Method for preparing polyacrylonitrile-based porous hollow carbon fibers by coaxial electrospinning

Abstract

The invention discloses a method for preparing PAN (polyacrylonitrile)-based porous hollow carbon fibers by coaxial electrospinning. The method includes the steps: mixing polyacrylonitrile with additives to serve as outer solution; taking inner polymer to serve as inner solution; inputting the outer solution and the inner solution into outer layers and inner layers of coaxial needles respectively at the constant flow velocity and in the constant velocity ratio for electrospinning so that PAN-based sheath-core composite fibers are obtained; and subjecting the PAN-based sheath-core composite fibers to washing, pre-oxidation and carbonization so that the PAN-based porous hollow carbon fibers are obtained. The PAN-based porous hollow carbon fibers combine structural characteristics of original porous carbon fibers and original hollow carbon fibers, the specific surface area of the fibers can be greatly increased, and use efficiency of materials is improved. When the PAN-based porous hollow carbon fibers prepared by the method are applied to gas adsorption, gas can enter hollow portions of the fibers more easily, so that adsorbability is enhanced while time required by adsorption is shortened.

Description

technical field [0001] The invention belongs to the field of chemical fiber materials, in particular to a method for preparing PAN-based carbon fibers, in particular to a method for preparing PAN-based porous hollow carbon fibers by coaxial electrospinning. Background technique [0002] Carbon fiber is a fibrous carbon material formed after carbonization of organic fiber or low-molecular hydrocarbon gas raw materials. The carbon content is more than 90%. It has excellent properties such as conductivity, low thermal expansion and radiation resistance, and also has good flexibility. It is widely used in aerospace industry, aviation industry, transportation, sports equipment and other fields. [0003] With the development of nanotechnology, carbon ultrafine or nanofibers have received extensive attention. Since carbon ultrafine fibers not only have the excellent characteristics of the above-mentioned carbon fibers, but also have a very large specific surface area, carbon ultraf...

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Problems solved by technology

However, the traditional electrospinning method can only obtain dense carbon fibers. When the carbon fibers are used as hydrogen storage materials, hydrogen gas can only exist in the gaps formed between the fibers; the blended electrospinning method can obtain porous carbon fibers. The specific surface area is further increased, and the size and distribution of the pores change with the change of the additives. However, the size of the carbon fiber itself is very fine, so the pore size will not be too large, generally less than 50 nanometers, and the specific surface area of ​​the carbon fiber increases limited; at the same time The axial electrospinning method can obtain hollow carbon fibers, and there is a hollow structure inside the carbon fibers, which not only increases the specific surface area of ​​the carbon fibers, but also improves the stability of the carbon fibers. For example, when used for hydrogen storage materials, hydrogen can enter the interior of the carbon fibers. The stability of hydrogen storage is improved. However, since this hollow carbon fiber is a continuous fiber, it often takes a long time to achieve the high efficiency of carbon fiber when storing hydrogen or using it as a reinforcement.

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