Acoustic/mechanical properties of polyurethane composites with syntactic hollow spheres

Abstract

In this investigation, a variety of polyurethane composites with different syntactic hollow spheres were prepared by casting method, using 316 L stainless steel hollow spheres and 316 L stainless steel–Al2O3 double‐layer hollow spheres as reinforcements. The sound insulation and absorption properties of polyurethane composites with different syntactic hollow spheres were tested by impedance tube. The effects of the hollow spheres on the acoustic properties of composites were analyzed and compared with polyurethane resin and polyurethane/solid spheres composites. The experimental results reveal that the sound transmission loss of polyurethane can be improved by the addition of hollow spheres, and the range of sound absorption frequency of polyurethane tends to move to lower frequency. Otherwise, the sound insulation and absorption frequency range of polyurethane can be broadened by the effect of 316 L stainless steel–Al2O3 double‐layer hollow spheres. In addition, the compressive strength and stiffness of polyurethane composites have been significantly improved after hollow spheres added. Comparing with polyurethane, the compressive strength and stiffness of PU/316 L–Al2O3 HS increased by 47.9% and 115.9%, respectively.

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),…”

“…The bulk modulu B of every component can be calculated by formula 6. 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 31–35 through ultrasonic method and quasi‐static compression method. Table 2 lists the elastic modulus ( E ), Poisson ratio ( μ ), and bulk modulus ( B ) of SR, PU, single layer MHSSR and MSHP.…”

“…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.…”