KR102153921B1 - Carbon fiber composite and method of manufacturing the same - Google Patents

Abstract

Provided are a method of manufacturing a carbon fiber composite material, which is eco-friendly, cheap, and simple, and a carbon fiber composite material manufactured by using the same. According to one embodiment of the present invention, the method of manufacturing a carbon fiber composite material comprises the steps of: dissolving shellac in a polar solvent to form a shellac solution; forming a shellac solution layer by applying the shellac solution to a surface of a carbon fiber; thermally treating the shellac solution layer to form a shellac-induced reduced graphene oxide layer containing a shellac-induced reduced graphene oxide; forming a sizing layer by applying a sizing material on the shellac-induced reduced graphene oxide layer; and forming a bonding layer in which the shellac-induced reduced graphene oxide and the sizing material are chemically bonded between the shellac-induced reduced graphene oxide layer and the sizing layer.

Description

Carbon fiber composite and method of manufacturing the same

The technical idea of the present invention relates to a carbon fiber composite and a method of manufacturing the same.

Recently, a fiber composite material has been actively researched in various fields, and a fiber composite material composed of a carbon-based material is attracting attention as a new structural material because it is lighter than iron and has high strength. Among the carbon-based materials, graphene is a carbon nanostructure having a two-dimensional shape, and has excellent fracture stress, stiffness, thermal conductivity, and electrical conductivity, and thus it is expected to be used as a structure. Graphene may be formed by using a mechanical cleavage method or an oxidation exfoliation method of graphite. The thus formed graphene can be coated on the surface of the carbon fiber to form a structural material. However, in the conventional method, a high-temperature reduction reaction occurs and the carbon component of graphene oxide is consumed, generating water and carbon dioxide, forming various defects, and there is a limitation in that the reduced graphene is aggregated. In addition, since the conventional chemical reduction method uses a toxic reducing agent, there are environmental restrictions. Accordingly, there is a need for a technology for forming a carbon fiber composite material by coating reduced graphene on the surface of carbon fibers in an environmentally friendly, inexpensive, and simple process.

Korean Patent Registration No. 10-1642426

The technical problem to be achieved by the technical idea of the present invention is to provide a method of manufacturing a carbon fiber composite material that is environmentally friendly, inexpensive, and simple in process, and a carbon fiber composite material formed using the same.

However, these problems are exemplary, and the technical idea of the present invention is not limited thereto.

A method of manufacturing a carbon fiber composite according to the present invention for achieving the above technical problem comprises the steps of dissolving shellac in a polar solvent to form a shellac solution; Forming a shellac solution layer by applying the shellac solution to the surface of the carbon fiber; Heat-treating the shellac solution layer to form a shellac-induced reduced graphene oxide layer including a shellac-induced reduced graphene oxide; Forming a sizing layer by applying a sizing material on the shellac-induced reduced graphene oxide layer; And forming a bonding layer in which the shellac-induced reduced graphene oxide and the sizing material are chemically bonded between the shellac-induced reduced graphene oxide layer and the sizing layer.

In some embodiments of the present invention, preparing the shellac solution may be performed by dissolving the shellac in a polar solvent.

In some embodiments of the present invention, the polar solvent may include ethanol, methanol, or isopropyl alcohol.

In some embodiments of the present invention, before performing the step of forming the shellac solution layer, the surface of the carbon fiber may be plasma-treated.

In some embodiments of the present invention, the step of heat-treating the shellac solution layer to form a shellac-induced reduced graphene oxide layer may be performed at a temperature in the range of 500°C to 900°C.

In some embodiments of the present invention, the sizing material may include polyamide.

In some embodiments of the present invention, the shellac-induced reduced graphene oxide and the sizing material may form hydrogen bonds.

In some embodiments of the present invention, the shellac-induced reduced graphene oxide and the carbon fiber may form a covalent bond.

In some embodiments of the present invention, the content of the shellac-induced reduced graphene oxide with respect to the sizing material may be in the range of more than 0 wt% to 2 wt% or less.

A method for manufacturing a carbon fiber composite material according to the present invention for achieving the above technical problem comprises: forming a mixed solution by mixing a sizing material and deionized water; Mixing by adding a surfactant to the mixed solution; Mixing by adding a shellac-induced reduced graphene oxide to the mixed solution; Removing the surfactant from the mixed solution; Applying the mixed solution to the surface of the carbon fiber; And drying the carbon fiber to form a bonding layer in which the shellac-induced reduced graphene oxide and the sizing material are chemically bonded on the surface of the carbon fiber.

