Preparation And Properties Of Graphene Film Modified With Carbon Nanofibers

With the rapid growing of the science development, the emergence of new materials for the development of science and technology provides more likely. In 2004 Geim team prepared the monolayer graphene by micro mechanical stripping method, the upsurge of graphene research was raised. Graphene material with its perfect synthesis of hybrid structure, low cost and unique electronic and mechanical performance, becomes a rising star in the new carbon materials. Carbon nanofiber is a kind of nanoscale carbon fiber material, in addition to high specific modulus, large strength, good electrical conductivity, and specific large surface area as the advantages of compact structure. Combining carbon nanofibers with graphene materials, soft and thin film materials with unique electrical and mechanical properties was prepared. This film materials can be applied to microstrip antenna, cell electrode, sensor, and other areas of the application. This paper is to study carbon nanofibers(CNF)/graphene films as the research object,and do research on the preparation and performance of CNF/grapheme films. Specific content is as follows:In the first part of work, using the improved Hummers method graphene oxide was prepared from natural flake. After several times of washing, centrifugal, ultrasonic oscillation, the pH value of graphene oxide solution was around 6. Then using the drop costing method the graphene oxide thin film was prepared. By reducing in HI solution at room temperature, the graphene films was prepared. At the same time,using atomic force microscope(AFM), scanning electron microscope(SEM) and X-ray diffraction(XRD), and other detection technology, graphene layer structure and reduction degree were characterized and analyzed.In the second part, to add different amounts of carbon nanofibers in graphene oxide solution,graphene oxide solution with different proportion of 1%, 3%, 5% of the carbon nanofibers(CNF)was prepared, and then using the magnetic stirring and ultrasonic vibration, carbon nanofibers are evenly dispersed in graphene oxide solution, and using the drop costing method, graphene oxide modified with carbon nanofibers thin films was prepared. After reduction in HI solution at room temperature, the CNF/graphene films was prepared. Using SEM CNF/graphene films' surface morphology were observed; And by using the four-point probe sheet resistance testing technology,electrical conductivity of thin films were tested and analysis.In the third part of the work, in order to further explore the effect of CNF proportion of graphene films, and optimizing the electrical and mechanical film with better comprehensive properties, the CNF addition amount was increased to 10%, 25% and 50% separately. At the same time, using the four-point probe sheet resistance, fiber strength and SEM test technology on CNF/graphene films, their electrical, mechanical properties and surface morphology were tested,Finally high comprehensive performance belonged to CNF/graphene film materials containing25% CNF, and this material was used in the fourth part of the research to load on antenna.In the fourth part, using 25% of the CNF/graphene films on the back of conductive elementtype feed microstrip patch antenna impedance loading research, the results showed that after loading 1 to 6 layers, antenna return loss,-7.14 dB of no loading down to-11.57 dB,-14.29 dB and-18.55 d B and-19.93 dB and 1-4.87 dB and-13.18 dB respectively. It showed that after loading CNF/graphene film antenna impedance matching was improved, the specific data also showed that after loading 4 layers of CNF/graphene films, antenna lowest return loss arrived, and impedance matching was the best; In addition, after loading CNF/graphene film, the resonance frequencies of the antenna was changed from 915 MHZ to 899 MHZ. Tthis small slant was due to actual film loading size and precision and so on.To sum up, this paper was mainly composed of these three aspects of the preparation,modification and application to explore the CNF/graphene film and its performance. First of all,the preparation of graphene and graphene oxide thin film was finished; Secondly, on the basis of in graphene oxide solution doped with different proportion of carbon nanofibers in mixed solution,the CNF/graphene films were prepared; Finally, the mechanical and electrical integrated excellent performance of a set percentage of CNF/graphene film was used to coaxial feed rectangular microstrip patch antenna with not ideal impedance matching caused by machining error. To make it fit for processing, after the poor fit of the impedance of the microstrip antenna improvement a new train of thought was provided.