Study On The Preparation And Electromagnetic Shielding Performance Of Graphene@Carbon Felt Composite

With the rapid development of science and technology,the new generation of electronic intelligent devices continue to trend toward miniaturization and high-frequency.These electronic products take people's work and life more convenient,but the electromagnetic radiation pollution is increasingly serious by many electronic components,which not only affects the performance of precision devices,but also threatens the health of human beings.To tackle this problem,various EMI shielding materials have been used in the field of EMI shielding.Conductive Polymer Composites(CPCs)have received extensive attention and become ong of the most promising electromagnetic shielding materials due to their light weight,good molding properties,chemical resistance,excellent processability,and low cost.However,traditional CPCs usually require high filler content and large shielding thickness to obtain the desired electromagnetic shielding effectiveness(EMI SE),which largely limits their practical applications.Therefore,the design and fabrication of CPCs with low filler content and high electromagnetic shielding effectiveness has urgent theoretical significance and potential application prospects.In order to meet the development trend of "low cost and high absorption strength" of electromagnetic shielding materials,In this paper,we first used a simple and efficient impregnation process to attach graphene(GNs)to the surface of carbon felt(CF),and successfully prepared GNs@CF three-dimensional conductive skeletons with different graphene contents,Then the GNs@CF/EP-CE composites were obtained by curing the epoxy-modified cyanate precursors(EP-CE)introduced by a vacuum impregnation process.The microstructure and electromagnetic shielding effectiveness(EMI SE)of GNs@CF/EP-CE composites were investigated by scanning electron microscopy(SEM)and vector network analysis.It was found that due to the multi-sheet layer structure of GNs folds,GNs formd a dense conductive network on the surface of the carbon felt,which will experience multiple reflection losses when there is electromagnetic wave transmission from outside,thus effectively enhancing the shielding performance of the composite.When the GNs content is 0.49 wt%,the conductivity of the composite material can reach 10.15 S/m,and its total electromagnetic shielding effectiveness in the X band(8.2?12.4 GHz)is as high as 41.85dB.It is a kind of composite material whose shielding mechanism is absorption.Secondly,due to the impregnation method,a conductive network of GNs can be constructed on the carbon fiber skeleton.the effect of the synergistic effect of multiple materials on the performance of composite materials can be studied by introducing Fe3O4 nanoparticles.The solvothermal method was used to prepare Fe3O4 nanoparticles on the surface of CF and then the GNs were uniformly distributed on the surface of Fe3O4@CF by a simple dipping process,and finally the three-dimensional structure of GNs@Fe3O4@CF/TPU composites were prepared by encapsulation with thermoplastic polyurethane(TPU)solution.The composition and structure of GNs@Fe3O4@CF/TPU were investigated by means of hysteresis lines(VSM),X-ray diffraction(XRD),scanning electron microscopy(SEM),energy spectrum analysis(EDS)and thermal weight loss curves(TGA).The results show that Fe3O4 nanoparticles were successfully prepared and loaded onto the CF surface by the experiment.Because Fe3O4 and GNs make GNs@Fe3O4@CF/TPU compositesl with both magnetic and dielectric losses,coupled with the synergistic effect of both,the prepared composite materials have higher conductivity(24.87 S/m)and excellent shielding effectiveness(49.9 dB).It has potential application prospects in the field of electromagnetic shielding.This work further lays the foundation for the research of three-dimensional structured electromagnetic shielding composites.