Modeling the dielectric breakdown strength and energy storage density of graphite-polymer composites with dielectric damage process
Modeling the dielectric breakdown strength and energy storage density of graphite-polymer composites with dielectric damage process
复制标题
通过介电损伤过程对石墨聚合物复合材料的介电击穿强度和储能密度进行建模
DOI：
10.1016/j.matdes.2020.108531
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发表时间：
2020
影响因子：
8.4
通讯作者：
George J.Weng
中科院分区：
文献类型：
--
作者：
Xiaodong Xia;Bai-Xiang Xu;Xiazi Xiao;George J.Weng
最近的实验数据表明，石墨体积浓度对石墨-聚合物复合材料的介电击穿和储能行为有显著影响，但目前还没有建立均匀化理论来解释在交流负载下这种依赖关系。本文提出了一种新的均匀化方案，将组成相的微观结构参数和交流频率与整体复合材料的介电击穿强度和储能密度联系起来。主要的微观结构特征包括石墨体积浓度、不完全成键效应、石墨长径比、渗透阈值、与填充物相关的电子隧穿、麦克斯韦-瓦格纳-西拉极化、与频率相关的电子跳变和介电弛豫。建立了一个描述介电损伤参数随电场变化的热力学框架。我们通过石墨/PVDF复合材料在石墨体积浓度和交流频率范围内的实验数据验证了所开发的理论。结果表明，石墨-聚合物复合材料的介电击穿强度随石墨体积浓度的增大而减小，而储能密度随石墨体积浓度的增大而增大。
Recent experimental data has demonstrated significant influences of graphite volume concentration on the dielectric breakdown and energy storage behavior of graphite-polymer composites, but no existing homogenization theory has been established to illustrate such dependence in the context of alternating current (AC) loading. In this paper we develop a novel homogenization scheme to connect the microstructural parameters of constituent phases and the AC frequency to the dielectric breakdown strength and energy storage density of the overall composite. The major microstructural features covered are the graphite volume concentration, imperfect bonding effect, graphite aspect ratio, percolation threshold, filler-dependent electron tunneling, Maxwell-Wagner-Sillars polarization, and frequency-dependent electron hopping and dielectric relaxation. A thermodynamic framework is developed to describe the evolution of a dielectric damage parameter with respect to the electric field. We highlight the developed theory with validation through the experimental data of graphite/PVDF composite over a wide range of graphite volume concentration and AC frequency. The results indicate that the dielectric breakdown strength of the graphite-polymer composite decreases with respect to the graphite volume concentration, while the energy storage density increases with it.