Preparation method of polyacrylonitrile-based high-strength high-modulus carbon fibers

Abstract

The invention relates to a preparation method of polyacrylonitrile-based high-strength high-modulus carbon fibers. After polyacrylonitrile (PAN) precursors are subjected to conventional pre-oxidationand low-temperature carbonization, the carbon crystalline orientation can be effectively controlled by increasing the high-temperature carbonization temperature and matching a certain stretching, or increasing the high-temperature carbonization stretching ratio to obtain high-temperature carbonized fibers with an orientation angle of being not greater than 17.5 degrees, and high-temperature graphitization hot drawing treatment is conducted at a relatively low temperature to obtain the high-strength high-modulus carbon fibers with tensile strength of 3.8-5.0 GPa and tensile modulus of 500-600 GPa. The preparation method reduces the requirements on equipment for high-temperature graphitization, which is beneficial to energy saving and cost reduction, and the operation is simple and easy.

Description

technical field [0001] The invention relates to a method for preparing polyacrylonitrile-based high-strength and high-modulus carbon fibers Background technique [0002] Polyacrylonitrile-based carbon fibers are widely used in aerospace, national defense, building reinforcement, petrochemical and Leisure sports and other fields. With the continuous progress and development of the application technology of carbon fiber composite materials, high-strength and high-model carbon fiber has become an indispensable key material in the special field of aerospace because of its characteristics of high strength and high modulus. [0003] High-modulus carbon fibers are usually prepared by high-temperature graphitization of high-strength carbon fibers. After high-temperature treatment of polyacrylonitrile (PAN)-based carbon fibers at a temperature higher than 2000 ° C, carbon content of more than 99% and carbon crystallites in the fibers can be obtained. High modulus carbon fiber with ...

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Problems solved by technology

Stretching is an effective method to improve the preferred orientation of carbon crystallites in carbon fibers. The adjustment of high-temperature graphitization temperature and tension to change the orientation of carbon crystallites in graphite fibers has become a research hotspot for many scholars. Little research has been done on the effects of plasticity

At the same time, in the research process of T series high-strength carbon fibers, some studies believe that 1500°C is the optimal carbonization temperature point of high-strength carbon fibers. Increasing the high-temperature carbonization treatment temperature will cause the simultaneous changes in the strength and modulus of carbon fiber mechanical properties, which cannot match the T series. Therefore, when preparing high-temperature carbonized fibers, scholars hardly try to make higher carbonization temperatures.

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