Continuous construction method of carbon fiber nano-implanted topological interface reinforced structure

Abstract

The invention discloses a continuous construction method of a carbon fiber nano-implanted topological interface enhanced structure, and belongs to the field of carbon fiber preparation. The method comprises the following steps: heating and vaporizing an organic solvent with solubility to PAN to obtain dissolving agent steam, and spraying out the dissolving agent steam at a specific speed and temperature; and meanwhile, a carbon nanotube gas-phase dispersion particle flow is obtained through a plasma dispersion technology and is sprayed out. Dissolving agent steam and carbon nano tube particles are intersected in a specific space point, relevant parameters are controlled to enable the dissolving agent steam to be condensed and coated on the surfaces of the carbon nano tube particles, under the action of Van der Waals force and dissolving agent wetting force, the carbon nano tubes with the surfaces coated with the dissolving agent are adhered to the surfaces of the PAN fibers, and the PAN fibers are formed through heating embedding. And preparing a target product according to a carbon fiber carbonization method. According to the method, the problem that the quality of the carbon fibers is influenced by impurities generated by decomposition of the dissolving agent during conventional plasma preparation is solved, the ratio of the carbon nanotube particles to the dissolving agent is proper, the carbon nanotube particles can be attached to the carbon fiber precursors in an embedded manner, and the performance of the carbon fibers is improved.

Description

Technical Field

[0001] The invention relates to a method for preparing carbon fibers by spraying after combining gas-phase carbon nanotubes with a solvent, and belongs to the field of carbon fiber preparation. Background Art

[0002] Carbon fiber is a high-performance engineering material widely used in aerospace, automotive, and other sectors requiring lightweight materials. To enhance its performance, it is typically combined with functional materials. For example, spraying carbon nanotubes onto its surface can significantly improve its mechanical, thermal, and electrical properties. The preparation of carbon fiber requires multiple process steps and highly specialized equipment and technology, resulting in high raw material and manufacturing costs.

[0003] Polyacrylonitrile (PAN) fiber is a fiber with excellent physical properties, such as wear resistance, UV resistance, warmth retention, chemical stability and biodegradability. It can be made into a variety of products through different polymerization, spinning and post-processing processes and is widely used in textiles, industry and many other fields.

[0004] Patent CN202411699702.3 discloses a method for preparing semi-implanted nanostructured carbon fibers based on dry-jet wet spinning. This involves connecting one pole of a high-voltage DC electric field to the spinneret of a spinning device, where the desired nanomaterial is dispersed in the vapor phase using a plasma method. Plasma dispersion is highly active, achieving efficient dispersion under mild conditions and effectively breaking down agglomerates. It has been shown to improve material properties, promote the construction of uniformly dispersed systems, and has a rapid, precise, and broadly applicable application.

[0005] Patent CN201910586775.4 discloses a process for preparing carbon fiber with surface embedded carbon nanotubes. The carbon fiber raw yarn is electrostatically charged and gas-dispersed carbon nanotubes are adsorbed before curing, so that a small amount of carbon nanotubes only treat the surface of the carbon fiber. Part of the carbon nanotubes are embedded in the carbon fiber, and part is exposed on the surface of the carbon fiber, forming a surface structure that is beneficial to enhancing the bonding strength between the carbon fiber and the resin matrix.

[0006] However, judging from the publicly available technology, the preparation process of this type of technology utilizes the electrostatic attachment of carbon nanotubes to the surface of carbon fiber. However, due to the smooth surface of carbon fiber, it is difficult for carbon nanotubes to penetrate deep into the interior of the carbon fiber through electrostatic adsorption to form an effective composite structure. Summary of the Invention

[0007] In order to solve the above problems, the present invention proposes a method for preparing carbon fibers by spraying gas-phase carbon nanotubes combined with a solvent:

[0008] 1. Heating a solvent to vaporize it to obtain solvent vapor, wherein the solvent is an organic solvent that is soluble in PAN, such as one or more of DMSO and DMF, and spraying the solvent vapor along path 1 through an inclined nozzle A at a speed of 0.05-0.85 m / s. The vapor outlet temperature is not less than 120% of the boiling point of the lowest boiling point substance of the solvent, not more than 140% of the boiling point of the highest boiling point substance of the solvent, and not less than 110% of the average dew point temperature of the solvent vapor, so as to prevent the solvent vapor from being atomized in the running path and losing the solvent vapor substance ratio;

