Properties and mechanism of a novel metallic‐hollow‐spheres/polyurethane acoustic composite

Abstract

In this article, 316L stainless steel hollow spheres (316L HS) and polyurethane (PU) resins were used to prepare a novel metallic-hollow-sphere/polyurethane (MHSP) acoustic composite by casting. The acoustic experimental results of this composite revealed that compared to monolithic PU, the sound transmission loss of the composites increased and the maximum sound absorption peak shifted to lower frequency with the change of acoustic impedance and resonance frequency. When the surface of metallic hollow sphere used in MHSP composite was modified by silane coupling agent, the sound insulation and sound absorption performance of MHSP composites were further improved. This is related to the addition of the molecular layer of coupling agent between MHSP matrix. In addition, the addition of silane coupling agent creates PU foaming in matrix, resulting in a large number of pores and gaps that can increase the sound waves energy loss through air friction and heat exchange.

Sound insulation of a novel laminated polymer matrix composite containing metallic hollow spheres based on phononic crystal structure design

“…In the above formula 6, E represents the elastic modulus and μ represents the Poisson ratio. In this study, the elastic modulus and Poisson ratio of the matrix material and single layer composites were obtained from our previous researches [31][32][33][34][35] through ultrasonic method and quasi-static compression method. Table 2 lists the elastic modulus (E),…”

“…In this experiment, according to ASTM D72‐08 standard, the density of single layer material was measured by drainage method and Archimedes principle 31–35 . The density of SR, PU, single layer MHSSR and MSHP were 1.13, 1.09, 2.22, and 2.18 g·cm −3 , respectively.…”

“…The sound insulation performance of the one-dimensional phononic crystal laminated composites in this study were tested by BSWA422/477 impedance tube. The principle of sound insulation test was based on ASTM E2611-09 standard, [31][32][33][34][35] that is, the sound signal and data are collected by four microphones, and the STL was calculated by the transfer matrix method. The size of low frequency (64$1000 Hz) sample was 100 mm in diameter and 18 mm in thickness, and the high requency (1000$6300 Hz) sample is 30 mm in diameter and 18 mm in thickness.…”

“…However, most of the above researches on one‐dimensional phononic crystals are focused on the design and theoretical analysis, there are few reports on the one‐dimensional phononic crystal with good sound insulation properties actually prepared. Recently, our team found that metallic hollow spheres can effectively improve the acoustic performance of silicone rubber, polyurethane, and aluminum alloy 31–35 . The elastic silicon rubber and the harder polyurethane may be arranged periodically to form a one‐dimensional phonon crystal.…”

Effects of Isocyanate-to-Polyols (NCO/OH) Ratio on Bio-based Polyurethane Film from Palm Kernel Oil based Monoester Polyols (PKO-p) for Polymer Electrolytes Application

“…Recently, polyurethane (PU) has attracted the attention of the research community due to its wide application as a polymer electrolyte in composites [1], medical engineering [2], coatings and adhesives, and electrochemical devices [3 -6]. In particular, the physical stability and flexibility to withstand the pressure between the anode and cathode are essential characteristics of polymer electrolytes to function properly in electrochemical devices.…”