An upright carbon nanotube grafted carbon fiber, a carbon fiber composite material and a preparation method thereof

Abstract

The application provides a vertical carbon nanotube grafted carbon fiber, a carbon fiber composite material and a preparation method, and the preparation method comprises the following steps: S1, immersing a carbon fiber cloth into a glass source solution, then taking out and drying, and calcining to obtain a carbon fiber cloth containing a bioactive glass coating; the glass source solution comprises tetraethyl orthosilicate, triethyl phosphate, calcium nitrate, ethanol and water; S2, growing carbon nanotubes on the carbon fiber cloth containing the bioactive glass coating by a chemical vapor deposition method. The method introduces a bioactive glass coating on the surface of the carbon fiber, and then uses a catalytic chemical deposition method to quickly grow the vertical carbon nanotubes.

Description

Technical Field

[0001] This invention relates to a method for preparing carbon nanotubes on carbon fibers, and particularly to an upright carbon nanotube grafted onto carbon fibers, a carbon fiber composite material, and a method for preparing the composite material. Background Technology

[0002] Carbon nanotubes, due to their unique one-dimensional nanostructure, possess high specific surface area, high strength, and excellent electrical and thermal conductivity. As a secondary reinforcement in carbon fiber reinforced composites, they improve the mechanical properties of these composites. Carbon nanotubes share the same chemical composition, similar structure, and comparable coefficients of thermal expansion and physical properties as carbon fibers, making them highly suitable as a secondary reinforcement phase in carbon fiber composites. However, metal catalysts readily react with carbon at high temperatures and diffuse, losing their catalytic activity. Furthermore, carbon surfaces have a weak ability to capture and immobilize metal catalysts, leading to the tendency for loaded metal particles to migrate and aggregate. Consequently, the carbon nanotubes grown on carbon fiber surfaces via catalytic chemical deposition exhibit poor growth quality, characterized by nanotube curling, disordered orientation, and low density. Additionally, the growth rate of carbon nanotubes on carbon fiber surfaces is low; therefore, further research is needed to develop high-rate growth methods for upright carbon nanotubes on carbon fiber surfaces. Moreover, carbon nanotube-reinforced carbon fiber composites are frequently used in the manufacture of artificial bones, but the strong chemical inertness and lack of bioactivity of carbon fiber surfaces significantly limit their application in the biomedical field. Therefore, further research is warranted to simultaneously improve the mechanical properties and bioactivity of carbon fiber composites.

[0003] Reference 1 (Hui Qian, Alexander Bismarck, Emile S. Greenhalgh, Gerhard Kalinka, Milo SP Shaffer. Hierarchical composites reinforced with carbon nanotube-grafted fibers: the potential assessed at the single fiber level. Chemistry of Materials, 2008, 20(5): 1862-1869.) reported the growth of bent carbon nanotubes on the surface of carbon fibers in 1 hour, with a growth rate of less than 0.17 μm / min.

[0004] Reference 2 (Jianguo Zhao, Lang Liu, Quangui Guo, Jinli Shi, Gengtai Zhai, Jinren Song. Growth of carbon nanotubes on the surface of carbon fibers. Carbon, 2008, 46(2):380-383.) reported the in-situ growth of bent carbon nanotubes on the surface of carbon fibers using acetylene as the carbon source. The growth time was 30 minutes, and the growth rate of carbon nanotubes was less than 0.7 micrometers / minute.

[0005] Reference 3 (Qiang Song, Kezhi Li, Hailiang Li, Hejun Li, Chang Ren. Graftingstraight carbon nanotubes radially onto carbon fibers and their effect on the mechanical properties of carbon / carbon composites. Carbon, 2012, 50(10): 3949-3952.) reported the preparation of vertically oriented carbon nanotubes on the surface of carbon fibers. The carbon fibers were subjected to a strong acid immersion treatment for 24 hours, and the growth time of the carbon nanotubes was 2 hours. The growth rate of the carbon nanotubes was less than 0.17 μm / min.

[0006] Reference 4 (Feng Lei. Structure and mechanical properties of CNT-modified C / C composites grown by injection CVD [D]. Northwestern Polytechnical University, 2016) discloses a method of coating carbon fiber with silica and then growing carbon nanotubes, but the carbon nanotube growth rate of this method is low.

