Study On The Evolvement Of Pan Molecular Structure In The Effect Of Field

The heat treatment, especially the pre-oxidative stabilization of polyacrylonitrile is a crucial step in the production of PAN-based carbon fibers. I t is so complex and influenced. In the process, the field including temperature, time, tensility, airflow and so on, bring important action for the evolution law of molecular structure and properties of PAN fibers.In the paper, we will analyze structure and properties of PAN fibers, combine study condition and elements in item team, develope the study that influence of aggregation state structure by various field in pre-oxidative and carbonization, discover the factors of controlling crystal size in carbon fiber, and preparation PAN-based carbon fibers bearing microlite structure. By means of SEM, TEM, XRD etc, we investigate the structure and properties of PAN fibers. And this paper will also try to build technics-structure-properties pertinency of PAN-based carbon fibers bearing microlite structure.The results showed that before190℃, heat-decomposition and cyclization of cyanogens groups is slowness; After200℃, the reaction’s stage become deep. When the equivalent time increased from51min to60min, heat-decomposition and cyclization of cyanogens groups is drastic. In this scope, extending heat treatment time is advantageous to raising utilization of cyanogen groups and reducing crystalline size. In the forepart of heat-decomposition and cyclization cyanogens groups of PAN fiber, tensility can accelerate the heat-decomposition and cyclization of PAN molecule, especially molecular interior, when the tensility reach161.4CN/dtex, the crystalline size can minish, which is further some to increase fiber’s intensity. In the pre-oxidative first phases, H2O make fibers having plasticity and reinforce the molecular chain’s movement ability; In the pre-oxidative second phases, H2O combine oxygenous group and slower heat-decomposition and cyclization of cyanogens groups.