| Nowadays,electronic devices are now used in all aspects of society due to the rapid development of information technology,but this also causes electromagnetic pollution,electromagnetic leakage,and other issues.The primary means of reducing electromagnetic pollution are electromagnetic shielding materials.In today’s society,with the growing demand for sustainable development,people have raised the bar for materials that are renewable,environmentally friendly,recyclable,or degradable.Wood,as a rich biomass resource on the planet,is a green structural material that grows naturally in nature and is therefore a sustainable green structural material.As a result,designing a renewable and sustainable EMI shielding material with wood as the substrate is required.In this paper,vacuum impregnation,chemical plating,and hot-press treatment methods on wood were used to successfully prepare wood-based electromagnetic shielding materials:（1）The delignified wood was first acid treated with Na Cl O2,and the lignin content was reduced from 11.20%to 0.82%.PVP was used to disperse MWCNTs solution,followed by vacuum impregnation of the delignified wood in the PVP-MWCNTs solution,which successfully immersed MWCNTs into the cell wall channels of the wood,and then used.By connecting inside the wood channels,the high aspect ratio of MWCNTs was used to form a conductive pathway.When the MWCNTs content was 5mg/m L,the conductivity of wood/PVP-MWCNTs was 0.35 S/cm and the shielding effectiveness in X-band was 14.3 d B.（2）Through the self-adhesive properties of dopamine,which was used as a connecting structure between the cell wall and silver particles,the polydopamine layer is formed in the cell wall of delignified wood.Polydopamine’s benzoquinone and amino structures can adsorb silver ions to form nucleation sites inside the wood via in situ reduction,and then add glucose to form a complete silver layer encapsulated on the cell wall via silver mirror reaction,forming a good conductive pathway.After testing,when the Ag NO3content was 15 g/L,the wood/Ag had a conductivity of 480S/cm and the shielding effectiveness in X-band was 50.0 d B.（3）The lignin and hemicellulose components of the wood chips were removed using sodium chlorite and sodium hydroxide,respectively,while the cellulose component was retained.The cross-linking effect of Ca2+was then used to form a cross-linked network by the-COOH of graphene and cellulose,which was hot pressed into boards at 10 MPa and 100°C to form chips/graphene conductive board.When the chips:graphene=1:1,the electrical conductivity was 100 S/cm and the electromagnetic shielding effectiveness in the X-band was 49.0 d B.The wood-based shielding material with chips/graphene/Fe3O4（GFC）reflection and absorption was formed by adding the magnetic Fe3O4 to the chips/graphene.When chips:graphene:Fe3O4=1:1:0.6,at 2.5mm thickness,the reflection loss was-53.63 d B at 11.15 GHz,the effective shielding bandwidth of GFC-3 material was 4.6G Hz（9.6-14.2 GHz）and the shielding performance in X-band was greater than 57.4 dB. |
