Study On The Carbon Nanotube Chemically Modified Carbon Fiber And Its Electromagnetic Properties

In the era of rapid development of science and technology, electromagnetic waves is full of ours life, but the complex electromagnetic environment caused a great threat to human beings. In order to effectively suppress and prevent all kinds of harm caused by electromagnetic wave, people have taken corresponding measures. Through the comparison, it is found that the best measure is use wave absorbing materials. Because of the excellent properties of Carbon nanotube(CNT) and carbon fiber(CF), have been widely used in radar absorbing composites. But the carbon nanotube/carbon fiber composite faces some problems, such as CF have a small surface area, poor surface polarity intensity, lack of surface active groups and other shortcomings, resulting in poor performance of its interface, influnce its excellent characteristics; CNT easily aggregate in the matrix; poor interfacial adhesion with CNT/CF composite. So,it’s a concern of task that develop the advantage of carbon nanotube/carbon fiber composites to achieve better absorbing performance.This paper mainly study on the carbon nannotubes chemically modified carbon fiber and it’s electromagnetic peoperties and explore its absorbing properties. Mainly launched the following work:(1) In view of the poor performance of CF surface, the surface treatment of CF is carried out in this paper. Includes that acid oxidation treatment and ammoniation, after acid oxidation treatment of carbon fiber surface roughness were increased, and the higher concentration of oxidizing acid the deeper groove on the CF surface, at the same time, develop hydroxyl and carboxyl functional groups in CF surface; Though aminated CF surface rough degree did not change,appear amino functional groups in the surface.(2) The surface modification of CNT by acid oxidation, to alleviate the CNT agglomerate phenomenon. After the modification of CNT, the aggregation of CNT was alleviated, and the infrared spectrum analysis(FTIR) showed that the hydroxyl group, carboxyl group and other oxygen functional groups were generated on the CNT surface.(3)In order to improve the interfacial properties of composites, prepared CNT/CF composite materials by chemical grafting method. It was found that for acid oxidation of CF, when CNT and CF reaction time is 8h, the most number of CNTs in the 65%-CF surface and no agglomeration; For ammoniation CF, the number of CNTs is most in 24 h. The curves of electromagnetic parameters of CNT/CF composites were analyzed. It was found that the difference of CF surface treatment method and the grafting time had influence on the dielectric constant of CNT/CF composites.(4) To simulate the reflectivity of CNT/CF composites using MATLAB software. Simulation results show that when the reaction time is 8h and the thickness is 1.5mm, the 65%-CF/CNT composite absorption effect of the best, in 14.6GHz to 17.7GHz band the reflectivity R≤-10 dB, which at16 GHz the reflectivity reached the maximum value R=-35.2dB.In summary, through surface modification of CF and CNT, the surface morphology and electromagnetic parameters of the curve occurred corresponding changes, the CNT/CF composite absorbing performance has also been improved.