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

利用聚合物共混物的相分离结构和交联网络的优选链长，形成纳米碳颗粒的网络。电导率和电磁波吸光度因网状结构的形成而大大提高。以下复合材料在浓度略高于（或等于）各阈值时，对GHz波段电磁波的吸光度均达到95%以上。1)乙炔黑（AB）的聚集团簇形状各异，在阈值附近形成非分形结构。在聚甲基丙烯酸甲酯中长时间退火，阈值低至22vo1%。2)利用平均网链长度与AB直径相当的硅橡胶可以控制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，与HDPE或PP相比，气相生长碳纤维（VGCF）在HDPE相中的选择性位置导致阈值降低，电导率提高。4）在PMMA基体中添加极少量的HDPE，HDPE链吸附在VGCF末端的粗糙表面，有助于VGCF的连通性，从而提高电导率和电磁波吸光度。VGCF悬浮在活性有机硅中的电取向过程中，视介电常数和损耗因子随时间的增加而增加。

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.