Preparation, Characterization And Microwave Absorbing Properties Of Silicon Carbide Modified By Polyaniline Composites

The increasing electromagnetic radiation and the development of stealthytechnique promote the study of the microwave absorbing materials. In recent years,polyaniline (PANI) has been widely used in compositing and modifying the traditionalinorganic microwave absorbing materials due to its low density, controllableconductivity, environmental stability, rather simple synthesis and various applications.Thus， in the present study PANI/SiC composites were prepared by emulsionpolymerization in order to improve the microwave absorption property and widen theabsorption bandwidth.In this study, polyaniline (PANI)/silicon carbide (SiC) composites were preparedfor the first time by emulsion polymerization using sodium dodecylbenzene sulfonate(SDBS), ammonium persulfate(APS) as emulsifier and oxidant, respectively. And theeffect of the molar ratio of SDBS to An, APS to An, SiC to An and the reaction time onthe cyclic voltammetry curves, tafel curves, conductivity and yield for PANI/SiCcomposites were discussed. The structure and micro-morphology of PANI andPANI/SiC composites were characterized by UV-Vis, FTIR, XRD and SEM. Thethermal stability was tested by TGA. The electromagnetic parameters and microwaveabsorbing properties were measured by vector network analyzer (VAN) at26.5-40GHz.The experimental results indicated:①The effect of concentrations of SDBS, APS,and the reaction time on electrochemical properties and yield of PANI/SiC compositeswas discussed. When the molar ratio of SDBS to An is1:1, the molar ratio of APS to Anis1:1and the reaction time is12h, the peak current of cyclic voltammetry, corrosionpotential, conductivity and yield for PANI/SiC composites were higher. And when themolar ratio of SiC to An is5:1, the microwave absorbing properties were better.②Thestructure and morphology of the composites were characterized by UV-Vis spectroscopy(UV-Vis), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) andscanning electron microscope (SEM). The UV-Vis, FTIR and XRD results indicated thatthere existed an interaction between PANI molecules and SiC particles. The SEMresults indicated that SiC particles were covered with the conducting polyaniline. TheTGA test manifested that the thermal stability of PANI/SiC composites was much betterthan PANI.③Microwave absorbing properties were investigated by measuringelectromagnetic parameters at26.5-40GHz. The results showed that the real part and imaginary part of complex permittivity, the imaginary part of complex permeability,dielectric loss and magnetic loss were improved after modified by PANI. Moreover, thereflection loss of PANI/SiC composites exhibited significant improvements comparedwith pure SiC. A maximum reflection loss at38.6GHz increased3times with athickness of0.9mm for the composites and the effective absorption band under-10dBreached6.2GHz.Obviously, silicon carbide composites were modified by PANI, the absorptionefficiency was significantly improved, the absorption band was also broadened, and theweight was lightened. This provides a way for the study on “thin, light, wide, strong”high-performance microwave absorbing materials.