Institute of Polymers, Composites and Biomaterials, National Research Council, P.le Fermi, 1-80055 Portici, NA, Italy.
Nanoscale. 2019 Jan 17;11(3):1011-1020. doi: 10.1039/c8nr07351a.
Natural rubber/carbon nanotubes composite foams (F-NR/CNTs) with high electrical conductivity and excellent electromagnetic interference (EMI) performance were developed through a multi-step process including: (a) CNTs assembled on natural rubber latex particles, (b) pre-crosslinking of natural rubber, (c) supercritical carbon dioxide foaming of pre-crosslinked composite samples and (d) post-crosslinking of foamed composite samples. A closed-cell porous structure and a segregated CNT network are clearly observed in the resulting foams. Due to this morphology, F-NR/CNTs exhibit low density, good mechanical properties, and high electrical conductivity. Owing to the multiple radiation reflections and scattering between the cell-matrix interfaces, the composite foams presented an excellent specific shielding effectiveness (SSE) of 312.69 dB cm2 g-1 for F-NR/CNTs containing 6.4 wt% of CNTs, which is significantly higher than those already published for rubber composites containing comparable filler content. Furthermore, the analysis of EMI SE highlights that absorption efficiency is more significant than reflection efficiency, implying that most of the incident electromagnetic radiation is dissipated in the form of heat. This work provides the fundamentals for the design of innovative light weight and efficient EMI shielding foams characterized by a three-dimensional segregated CNT network with huge potential for use in the electronics and aerospace industries.
天然橡胶/碳纳米管复合泡沫（F-NR/CNTs）具有高导电性和优异的电磁干扰（EMI）性能，通过包括以下步骤的多步工艺制备：（a）将 CNTs 组装在天然橡胶胶乳颗粒上，（b）对天然橡胶进行预交联，（c）对预交联的复合材料样品进行超临界二氧化碳发泡，以及（d）对发泡的复合材料样品进行后交联。在得到的泡沫中可以清楚地观察到闭孔多孔结构和分离的 CNT 网络。由于这种形态，F-NR/CNTs 表现出低密度、良好的机械性能和高导电性。由于在胞-基质界面之间存在多次辐射反射和散射，含有 6.4wt% CNTs 的 F-NR/CNTs 复合材料泡沫表现出优异的特定屏蔽效能（SSE）为 312.69 dB cm2 g-1，明显高于已发表的含有可比填充含量的橡胶复合材料的 SSE。此外，对 EMI SE 的分析表明，吸收效率比反射效率更重要，这意味着大部分入射的电磁辐射以热的形式耗散。这项工作为设计创新的轻质和高效 EMI 屏蔽泡沫提供了基础，这些泡沫具有巨大潜力，可用于电子和航空航天行业，其特点是具有三维分离的 CNT 网络。
