Preparation And Electromagnetic Shielding Properties Of Ferrite-Graphite Nanosheet Hybrid Particle/Polyaniline Modified Polyester Composite Fabric

With the rapid development of the information technology,the negative impact of electromagnetic wave cannot be ignored.It brings many hidden dangers to people’s health,information security and military security.In terms of military security,electromagnetic wave reflection is not conducive to reconnaissance stealth.Due to its high conductivity,existing electromagnetic shielding materials have strong reflection on electromagnetic wave,which increases secondary pollution of electromagnetic wave and is not conducive to the“stealth”of military targets.Therefore,materials with“low reflection and high absorption”are conducive to reducing the negative impact of electromagnetic wave.Graphene is one of the most popular electromagnetic shielding materials due to its light weight,corrosion resistance and good electrical conductivity.However,graphene has some shortcomings such as difficult dispersion,high cost and high reflectance of electromagnetic wave.The hybrid of graphene and magnetic particles can effectively improve the impedance matching between materials and electromagnetic wave and improve the absorption of electromagnetic wave.Graphite nanosheets（GNS）,as“graphene-like”materials,have similar electromagnetic shielding properties and lower cost compared with graphene.Hybridized magnetic particles and graphite nanosheets and constructed gradient structures in a certain sequence are conducive to the fusion of shielding and absorbing,thus obtaining a multifunctional electromagnetic shielding material.In view of this,this paper firstly studied the surface conductivity changes of the modified polyester fabric by in-situ polymerization modified by polyaniline（PANI）under different amounts of doping acid,initiator and aniline.Then,the flake graphite was prepared by the method of chemical oxidation intercalation,thermal expansion and ultrasonic stripping.The influence of specific gravity of GNS on the electromagnetic shielding and absorbing properties of the modified fabric was studied,and the sample with the best comprehensive shielding performance was determined to be GNS/PANI modified polyester fabric with specific gravity of 16wt%GNS.In order to control the electromagnetic parameters of fabric surface,the hybrid particles of Ni Fe₂O₄ and Fe₃O₄ and GNS were prepared by hydrothermal method and coprecipitation method,respectively.The influence of changing the feeding ratio of magnetic material and GNS on the structure composition,morphology and electromagnetic characteristics of hybrid particles was studied.The results show that when Ni Fe₂O₄:GNS is 1:1 and Fe₃O₄:GNS is 1:2,the minimum reflection loss（RL）are-14.2 d B and-55.1 d B,and the effective absorption bandwidth（EAB）are6.4 GHz and 2.8 GHz,respectively.Finally,GNS coating and magnetic hybrid particle coating were successively coated on the surface of PANI modified polyester fabric to prepare Ni Fe₂O₄@GNS coating/GNS coating/PANI modified polyester fabric（NGGP）and Fe₃O₄@GNS coating/GNS coating/PANI modified polyester fabric（FGGP）with conductive and magnetic gradient structure composite fabric,the electromagnetic shielding efficiency（SE_T）are 22.3 d B and 18.2 d B,RL are-51.6 d B and-58.4 d B,respectively.Because of the unique multiple reflection and absorption mechanism of“absorption-reflection-absorption”,the composite fabric can improve the absorption of electromagnetic wave,and show excellent tensile strength,washable resistance,bending performance and one side hydrophobic characteristics,so it has great application prospects.