Although hindered phenol/polymer-based hybrid damping materials, with excellent damping performance, attract more and more attention, the poor stability of hindered phenol limits the application of such promising materials. To solve this problem, a linear hindered phenol with amorphous state and low polarity was synthesized and related polyurethane-based hybrid materials were prepared in this study. The structure and state of the hindered phenol were confirmed by nuclear magnetic resonance spectrum, Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The existence of intermolecular hydrogen bonds (HBs) between hindered phenol and polyurethane was confirmed by FT-IR, and the amorphous state of the hybrids was confirmed by XRD. Moreover, by a combination of molecular dynamics simulation and dynamic mechanical analysis, the relationship between the structure optimization of the hindered phenol and the high damping performance of the hybrids was quantitatively revealed. By constructing the synthetic hindered phenol, the intramolecular HBs between hindered phenols were restricted, while the strength and concentration of the intermolecular HBs increased by increasing the amount of hindered phenol. Thus, intermolecular interactions were enhanced, which lead to the compact chain packing of polyurethane, extended chain packing of hindered phenol, and good dispersion of hindered phenol in polyurethane. Therefore, the stability of the hindered phenol and the damping properties of the hybrids were both improved. The experiment results are expected to provide some useful information for the design and fabrication of high-performance polymeric damping materials.Keywords:hindered phenol/polymer-based hybrid damping materials;stability;high damping performance;structure optimization;damping mechanism
Wenzheng Chen,Sijia Li,Mingyu Lu,Yiping Guo,Hao Yin,Yujie Chen,Qunfu Fan,Hezhou Liu,Hua Li
The “Brick-and-Mortar” structure endows the nacre outstanding abilities of dissipating kinetic energy, attenuating stress wave and keeping high mechanical strength. However, current artificial bio-inspired materials, such as the materials with unit structure arranged in an ordered hierarchy at merely one dimension, have yet to achieve desirable damping and mechanical behavior under monotonous damping mechanisms. Herein, the nacre-like structure, conductive network, and nano piezoelectric thin film are synergistically combined in multidimension to enhance the damping and vibration attenuating behavior by different mechanisms. The continuous piezoelectric composites with nacre-like lamellar structure demonstrates superior damping property. By introducing a conductive network, piezoelectric damping is enabled, and the damping behavior is further promoted, achieving a maximum loss factor of 1.19 and tanδ area value of 34.28. The nacre-like structure in macro dimension offers the framework of PZT thin film in nano dimension, and the conductive network in micro dimension stimulates the continuous piezoelectric damping, in which the contribution of each dimension is decoupled. Based on this finding, the vibration attenuating behavior is evaluated by cantilever beam vibration test where the composites lower 26.2 dB and damping ratio increase by 95%, which are greatly demanded for many damping applications including watercraft structures and aerospace scaffold.
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