Electromagnetic Microwave Absorption Performances of Aminated Carbon Fibers

Abstract

Here we reported the effect of the amination of the brominated polyacrylonitrile carbon fibers (PAN CFs) on the efficiency of absorption of electromagnetic radiation studied for the X- and Ka-bands. The fiber modification was carried out by bromination with bromine liquid followed by amination with one of the amines: ethylenediamine (En), sulfolanylethylenediamine (SuEn), diethylamine (Et2N), monoethanolamine (MEA), and piperazine (Py). The amination caused the replacement of attached bromine groups with amino groups. The thermal desorption properties of the prepared PAN CFs were investigated using TGA and TPD MS methods. Thermal desorption of the products of amino groups decomposition from the surface of PAN CFs ranges from 140 to 415 °C with maxima at 240–258 °C depending on the modifying amine and the surface concentration of the amino groups. For the X-band, the type of amine used is not of significant importance, and the value of the absorption for electromagnetic radiation does not exceed −18 dB. In the Ka range, the brominated PAN CFs modified with Py, En, and SuEn reduce the electromagnetic radiation by about −19 dB, −23 dB, and −28 dB, correspondingly. From all the above, it is clear that the brominated PAN CFs modified with amines have a perspective for use as a protective material against the harmful effects of electromagnetic radiation on biological tissues in the Ka-band frequency range. By choice of amine modifier, the absorption magnitude can be regulated when forming a surface protective-and-absorptive layer.