Ultra-high strength and middle high-modulus polyacrylonitrile carbon fibers as well as preparation method thereof

Abstract

The invention discloses an ultra-high strength and middle high-modulus polyacrylonitrile carbon fibers as well as preparation method thereof. The method comprises the following steps: (1) using dimethyl sulfoxide or dimethylformacetamide as a solvent, and performing copolymerization on acrylonitrile and itaconic acid or acrylonitrile, methyl acrylate and itaconic acid; (2) spinning, drafting, washing, oiling, drying, and heat setting a polymer spinning solution in sequence; (3) performing pre-oxidation and carbonization on polyacrylonitrile strand to obtain ultra-high strength, middle high-modulus carbon fiber. The components of the coagulation bath system in a spinning process cannot penetrate into a spinning stream formed by the polymer spinning solution, and the solvent in the spinningstream formed by the polymer spinning solution can diffuse into the coagulation bath system.According to the method provided by the invention, a raw wire hole defect and a skin and core structure inhomogeneity defect formed by a traditional wet or dry-wet solidification molding process can be reduced; highly oriented raw silkstrand can be easily obtain from a fiber initial structure; the raw silkstrand is used to obtain carbon fiber with tensile strength of 5,500-7,000 MPa and tensile modulus 310-390 GPa.

Description

technical field [0001] The invention belongs to the technical field of carbon materials. Specifically, the invention relates to a polyacrylonitrile carbon fiber with ultra-high strength and medium-high modulus properties and a preparation method thereof. Background technique [0002] Carbon fiber is the most important reinforcing material for advanced composite materials. Due to its high specific strength, high specific modulus, high temperature resistance, ablation resistance and a series of excellent properties, it is widely used in cutting-edge industries such as aerospace, aviation, atomic energy, general industry and sports and leisure. fields are widely used. Continuously improving mechanical properties and increasingly mature preparation technology make polyacrylonitrile (PAN)-based carbon fiber become the mainstream in the field of carbon fiber in the world today, and has an irreplaceable position in the fields of aerospace, automobile industry and sports. [0003] ...

AI Technical Summary

Problems solved by technology

[0005] Existing studies have shown that in the coagulation molding process of most spinning processes at present, the thin flow of PAN solution coming out of the spinneret is due to the diffusion of the solvent in the filament to the coagulation bath and the diffusion of the precipitant (such as water) into the filament. Diffusion, especially the diffusion of precipitant (such as water) into the filaments, the PAN filaments formed are prone to devitrification and skin-core problems, that is, the hole-type defects in the fibers, and the radial skin and core of the fibers observed by the scanning electron microscope. Skin-core structure with obvious difference in internal compactness

For brittle materials such as carbon fibers, there is no doubt that the hole defects and inhomogeneous radial structure on the precursor structure will inevitably cause the performance of the precursor to decline, affecting the final carbon fiber strength and modulus.

[0006] Therefore, the existing technology for preparing carbon fiber precursors needs to be further explored.

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