Preparation And Structure Properties Of Graphene/Mesophase Pitch-Based Composite Carbon Fiber

Mesophase pitch-based carbon fiber (MPCF) has broad application prospects in the areas of aerospace, transportation, military, electronics, biology, energy and other fields because of its low density, high modulus, high heat conductivity and other excellent performance. But the tensile and compressive strength of MPCF is lower than PAN based carbon fibers, which makes it difficult to preparation and application. Therefore, a method to improve the mechanical properties of MPCF at the same time not affect its conductive properties and modulus is worth looking forward to.As one of research hotpot in recent years, Graphene has excellent strength thermal conductivity closed to the theoretical value. But it is difficult to be used independently and macroscopicly for graphene, and it is always utilized as a functional filler now. graphene/mesophase pitch-based composite fiber was prepared with using mesophase pitch as the main raw and graphene as filler.Mesophase was mixed with graphene by solution method, and the rheological properties of the mixture was analyzed by the rotating plate rheometer. We found that the storage modulus, loss modulus, loss factor and viscosity of the mixture decrease as temperature increases and the viscosity of the mixture increases as graphene content increases at the same temperature. It is began to low viscosity smooth area near 320℃.The melt spinning temperature range is selected according the analysis of mesophase pitch rheological properties and thermo stability. Mesophase pitch-based composite carbon fibers with various levels of added graphene content were produced by melt-spun, stabilization, carbonization and graphitization. The mechanical properties of stabilization fibers treated on condition that the heating rate is 0.5℃/min, the final temperature is 280℃is the best.The addition of graphene can effectively lead to the avoidance of unwanted radial transverse structure and wedge splitting of the carbon fibers prepared from pure mesophase pitch. The cross section of composite fiber structure presents different cross section with the change of the graphene content, for example, radial-folded, flat layer-core onion-skin texture, petals-core radial-skin texture, random and other cross section.The addition of graphene can significantly enhance the tensile strength as well as the conductivity of the composite carbon fibers. When the graphene content is 0.1%, the tensile strength, thermal conductivity, orientation degree of the composite carbon fiber and composite graphite fiber are the best value. the tensile strength are 2.02 Gpa and 1.88 Gpa, thermal conductivity are 166.01 W/m-K and 1321.80 W/m-K, orientation degree are 86.51% and 91.74% respectively.