Polyurethane (PU) foams are highly established material in noise control engineering, but also in other remarkably versatile domains. Unfortunately, this increases the amount of PU waste disposal in the landfills. Concerning the new strategies for sustainable and green polyurethanes, this study investigates the sound absorption properties of Rebonded PolyUrethane (RPU) foam. Measurements of sound absorption coefficient, α, under normal incidence were made using an impedance (Kundt) tube for RPU foam samples with two different densities (40 kg/m3±15% and 60 kg/m3±15%) and three different thicknesses (45 mm, 70 mm and 95 mm). The airflow resistivity was also measured for the same samples.

The Transfer Matrix Method (TMM) was employed to simulate the sound absorption phenomenon for normal and diffuse sound incidence of unbounded poro-elastic RPU layer with hard wall termination. The visco-inertial dissipative effects inside the porous layer were described with Johnson-Champoux-Allard (JCA) model.