Lignin pretreatment method used for preparing carbon fiber

Abstract

The invention discloses a lignin pretreatment method for preparing carbon fibers, comprising the following steps: (1) degrading the lignin with biological enzymes; (2) adding alkali to the degraded lignin for reaction, After the reaction is completed, an oxidizing agent is added for oxidation treatment; (3) Organic acid is added to the oxidized lignin for polymerization reaction, and the pretreated lignin is obtained after the reaction is completed; Methods The lignin molecular chain was adjusted so that the structural units in the lignin were arranged in an orderly manner, with less branched chains on the molecular chain and a stable structure, which had a positive effect on improving the mechanical properties, chemical stability and processability of carbon fibers.

Description

technical field [0001] The invention relates to the treatment of carbon fiber raw materials, in particular to a lignin pretreatment method for preparing carbon fibers. Background technique [0002] Carbon fiber (CF for short) is a new fiber material with high strength and high modulus with a carbon content of more than 95%. It is a microcrystalline graphite material obtained by stacking organic fibers such as flake graphite microcrystals along the axial direction of the fiber, and undergoing carbonization and graphitization. At present, industrialized production of carbon fibers can be mainly divided into three categories: polyacrylonitrile (PAN)-based carbon fibers, pitch-based carbon fibers and viscose-based carbon fibers according to the raw material route. However, with the wide application of carbon fiber in more fields, the demand for carbon fiber continues to increase. In order to reduce the production cost of carbon fiber, increase the production capacity of carbon ...

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Problems solved by technology

[0004] Although lignin has the above-mentioned advantages for preparing carbon fibers, there are also defects: the carbon content in lignin is low, the molecular chains are arranged irregularly, and the structure is also disorderly, which leads to the formation of flake graphite crystallites in the prepared carbon fibers. The arrangement is not neat, the structure is loose, and the fiber surface is rough, so that the resulting lignin-based carbon fibers have problems such as poor mechanical properties, poor chemical stability, and poor processability, which limit the application of lignin-based carbon fibers in cutting-edge fields.