In some embodiments of the present invention, the sizing material may include polyamide.

In some embodiments of the present invention, the surfactant may include sodium dodecylbenzene sulfonate.

In some embodiments of the present invention, in the step of forming the mixed solution, the content of the sizing material with respect to the deionized water may range from 1 wt% to 5 wt%.

In some embodiments of the present invention, the step of removing the surfactant may be performed using ethyl acetate.

In some embodiments of the present invention, the step of removing the surfactant may be performed by heating the mixed solution to vaporize the ethyl acetate.

Carbon fiber composite material according to the technical idea of the present invention for achieving the above technical problem, carbon fiber; A shellac-induced reduced graphene oxide layer comprising a shellac-induced reduced graphene oxide and covering the surface of the carbon fiber; A sizing layer covering the shellac-induced reduced graphene oxide layer and including a sizing material; And a bonding layer interposed between the shellac-induced reduced graphene oxide layer and the sizing layer, wherein the shellac-induced reduced graphene oxide and the sizing material are chemically bonded to each other.

In some embodiments of the present invention, the content of the shellac-induced reduced graphene oxide with respect to the sizing material may be in the range of more than 0 wt% to 2 wt% or less.

In some embodiments of the present invention, the shellac-induced reduced graphene oxide layer may be derived from shellac.

In some embodiments of the present invention, the sizing layer may include polyamide.

In some embodiments of the present invention, the carbon fiber may include woven carbon fiber.

The method of manufacturing a carbon fiber composite according to the technical idea of the present invention is to increase the surface area by forming reduced graphene oxide and sizing material derived from shellac on the surface of the carbon fiber, and oxygen in the shellac-derived graphene oxide. By forming hydrogen bonds and mechanical crosslinking between the functional group and the sizing material, and the carbon fiber, it is possible to increase the chemical bonding strength with an organic material such as nylon 6 that adheres to the carbon fiber. In addition, the shellac-derived graphene oxide is not only strongly bonded to the carbon fiber surface by covalent bonds, but is uniformly dispersed in the sizing material to form hydrogen bonds, thereby increasing the mechanical properties of the carbon fiber composite material. Since the shellac is a natural material and does not use toxic substances in the manufacturing method, the manufacturing method of the carbon fiber composite material according to the technical idea of the present invention can provide an environmentally friendly, inexpensive and simple process.

The above-described effects of the present invention have been exemplarily described, and the scope of the present invention is not limited by these effects.

1 is a flow chart showing a method (S100) of manufacturing a carbon fiber composite according to an embodiment of the present invention.
2 is a cross-sectional view showing a carbon fiber composite according to an embodiment of the present invention.
3 is a flow chart showing a method of manufacturing a carbon fiber composite according to an embodiment of the present invention.
4 is a view illustrating a process of forming a shellac-induced reduced graphene oxide applied to a carbon fiber composite according to an embodiment of the present invention.
5 is a photograph of a PA-SRGO bond applied to a carbon fiber composite according to an embodiment of the present invention.
6 are scanning electron micrographs of a PA-SRGO bond applied to a carbon fiber composite according to an embodiment of the present invention.
7 is a graph showing a Fourier transform infrared spectroscopy analysis result of a PA-SRGO bond applied to a carbon fiber composite according to an embodiment of the present invention.
8 is a schematic diagram showing the chemical structural formula of a PA-SRGO bond applied to a carbon fiber composite according to an embodiment of the present invention.
9 are graphs showing the results of differential scanning calorimetry analysis of PA-SRGO bonds applied to carbon fiber composites according to an embodiment of the present invention.
10 are graphs showing X-ray diffraction analysis results of PA-SRGO bonds applied to carbon fiber composites according to an embodiment of the present invention.
11 is a graph showing the fine crystal size derived by X-ray diffraction analysis of a PA-SRGO bond applied to a carbon fiber composite material according to an embodiment of the present invention.
12 are scanning electron micrographs of a case where a PA-SRGO bond is applied on various carbon fibers in order to analyze the surface shape of a carbon fiber composite according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments of the present invention are provided to more completely explain the technical idea of the present invention to those of ordinary skill in the art, and the following examples may be modified in various other forms, and The scope of the technical idea is not limited to the following examples. Rather, these embodiments are provided to make the present disclosure more faithful and complete, and to completely convey the technical idea of the present invention to those skilled in the art. In this specification, the same reference numerals mean the same elements. Furthermore, various elements and areas in the drawings are schematically drawn. Therefore, the technical idea of the present invention is not limited by the relative size or spacing drawn in the accompanying drawings.

