Physico-Chemical nanomaterials science

Effect of chlorination on the interaction of carbon fibers with electromagnetic radiation in the ultrahigh-frequency range
Zhytnyk D.O.1, Moiseienko V.A.1, Mischanchuk O.V.2, Matushko I.P.1, Diyuk V.E.1, Grishchenko L.M.1, Boldyrieva O.Yu.1
1 Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska St., Kyiv-01601, Ukraine. liudmyla.grishchenko@gmail.com
2 O.O. Chuiko Institute of Surface Chemistry, NAS of Ukraine, Gen. Naumova St., 17, Kyiv-03164, Ukraine.

Carbon materials are widely used as fillers to prepare composite materials for personal protective equipment and arm protection or can be integrated into stealth technologies [1]. But, there is almost no data on the effect of chemical modification on the nature of the interaction of carbon materials with electromagnetic radiation in the modern literature.
We used commercial carbon fibers (CFs) as starting material in this study. They were prepared by high-temperature carbonization of polyacrylonitrile (PAN) fibers.  This work aims to study the effect of chlorination of PAN CFs on the radio wave absorbing properties of the resulting chlorinated PAN CFs. The chlorination process was performed with carbon tetrachloride vapor in an argon flow at 300 °C, 450 °C, and 600 °C. We investigated the temperature effect on the chlorination process and, therefore, on the chlorine concentration in the chlorinated PAN CFs on the microwave attenuation. We found that added chlorine has a crucial impact on the attenuation of the power of electromagnetic radiation S21 and the reflection coefficient of electromagnetic radiation S11. This statement is true in a wide frequency range for a single layer of the chlorinated PAN CFs, considering that our studies were performed in the ultrahigh-frequency X and Ka bands. We proved that the attenuation magnitude and the reflection coefficient are increased with the chlorine concentration. Besides, their values are constants in a wide range of frequencies. This observation enables the construction of the latest generation of microwave attenuators; their attenuation can be programmed once by the chlorine concentration in the PAN CFs. 

1.	Wu, T., Liu, Y., Zeng, X., Cui, T., Zhao, Y., Li, Y., & Tong, G.. Facile Hydrothermal Synthesis of Fe3O4/C Core–Shell Nanorings for Efficient Low-Frequency Microwave Absorption // ACS Appl Mater Interf. -2016. -8, N 11. -P. 7370-7380.