Preparation And Microwave Absorption Properties Of Magnetic Inorganic Clay/Polyaniline Composites

With the development of the information society,electronic devices have been widely used in civilian and military applications,and the problem of electromagnetic pollution has become increasingly serious.The use of absorbing materials to attenuate electromagnetic waves is an effective method to purify the electromagnetic environment.It is difficult for a single material to meet the requirements of low density,thinness,frequency bandwidth,and strong absorption at the same time.Therefore,the recombination of conductive polymers and inorganic nanomaterials has become one of the research hotspots in the microwave absorption field.Based on the influence of the material structure on the microwave absorption performance,in this paper,three kinds of magnetic inorganic clay/polyaniline composites were prepared by compounding attapulgite（ATP）,halloysite nanotubes（HNTs）and montmorillonite（MMT）with polyaniline（PANI）and Fe₃O₄.The microstructure and composition were characterized by transmission electron microscopy（TEM）,Fourier transform infrared spectroscopy（FT-IR）,X-ray diffractometer（XRD）and scanning electron microscope（SEM）.The electromagnetic parameters and absorbing properties were tested using a vector network analyzer（VNA）.The main contents are as follows:（1）Magnetic Fe₃O₄ nanoparticles were prepared by co-precipitation method,and ATP/PANI/Fe₃O₄ composites with electromagnetic properties were prepared by one-step in-situ polymerization.The effect of the amount of aniline on the microwave absorption properties was studied.The results show that the loss of electromagnetic wave mainly depends on the dielectric loss of the composite material,and the addition of aniline has a great influence on the dielectric loss.When the mass ratio of aniline to attapulgite is 3:2,the minimum reflection loss reaches-22.2 d B at 6.32 GHz,the corresponding matching thickness is 5.0 mm,and the bandwidth of less than-10 d B is2.32 GHz（5.36⁷.68 GHz）.When the matching thickness is 2.5 mm,the bandwidth less than-10 d B in the Ku band can reach 4.16 GHz（12.16¹6.32 GHz）,which makes ATP/PANI/Fe₃O₄ composites composite material has potential application value in the microwave absorption field.（2）The HNTs/PANI composites were prepared by polymerizing aniline onto the surface of HNTs,and HNTs/PANI/Fe₃O₄ composites were prepared by co-precipitation method with Fe₃O₄.Using HCl for secondary doping,we studied the effect of different dopingconcentrationsonthemicrowaveabsorptionproperties.After HNTs/PANI/Fe₃O₄ composites were doped with HCl,the microwave absorbing properties were significantly improved.When the doping concentration is 0.50 M,the minimum reflection loss reaches-45.3 d B at 7.04 GHz,the corresponding matching thickness is 4.0 mm,and the bandwidth below-10 d B is 2.4 GHz（5.92⁸.32 GHz）.When a matching thickness is 2.0 mm,the absorbing bandwidth o is 4.32 GHz（13.12¹7.44 GHz）.This indicates that adjusting the doping concentration of hydrochloric acid can change the electromagnetic parameters and make the HNTs/PANI/Fe₃O₄ composite material get the best microwave absorbing performance.（3）MMT/PANI composites were obtained by in-situ polymerization,using MMT as matrix,and MMT/PANI/Fe₃O₄ composites were prepared by mechanically blending Fe₃O₄ with MMT/PANI composites.The effect of the mass ratio of MMT and aniline on the microwave absorption properties was studied.As the matching thickness increases,the reflection loss peak moves toward a lower frequency.When the mass ratio of MMT to aniline is 2:3 and the matching thickness is 4.5 mm,the minimum reflection loss can reach-43.2 d B at 6.48 GHz,and the bandwidth below-10 d B is 2.24GHz（5.36⁷.6 GHz）.In addition,the factors affecting the microwave absorbing properties of MMT/PANI/Fe₃O₄ composites include natural resonance,eddy current loss,interface relaxation process,and interference cancellation principle.