The technical idea of the present invention uses shellac as a carbon supply material. Shellac is a carbon-based natural polymer resin that can be obtained from the secretions of Lacifer lacca, which is a common insect in India and Thailand, and has thermoplastic properties. The shellac has a chemical formula of C ₃₀ H ₅₀ O ₁₁ , and has a melting point of 150°C, a softening point of 95°C, a specific gravity of 1.113 to 1.214, a liver value of 60, a saponification value of 200, and an iodine value of 18. The shellac is pale yellow or yellowish brown, and has various shapes such as a thin plate shape, a particle shape, and a powder shape. The shellac is not soluble in water, but soluble in alcohol or boric acid solution, and partially soluble in ether, acetone, carbon disulfide, and the like. Industrially, it is used as a final material for floors, varnishes, waxes, and adhesives. In the shellac, a bond rearrangement in which a hydroxyl group of an aliphatic chain is removed occurs at a high temperature, and thus a carbon thin film such as reduced graphene oxide can be formed. Since the shellac in which such bond rearrangement has occurred contains a large number of hetero oxygen atoms, it can have very good adhesion to the surface of the substrate.

1 is a flow chart showing a method (S100) of manufacturing a carbon fiber composite according to an embodiment of the present invention.

Referring to Figure 1, a method of manufacturing a carbon fiber composite (S100), preparing a shellac solution (S110); Forming a shellac solution layer by applying the shellac solution to the surface of the carbon fiber (S120); Forming a shellac-induced reduced graphene oxide layer including a shellac-induced reduced graphene oxide by heat-treating the shellac solution layer (S130); Forming a sizing layer by applying a sizing material on the shellac-induced reduced graphene oxide layer (S140); And forming a bonding layer in which the shellac-induced reduced graphene oxide layer and the sizing layer are chemically bonded to the shellac-induced reduced graphene oxide and the sizing material (S150).

Preparing the shellac solution (S110) may be performed by dissolving the shellac in a polar solvent. The polar solvent may include ethanol, methanol, or isopropyl alcohol. The content of the shellac with respect to the entire shellac solution may be, for example, in the range of 1 wt% to 10 wt%, and may be, for example, 4 wt%.

The step of forming the shellac solution layer by applying the shellac solution to the surface of the carbon fiber (S120) may be formed using various methods such as spray coating, drop coating, and spin coating, and may be performed once or multiple times. have. The content of shellac with respect to the entire carbon fiber may be, for example, in the range of 1 wt% to 10 wt%, and may be, for example, 6.5 wt%.

Before performing the step of forming the shellac solution layer (S120), the surface of the carbon fiber may be cleaned by plasma treatment. The plasma treatment may be performed using vacuum plasma or atmospheric pressure plasma.

The carbon fiber may be a woven carbon fiber (WCF). However, this is exemplary, and the technical idea of the present invention is not limited thereto, and the present invention is also in the case of graphene, carbon nanotubes, exfoliated graphite nanoPlatelet (xGnP), etc. Is included in the technical idea of In addition, a case of various fibers composed of other materials in place of carbon fibers is also included in the technical idea of the present invention.

In the step of forming the shellac-induced reduced graphene oxide layer (S130), the heat treatment may be performed at a temperature in the range of 500°C to 900°C, for example, to be performed at a temperature in the range of 700°C. I can. The heat treatment time may be, for example, in the range of 1 minute to 60 minutes, and may be, for example, 30 minutes. The heating rate may be, for example, in the range of 1°C/min to 10°C/min, and may be, for example, 3°C/min. The heat treatment may be performed in a vacuum in the range of 0.1 mbar to 0.3 mbar, for example, and may be performed in a vacuum of 0.16 mbar, for example. However, these heat treatment conditions are exemplary and the technical idea of the present invention is not limited thereto.

