JP4819138B2 - Quartz-clad carbon nanotube fiber bundle - Google Patents

Description

  The present invention relates to a quartz-clad carbon nanotube fiber bundle that heats a carbon nanotube bundle housed in a quartz tube and pulls the carbon nanotube while being softened together with the quartz tube to draw it into an integral linear body.

  With regard to conventional carbon nanotubes, research on the measurement of elastic constants of carbon nanotubes and the elastic limit of tensile strength has been reported to date by applying a measurement method of a tunneling microscope.

However, there has not been reported yet an example of measuring the critical tension when the tube is cut by tension. In the previous research, we tried a method in which carbon nanotubes were put into a quartz tube in a nitrogen stream, and the sample was stretched thinly instantaneously during the heating process and used to measure critical tension. In addition, the microstructure of the sample produced by this method was observed with a metal microscope with a magnification of 500 times, and an enlarged image was recorded on a CCD camera, and the relationship between the imperfection of the microstructure and the critical tension was investigated. .
However, this experiment is only a measurement experiment of critical tension by heating and stretching of carbon nanotubes.

The present inventor conducted experiments on the above carbon nanotubes, vacuum-sealing a bundle of carbon nanotubes in a quartz tube for the purpose of obtaining a linear body having a higher tension, and heating the outside of the carbon nanotube bundle, It is in an integrated linear quartz-clad carbon nanotube fiber bundle produced by drafting.
That is, in the present invention, a plurality of carbon nanotube fibers are vacuum sealed in a quartz tube having an inner diameter of 3 mm and an outer diameter of about 5 mm, and the quartz nanotube fibers are heated to incandescently soften at a temperature of 900 ° C. to 1300 ° C. Heating the tube externally to soften the carbon nanotube fiber;
During the softening, drafting the carbon nanotube fiber together with the quartz tube until the outer diameter of the quartz tube is 0.1 mm or less;
Quenching this to room temperature, producing a flexible quartz-clad carbon nanotube fiber bundle containing carbon nanotube fiber bundles,
A quartz-clad carbon nanotube fiber bundle obtained through a manufacturing process is provided.
The inventor has developed a new and simple method for producing quartz-clad carbon nanotubes.
In the present invention, the above-mentioned quartz-clad carbon nanotube is a heat-resistant body up to 900 ° C., and this is coated with a quartz tube so that the quartz-coated body is chemically stable so as not to react with the surrounding atmosphere. It is a thing.

The fibers in the quartz tube observed with a CCD camera are made of tube bundles having a line width of 2 to 10 microns, which corresponds to the thickness of about 100 to several thousand nanotube bundles. Preliminary measurements, critical tension was 3ton heavy / mm ² to 40ton heavy / mm ² approximately. This large variation in critical value is thought to be due to the fact that the structural defects of the tube and the friction between the tubes in the axial direction of the tube greatly vary depending on the chemical treatment of the surface.

It is explanatory drawing which shows the principle which measures the fracture | rupture critical tension of the quartz clad carbon nanotube bundle | flux of this invention. It is a figure which shows the measurement principle which records the spectrum of a sample about the sample of the quartz-clad carbon nanotube bundle | flux of this invention using the high-resolution Raman spectroscope with a built-in high interference wavelength selection type filter. FIG. 4 is a principle diagram when a quartz-clad carbon nanotube bundle is manufactured by vacuum-sealing a cut piece of a carbon nanotube bundle in a quartz tube, externally heating and rapidly drawing from both sides. (A), (b) and (c) are examples of carbon nanotubes used in the experiments of the present invention divided into an armchair type (a), a zigzag type (b), and a chiral type (spiral) type (c). It is a schematic diagram of the molecular structure of a nanotube. For the load on the horizontal axis, the critical tension (ton / mm ² ) of the quartz clad carbon nanotube bundle obtained from the diameter of the quartz tube taken on the vertical axis was measured with a microscope. It is a figure which shows a result. It is a figure which shows the intensity | strength looked at the Raman scattering spectrum about the quartz clad carbon nanotube of this invention. It is a figure which shows the intensity | strength looked at the Raman scattering spectrum about the quartz clad carbon nanotube of this invention. It is a figure which shows a measurement spectrum intensity | strength about the quartz clad carbon nanotube of this invention.

(Example)
In order to manufacture this linear body, the carbon nanotube raw material is vacuum-sealed in a quartz tube having an inner diameter of 3 mm and an outer diameter of 5 mm, and the carbon nanotubes in the quartz tube are softened by carbon at 900 to 1300 ° C, especially 1200 ° C. Until heated. While measuring the temperature of the sample, the quartz tube is quickly stretched and rapidly cooled to room temperature so that the outer diameter of the quartz tube is 0.1 mm or less. When observed with an optical microscope using a microscope with a computer controlled CCD camera, it was found that the cross section of the carbon nanotube bundle was reduced to 50 to 70 nm. The carbon nanotube bundle was analyzed by a Raman spectrum measurement method. Its spectrum was close to a frequency of 1580 cm ⁻¹ and showed a breathing mode LT split, indicating the presence of a graphene sheet scroll (roll) structure.

