Carbon nanotube films (BPs) as EMI shielding materials can be applied in electronic and communication devices due to their high electrical conductivity. Sandwich structures can offer excellent shielding effectiveness by introducing a wave-transmitting layer between conductive films. However, the optimization of the structure demands a deep investigation and plays a crucial role in the final shielding properties of the composites. In this work, BPs are incorporated into epoxy substrates with variable thicknesses (1–6 mm) to fabricate epoxy/BP sandwich structures. The morphology of the CNT films is analyzed by SEM, and the electrical conductivity of all prepared samples is measured by 4-point method. The electromagnetic tests are carried out in the X-band (8.2–12.4 GHz) through the scattering parameters. SEM images reveal a porous structure without visible agglomeration. The electrical conductivity of the BP reaches up to 996 S/m, whereas the values for epoxy/BP composites varies in the range of 8.51–3.13 S/m (1 to 3 mm). BP total shielding efficiency (SE_T) is approximately 14 dB along the X-band spectrum, with similar contributions of reflection and absorption losses. While, the composites show mainly absorbing behavior, especially in the thicker samples, with more significant SE_T values (23.4 dB–6 mm).

中文翻译：

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透明层厚度对环氧树脂/碳纳米管巴克纸X波段吸收能力的影响

碳纳米管薄膜 (BPs) 作为 EMI 屏蔽材料，由于其高导电性，可应用于电子和通信设备。通过在导电膜之间引入透波层，三明治结构可以提供出色的屏蔽效果。然而，结构的优化需要深入研究，并且在复合材料的最终屏蔽性能中起着至关重要的作用。在这项工作中，BP 被结合到具有可变厚度（1-6 毫米）的环氧树脂基板中，以制造环氧树脂 / BP 夹层结构。通过SEM分析CNT薄膜的形貌，并通过4点法测量所有制备样品的电导率。通过散射参数在 X 波段 (8.2-12.4 GHz) 中进行电磁测试。SEM 图像显示多孔结构，没有可见的团聚。BP 的电导率高达 996 S/m，而环氧树脂/BP 复合材料的电导率在 8.51–3.13 S/m（1 到 3 mm）的范围内变化。BP 总屏蔽效率 (SE_T ) 沿 X 波段频谱约为 14 dB，反射和吸收损耗的贡献相似。同时，在复合材料展主要吸收行为，特别是较厚的样品中，与更显著SE _Ť值（23.4分贝-6毫米）。