Research On The Synthesis And Electromagnetic Wave Absorbing Properties Of Carbon Nanofiber Composites By Electrospinning

In recent years,carbon nanofibers have been utilized as excellent microwave absorbing materials due to its one-demensional structure,good conductivity and lightweight.Among the varied methods for the synthesis of carbon nanofibers,electrospinning is quite easy and mature.In this manuscript,we achieved a series of caobon nanofibers absorbents.The structure-activity relationship between microstructure,one-dimensional morphology,electromagnetic parameters and microwave absorption was studied.These nanofibers show great microwave absorption abilities with smaller matching thickness.And the main research results are given as below:?1?Firstly,in this experiment,the content of PAN is constant.The morphology of the PAN nanofibers has been modified by different contents of PVP.After heated at 800 ^oC under N₂armosphere,we obtained the carbon nanofibers.This kind of nanofibers have many contact points,which helps build a conductive network.Based on this special nanostructure,our carbon nanofibers show excellent microwave absorption abilities.Specifically,the RL_min value is-51.3 dB at 15.2 GHz and the effective band width is 5.1 GHz when the matching thickness is only 1.8 mm.?2?Secondly,in order to decrease the density of the carbon nanofibers and extend the effective frequency bandwidth of the carbon nanofibers,this experiment introduces a porous structure into carbon nanofibers,which can also enhance its attenuation abilities.Based on the facts that the Zn-based MOF?ZIF-8?would become into a porous structure,we inserted ZIF-8 nanoparticles into the precursor solution.So,the ZnO/C porous nanofibers could be got after the high-temperature anealling.The porous structures of the materials are evenly distributed inside the carbon nanofibers,and the nanofibers stack with each other to form a conductive network.When the filler ratio is only20%,the effective band width value can reach to 5.64 GHz at the thickeness of 2.5 mm.The facts imply these nanofibers have obvious application prospect of light-weight absorbers.?3?Finally,we designed and synthesized FeNi/C nanofibers,which can not only ensure enhanced magnetic and interfacial polarization loss,but also chemical stability of inner alloy particles.Carbonization time has a great influence on the morphology of FeNi/C nanofibers,thus affecting electromagnetic parameters and wave absorption performance.After 6 h at 700 ^oC,as-prepared samples own effective frequency bandwidth of 4.4 GHz at the thickness of 1.8 mm and RL_min value of-24.8 dBat the thickness of 2.7 mm.However,the reflection loss of the irregular FeNi/C composites did not reach-10 dB.Compared with the irregular FeNi/C composites,we believe that the one-dimensional structure of carbon nanofibers does do great help for microwave absorption perfoemance.Generally speaking,we designed a series of one-dimansional carbon nanofibers composites and we studyed the effect of the microstructures of carbon nanofibers on the electromagnetic and the absorbing properties.When with smaller matching thickness and samller filler ratio,carbon nanofibers absorbers with broader effective aborption frequency were achieved.The nanostructures of carbon nanofibers can be effectively regulated,which indicates the directions for the light-weight absorbers by electrospinning.