[0007] The aforementioned literature reports difficulties in the high-rate, upright growth of carbon nanotubes on carbon fibers, and the strong acid treatment process severely damages the surface structure of the carbon fibers, resulting in a significant reduction in fiber strength. Therefore, it is challenging to grow upright carbon nanotubes in situ on the carbon fiber surface at a high rate without damaging the carbon fibers. Summary of the Invention

[0008] To overcome the problems of existing preparation methods that result in carbon nanotubes being curled and randomly oriented on the surface of carbon fibers, and that the preparation process severely damages carbon fibers and has a low growth rate, this invention provides a method for grafting upright carbon nanotubes onto carbon fibers, carbon fiber composite materials, and preparation methods. This method involves introducing a bioactive glass coating onto the surface of carbon fibers and then using a catalytic chemical deposition method to rapidly grow upright carbon nanotubes.

[0009] This invention is achieved through the following technical solution:

[0010] A method for preparing upright carbon nanotube-grafted carbon fibers includes the following steps:

[0011] S1, immerse carbon fiber cloth in a glass source solution, then remove, dry, and calcine to obtain carbon fiber cloth with a bioactive glass coating; the glass source solution includes tetraethyl orthosilicate, triethyl phosphate, calcium nitrate, ethanol, and water;

[0012] S2, carbon nanotubes are grown on carbon fiber cloth with a bioactive glass coating by chemical vapor deposition.

[0013] Preferably, the mass ratio of tetraethyl orthosilicate to ethanol is 1:(2-1), and the mass ratio of ethanol to water is (2-3):1.

[0014] Preferably, the mass ratio of triethyl phosphate to calcium nitrate is 1:(7-8), and the mass ratio of triethyl phosphate to tetraethyl orthosilicate is 1:(10-11).

[0015] Preferably, in S1, the carbon fiber cloth is pretreated by immersing it in an acetone solution for 24 to 72 hours.

[0016] Preferably, in S1, the carbon fiber cloth is immersed in the glass source solution for 5 to 10 minutes, the drying temperature is 50 to 70 degrees Celsius, and the drying time is 8 to 12 hours.

[0017] Preferably, in S1, the calcination temperature is 700-750 degrees Celsius and the calcination time is 2-3 hours.

[0018] Preferably, S2 specifically involves: mixing ferrocene, anhydrous ethanol, and ethylenediamine to obtain a mixed solution of carbon source and catalyst; arranging carbon fibers containing a bioactive glass coating in a chemical vapor deposition furnace, heating to 800–900 degrees Celsius, injecting the mixed solution of carbon source and catalyst into the chemical vapor deposition furnace, and reacting to obtain upright carbon nanotube-grafted carbon fibers.

[0019] Preferably, the mass ratio of ferrocene to ethylenediamine is 1:(15-18).

[0020] The upright carbon nanotube grafted carbon fiber obtained by the preparation method described above.

[0021] A carbon fiber composite material comprising a resin matrix and, as a reinforcing phase of the resin matrix, the upright carbon nanotube-grafted carbon fiber of claim 9.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention introduces a bioactive glass coating onto carbon fibers. The functions of the bioactive glass include: (1) morphology induction: because the bioactive glass coating can support high-density metal catalyst particles, carbon atoms adsorb and deposit carbon nanotubes at high-density nucleation sites, forming a "competitive" mechanism among the carbon nanotubes, forcing them to grow perpendicular to the substrate surface; (2) the bioactive glass can induce an increase in the growth rate of carbon nanotubes, because the calcium and phosphorus ions in the bioactive glass can better capture the metal catalyst particles. Thus, the carbon nanotubes grown on the carbon fibers grow vertically and at an extremely fast rate, with a growth rate of 2-2.57 micrometers / minute, reaching a maximum of 2.57 micrometers / minute, which is 357% higher than the highest growth rate of carbon nanotubes reported in the background art (0.7 micrometers / minute). This invention achieves high-speed and vertical growth of carbon nanotubes on the carbon fiber surface. Furthermore, in the carbon nanotube preparation method of this invention, the introduction of a bioactive glass coating instead of strong acid treatment does not damage the carbon fibers, while simultaneously giving the carbon fiber composite material bioactivity.

