In all prior electromagnetic modeling studies of carbon nanotube (CNT) composites, the exact three-dimensional (3D) shape and spatial distribution of the CNTs in the composite were unknown. Therefore, simplifying assumptions had to be made regarding the CNT distributions. The effect of such assumptions on the electromagnetic response of CNT composites has not been quantified. Recent advances in electron-tomography and image analysis have allowed the generation of 3D maps of multi-walled carbon nanotube (MWCNT) distributions with sub-nanometer resolution. In this work, the electromagnetic responses of experimentally mapped 3D structures of aligned-CNT polymer nanocomposites were calculated using both full-wave electromagnetic solvers and dilute-limit Effective Medium Approximations (EMA). Our results show that the electromagnetic response calculated using the full-wave solver exhibits additional resonances that are absent in the response calculated using the dilute-limit EMA. This difference is due to the strong electromagnetic coupling between adjacent MWCNTs, within five CNT radii, of each other. Using the mapped 3D MWCNTs, we also studied the anisotropy in the electromagnetic response of the composites and showed that it increases with the MWCNT volume fraction. The full-wave analysis presented in this work provides a more accurate understanding of the electromagnetic reflection and anisotropy of CNT composites.

中文翻译：

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用3-D层析透射电子显微镜表征碳纳米管复合材料的电磁散射特性

在所有先前的碳纳米管（CNT）复合材料电磁建模研究中，碳纳米管在复合材料中的确切三维（3D）形状和空间分布都是未知的。因此，必须对CNT分布进行简化假设。这些假设对CNT复合材料的电磁响应的影响尚未量化。电子断层扫描和图像分析的最新进展已允许生成亚纳米级分辨率的多壁碳纳米管（MWCNT）分布的3D图。在这项工作中，使用全波电磁求解器和稀释极限有效介质近似（EMA）来计算对齐的CNT聚合物纳米复合材料的实验映射3D结构的电磁响应。我们的结果表明，使用全波求解器计算出的电磁响应表现出了额外的共振，而使用稀释极限EMA计算出的响应中却没有。该差异是由于彼此相邻的CNT在五个CNT半径之内的强电磁耦合造成的。使用映射的3D MWCNT，我们还研究了复合材料电磁响应中的各向异性，并显示其随MWCNT体积分数的增加而增加。这项工作中提出的全波分析提供了对CNT复合材料的电磁反射和各向异性的更准确的了解。彼此在五个CNT半径之内。使用映射的3D MWCNT，我们还研究了复合材料电磁响应中的各向异性，并显示其随MWCNT体积分数的增加而增加。这项工作中提出的全波分析提供了对CNT复合材料的电磁反射和各向异性的更准确的了解。彼此在五个CNT半径之内。使用映射的3D MWCNT，我们还研究了复合材料电磁响应中的各向异性，并显示其随MWCNT体积分数的增加而增加。这项工作中提出的全波分析提供了对CNT复合材料的电磁反射和各向异性的更准确的了解。