Post-treatment method for improving densification degree of carbon nanotube fibers

Abstract

The invention discloses a post-treatment method for improving the densification degree of carbon nanotube fibers. The post-treatment method comprises the following steps: firstly, fully infiltrating original carbon nanotube fibers in chlorosulfonic acid, taking out the original carbon nanotube fibers, and standing the original carbon nanotube fibers in air to enable the chlorosulfonic acid to fully react with moisture in the air; infiltrating the carbon nanotube fiber into chlorosulfonic acid again at a relatively high rate to enable the carbon nanotube fiber to expand quickly, and continuing to stand in the chlorosulfonic acid until the volume of the carbon nanotube fiber is reduced; slowly taking out from the chlorosulfonic acid, and standing in the air, so that the chlorosulfonic acid fully reacts with moisture in the air; and finally, carrying out high-temperature annealing treatment under a vacuum condition to obtain the high-densification carbon nanotube fiber. The post-treatment method provided by the invention is simple in operation process, the existence of tiny gaps in the fiber is reduced, the densification degree of the carbon nanotube fiber is improved, and the actual cross-sectional area of the carbon nanotube fiber is greatly reduced, so that the electrical property of the carbon nanotube fiber is improved.

Description

technical field [0001] The invention relates to a post-treatment method capable of effectively improving the densification degree of carbon nanotube fibers, and belongs to the technical field of post-treatment of carbon nanotubes. Background technique [0002] The P orbital electrons of carbon atoms that make up carbon nanotubes can form delocalized π bonds in a wide range. The special conjugation effect of this electronic structure endows carbon nanotubes with unique electrical properties. The aspect ratio makes carbon nanotubes have a very large mean free path of electrons. Studies have shown that the mean electron free path of carbon nanotubes can exceed 30 μm (copper is 40nm), and the extremely large electron mean free path is of great significance to the improvement of the conductivity of carbon nanotubes, and its theoretical conductivity can be an order of magnitude higher than that of copper. At the same time, carbon nanotubes also have excellent characteristics such...

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Problems solved by technology

[0005] (1) The existing chlorosulfonic acid treatment process cannot effectively remove the tiny voids inside the carbon nanotube fibers, cannot effectively improve the degree of fiber densification, and then achieve the purpose of reducing the cross-sectional area of ​​the fibers;

[0006] (2) The existing chlorosulfonic acid treatment process involves the pyrolysis of sulfuric acid. Sulfuric acid will produce gas during thermal decomposition. The decomposition of sulfuric acid molecules inside the fiber and the generation of gas will further lead to the increase of tiny voids inside the fiber. Increase the cross-sectional area of ​​carbon nanotube fibers, which is not conducive to the improvement of the final electrical properties of carbon nanotube fibers;

[0007] (3) The existing chlorosulfonic acid treatment process basically does not change the appearance of carbon nanotube fibers, and there are still more fluffy sponge-like microstructures on the surface of carbon nanotube fibers after treatment. The connection between tubes and carbon nanotubes is relatively weak, and the weak connection between carbon nanotube monomers will inevitably reduce the electron transmission ability between them, which will eventually lead to the reduction of the macroscopic electrical properties of carbon nanotube fibers.

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