Preparation And Microwave Absorbing Properties Of Carbon Nanotubes/Co_0.5Ni_0.5Fe₂O₄/Polyaniline Nanocomposites

The study of microwave absorbing materials applying to military stealth,information and environment protection is an important research project. The challenge in absorber technology is to produce lowcost absorbers with strong, wide, thin, light, corrosion resistant. However, no single kind of absorbent could meet all the requirements. The composite of several absorbents is considered to be the best microwave absorption materials.In this paper, considering the ferrite magnetic loss, polyaniline (PANI) and carbon nanotubes(MWCNTs) dielectric loss,and their respective physical and chemical properties, nano inorganic/PANI composites were primarily prepared by the in-situ polymerization. The phase structure,morphology, thermal stability and absorbing properties of the products were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Vector Network Analyzer,respectively.The results were as followed:(1) MWCNTs/PANI nanocomposites could be prepared by the in-situ polymerization, the outer diameter of synthesized nanocomposites were50-80nm, the thermal stability of the nanocomposites was enhanced compared with PANI.With the addition of3wt%nano-inorganic, the polymerization time and temperature were6h and20℃, the coating thickness was1.5mm.the samples have the best impedance matching in the frequency range from2to18GHz,but the electromagnetic loss was small.(2)Coo.5Nio.5Fe204/PANI nanocomposites with core-shell structure could be prepared by the in-situ polymerization, the particle diameter of nanocomposites was about100nm, and the polyaniline coating layer have some influence on crystallinity of Coo.5Nio.5Fe2O4;the thermal stability of the nanocomposites were enhanced compared to PANI.With the addition of40wt%Coo.5Ni0.5Fe204, the polymerization time and temperature were6h and20℃. the samples have the best impedance matching in the frequency range from2to18GHz,but the electromagnetic loss was small. The influence of ferrite types on the absorbing properties of ferrite/PANI nanocomposites were studied,compared with CoFe2O4/PANI nanocomposites and Nio.5Zno.5Fe2O4/PANI nanocomposites, the microwave absorbing properties of Co0.5Ni0.5Fe204/PANI nanocomposites is better..(3)MWCNTs/Coo.5Ni0.5Fe204nanocomposites were prepared by the sol-gel method, MWCNTs/Coo.5Nio.5Fe2O4/PANI nanocomposites were prepared by the in-situ polymerization. XRD, FTIR and TGA results confirmed the existence of MWCNTs/Coo.5Nio.5Fe2O4/PANI there existed chemical bonds between the two; XRD, FTIR and TGA results confirmed the existence of MWCNTs/Coo.5Nio.5Fe2O4/PANI and the chemical bonds between them;and the thermal stability of the nanocomposites was enhanced compared with PANI.With the addition of MWCNTs was7wt%,the addition of MWCNTs/Coo.sNio.sFe2O4was30wt%, the polymerization time was6h, the polymerization temperature was20℃, the samples have the best microwave absorbing properties in the frequency range from2to18GHz. Ternary complex were respectively prepared through simple blending,solution blending and the in-situ polymerization,respectively,the microwave absorbing properties of the nanocomposites obtained by the in-situ polymerization was the best.