[0009] 2. A gas-phase dispersed carbon nanotube particle flow is obtained by plasma dispersion technology and ejected through an inclined nozzle B along path 2. The gas-phase dispersed carbon nanotube particle concentration is 0.001-1 mg / ml, the velocity is 0.05-1.25 m / s, and the temperature is 500-1000°C;

[0010] 3. The inclined nozzle A and the inclined nozzle B are arranged at a relative angle so that the paths 1 and 2 along the nozzle direction intersect at a point in space, and the intersection point is located on the perpendicular bisector of the line connecting nozzle 1 and nozzle 2. The solvent vapor flow and the carbon nanotube particles are mixed at the intersection point, wherein the distance from the inclined nozzle A to the intersection point is such that the temperature drop loss of the solvent vapor during operation is no more than 85% of the difference between its outlet temperature and the average dew point temperature of the solvent vapor;

[0011] 4. To condense the solvent vapor in step 1 on the surface of the carbon nanotube vapor-phase dispersed particles in the intersection region of step 3, the velocity of the carbon nanotube vapor-phase dispersed particles ejected from the inclined nozzle B in step 2 is reduced to 80%-120% of the solvent vapor velocity in the intersection region of step 3, and the temperature is reduced to 3%-100% of the average dew point temperature of the solvent vapor;

[0012] 5. When the carbon nanotube particles in step 4 and the solvent vapor in step 1 meet at the intersection point in step 3, the solvent vapor condenses on the surface of the carbon nanotube particles because the surface temperature of the carbon nanotube particles is 3%-100% of the average dew point temperature of the solvent vapor. By controlling three parameters: the solvent vapor concentration in the intersection area, the concentration of the carbon nanotube particles after gas phase dispersion, and the surface temperature of the carbon nanotube particles, the content of the solvent condensed on the surface of the carbon nanotube particles is adjusted to be 1%-200%, and the condensed solvent can completely cover the individual carbon nanotube particles.

[0013] 6. The carbon nanotubes coated with the solvent in step 5 continue to move to the PAN fiber at the residual speed and adhere to the surface of the PAN fiber under the combined action of van der Waals force and solvent wetting force, thereby obtaining surface-modified PAN fiber;

[0014] 7. Heating the surface-modified PAN fiber obtained in step 6 at 20%-100% of the average boiling point of the solvent for 1-80 min so that the carbon nanotubes on the surface of the PAN fiber are embedded into the surface of the PAN fiber under the action of the solvent, thereby obtaining a PAN fiber with a nano-implanted topological interface enhancement structure;

[0015] 8. The PAN fiber with a nano-implanted topological interface reinforcement structure obtained in step 7 is prepared according to a carbon fiber carbonization method to obtain a carbon fiber with a nano-implanted topological interface reinforcement structure.

[0016] The beneficial effect of the present invention is that it improves the conventional formula for preparing plasma, avoids the decomposition of the solvent in a high temperature and high pressure environment to produce impurities when using arc to disperse plasma, and thus affects the quality of the carbon fiber. In the present invention, carbon nanotube particles and solvent vapor are first combined into one at a certain point in the air, and the solvent vapor condenses into droplets after contacting the surface of the carbon nanotube particles, and completely coats the individual carbon nanotube particles before being sprayed onto the PAN surface. The ratio of carbon nanotube particles to solvent is appropriate, and the solvent dissolves the PAN precursor just enough to cause the carbon nanotubes to be embedded in the carbon fiber precursor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention is a schematic diagram of the operation flow of the method for preparing carbon fibers by combining gas-phase dispersed carbon nanotubes with a solvent.

[0018] Figure 2 It is a schematic diagram of the process of the method for preparing carbon fibers by combining gas-phase dispersed carbon nanotubes with a solvent according to the present invention. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be fully described below with reference to the accompanying drawings, and the following is one example:

[0020] 1. Heating a solvent to vaporize it to obtain solvent vapor, wherein the solvent has a dissolving effect on PAN precursor and is a mixture of 50% DMSO and water. The heating time is 5 minutes and the temperature is 190° C. The solvent vapor is ejected along path 1 through inclined nozzle 1 at a rate of 0.08 m / s.