By this heat treatment, the polar solvent is removed from the shellac solution layer, and the shellac is changed to the shellac-derived reduced graphene oxide (SRGO) to cover the surface of the carbon fiber. -Induction reduction type graphene oxide layer is formed. The formed shellac-induced reduced graphene oxide may be about 12 wt% based on the whole shellac, and 0.8 wt% based on the carbon fiber.

In the step of forming the sizing layer (S140), the sizing material may include polyamide. However, this is exemplary, and the technical idea of the present invention is not limited thereto, and various sizing materials may be included. The content of the shellac-induced reduced graphene oxide with respect to the sizing material may be in the range of more than 0 wt% to 2 wt% or less.

The sizing treatment can form a thin and uniform coating layer on the surface of the carbon fiber. The sizing material includes one or more polymer materials capable of forming a film in a form in which it is dissolved, emulsified, or dispersed in a solution, and further includes a binder, a lubricant, a surfactant, a softener, an adhesion promoter, and a flow modifier. can do. The layer made of the sizing material on the surface of the carbon fiber may improve properties such as bonding of the carbon fiber and the matrix, mechanical properties, chemical resistance, waterproofness, and thermal stability. Thus, the function of these sizing materials is important and complex in the manufacture of composites. When these sizing materials are applied to carbon fiber composites, various properties such as compressive strength, tensile strength, bending strength, impact strength, fatigue properties, thermal stability, heat resistance, oil resistance, corrosion resistance, hydrolysis stability, and electrical conductivity are improved. Can be implemented.

In the step of forming the bonding layer (S150), the shellac-induced reduced graphene oxide and the sizing material may be hydrogen-bonded. In the sizing layer, the shellac-induced reduced graphene oxide may be dispersed by diffusion.

2 is a cross-sectional view showing a carbon fiber composite material 100 formed by the method of manufacturing the carbon fiber composite material of FIG. 1 according to an embodiment of the present invention.

Referring to FIG. 2, the carbon fiber composite material 100 covers the surfaces of the carbon fibers 110 and the carbon fibers 110, and includes a shellac-induced reduced graphene oxide-containing shellac-induced reduced graphene oxide layer ( 120), a sizing layer 140 covering the shellac-induced reduced graphene oxide layer 120 and including a sizing material; And a bonding layer 130 interposed between the shellac-induced reduced graphene oxide layer 120 and the sizing layer 140, wherein the shellac-induced reduced graphene oxide and the sizing material are chemically bonded to each other.

The carbon fibers 110 may include woven carbon fibers. The shellac-induced reduced graphene oxide layer 120 may be derived from shellac. The sizing layer 140 may include polyamide. The shellac-induced reduced graphene oxide and the carbon fiber may form a covalent bond. The shellac-induced reduced graphene oxide and the sizing material may form hydrogen bonds. In addition, the bond between the carbon fiber 110 and the shellac-induced reduced graphene oxide layer 120 and the bond between the shellac-induced reduced graphene oxide layer 120 and the sizing layer 140 are diffusion, entanglement with each other. ), mechanical interlockling, and molecular interaction force. In addition, the content of the shellac-induced reduced graphene oxide with respect to the sizing material may be in the range of more than 0 wt% to 2 wt% or less.

3 is a flowchart illustrating a method (S200) of manufacturing a carbon fiber composite according to an embodiment of the present invention.

Referring to FIG. 3, a method of manufacturing a carbon fiber composite material (S200) includes the steps of forming a mixed solution by mixing a sizing material and deionized water (S210); Adding and mixing a surfactant into the mixed solution (S220); Mixing shellac-induced reduced graphene oxide into the mixed solution (S230); Removing the surfactant from the mixed solution (S240); Applying the mixed solution to the surface of the carbon fiber (S250); And drying the carbon fiber to form a bonding layer in which the shellac-induced reduced graphene oxide and the sizing material are chemically bonded on the surface of the carbon fiber (S260).

In the above steps, mixing of the materials may be performed through various methods such as mechanical stirring and ultrasonic stirring.

The sizing material may include polyamide as described above. The content of the sizing material with respect to the deionized water may be, for example, in the range of 1 wt% to 5 wt%, and may be, for example, 3 wt%.

The surfactant may include sodium dodecyl benzene sulfonate (SDBS), but the technical idea of the present invention is not limited thereto. The content of the surfactant may range from, for example, 1 wt% to 5 wt%, and may be, for example, 1.66 wt% with respect to the entire mixed solution.

