LIU Ruigang, XU Jian
Recent progresses in the production of high performance polyacrylonitrile (PAN) based carbon fibers are reviewed in this paper, focusing on the polymerization, the production of PAN precursors, the stabilization and carbonization procedures for the production of PAN based carbon fibers. The polymerizing method is the key procedure for the distribution of co-monomers on the PAN line and the homogeneity of the spinning solution. Compared with the bath and semi-continuous polymerizing process, the continuous polymerizing process can produce a homogeneous and stabilizing PAN solution, reducing the formation of PAN microgels, which is beneficial for producing high quality PAN carbon fiber precursors and hereafter the PAN based carbon fibers. The coagulating parameters, as well as the phase separation process of the PAN solutions, determine the formation, the development, and the content of the microvoids in the PAN precursor fibers, which in turn influences the performance of the PAN precursors and thereafter the carbon fibers. The drawing and drying parameters are critical for the optimization of the orientation and the crystallization, as well as the quality of PAN precursor fibers. The heating rate, the highest temperature, and the tensile strength determine the core-shell structure and the cyclization index, which influences the carbonizing process and the properties of the resultant carbon fibers. The strength and the modulus of the carbon fibers are closely related with the temperature and the strength of the carbonizing procedure. The correlation between the structure and the properties of PAN based carbon fibers remains an issue to be further explored, as well as the technology of the production of high performance carbon fibers in China. The combination of fundamental and applied researches are critically needed.
