials to prepare sound absorber samples using the foam-forming technique. The fully bio-based sound absorbers prepared were mechanically stable. However, an increase in CSs content decreased their mechanical properties, and samples with high CSs content became difficult to handle. The CP increased the mechanical properties, but it did not affect the sound absorption of the samples. The sound absorption properties of these fully bio-based materials could be tuned by carefully selecting CSs and fiber contents and adjusting the thickness of the material. Greater CSs content decreased the sound absorption properties of the materials. This decrease was mainly due to an increase in the average pore size, leading to poorer sound energy dissipation by visco-thermal effects.