The step of removing the surfactant (S240) may be performed using ethyl acetate. The ethyl acetate may be in the range of 1 wt% to 10 wt%, for example, 5 wt% with respect to the whole mixed solution. However, this is exemplary, and the technical idea of the present invention is not limited thereto, and all kinds of substances capable of removing a surfactant may be included. The step of removing the surfactant (S240) may be performed by heating the mixed solution to vaporize the ethyl acetate.

The applying step (S250) may be performed by immersing the carbon fiber in the mixed solution. Alternatively, the applying step (S250) may be performed using various methods such as spray coating, drop coating, and spin coating of the mixed solution on the carbon fiber.

In the step of forming the bonding layer (S260), in a vacuum oven, for example, at a temperature in the range of 150°C to 200°C, for example, at a temperature of 180°C, for a time in the range of 1 minute to 10 minutes, for example For example, it can be carried out for a time of 5 minutes.

4 is a view illustrating a process of forming a shellac-induced reduced graphene oxide applied to a carbon fiber composite according to an embodiment of the present invention.

Referring to FIG. 4, a process of forming a shellac-induced reduced graphene oxide formed by a thermal reduction method based on shellac is shown. First, when the shellac is heated, a dehydration reaction occurs at a temperature of about 150°C, and as water vapor is formed, the long hydrocarbon chain of the shellac is decomposed. At a temperature of about 500 °C, incompletely formed graphene oxide is observed. At temperatures higher than 500° C., cyclization is formed by carbon-carbon bonds to form sp2 hybrid carbon networks in various sizes. Finally, the shellac-induced reduced graphene oxide made of carbon six-membered rings is formed.

Hereinafter, an experimental example of a PA-SRGO bond formed by combining a shellac-induced reduced graphene oxide (SRGO) and a polyamide (PA) as a sizing material will be described.

A mixed solution of deionized water and polyamide is formed. The content of the polyamide with respect to the deionized water was 3 wt%. That is, 3 g of polyamide was mixed with 100 ml of deionized water. The mixed solution was mechanically stirred at room temperature (25° C.) at 500 rpm for 10 minutes. 1.74 g of a surfactant was added to the mixed solution, stirred and stirred for 30 minutes, and ultrasonically stirred for 1 hour using a water bath type ultrasonic device. Sodium dodecyl benzene sulfonate (SDBS) was used as the surfactant. Subsequently, a desired volume of shellac-induced reduced graphene oxide was added to the mixed solution, stirred for 15 minutes, stirred, ultrasonically stirred for 2 hours using a water bath type ultrasonic device, and a horn type ultrasonic device It was stirred with ultrasonic waves for 1 hour. To remove the surfactant from the mixed solution, 5 ml of ethyl acetate was added to the mixed solution, and the mixed solution was repeatedly heated four times to evaporate and remove the ethyl acetate. At this time, in the mixed solution, polyamide, shellac-induced reduced graphene oxide, and deionized water remain. The mixed solution was dried at a temperature of 25° C. for 24 hours, and dried at 70° C. for 4 hours to completely remove deionized water to form a PA-SRGO conjugate.

Table 1 is a table showing the SRGO content of the PA-SRGO conjugate formed by the above-described method for PA.

SRGO content Weight of polyamide (g) Weight of shellac-induced reduced graphene oxide (mg) The proportion of shellac-induced reduced graphene oxide (wt%) 0 wt% 1.5 0 0 0.5 wt% 1.5 7.5 0.5 1 wt% 1.5 15 One 1.5 wt% 1.5 22.5 1.5 2 wt% 1.5 30 2

5 is a photograph of a PA-SRGO bond applied to a carbon fiber composite according to an embodiment of the present invention. Referring to FIG. 5, a liquid shellac-induced reduced graphene oxide and a polyamide PA-SRGO are combined. When the bond is dried, it can be seen that the PA-SRGO bond in the form of a solid film is formed.

6 are scanning electron micrographs of a PA-SRGO bond applied to a carbon fiber composite according to an embodiment of the present invention.

Referring to FIG. 6, when only SRGO is included, a thin layer having a crumpled surface is formed, and in some areas, SRGOs are aggregated with each other. On the other hand, it can be seen that when the SRGO is mixed and combined with PA, it shows a uniform dispersion. However, when the content of SRGO is increased more than 1 wt%, agglomeration occurs, and at 2 wt%, aggregation of the SRGO is well shown.

