Method for preparing lignin/polyacrylonitrile blended melt-spun fiber by adopting physical blending

The invention relates to a method for preparing lignin/polyacrylonitrile blended melt-spun fiber by adopting physical blending. The method comprises the steps of evenly mixing polyacrylonitrile, lignin and plasticizer, then adding mixed materials into a closed feed hopper of a double-screw spinning machine, carrying out melt-spinning at 140-220DEG C, and performing hot-air setting, washing and drafting, and winding to obtain lignin/polyacrylonitrile blended melt-spun fiber. According to the method, the active ingredient lignin is low in cost, less in environment pollution and suitable for industrial production; the lignin contains a great amount of hydroxyl groups which can have hydrogen-bond interaction with polar group cyano on polyacrylonitrile molecular chains, and the two have better compatibility; the section of the fiber is round, so that the skin-core difference is small, and the structure of the fiber is compact and uniform; due to the addition of lignin, the thermal performance and oxidation resistance of the fiber can be enhanced, and the degradation capability can be improved.