Structural Design and Sound Absorption Properties of Nitrile Butadiene Rubber-Polyurethane Foam Composites with Stratified Structure

Abstract

Sound absorbing composites with stratified structures, including double-layer and sandwich structures, were prepared through the combination of nitrile butadiene rubber (NBR) and polyurethane foam (PUFM). The effects of the thickness ratio of layers, different stratified structures and the variety of fillers on the sound absorption performance of the NBR-PUFM composites and the sound absorption mechanism were studied. The results show that the NBR-PUFM composite with a sandwich structure and thickness ratio of 1:8:1 displays good sound absorption, which could be improved further by adding fillers. Because the airflow resistivity, resonance absorption, interface dissipation and interface reflection were combined organically in the sandwich structure, the composites show excellent low-frequency sound absorption performance. Moreover, the composite also has advantages in cost and functionalization aspects.

Improving and Optimizing Sound Absorption Performance of Polyurethane Foam by Prepositive Microperforated Polymethyl Methacrylate Panel

“…It could be easy to confirm that reasonable range of the porosity φ was (0,1) according to its definition, as shown in Equation (18). Meanwhile, it was reported by the present literatures [1][2][3][4][8][9][10][11][12][13][14] that normal possible boundary of the static flow resistivity σ was [10000, 50000], so the investigated range in this research was set to [1000,200000], as shown in Equation (19). Moreover, the optimization target was to achieve minimized differences between the sound absorption coefficient of the experimental data α a f , d p f and that of the theoretical data α t f , d p f , as shown in Equation (20).…”

“…Polyurethane foam is considered a promising and prospective sound-absorbing material for its high porosity, low density, fine transparency, mature fabrication technology, low manufacturing cost, excellent machinability, and so on [1,2], which meets some special requirements in the fields of sound absorption and noise reduction [3,4]. Gwon et al [1] studied sound absorption behavior of the flexible polyurethane foam with distinct cellular structure, the research result of which indicated that the strong gelling catalyst could generate a high number of small cells for a better sound absorption property.…”

“…The nitrile butadiene rubber-polyurethane foam composites (NBRPFCs) with stratified structure were designed and optimized by Jiang et al [4], and the sandwich structure with thickness ratio 1:8:1 could achieve the optimal average sound absorption coefficient of 0.56 in the 500-1600 Hz range. These sound absorbers with fine sound absorption performance [1][2][3][4] prove that the polyurethane foam has huge potential in the noise reduction, which makes it a new research hotspot in acoustics and material science.In order to promote practical application of the polyurethane foam in the sound absorption and noise reduction, it is essential to identify its acoustic characteristic parameters, especially the porosity and static flow resistivity, because they are the most important factors to determine the sound absorption performance [5][6][7][8][9]. Zhang et al[5] studied sound absorption performance of the polyurethane foam with porosity in the range from of 16.0% to 88.6%, which achieved the optimal sound absorption coefficient of 0.66 in the low frequency range of 250-600 Hz.…”

“…Wang et al [3] proposed and fabricated multifunctional fabric-reinforced composites (MFRCs), which could obtain the average sound absorption coefficient of 0.7 in the 1000-4000 Hz range. The nitrile butadiene rubber-polyurethane foam composites (NBRPFCs) with stratified structure were designed and optimized by Jiang et al [4], and the sandwich structure with thickness ratio 1:8:1 could achieve the optimal average sound absorption coefficient of 0.56 in the 500-1600 Hz range. These sound absorbers with fine sound absorption performance [1][2][3][4] prove that the polyurethane foam has huge potential in the noise reduction, which makes it a new research hotspot in acoustics and material science.…”

Parameter Optimization for Composite Structures of Microperforated Panel and Porous Metal for Optimal Sound Absorption Performance

“…Based on the obtained transfer matrixes for the porous metal, microperforated panel, and the cavity, total transfer matrixes TT for the investigated five composite structures can be derived by the Equations (16)- (20), respectively, which correspond to the sound absorbers in the Figure 1a-e. By this method, sound absorption coefficient α of the investigated composite structures can be calculated, as shown in Equation 21.…”