Li Zhonglei, Su Jingang, Du Boxue, Hou Zhaohao, Han Chenlei
Key Laboratory of Smart Grid of Education Ministry, School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China.
Nanomaterials (Basel). 2018 Nov 20;8(11):956. doi: 10.3390/nano8110956.
Space charge injection and accumulation is attracting much attention in the field of dielectric insulation especially for electronic devices, power equipment and so on. This paper proposes using the inhibition effect of graphene for the injection and accumulation of space charge in low-density polyethylene (LDPE). Scanning electron microscope (SEM) and transmission electron microscopy (TEM) images were employed to observe the dispersion of graphene with a two-dimensional structure in LDPE. The time-dependent space charge dynamic behaviors of graphene/LDPE nanocomposites with the filler content of 0, 0.003, 0.005, 0.007 and 0.01 wt % were characterized by the pulsed electro-acoustic (PEA) test at 40, 60 and 80 °C, and the charge mobility was evaluated by its depolarization processes. The experimental results show that for the undoped LDPE film, large amounts of space charges were injected from the electrodes into samples, especially at 60 and 80 °C. The graphene/LDPE nanocomposites with a filler content of 0.005 wt % could markedly suppress the space charge injection and accumulation even at 80 °C, which is attributed to the large quantities of graphene-polymer in interface regions. These interface regions introduced numbers of deep trap sites within the forbidden band of nanocomposites, which can reduce the de-trapping rate of charges and suppress the space charge accumulation in the polymer bulks. The graphene/LDPE nanocomposites are suggested for dielectric applications, intending the inhibition of space charge injection and accumulation.
空间电荷注入与积累在介电绝缘领域备受关注，尤其是对于电子设备、电力设备等。本文提出利用石墨烯对低密度聚乙烯（LDPE）中空间电荷注入与积累的抑制作用。采用扫描电子显微镜（SEM）和透射电子显微镜（TEM）图像来观察具有二维结构的石墨烯在LDPE中的分散情况。通过脉冲电声（PEA）测试对填料含量分别为0、0.003、0.005、0.007和0.01 wt%的石墨烯/LDPE纳米复合材料在40、60和80°C下的随时间变化的空间电荷动态行为进行了表征，并通过其去极化过程评估了电荷迁移率。实验结果表明，对于未掺杂的LDPE薄膜，大量空间电荷从电极注入到样品中，尤其是在60和80°C时。填料含量为0.005 wt%的石墨烯/LDPE纳米复合材料即使在80°C时也能显著抑制空间电荷的注入与积累，这归因于界面区域大量的石墨烯-聚合物。这些界面区域在纳米复合材料的禁带内引入了大量深陷阱能级，这可以降低电荷的脱陷阱速率并抑制聚合物本体中的空间电荷积累。建议将石墨烯/LDPE纳米复合材料用于介电应用，旨在抑制空间电荷的注入与积累。