7 is a graph showing a Fourier transform infrared spectroscopy analysis result of a PA-SRGO bond applied to a carbon fiber composite according to an embodiment of the present invention.

In Figure 7, (a) shows a Fourier transform infrared spectroscopy (FT-IR) spectrum at a wave number in the range of 750 cm ^-1 to 4000 cm ^-1 of the PA-SRGO conjugate, (b) the PA-SRGO conjugate Represents a Fourier transform infrared spectroscopy spectrum at a wavenumber in the range of 1200 cm ^-1 to 2000 cm ^-1 , (c) represents the Fourier transform infrared spectroscopy spectrum at a wave number in the range of 750 cm ^-1 to 4000 cm ^-1 of SRGO, (d) is a graph showing the change in amide bond strength according to the content of SRGO of the PA-SRGO bond.

Table 2 is a table showing the band assignment for Fourier transform infrared spectroscopy of the PA-SRGO conjugate.

Band (cm ^-1 ) Band assignment 1201 Amide III, crystal band 1263 C-H stretching 1544 Amide II band (C-N stretch) 1640 Amide I band (C=O stretching) 2852 CH ₂ symmetry 2919 CH ₂ asymmetry 3299 N-H stretching

Referring to FIG. 7, as the content of the SRGO increases to 1 wt%, the strength of the amide I band and the amide II band increases, indicating the formation of a hydrogen bond between the PA and the SRGO. The SRGO content shows the strongest relative strength at 1 wt%, indicating that the SRGO and PA are most effectively combined through hydrogen bonding. On the other hand, when the content of SRGO is greater than 1 wt%, the relative strength is rapidly reduced. This decrease is analyzed because the SRGO aggregates according to the van der Waals attraction, and the hydrogen bonding is reduced. These results are in good agreement with the results of the scanning electron microscope analysis of FIG. 6. FIG. 8 is a schematic diagram showing the chemical structural formula of a PA-SRGO bond applied to a carbon fiber composite material according to an embodiment of the present invention.

Referring to FIG. 8, positions of the amide I band, the amide II band, and the amide III band formed by the bonding of the PA and the SRGO are shown. The hydrogen bonds between the hydrogen of the COOH group of SRGO and the C=O oxygen of the PA are shown together.

9 are graphs showing the results of differential scanning calorimetry analysis of PA-SRGO bonds applied to carbon fiber composites according to an embodiment of the present invention.

Table 3 is a table showing the results of differential scanning calorimetry (DSC) analysis of the PA-SRGO conjugate.

SRGO
content T _c
(℃) T _m1
(℃) T _m2
(℃) ΔH _m
(J/g) X _c
(%) Cl
(%) 0 wt% 94.60 147.18 157.13 12.98 5.64 32.76 0.5 wt% 105.55 149.78 157.01 13.06 5.68 39.02 1 wt% 106.44 149.13 156.33 15 6.52 44.61 1.5 wt% 106.02 149.84 156.73 12.74 5.54 23.61 2 wt% 103.66 - 156.41 11.44 4.97 17.79

In FIG. 9, (a) shows a primary cooling curve cooled at a cooling rate of 10°C/min, (b) shows a secondary heating curve heated at a heating rate of 10°C/min, and (c) Shows the degree of crystallinity. Here, when determining the degree (crystallinity, X _c) the crystallinity _{(X c) = ΔH m /} ΔH is calculated as _m0 x 100. 9 and Referring to Table 3, the amount of the SRGO 1 wt% is The highest T _c was shown, and the SRGO content was 11.84° C. higher than when the SRGO content was 0 wt%, that is, compared to the case without SRGO. In addition, when the SRGO content was 1 wt%, the crystallization peak was narrow. These results are analyzed because SRGO provides a nucleation site and increases the crystallization rate. The γ-crystal phase was analyzed to be due to incomplete crystal formation with hydrogen bonds formed between parallel chains, whereas the α-crystal phase was analyzed as a more stable phase by hydrogen bonding. As the content of SRGO increases, T _m1 gradually merges with T _m2, and there is no effect at about 156°C. This result is because the thickened layers melt as the crystal thickness increases, and interlayer hydrogen bonding is induced by the interaction between the SRGO and the PA chain. The crystallinity was 5.64 when SRGO was not included, and slightly increased to 6.52 when the SRGO content was 1 wt%. In addition, when the content of SRGO was 1 wt%, the crystallinity was greatest. These results are in good agreement with the scanning electron microscope analysis results of FIG. 6 and the Fourier transform infrared spectroscopy analysis results of FIG. 7.