[0021] 2. Using plasma dispersion technology, the carbon nanotubes are dispersed into carbon nanotube particles. The gas-phase dispersed carbon nanotube particles are ejected along path 2 by tilting nozzle 2. The gas-phase dispersed carbon nanotube particles have a concentration of 0.5 mg / ml, a velocity of 0.16 m / s, and a temperature of 700°C.

[0022] 3. The inclined nozzle 1 and the inclined nozzle 2 are arranged at an angle of 120 degrees, so that the paths 1 and 2 along the nozzle direction intersect at a point in space, and the intersection point is located on the perpendicular midline of the line connecting nozzle 1 and nozzle 2, and the solvent vapor flow and the carbon nanotube particles are mixed at the intersection point;

[0023] 4. To reduce the temperature and velocity of the carbon nanotube particles after gas phase dispersion in step 1, an annular air cooling device is provided on path 1 to eject the carbon nanotube particles through the circular hole of the device. The annular air cooling device is hollow, with an air duct connected to the bottom and a continuous air gap provided on the inner wall. When gas is introduced into the air duct, the gas is ejected from the gap in a direction opposite to and perpendicular to the direction of movement of the carbon nanotube particles at a velocity of 0.05 m / s and a temperature of 15°C. After being ejected from the annular air cooling device, the carbon nanotube particles continue to move in a spiral manner along path 1, with their velocity reduced to 0.18 m / s and their temperature reduced to 125°C.

[0024] 5. When the carbon nanotube particles in step 4 intersect with the solvent vapor in step 1 at a point in space, because the surface temperature of the carbon nanotube particles is lower than the solvent vapor temperature, and the solvent vapor moves slowly and has a large relative content, the vapor condenses into droplets on the surface and can completely cover the single carbon nanotube particle, causing it to carry 80% of its own mass of solvent.

[0025] 6. The carbon nanotube particles wrapped by the solvent are sprayed onto the PAN fiber at the final speed after secondary deceleration. Due to their solubility in PAN precursor, the carbon nanotube particles are embedded in the carbon fiber precursor.

[0026] 7. The surface-modified PAN fiber obtained in step 6 is heated at 100° C. for 5 min to allow the carbon nanotubes on the surface of the PAN fiber to be embedded into the surface of the PAN fiber under the action of the solvent, thereby obtaining a PAN fiber with a nano-implanted topological interface enhancement structure.

[0027] 8. After a series of conventional operations such as carbonization and surface treatment, carbon fibers with nano-implanted topological interface reinforcement structures can be obtained.

Claims

1. The solvent is heated to vaporize it to obtain solvent vapor, and the solvent vapor is ejected along path 1 through an inclined nozzle A, and the vapor outlet temperature is not lower than 120% of the boiling point of the lowest boiling point substance of the solvent, not higher than 140% of the boiling point of the highest point substance of the solvent, and not lower than 110% of the average dew point temperature of the solvent vapor. A carbon nanotube gas phase dispersed particle flow is obtained by plasma dispersion technology and ejected along path 2 through an inclined nozzle B. In order to reduce the temperature and speed of the carbon nanotube particles after gas phase dispersion, an annular air cooling device is provided on path 1. The annular air cooling device is hollow with an air duct connected to the bottom, and a continuous air gap is provided on the inner wall. When gas is introduced into the air duct, the gas is ejected from the gap in a direction opposite to and perpendicular to the direction of movement of the carbon nanotube particles. The inclined nozzle A and the inclined nozzle B are set at a relative angle so that paths 1 and 2 along the nozzle direction are at a point in space. The solvent vapor flow and the carbon nanotube particles are mixed at the intersection point. The surface temperature of the carbon nanotube particles is lower than the solvent vapor temperature, and the solvent vapor movement rate is slow and the relative content is large. The vapor condenses into droplets on its surface and can completely cover a single carbon nanotube particle. The carbon nanotube particles wrapped by the solvent are sprayed onto the PAN fiber at the final speed after secondary deceleration. Due to their solubility in the PAN precursor, the carbon nanotube particles are attached to the carbon fiber precursor in an embedded state. The surface-modified PAN fiber is heated at 100°C for 5 minutes so that the carbon nanotubes on the surface of the PAN fiber are embedded into the surface of the PAN fiber under the action of the solvent, thereby obtaining a PAN fiber with a nano-implanted topological interface reinforcement structure. After a series of conventional operations such as carbonization and surface treatment, a carbon fiber with a nano-implanted topological interface reinforcement structure can be obtained.

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