[0024] Furthermore, the carbon fiber cloth is pretreated with an acetone solution to remove the resin on the carbon fiber cloth, thereby improving the bonding between the bioactive glass coating and the carbon fiber cloth.

[0025] The upright carbon nanotubes prepared by this invention have a better reinforcing effect on carbon fibers than the bent carbon nanotubes. Compared with bent carbon nanotubes, the tensile strength and elastic modulus of the resin composite material with upright carbon nanotubes grafted with carbon fibers by this invention are significantly improved. Attached Figure Description

[0026] Figure 1 This is a scanning electron microscope image of the upright carbon nanotubes grown at a high rate on the surface of the carbon fiber prepared in Example 1.

[0027] Figure 2 This is a scanning electron microscope image of the upright carbon nanotubes grown at a high rate on the surface of the carbon fiber prepared in Example 2.

[0028] Figure 3 This is a scanning electron microscope image of the upright carbon nanotubes grown at a high rate on the surface of the carbon fiber prepared in Example 3.

[0029] Figure 4 This is a scanning electron microscope image of the bent carbon nanotubes grown on the surface of the carbon fiber prepared in Example 4.

[0030] Figure 5 The force-displacement curves and bar charts of tensile strength and elastic modulus of the carbon fiber reinforced phenolic resin matrix composites based on Example 1 and Comparative Example 1 are shown.

[0031] Figure 6This is the EDS spectrum of the upright carbon nanotube grafted carbon fiber obtained in Example 1.

[0032] Figure 7 This is a scanning electron microscope image of the upright carbon nanotube grafted carbon fibers obtained in Example 1 after being immersed in human simulated body fluid (SBF solution) at a constant temperature of 37°C for 3 days.

[0033] Figure 8 This is a scanning electron microscope image of the upright carbon nanotube grafted carbon fibers obtained in Example 1 after being immersed in human simulated body fluid (SBF solution) at a constant temperature of 37°C for 7 days. Detailed Implementation

[0034] To further understand the present invention, the present invention will be described below with reference to embodiments. These descriptions are only for further explaining the features and advantages of the present invention and are not intended to limit the claims of the present invention.

[0035] The method for preparing upright carbon nanotube-grafted carbon fibers according to the present invention includes the following steps:

[0036] (1) Soak the carbon fiber cloth in acetone solution for 24 to 72 hours, and the resulting sample is labeled as sample A.

[0037] (2) Tetraethyl orthosilicate, anhydrous ethanol, and deionized water are mixed evenly, wherein the mass ratio of tetraethyl orthosilicate to anhydrous ethanol is 1:(2-1), and the mass ratio of anhydrous ethanol to deionized water is (2-3):1. The pH value is adjusted to 2-5 using hydrochloric acid, and the mixture is magnetically stirred at room temperature for 40-60 minutes. Then, triethyl phosphate is added and magnetically stirred for 20-30 minutes. Finally, calcium nitrate is added and magnetically stirred until homogeneous, wherein the mass ratio of triethyl phosphate to calcium nitrate is 1:(7-8), and the mass ratio of triethyl phosphate to tetraethyl orthosilicate is 1:(10-11), to obtain solution B (i.e., glass source solution).

[0038] (3) After immersing sample A in solution B for 5 to 10 minutes, place it in an oven and keep it at 50 to 70 degrees Celsius for 8 to 12 hours to obtain sample C.

[0039] (4) Mix ferrocene, anhydrous ethanol and ethylenediamine evenly, wherein the mass ratio of ferrocene to anhydrous ethanol is 1:(80-100) and the mass ratio of ferrocene to ethylenediamine is 1:(15-18), and stir evenly to obtain solution D (i.e., a mixed solution of carbon source and catalyst).

[0040] (5) Place sample C in a tubular chemical vapor deposition furnace and heat it to 700-750 degrees Celsius for 2-3 hours to obtain carbon fiber cloth with a bioactive glass coating; then heat it to 800-900 degrees Celsius and inject solution D into the tubular chemical vapor deposition furnace at a rate of 5-15 ml / h for 10-30 minutes. After the temperature inside the furnace cools down to room temperature, take out the sample to obtain upright carbon nanotubes grown at a high rate on the surface of carbon fiber, i.e., upright carbon nanotube grafted carbon fiber.

