Effect Of Temperature On The Stucture And Properties Of Pan Fiber During Pre-Oxidation

Recent years, we have made great progress on quality of 1K and 3 K domestic carbon fiber in our country.However; the market share and application of 12K carbon fiber have reached above 90% in the world. So the next stage of the goals is to expand the basic needs of the carbon fiber market. Therefore, the related basic research on 12K carbon fiber is particularly important.The United Kingdom Courtaulds commercial 12K Polyacrylonitrile (PAN) fiber and 12K Polyacrylonitrile fibers of the domestic petrochemical manufacturers are studied in the article. Through changing the pre-oxidation temperatures and heat drawing, we studied the relationship between process conditions and structure. In addition, we also learned the effect of oxygen uptake on the skin-core morphology during the oxidative stabilization of polyacrylonitrile fibers.The variety of thermal behavior for different PAN fibers was studied by using DSC. The continuum experiment was carried out to compare the effect of the parameters on the properties of fiber by using the mechanic test, FT-IR, XRD etc. The mechanism of oxygen elements in the chemical changes and effect of oxygen uptake on the skin-core morphological structure during the oxidation process of PAN-fibers has been examined by using FTIR, SEM, EDS, EA, skin-core structure test.The results show, the performance of three kinds of PAN fiber is different. The diameter, density, tensile strength of PO is all lower than those of abroad PAN fiber. This can be concluded that the internal structure of domestic and abroad PAN fiber have a certain gap. Through the optimization of pre-oxidation process parameters, tensile strength of carbon fiber made from P0, P1 and P2 have reached 3.53GPa,3.65GPa, 3.69GPa. The mechanism of oxygen elements in the chemical changes and effect of oxygen uptake on the skin-core morphological structure during the oxidation process of PAN-fibers has been examined. The results show that oxygen makes the cyclization occurred in advance and cyclized structure is the precondition of oxidation. From the linear distribution of oxygen elements on the cross-section of stabilized fiber and the skin-core structure photos, we can see that the uneven distribution of oxygen elements on the fiber cross-section and oxidation is the main reason of forming skin-core morphological structure. Besides, a parabola relationship has been established between stabilization time and the oxygen uptake of stabilized fiber at different regions in fiber.