Microwave Absorption And Mechanical Properties Of Reduced Graphene Oxide/Fe₃O₄ Composite Film Reinforced By Carbon Fiber

Because of its extraordinary two-dimensional structure and the very high specific surface area,and graphene has attracted great attention of scientific and technological circles since Geim and Novoselov of Manchester University obtained monolayer graphene through exfoliating graphite by mechanical method.After several decades of exploration,a variety of methods have been developed for the preparation of graphene and derivatives,in the field of electronics,energy,composite materials,biomedical and other fields to show the unique properties and potential applications.Fe3O4 nanoparticles(F-NPs)with low toxicity and good biocompatibility,but also has high saturation magnetization and high catalytic activity characteristics,has a broad application prospect in sensor,biological agents,magnetic storage and electromagnetic absorption etc.In order to improve the utilization rate of F-NPs,reduce the occurrence of aggregation and oxidation phenomenon,researchers often combine F-NPs with other materials,such as the preparation of core-shell structure or deposition of F-NPs on a substrate with a large specific surface area,achieve effective synergies to achieve the purpose of complementary advantages.Based on the unique two-dimensional planar structure of graphene films,researchers have made a lot of exploration and research on the preparation,characterization and application of reduced graphene oxide(rGO)/F-NPs composite membranes.The rGO/F-NPs composite was prepared by hydrothermal/solvothermal method,and then obtained the composite film by vacuum filtration method.The composite films can be used as the flexible electrode materials of lithium ion batteries and supercapacitors,water treatment adsorption film,magnetic switch,biosensor and other potential applications.The quality of the film depends on the filtration process,although the film can be neatly arranged,the crystal structure is relatively complete,excellent mechanical properties and other targets,but there are also problems of long time,low filtration efficiency and small area,and there are some limitations in the large scale preparation of composite membrane materials.In this paper,the rGO/F-NPs composite membrane was prepared by modified method,and their microwave absorption and mechanical properties were tested.The mechanical properties and microwave absorption capacity of composite film were improved by adding carbon fiber powder(CF),for which we have carried out the following two aspects of the experimental work:1)First,the graphite oxide(GO)solution was prepared by modified Hummers method and the GO was stripped by ultrasonic oscillation.Then,rGO/F-NPs composite film was prepared by solution blending and step-by-step heating method.The experimental results show that the surface of rGO/F-NPs composite film is smooth and there are no pores and cracks on it,the surface of the sample was characterized by typical graphene fold and undulating morphology,and F-NPs were uniformLy attached to the surface of graphene,the particle size is about 20-80 nm.2)With CF as reinforcing phase,the surface treatment of carbon fiber powder was carried out.And then the same method was used to prepare the rGO/F-NPs/CF composite film with different carbon fiber content.The mechanical strength was measured to determine the optimal amount of carbon fiber.The results show that when the carbon fiber content is 10%of the mass of GO,the strength optimization is the most significant.To maintain the optimal amount of carbon fiber and change the F-NPs content,we prepared three-phase composite film samples,and tested the microwave absorption characteristics.We find that when the content of nanoparticles is 200 mg,the composite film has the best microwave absorption performance.It has the lowest reflection loss value of-22.18 GHz and the effective absorbing bandwidth is 3.12 GHz at 2 mm and 10.64 GHz,which is twice as high as the reflection loss of rGO/F-NPs(200 mg)composite film without carbon fiber,and its absorption band is effectively widened.In conclusion,this paper presents a technique for the composite film formation of graphene and ferrite,which has the characteristics of simple and easy-to-scale processing.After doping,the composite film of three elements is flexible,high strength,synergistic effect can effectively improve of the absorbing properties.