[0041] Example 1

[0042] (1) Immerse the carbon fiber cloth in acetone solution for 24 hours and the resulting sample is labeled as sample A.

[0043] (2) Tetraethyl orthosilicate, anhydrous ethanol, and deionized water are mixed evenly, with the mass ratio of tetraethyl orthosilicate to anhydrous ethanol being 1:2 and the mass ratio of anhydrous ethanol to deionized water being 2:1. The pH value is adjusted to 2 using hydrochloric acid, and the mixture is magnetically stirred for 40 minutes at room temperature. Then, triethyl phosphate is added and magnetically stirred for 20 minutes. Finally, calcium nitrate is added and magnetically stirred until homogeneous, with the mass ratio of triethyl phosphate to calcium nitrate being 1:7 and the mass ratio of triethyl phosphate to tetraethyl orthosilicate being 1:10, to obtain solution B.

[0044] (3) After immersing sample A in solution B for 5 minutes, place it in an oven and keep it at 50 degrees Celsius for 8 hours to obtain sample C.

[0045] (4) Mix ferrocene, anhydrous ethanol and ethylenediamine evenly, wherein the mass ratio of ferrocene to anhydrous ethanol is 1:80 and the mass ratio of ferrocene to ethylenediamine is 1:15, and stir evenly to obtain solution D.

[0046] (5) Place sample C in a tubular chemical vapor deposition furnace, heat it to 700 degrees Celsius and keep it at that temperature for 2 hours, then heat it to 800 degrees Celsius. Inject solution D into the tubular chemical vapor deposition furnace at a rate of 10 ml / h for 10 minutes. After the temperature inside the furnace cools down to room temperature, take out the sample to obtain upright carbon nanotubes grown at a high rate on the surface of carbon fibers, i.e., upright carbon nanotubes grafted onto carbon fibers.

[0047] like Figure 1 As shown, in this Example 1, upright carbon nanotubes were prepared on the surface of carbon fibers, and the growth rate of the carbon nanotubes was 2.57 micrometers / minute.

[0048] Example 2

[0049] (1) Immerse the carbon fiber cloth in acetone solution for 72 hours and the resulting sample is labeled as sample A.

[0050] (2) Tetraethyl orthosilicate, anhydrous ethanol, and deionized water are mixed evenly, with the mass ratio of tetraethyl orthosilicate to anhydrous ethanol being 1:1 and the mass ratio of anhydrous ethanol to deionized water being 3:1. The pH value is adjusted to 5 using hydrochloric acid, and the mixture is magnetically stirred for 60 minutes at room temperature. Then, triethyl phosphate is added and magnetically stirred for 30 minutes. Finally, calcium nitrate is added and magnetically stirred until homogeneous, with the mass ratio of triethyl phosphate to calcium nitrate being 1:8 and the mass ratio of triethyl phosphate to tetraethyl orthosilicate being 1:11, to obtain solution B.

[0051] (3) After immersing sample A in solution B for 10 minutes, place it in an oven and keep it at 70 degrees Celsius for 12 hours to obtain sample C.

[0052] (4) Mix ferrocene, anhydrous ethanol and ethylenediamine evenly, wherein the mass ratio of ferrocene to anhydrous ethanol is 1:100 and the mass ratio of ferrocene to ethylenediamine is 1:18. Stir evenly to obtain solution D.

[0053] (5) Place sample C in a tubular chemical vapor deposition furnace, heat it to 750 degrees Celsius and keep it at that temperature for 3 hours, then heat it to 900 degrees Celsius. Inject solution D into the tubular chemical vapor deposition furnace at a rate of 10 ml / h for 20 minutes. After the temperature inside the furnace cools down to room temperature, take out the sample to obtain upright carbon nanotubes grown at a high rate on the surface of carbon fibers, i.e., upright carbon nanotubes grafted onto carbon fibers.

[0054] like Figure 2 As shown, in Example 2, upright carbon nanotubes were prepared on the surface of carbon fibers, and the growth rate of the carbon nanotubes was 2.18 micrometers / minute.

