Study on characteristic parameters identification and low frequency sound absorption performance of polyurethane foam filled with carbonyl iron particles

Abstract

In this paper, the addition of carbonyl iron particles addtion and the ratio of polyether polyol and isocyanate on the physical characteristics parameters and sound absorption performance of polyurethane foams (PUF) are investigated to improve the low frequency sound absorption effect of traditional polyurethane foam. Firstly, the least squares method is used to estimate the physical characteristic parameters of magnetic polyurethane foam (MPUF), including flow resistivity, porosity, tortuosity, viscous length and thermal length, based on the Johnson-Champoux-Allard (JCA) acoustic propagation model. At the same time, sound absorption performance of 64–1600 Hz are tested by the transfer function method and impedance tube. The results show that adding carbonyl iron particles can obviously change the physical characteristic parameters of PUF/MPUF with the same ratio of polyether polyol and isocyanate. The flow resistivity and porosity are both increased by 82.9%–211.3% and 0.8%–5.3% respectively, while the tortuosity and the viscous length both decreased by 32.7%–74.5% and 81.4%–94.0% respectively. However, the thermal length has no obvious changes. The PUF/MPUF sound absorption performance of 64–500 Hz is significantly improved, and its low-frequency sound absorption performance can be increased by 64% due to the addition of carbonyl iron particles, especially when the ratio of polyether polyol and isocyanate is 100:60. The new intelligent MPUF is feasible to meet different functional requirements of the frequency sound absorption and offers references for the intelligent noise abatement device optimization design by MPUF.