Pan-based Carbon Fiber Structure And Properties Of Correlation

Although the performance of carbon fibers is related to polyacrylonitrile (PAN) precursors, the preoxidization and carbonization technology are also the key factors. In order to manufacture high performance carbon fibers, the structure factors of carbon fibers and its' suitable technology parameters should be considered.It was found that the structures of carbon fibers have generic characteristics, such as the structures of PAN precursors, the optimized orientation of fibrils, the cross section shape of single fiber, and so on, which have almost been kept in the carbon fibers. The fibers' structures have taken great place after being preoxidized and carbonized, the core structures of fibers become compact, and the skin-core structure still exists. During the preoxidization and carbonization process, the fibers' linear density reduces; the elongation at break of fibers decreases; the fibers' strength decreases firstly, then increases greatly.It was found that the carbon fibers were of low strength, which were made from three comonomers as acrylonitrile(AN), itaconic acid(IA), ammonia itaconate, dimethyl itaconate. The linear density was changed greatly. All these showed: The weight of fibers reduced sharply, so the defects were formed more easily, the strength of carbon fibers was weakened.The technology improvement in carbonization process has been studied. First, preoxidized fibers were acidized before being carbonization at low temperature. By means of differential thermal analysis meter (DTA) and thermogravimetry (TG), it can be discovered that the aromatization were preferred and the strength of carbon fibers were increased. Then, the fibers were modified and reinforced before high temperature carbonization process. Three reagents, such as tetrachloromethane, n-heptane, were used to improve the performance of carbon fibers. The results showed that all of them could enhance the strength of carbon fibers. So reinforcement at high temperature carbonization is a important way to enhance the carbon fibers' tensile strength.The carbon fibers of different strength were studied by the method of x-ray...