Preparation method of polyacrylonitrile pre-oxidation fiber and carbon fiber

The invention discloses a preparation method of a polyacrylonitrile pre-oxidation fiber and a carbon fiber, belonging to the technical field of fiber preparation. The preparation method comprises the steps of: enabling polyacrylonitrile protofilament to pass through a continuous pre-oxidization device at a constant speed in a normal pressure and an air medium and carrying out pre-oxidization treatment, wherein the temperature rises by adopting 2-4 temperature zone gradients, and the total time is controlled within 30-45 min; in the low temperature stage of the pre-oxidization process, the reaction temperature is 200-240 DEG C, positive drafting accounting for 0%-8% of the total drafting is added, and the total time is 15-25 min; and in the high temperature stage, the reaction temperature is 240-275 DEG C, negative drafting accounting for 0%-3% of the drafting is added, the total time is 15-20min, the low temperature stage is divided into one or two temperature zones, and the high temperature stage is divided into one or two temperature zones, and the temperature of the 2-4 temperature zones rises in sequence, therefore the pre-oxidization fiber is obtained; furthermore, performing a regular carbonization treatment in the atmosphere of nitrogen for 5-8 min to obtain the carbon fiber. The preparation method of the polyacrylonitrile pre-oxidation fiber and the carbon fiber, disclosed by the invention, has the advantages of improving production efficiency of the pre-oxidization and shortening the pre-oxidization heat treatment time.