[0055] Example 3

[0056] (1) The carbon fiber cloth was soaked in acetone solution for 48 hours, and the resulting sample was labeled as sample A.

[0057] (2) Tetraethyl orthosilicate, anhydrous ethanol, and deionized water are mixed evenly, with the mass ratio of tetraethyl orthosilicate to anhydrous ethanol being 1:2 and the mass ratio of anhydrous ethanol to deionized water being 3:1. The pH value is adjusted to 2 using hydrochloric acid, and the mixture is magnetically stirred for 60 minutes at room temperature. Then, triethyl phosphate is added and magnetically stirred for 20 minutes. Finally, calcium nitrate is added and magnetically stirred until homogeneous, with the mass ratio of triethyl phosphate to calcium nitrate being 1:8 and the mass ratio of triethyl phosphate to tetraethyl orthosilicate being 1:10, to obtain solution B.

[0058] (3) After immersing sample A in solution B for 5 minutes, place it in an oven and keep it at 70 degrees Celsius for 8 hours to obtain sample C.

[0059] (4) Mix ferrocene, anhydrous ethanol and ferrocene evenly, wherein the mass ratio of ferrocene to anhydrous ethanol is 1:100 and the mass ratio of ferrocene to ethylenediamine is 1:15. Stir evenly to obtain solution D.

[0060] (5) Place sample C in a tubular chemical vapor deposition furnace, heat it to 700 degrees Celsius and keep it at that temperature for 3 hours, then heat it to 800 degrees Celsius. Inject solution D into the tubular chemical vapor deposition furnace at a rate of 10 ml / h for 30 minutes. After the temperature inside the furnace cools down to room temperature, take out the sample to obtain upright carbon nanotubes grown at a high rate on the surface of carbon fibers, i.e., upright carbon nanotubes grafted onto carbon fibers.

[0061] like Figure 3 As shown, in Example 3, upright carbon nanotubes were prepared on the surface of carbon fibers, and the growth rate of the carbon nanotubes was 2.01 micrometers / minute.

[0062] Comparative Example 1

[0063] (1) Immerse the carbon fiber cloth in acetone solution for 24 hours and the resulting sample is labeled as sample A.

[0064] (2) Mix ferrocene, anhydrous ethanol and ethylenediamine evenly, wherein the mass ratio of ferrocene to anhydrous ethanol is 1:80 and the mass ratio of ferrocene to ethylenediamine is 1:15. Stir evenly to obtain solution B.

[0065] (3) Place sample A in a tubular chemical vapor deposition furnace and keep it at 700 degrees Celsius for 2 hours. Then raise the temperature to 800 degrees Celsius and inject solution B into the tubular chemical vapor deposition furnace at a rate of 10 ml / h for 10 minutes. After the temperature inside the furnace cools down to room temperature, take out the sample to obtain the bent carbon nanotubes grown on the carbon fiber surface.

[0066] like Figure 4 As shown, carbon nanotubes were prepared on the surface of carbon fibers in Comparative Example 1, but the carbon nanotubes were not upright. In addition, the growth rate of the carbon nanotubes was 0.3 micrometers / minute. Compared with Example 1, Comparative Example 1 had the same other conditions, except that steps (2) and (3) in Example 1 were omitted. Therefore, it was impossible to obtain upright-grown carbon nanotubes, and the growth rate was very slow. The growth rate of carbon nanotubes in Comparative Example 1 was significantly lower than that of carbon nanotubes in Examples 1-3.

[0067] To verify the reinforcing effect of upright carbon nanotubes on carbon fibers, the products of Example 1 and Comparative Example 1 were respectively immersed in a phenolic resin solution (the mass ratio of phenolic resin to anhydrous ethanol was 3:7) and then hot-pressed on a flatbed hot press for 300 seconds to obtain carbon fiber reinforced phenolic resin matrix composites. Tensile tests were then performed, and the results are as follows: Figure 5As shown, comparing the force-displacement curves and tensile strength and elastic modulus histograms of the carbon fiber reinforced phenolic resin matrix composites based on Example 1 and Comparative Example 1, it can be seen that the tensile strength and elastic modulus of the carbon fiber reinforced phenolic resin matrix composite based on Example 1 are 39.9% and 31.0% higher, respectively, than those of the carbon fiber reinforced phenolic resin matrix composite based on Comparative Example 1, proving that the reinforcing effect of upright carbon nanotubes on carbon fibers is better than that of bent carbon nanotubes.

