Study On Polyacrylonitrile Nanofiber Prepared By Electrospinning And Its Preoxidation

Polyacrylonitrile (PAN) carbon fiber, with high specific strength, high specific modulus and many other outstanding features, has been widely used in aerospace industry. With the continuous development and application in the carbon fiber products, carbon fiber is bound to become a basic production that will form a huge industry, so that it will be super irreplaceable. Now the carbon nanofiber can be prepared by a number of means, but electrostatic spinning is the only way to prepare the polymer nanofiber directly and continuous. With the gradually mature of electrostatic spinning method and the achievement of industrialization, electrostaticspinning technology which is used for the preparation of PAN carbon nanofiber has great potential value. In the process of preparing carbon nanofiber by electrostatic spinning, preoxidation is the bridge which connects the former (precursor fiber) and the later (carbon fiber). Through the changing of preoxidation parameters, get the best factor of preoxidation condition, which providing the theoretical basis of the preparing of high performance carbon nanofiber. The process of preoxidation is one of main scientific research direction of scholars domestically and abroad。In this article nanofiber was prepared by PAN and electrostatic spinning method, polyacrylonitrile preoxidation fiber was prepared by preoxidation process. By using scanning electron microscopy (SEM), transmission electron microscopy, thermal infrared spectroscopy (IR), X-ray diffraction (XRD), thermal gravimetric analysis (TG) as the main means of characterization, the surface shape and structure of PAN nanofiber and preoxidation fiber were systematically analyzed.In the electrospinning process,the effect of solution concentration, solvent type, spinning voltage and acceptation distance effect on the fiber diameter were discussed. Through the orthogonal experiment the most superior condition was determined. The PAN nanofiber about 80nm in diameter can be prepared by the concentration of 11wt%, distance of 20cm, voltage of 25kV, and electrospinning solution of DMF solvent. During polyacrylonitrile fiber preoxidating process, XRD analysis revealed that, with increasing temperature, polyacrylonitrile chainlike molecules gradually becomes a stable ladder structure which leads to crystallization degradation. The mechanical properties of polyacrylonitrile fiber showed that as preoxidation temperature increases, stiffness of PAN fiber raises, elongation at break increases at first then decreases, and tensile strength of PAN fiber gradually decreases; elemental analysis and thermogravimetric analysis showed that when the reaction temperature of the preoxidation techniques was 270℃for 20min, it could reach the preoxidating standard.