Preparation And Properties Of RGO/PPy Electromagnetic Shielding Composites

As an important means to avoid or reduce electromagnetic radiation interference,electromagnetic shielding composites play an important role in the field of electromagnetic shielding.Graphene based electromagnetic shielding materials have the characteristics of light weight,high efficiency and flexibility.However,in the preparation of composites,graphene is easy to agglomerate due to its poor self-supporting and stability.Therefore,other materials should be used to reduce these disadvantages.As a typical representative of conductive polymer,polypyrrole has the advantages of wide range of conductivity,controllable structure and morphology,good stability,low density,low price and simple synthesis route.It meets the standard of new electromagnetic shielding materials and has a wide application prospect in the field of electromagnetic shielding.However,pure polypyrrole has poor ground conductivity and almost no conductivity.Only by doping can it show high conductivity.In order to reduce the disadvantages of graphene and polypyrrole,reduced graphene oxide reinforced polypyrrole electromagnetic shielding composites were prepared by insitu polymerization with reduced graphene oxide as reinforcement,polypyrrole as matrix,sodium dodecyl sulfate as dopant and anhydrous ferric chloride as oxidant.In this paper,through the combination of computer simulation and experiment,the HFSS software is used to build the model,design the simulation and calculate the composite materials with different mass ratio and thickness to determine the optimal mass ratio and thickness of the composite materials.Then it was verified by experiments: the composites with the best thickness and different mass ratio were prepared by in-situ polymerization,and the composites with the best mass ratio and different thickness were characterized by four probe resistance tester and vector grid analyzer The electromagnetic shielding effectiveness of composites with different thickness is related to the doping amount,thickness and conductivity of reduced graphene oxide.The simulation and experimental results show that when the mass ratio of reduced graphene oxide/polypyrrole composite is constant,the electromagnetic shielding effectiveness of the composite increases with the increase of thickness;When the thickness of the composite is constant,the conductivity and electromagnetic shielding effectiveness of the composite increase with the increase of reduced graphene oxide doping amount.However,when the reduced graphene oxide doping amount increases to a certain extent,the conductivity and electromagnetic shielding effectiveness of the composite increase slightly or basically remain unchanged.Therefore,the electromagnetic shielding effectiveness of the composite is proportional to the conductivity,and increases with the increase of the conductivity.When the mass ratio of reduced graphene oxide to pyrrole is 3:10 and the thickness of the composite is 0.3 mm,the best electromagnetic shielding performance of the composite is 45.1 d B,in which the absorption loss of the composite accounts for 85.4% of the total electromagnetic shielding effectiveness,indicating that the reduced graphene oxide/polypyrrole composite achieves high electromagnetic shielding mainly by absorbing electromagnetic waves.In the broadband range of 2-18 GHz,the electromagnetic shielding effectiveness of the composites is more than 40 d B,which has met the needs of commercial applications.