Preparation And Properties Of Ni/Graphene/Cellulose Nanofiber Composite Electromagnetic Interference Shielding Papers

The rapid development of electronic information technology and the application of various electronic and communication equipment are becoming more and more common,making people's lives very convenient,However,the accompanying electromagnetic pollution is also seriously endangering the normal operation of other sensitive equipment,human health and even the ecological environment.Electromagnetic interference shielding?EMI?technology plays a vital role in suppressing electromagnetic radiation pollution.The preparation of lightweight,durable,flexible,and high-performance electromagnetic interference shielding materials is the key to achieving electromagnetic interference shielding.Graphene has wide application prospects in the preparation of electromagnetic shielding materials due to its good conductivity,large specific surface area and low density,but brittleness is an important factor restricting its development;Cellulose nanofibers are derived from natural cellulose,non-polluting and renewable,with excellent mechanical properties,especially excellent flexibility and good biocompatibility.Therefore,graphene and cellulose nanofibers can be effectively compounded to prepare electromagnetic shielding materials with excellent performance.In this study,nickel chloride hexahydrate,Graphene oxide as raw materials,two kinds of nano-Ni/reduced graphene oxide composite materials were prepared by using different reduction methods.Then,using Ni/reduced graphene oxide as the filler and CNF as the matrix,EMI composite papers with excellent performance was prepared in different ways.?1?Using chemical reduction method with hydrazine hydrate as reducing agent,through one-step hydrothermal method to reduce graphene oxide and nickel chloride hexahydrate simultaneously to obtain Ni/RGO composite material.Using high temperature reduction method to reduce graphene oxide at high temperature to obtain TGO,then,using hydrazine hydrate as the reducing agent,the liquid phase reduction method is used to obtain nano Ni,Ni/TGO was obtained by mixing them uniformly through ultrasound.Analysis of the morphology and structure of Ni/RGO and Ni/TGO,with good crystallinity and single composition,shows that both reduction methods can reduce graphene oxide and Ni Cl₂.6H₂O very well.In addition,it can be observed that the diameter of Ni particles in Ni/TGO is smaller and more uniform than that in Ni/RGO.?2?Ni/RGO/CNF composite electromagnetic interference shielding paper with a sandwich structure was fabricated by filtering Ni/RGO and CNF through a three-step vacuum filtration process.The composite electromagnetic shielding paper with Ni/RGO content of 67wt%has good mechanical properties,a tensile strength of 65.5 MPa and a fracture strain of 9.2%;the shielding effectiveness is20.9 d B,which can meet the general commercial requirements.When the Ni/RGO content increases to75wt%,the mechanical properties of the composite EMI paper decrease slightly,but its electrical conductivity and shielding effectiveness can reach 1664 S/m and 22.6 d B,respectively.?3?Ni/TGO and CNF are blended uniformly,and then Ni/TGO/CNF composite electromagnetic shielding paper with dense multi-layer structure can be prepared by a one-step vacuum filtration process.Among them,the composite electromagnetic shielding paper with better mechanical properties has a Ni/TGO content of 50wt%,a thickness of only 68?m,a tensile strength of 104.5 MPa,and a strain at break of 10.96%;the shielding efficiency is 21.7 d B,which can also meet commercial needs.As the Ni/TGO loading increases to 70wt%,the thickness of the composite electromagnetic shielding paper is74?m and the mechanical properties are slightly reduced;while its electrical conductivity and shielding effectiveness can reach 1881 S/m and 30.2 d B,respectively.?4?In conclusion,the electromagnetic shielding mechanism of Ni/RGO/CNF and Ni/TGO/CNF composite paper is dominated by microwave absorption,and the overall performance of Ni/TGO/CNF composite paper is better than Ni/RGO/CNF composite paper.