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.
Highlights
With the rapid development of modern industries, there are an increasing number of vibration tools and high-power mechanical devices with strong vibrations and high levels of noise pollution, both of which seriously affect the normal operation of electronic devices and instruments and human health [1,2,3,4]
Scanning Electron Microscopy (SEM) was utilized to explore the effect of EUG content on the microstructure of the millable polyurethane elastomer (MPU) matrix
In the matrix of various MPU/EUG composites, MPU is mainly cross-linked with EUG by the double bonds in its side chains and the number of crosslink sites was relatively low
Summary
With the rapid development of modern industries, there are an increasing number of vibration tools and high-power mechanical devices with strong vibrations and high levels of noise pollution, both of which seriously affect the normal operation of electronic devices and instruments and human health [1,2,3,4]. Traditional rubber damping materials such as styrene butadiene rubber (SBR) and polyurethane (PU) tend to deform under high pressure on account of their low modulus, resulting in the reduction of their vibration reduction and sound absorption performances [9]. Various MPU/EUG composites with a good damping performance were fabricated using a physical blending method, and the relationship between the microstructure of MPU/EUG composites and their macroscopic performance (including dynamic and static mechanical properties as well as sound absorption properties) was investigated systematically at different ratios of MPU and EUG. Compared with pure MPU material, the MPU/EUG composites exhibited improved sound absorption performance under high pressure, which provides a promising strategy for the development of new types of rubber damping materials
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