Invention of Electromagnetic-wave Absorbing Composites Utilizing Bicontinuous Polymer Structure and Percolation of Nano-carbons

本研究的目的是发明一种在GHz波段具有上级吸收能力的电磁波吸收复合材料。利用聚合物共混物的相分离结构和交联网络的优选链长，形成纳米碳颗粒网络。导电性和电磁波吸收性通过网络的形成而极大地增强。结果表明：1）乙炔黑（AB）聚集团簇的形状各异，在阈值附近呈现非分形结构;通过在多晶硅中长时间退火（甲基丙烯酸甲酯）的加入，可使AB的分散阈值降低到22 vol %; 2）利用平均网络链长与AB直径相当的硅橡胶可控制AB的分散; 3）在高密度聚乙烯（HDPE）/聚丙烯（PP）共混物的双连续结构中，气相生长碳纤维（VGCF）在HDPE相中的选择性位置使其导电阈值降低，电导率提高在PMMA基体中加入极少量的HDPE，HDPE链吸附在VGCF端部的粗糙表面上，在VGCF的电取向过程中，VGCF的表观介电常数和损耗因子随时间的增加而增加，而VGCF的介电常数和损耗因子随时间的增加而增加。反应性硅酮。

The objective of the present study is to invent electromagnetic-wave absorbing composites which show superior absorptive power in GHz band Network of nano-carbon particles is formed, utilizing phase separated structure of polymer blends and preferred strand length of cross-linked network. Electrical conductivity and electromagnetic-wave absorbance are extremely enhanced by formation of the network. More than 95% absorbance of electromagnetic-wave in GHz band is achieved for the following composites at concentration slightly higher than (or equal to) each threshold.1) Aggregated clusters of acetylene black (AB) takes various shapes, resulting in non-fractal structure near the threshold. By long time annealing in poly (methyl methacrylate), the threshold becomes as low as 22vo1%.2) Dispersion control of AB can be made utilizing silicon rubber with average network strand length comparable with diameter of AB.3) In bicontiuous structure of high density polyethylene (HDPE)/polyjappylene (PP) blend, selective location of vapor grown carbon fibers (VGCF) in HDPE phase results in decrease of threshold and enhancement of electrical conductivity compared with those in HDPE or PP.4) With addition of very small amount of HDPE to PMMA matrix, HDPE chains adsorb onto rough surface of VGCF ends, contributing to connectivity of VGCF and thus to enhancement of electrical conductivity and electromagnetic wave absorbance.The apparent dielectric constant and loss factor increased with time during the electrical orientation process of VGCF suspended in reactive silicone.