Electron Microscope Study On The Relationship Between Carbon Fiber Structure And Properties

As a novel carbon material, the inner structure and outer shape of Polyacrylonitrile (PAN) based carbon fiber has significant influence on its mechanical properties. In this thesis, the outer shape and inner structure of high strength and high modulus carbon fiber and the influence of shape and structure on the mechanical properties of the fiber were characterized by FESEM, TEM, HRTEM and XRD. T series and M series made in Japan and T series made in China shows that the existence of surface ditches, the extent of fine filaments and the defects of the fibers themselves are the main factors to cause the decrease of mechanical properties of the fibers. According to the research of the internal structure of carbon fibers mentioned above, the key factors to determine the modulus of carbon fibers are the quality of crystallization, the standard of the stripe of crystal grid and level of the chosen direction of crystal face united to the fiber axle, while the internal impurities have strong influence on tensile strength. In this thesis the domestic T300and imported T300have been taken as examples and the sampling method of carbon fibers was explored, as well as the influence of different sampling methods on the characterization of the morphology and structure of carbon fiber by electron microscopes was studied. Further more, the advantages and disadvantages of different sampling methods were compared.