[0068] like Figure 6 The image shows the EDS spectrum of the upright carbon nanotube-grafted carbon fiber obtained in Example 1. The EDS spectrum shows that the obtained upright carbon nanotube-grafted carbon fiber contains phosphorus and calcium elements, proving that the bioactive glass was successfully prepared.

[0069] The scanning electron microscope (SEM) image shows the result of immersing the upright carbon nanotube-grafted carbon fibers obtained in Example 1 in simulated human body fluid (SBF solution) at a constant temperature of 37°C for 3 days. Figure 7 As shown, the carbon nanotubes are covered with a layer of hydroxyapatite, which is due to the bioactive glass that gives the carbon fiber composite material its bioactivity.

[0070] The scanning electron microscope (SEM) image shows the result of immersing the upright carbon nanotube-grafted carbon fibers obtained in Example 1 in simulated human body fluid (SBF solution) at a constant temperature of 37°C for 7 days. Figure 8 As shown, the carbon nanotubes are covered with a layer of hydroxyapatite, and the carbon fibers and carbon nanotubes are no longer visible, indicating that they have very good biological activity.

Claims

1. A method for preparing upright carbon nanotube-grafted carbon fibers, characterized in that, Includes the following steps: S1, immerse carbon fiber cloth in a glass source solution, then remove, dry, and calcine to obtain carbon fiber cloth with a bioactive glass coating; the glass source solution includes tetraethyl orthosilicate, triethyl phosphate, calcium nitrate, ethanol, and water; S2, carbon nanotubes are grown on carbon fiber cloth with a bioactive glass coating by chemical vapor deposition.

2. The method for preparing upright carbon nanotube-grafted carbon fibers according to claim 1, characterized in that, The mass ratio of tetraethyl orthosilicate to ethanol is 1:(2-1), and the mass ratio of ethanol to water is (2-3):

1.

3. The method for preparing upright carbon nanotube-grafted carbon fibers according to claim 1, characterized in that, The mass ratio of triethyl phosphate to calcium nitrate is 1:(7-8), and the mass ratio of triethyl phosphate to tetraethyl orthosilicate is 1:(10-11).

4. The method for preparing upright carbon nanotube-grafted carbon fibers according to claim 1, characterized in that, In S1, the carbon fiber cloth is pretreated as follows: the carbon fiber cloth is soaked in an acetone solution for 24 to 72 hours.

5. The method for preparing upright carbon nanotube-grafted carbon fibers according to claim 1, characterized in that, In S1, the carbon fiber cloth is immersed in the glass source solution for 5 to 10 minutes, the drying temperature is 50 to 70 degrees Celsius, and the drying time is 8 to 12 hours.

6. The method for preparing upright carbon nanotube-grafted carbon fibers according to claim 1, characterized in that, In S1, the calcination temperature is 700–750 degrees Celsius, and the calcination time is 2–3 hours.

7. The method for preparing upright carbon nanotube-grafted carbon fibers according to claim 1, characterized in that, S2 specifically involves mixing ferrocene, anhydrous ethanol, and ethylenediamine to obtain a mixed solution of carbon source and catalyst; arranging carbon fibers containing a bioactive glass coating in a chemical vapor deposition furnace, heating to 800–900 degrees Celsius, injecting the mixed solution of carbon source and catalyst into the chemical vapor deposition furnace, and reacting to obtain upright carbon nanotube-grafted carbon fibers.

8. The method for preparing upright carbon nanotube-grafted carbon fibers according to claim 7, characterized in that, The mass ratio of ferrocene to ethylenediamine is 1:(15-18).

9. Upright carbon nanotube grafted carbon fibers obtained by the preparation method according to any one of claims 1 to 8.

10. A carbon fiber composite material, characterized in that, It includes a resin matrix and the upright carbon nanotube-grafted carbon fibers as described in claim 9, which serve as a reinforcing phase of the resin matrix.

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