Constructing hierarchical pore structures in melamine foams with silver and cellulose nanofiber to achieve broadband sound absorption and enhanced mechanical performance

It is a great challenge to prepare lightweight porous materials with high-efficiency broadband sound absorption and good mechanical properties. In this work, a series of melamine foams (MF) which were decorated by silver (Ag) and cellulose nanofiber (CNF) were prepared by the in-situ deposition and freeze-drying method. The deposition of Ag particles on the foam skeleton formed nanopores, and hierarchical porous structures were constructed along with the existence of micropores in MF. In addition, the formation of filamentous CNF structure further optimized the pore structure, which resulted in achieving excellent broadband sound absorption and enhanced mechanical properties of corresponding composite foams. Specifically, Ag@MF-6-CNF achieved more than 95 % sound absorption efficiency in the range of 2500-6400 Hz. Besides, the compressive strength of Ag@MF-6-CNF reached 13.8 kPa at a strain rate of 50 %, which was 75 % higher than pure MF. The proposed method provided a reference for preparing lightweight porous materials for noise attenuation applications in industrial sectors.