Abstract We report on a coordinated experimental and theoretical investigation into the evolution of the morphology of fluid-suspended graphene driven by an electric field, and the attainment of ultra-low percolation threshold in graphene-polymer nanocomposites. A remarkable outcome is that, due to the field-driven graphene rotation and agglomerate chaining, the percolation threshold can be as low as 0.03 vol%, as opposed to the 0.75 vol% without the application of the field. This is likely to be the lowest ever reported for a graphene-polymer nanocomposite. To quantify this and other measured conductivity data, a two-scale effective-medium theory with highly aligned, agglomerated nanofillers is developed. In this process Cauchy's cumulative probability function is introduced to describe the increased level of electron tunneling near the percolation threshold, and a statistical approach based on the projection length of graphene fillers is developed to characterize the agglomerate shape. We also built a kinetic equation from the torque of the applied electric field to calculate the time- and field-dependent rotation of graphene nanoplatelet. The study is highlighted with a direct comparison between the theory and the experiment. It is concluded that the measured ultralow percolation threshold can indeed be achieved through the concurrent graphene rotation and elongation of agglomerate shape toward the field direction.

中文翻译：

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外加电场驱动的流体悬浮石墨烯形态演变的实验和理论研究以及石墨烯-聚合物纳米复合材料中超低渗透阈值的实现

摘要 我们报告了对电场驱动的流体悬浮石墨烯形态演变的协调实验和理论研究，以及石墨烯-聚合物纳米复合材料中超低渗透阈值的实现。一个显着的结果是，由于场驱动的石墨烯旋转和团聚体链，渗透阈值可以低至 0.03 vol%，而不是在没有应用该场的情况下为 0.75 vol%。这可能是石墨烯-聚合物纳米复合材料有史以来报告的最低值。为了量化这个和其他测量的电导率数据，开发了一种具有高度对齐、聚集的纳米填料的两尺度有效介质理论。在这个过程中柯西' 引入了累积概率函数来描述在渗透阈值附近电子隧穿的增加水平，并开发了一种基于石墨烯填料投影长度的统计方法来表征团聚体形状。我们还根据外加电场的扭矩建立了一个动力学方程，以计算石墨烯纳米片的时间和场相关旋转。该研究通过理论和实验之间的直接比较来突出显示。得出的结论是，测量的超低渗流阈值确实可以通过同时发生的石墨烯旋转和团聚体形状向场方向的伸长来实现。我们还根据外加电场的扭矩建立了一个动力学方程，以计算石墨烯纳米片的时间和场相关旋转。该研究通过理论和实验之间的直接比较来突出显示。得出的结论是，测量的超低渗透阈值确实可以通过同时发生的石墨烯旋转和团聚体形状向场方向的伸长来实现。我们还根据外加电场的扭矩建立了一个动力学方程，以计算石墨烯纳米片的时间和场相关旋转。该研究通过理论和实验之间的直接比较来突出显示。得出的结论是，测量的超低渗流阈值确实可以通过同时发生的石墨烯旋转和团聚体形状向场方向的伸长来实现。