  The present inventor suspended a linear body 1 covered with a carbon nanotube with a quartz tube and stretched on a ceiling 2 in order to measure the breaking critical tension of the nanotube bundle, and via fishing fulcrums 3A and 3B as shown in FIG. The small bucket 4 was suspended and water was discharged into the bucket 4 while adjusting the water in the water tank 5 with the cock 6, and the breaking tension when the above-described quartz tube-clad carbon nanotube linear body 1 was broken was measured.

  FIGS. 1A, 1B and 1C show the state after the draft fracture of the quartz-clad carbon nanotube. In the case of FIG. 1A, the carbon nanotube protrudes from the quartz tube. This indicates a state in which the breaking tension cannot be measured. In the case of FIG. 1B, a measurable state is shown in which the quartz tube and the internal carbon nanotube are integrated and fractured at substantially the same cross section. In the case of FIG. 1 (C), the outer quartz tube is first stretched and is not drafted integrally with the inner carbon nanotube, and this also indicates a state in which the breaking tension cannot be measured.

In the rupture test of FIG. 1, it cannot be confirmed which of the quartz tube and the carbon nanotube bundle is ruptured earlier when the critical breaking tension is applied. However, when the cross section of the quartz-clad carbon nanotube was viewed with a microscope, the breakage showed that the quartz tube and the carbon nanotube inside were broken simultaneously.
The fracture limit tension was on the order of 10 ⁴ kgf / mm ² from the relative ratio between the cross section of the quartz-clad carbon nanotube and the cross section of the quartz tube serving as its sheath, and its value was extremely high.

  FIG. 2 shows an example of a test apparatus using a high-resolution Raman spectrometer with a built-in high interference wavelength selection filter for a carbon nanotube bundle as a sample of the present invention. The quartz-clad carbon nanotube bundle 6 is irradiated with incident laser light. 7, the scattered light 8 is converged by the optical lens 9, and this is received by a high resolution Raman spectrometer 10 with a built-in high interference wavelength selective filter, and its spectral output is detected by a CCD detector 11, and this output is Displayed by the spectrum recorder 13 via the control power source 12, and the time of single-walled nanotube is displayed on the spectrum recorder 13. Reference numeral 14 denotes a display for ordinary graphite.

In FIG. 3, carbon nanotubes 16 are vacuum-sealed in a quartz tube 15 (FIG. 3A), and both ends 19 and 19 of the quartz tube are drafted while being externally heated by a gas burner 17 (FIG. 3B). )), Showing a state of producing a quartz-clad carbon nanotube (FIG. 3C). 18 shows a cross section of the drafted quartz-clad carbon nanotube.
FIG. 4 is a schematic drawing showing examples of the number of molecular structures of single-walled carbon nanotubes used in the experiment.

[Experimental example]
The sample is a carbon fiber that has been subdivided mechanically as much as possible (diameter approx. 0.1 mm), and the surface is treated with hydrofluoric acid. Put. When the quartz tube 15 is heated from the outside with the oxygen gas 17 and the temperature of the carbon nanotube fiber 16 becomes high enough to incandescently soften, the carbon nanotube is quickly stretched together with the quartz tube. By this operation, a carbon nanofiber is covered with a quartz tube to form a linear body that is stretched into one body. As a result, the thickness of the carbon nanotube fiber can be reduced to about 10 microns. The fine structure of the fiber was observed with a metallographic microscope, and the fine structure was photographed with a CCD camera and analyzed. Next, a similar quartz microtube is produced without carbon fiber. When attaching metal thin wires to the fishing terminals attached to both ends of these two types of pipes (Figs. 1, 3A and 3B) and increasing the tension until the fiber is cut with the tension applied to the thin wires from both ends, and cutting Measure the tension.
The structure shown in FIG. 7 has more structural defects than the sample of FIG. 6 and the LT splitting is unclear. In the case shown in FIG. 8, the LT splitting is significantly unclear due to the annealing effect.

  In order to measure the tension, as shown in FIG. 1, one end of a sample tube 1 made of a thin quartz-clad carbon nanotube is fixed to the ceiling 2 and hung vertically through terminals 3A and 3B for bonding a quartz tube. The bucket 4 is suspended from the sample tube 1. A bucket 4 is suspended from the other end 3 </ b> B, and water is gradually injected into the bucket 4 while adjusting the valve 6 from the water tank 5. The critical tension normalized by the cross-sectional area is obtained from the amount of water injected when the sample is cut. The critical tension of only the quartz tube separately measured was subtracted from the critical tension of the quartz tube + carbon nanotube, and the difference was regarded as the critical tension of the quartz-coated carbon nanotube of the present invention.

Claims (2)

A plurality of carbon nanotube fibers are vacuum-sealed in a quartz tube having an inner diameter of 3 mm and an outer diameter of about 5 mm, and the quartz tube is externally heated so that the temperature becomes 900 ° C. to 1300 ° C. at which the carbon nanotube fibers soften incandescent. Softening the carbon nanotube fiber;
During the softening, drafting the carbon nanotube fiber together with the quartz tube until the outer diameter of the quartz tube is 0.1 mm or less;
Quenching this to room temperature, producing a flexible quartz-clad carbon nanotube fiber bundle containing carbon nanotube fiber bundles,
A quartz-clad carbon nanotube fiber bundle manufactured by a manufacturing process comprising:   2. The quartz-clad carbon nanotube fiber bundle according to claim 1, wherein the quartz-clad carbon nanotube fiber bundle is one of an armchair type, a zigzag type, and a chiral type.

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