宽温域高阻尼多形态ZnO杂化PVDF/PU复合材料的研究

By designing the material microstructure, a novel kind of damping composite is proposed to prepare, which consists of ZnO whiskers and polyurethane/polyvinylidene fluoride semi IPN. In this design, not only the controllability of polyurethane soft/hard segments and enforced compatibility of IPN structure are considered, but also the piezoelectricity of PVDF and different morphologies of ZnO whiskers are employed. This obtained composite will have preferable damping properties with effective damping temperature region (tanδ≥0.3) no lower than 150℃ and tanδmax≥1.3.. Based on the above ideas and previous research foundation, polyether-polyester type polyurethane prepolymer with different soft segments is mixed with polyvinylidene fluoride to form PVDF/PU semi-IPN via a stepwise cure process in order to broaden the damping temperature range. Then, the polymer matrix is hybrided with wire-like, rod-like，plate-like and tetra-like ZnO whiskers to prepare the hybrid damping composite with wider effective damping temperature and higher damping peak value. The relationship of structure, phase, piezoelectricity and damping feature will be clarified by studying semi-IPN. . ZnO whiskers with different morphology will be mixed, and how their scattering, morphology，piezoelectricity and so on affect the phase structure, glass transition temperature, damping temperature region will be explored. The damping mechanism under the action of multi-field coupling will also be interpreted.

本研究从材料微结构设计出发，利用聚氨酯(PU)软硬段结构的可控性、互穿聚合物网络(IPN)结构的强迫相容性、聚偏氟乙烯(PVDF)的压电性及氧化锌(ZnO)的多种立体结构来制备阻尼性能可控的多形态ZnO杂化PVDF/PU阻尼复合材料，使其有效阻尼温域（tanδ≥0.3）达到或超过150℃，最大损耗因子tanδmax≥1.3。. 根据上述研究思路及前期研究基础，首先制备具有不同分子量及体积的聚醚和聚酯型PU预聚体，然后与PVDF制成PVDF/PU 半互穿聚合物网络（semi-IPN），并通过掺杂具有线性、棒状、片状及四脚状结构的ZnO晶须制备宽温域高阻尼聚合物基复合材料；通过对具有不同结构单元的semi-IPN研究，解释化学组成、相结构、压电性与阻尼性能的关系；通过掺杂不同形貌的ZnO晶须，研究其分散、形态及压电性等因素对相结构、玻璃化温度、阻尼温域的影响，并解释在多场耦合作用下的阻尼机制。

本研究从材料微结构设计出发，首先通过两步法制备出了具有不同软硬段结构的聚醚聚酯型聚氨酯（PU）基体，然后将其与聚偏氟乙烯（PVDF）制成PVDF/PU 半互传聚合物网络（semi-IPN），并通过掺杂具有棒状、片状及四脚状结构的ZnO晶须来制备宽温域高阻尼semi-IPN复合材料；所制备的阻尼复合材料其有效阻尼温域达到了178.8℃，且ZnO晶须的加入使最大阻尼峰值达到了1.32。通过对具有不同结构单元的semi-IPN研究，解释了软段组成、相容性和微相分离结构与压电性和阻尼性能的关系。通过掺杂不同形貌的ZnO晶须，研究了其分散、粒子形态及压电性等因素对相结构、热稳定性和阻尼性能的影响，考察了高振动频率和不良散热等情况下的热-力-电的耦合效应以及性能随老化、生热的变化规律，并研究了压电效应和阻尼效果与压缩生热之间的关系。本项目的研究成果将为宽频率低生热阻尼材料的研制提供理论基础，并为新型压电阻尼材料的开发提供新思路。