Preparation And Microwave Absorption Properties Of Polypyrrole And Its Derived Carbon Composites

With the increase of electronic equipment,our bodies are exposed to electromagnetic waves frequently.Microwave absorbing materials are gradually used from the field of military industry into the field of daily life.Traditional microwave absorbing materials are heavy in weight and narrow in absorption frequency band,which have some limitations in application.At present,the purpose is to prepare new absorbing materials which are"thin,light,wide and strong".In this paper,polypyrrole and its derived carbon composites were prepared by compounding conductive polymer and its derived carbon with dielectric and magnetic materials.The structures,morphologies and microwave absorbption properties of the composites were studied.The details are as follows:(1)3D flower like molybdenum disulfide(MoS₂)was synthesized by microwave-assisted synthesis under the action of surfactant,then coated it with polypyrrole by chemical oxidation.The thickness of polypyrrole layer was controlled by controlling the amount of pyrrole monomer.When the amount of pyrrole monomer was 100?L,polypyrrole was uniformly coated on the surface of MoS₂ with a thickness of about 1?m,and there was no obvious self aggregation phenomenon.MoS₂@100 py can obtain the strongest microwave absorption performance.When the sample filling ratio is 50%,the reflection loss is up to-61.1 dB at 11.2 GHz,the effective absorption bandwidth(RL<-10 dB)is 4.3 GHz.(2)Tubular polypyrrole was synthesized by chemical oxidation method using methyl orange as template.A series of N-C/MoS₂ composites were prepared by microwave-assisted synthesis and high-temperature calcination method using polypyrrole as substrate.The impedance matching characteristics of the system can be adjusted for the existence of MoS₂and make the composites obtain better microwave absorption properties.When the ratio of polypyrrole to MoS₂ is 1:5,the N-C/M3 sample has a strong reflection loss performance,the filling ratio is reduced to 30%,the minimum reflection loss of-53.9 dB can be obtained at low frequency(6.6 GHz),and the maximum effective absorption bandwidth(RL<10 dB)is 3.9 GHz.(3)Tubular polypyrrole derived carbon was prepared,and then Fe₃O₄ nanoparticles were synthesised on its surface.The magnetic loss ability of Fe₃O₄ was excellent as ferrite material.Three samples were prepared by controlling the amount of carbon material.In the sample with C:Fe₃O₄ ratio of 1:3,Fe₃O₄ is more evenly distributed on the surface of carbon nanotubes.The addition of Fe₃O₄ can better coordinate the impedance of the composite and improve the microwave absorption performance of the system.When filling ratio is 30%,the ability to absorb low-frequency electromagnetic waves is strong.At 7.02 GHz,the minimum reflection loss is-50.4 dB;When thickness is 1.7 mm,maximum effective absorption bandwidth(RL<-10 dB)can be 4.0 GHz.