Fabrication of Millable Polyurethane Elastomer/Eucommia Ulmoides Rubber Composites with Superior Sound Absorption Performance

Abstract

Sound absorbing materials combining millable polyurethane elastomer (MPU) and eucommia ulmoides rubber (EUG) were successfully fabricated via a physical blending process of EUG and MPU. The microstructure, crystallization performances, damping, mechanical and sound absorption properties of the prepared MPU/EUG composites were investigated systematically. The microstructure surface of various MPU/EUG composites became rough and cracked by the gradual incorporation of EUG, resulting in a deteriorated compatibility between EUG and MPU. With the increase of EUG content, the storage modulus (E’) of various MPU/EUG composites increased in a temperature range of −50 °C to 40 °C and their loss factor (tanδ) decreased significantly, including a reduction of the tanδ of MPU/EUG (70/30) composites from 0.79 to 0.64. Specifically, the addition of EUG sharply improved the sound absorption performances of various MPU/EUG composites in a frequency range of 4.5 kHz–8 kHz. Compared with that of pure MPU, the sound absorption coefficient of the MPU/EUG (70/30) composite increased 52.2% at a pressure of 0.1 MPa and 16.8% at a pressure of 4 MPa, indicating its outstanding sound absorption properties.

Development of nitrile rubber/eucommia ulmoides gum composites for controllable dynamic damping and sound absorption performance

“…One is that the incorporated EUG crystals enhanced the modulus of NBR/EUG composites, which increased the propagation speeds of sonic waves and improved the impedance matching between the composites and water. 14,31,33 The other is that the sound impedance of the crystals in NBR/EUG composites mismatched that of water, and thus the incident sound wave reection happened and reected many times when it met the crystals. 15 As a result, the propagation path of sound waves was changed and increased, leading to the enhancement of the sound energy dissipation.…”

“… 13 Two crystal forms exist in EUG matrix including α-crystals and β-crystals with different melting points, and EUG owns outstanding damping properties on account of its crystal melting transition. 14 In the meantime, EUG possesses a higher modulus than traditional rubber because of the existing crystals, which could resist deformation under extreme operating conditions. A hopeful strategy for obtaining diversified new-type damping elastomers with excellent comprehensive properties could be implemented via blending EUG with other synthetic rubbers.…”

Improved covulcanization and dynamic properties of millable polyurethane elastomer/natural rubber blends: Thermal pretreatment

“…MPU/ Eucommia ulmoides rubber (EUG) was developed as a promising damping material. The MPU/EUG blend was manufactured using the physical mixing method, and the sound attenuation performance under high pressure was effectively improved by combining the special viscoelastic properties of MPU and the crystalline nature of EUG 13 …”

“…The MPU/EUG blend was manufactured using the physical mixing method, and the sound attenuation performance under high pressure was effectively improved by combining the special viscoelastic properties of MPU and the crystalline nature of EUG. 13 Natural rubber (NR) possesses a unique combination of toughness, flexibility, mechanical and dynamic properties together with a relatively low cost. 14 The blends of NR with different varieties of PU are quite interesting, as demonstrated in previous reports.…”

Finite Element Solution for Dynamic Mechanical Parameter Influence on Underwater Sound Absorption of Polyurethane-Based Composite

“…Among them, viscoelastic materials display the most typical damping materials and possess excellent damping performances [ 16 , 17 , 18 , 19 , 20 ] because, compared to other damping materials, their characteristic impedance is close to that of water, so they can convert vibration and sound energy to heat energy significantly [ 21 , 22 ]. The PU-based composite, as a type of viscoelastic damping material, owns a particular long-chain molecular structure, which can be used as an underwater sound absorption material [ 23 , 24 , 25 ]. The clearest advantage of the PU-based composite is that its sound absorption performance can be well-regulated via molecular designing, including choosing a variety of molecular chain segments and chemical synthesis methods, adjusting the molecular chain proportion of the hard and soft segments, and incorporating them with other polymers [ 20 , 26 ].…”