Table 4 is a table showing the element content analysis derived as a result of X-ray analysis of the PA-SRGO conjugate.

SRGO content Elemental concentration (at%) C1s N1s O1s O1s/C1s SRGO 81.56 0.35 18.09 0.222 0 wt% 79.8 1.46 18.73 0.235 0.5 wt% 78.2 1.02 20.78 0.266 1 wt% 72.76 1.09 26.15 0.359 1.5 wt% 73.3 1.82 24.88 0.339 2 wt% 77.67 2.01 20.32 0.262

Table 5 is a table showing the C1s peak and relative peak regions derived as a result of X-ray analysis of the PA-SRGO conjugate.

SRGO
content C1s peak in different states (eV) Peak 1 Peak 2 Peak 3 Peak 4 Peak 5 Peak 6 Activated carbon
element (%) 284.6 285.0 286.1 287.7 289.1 290.6 SRGO 94.68 0 0.86 4 0.46 0 5.32 0 wt% 69.15 9.92 10.08 8.76 0.51 1.58 20.93 0.5 wt% 70 12.78 9.26 7.28 0.68 0 17.22 1 wt% 70.25 11.42 9.46 8.15 0.72 0 18.33 1.5 wt% 73.22 14.55 3.98 7.59 0.66 0 12.23 2 wt% 89.73 0 2.1 8.17 0 0 10.27 Peak assignment Reference -C-C-C-H -CO
-CN -C=O
-C=N -COOH
-COOR -COO-
π-π ^*

Referring to Tables 4 and 5, as the content of SRGO increased, the oxygen content increased, and in particular, when the SRGO content was 1 wt%, the oxygen content was the most as 26.15 at%. When the SRGO content was increased more than 1 wt%, the oxygen content was reduced again. In addition, when the SRGO content is 1 wt%, the content of the amide functional group and the carboxyl functional group is the highest. The content of the activated carbon element was also highest when the SRGO content was 1 wt%. When the PA-SRGO bond is coated on the carbon fiber, the amide functional group and the carboxyl functional group may function to increase the interfacial adhesion between the carbon fiber and the polyamide. The reason is that polar functional groups such as amide functional groups and carboxyl functional groups have excellent wettability, and hydrogen bonds can be formed between the carbon fiber and polyamide. Therefore, when the content of SRGO is 1 wt%, it is analyzed that the adhesion of the PA-SRGO bond to carbon fibers is the highest. FIG. 10 is a view applied to a carbon fiber composite material according to an embodiment of the present invention. These are graphs showing the results of X-ray diffraction analysis of PA-SRGO conjugates.

Referring to FIG. 10, a peak at 20 degrees corresponds to a (100) crystal plane, and a peak at 23 degrees corresponds to a (010)/(110) crystal plane. The peak corresponding to the (100) crystal plane is analyzed to be generated by dispersion in the layer, that is, it is analyzed to be generated by dispersion in the polymer chains constituting the polymer layer. On the other hand, the peak corresponding to the (010)/(110) crystal plane is analyzed to be generated by interlayer dispersion, that is, it is analyzed to be generated by dispersion between polymer layers connected by hydrogen bonding. The peak corresponding to the (100) crystal plane continued to decrease as the content of SRGO increased. On the other hand, the peak corresponding to the (010)/(110) crystal plane increases until the SRGO content reaches 1 wt%, and has the largest value when the SRGO content is 1 wt%. After that, it decreased. That is, it is analyzed that as the content of SRGO increases, the inner bonds of the polymer layer are destroyed, but hydrogen bonds are formed, thereby increasing the bonding between the polymer layers.

11 is a graph showing the fine crystal size derived by X-ray diffraction analysis of a PA-SRGO bond applied to a carbon fiber composite material according to an embodiment of the present invention.

Table 6 is a table showing crystallization properties derived by X-ray diffraction analysis of the PA-SRGO conjugate.

SRGO content 0 wt% 0.5 wt% 1 wt% 1.5 wt% 2 wt% C1(%) 32.76 39.02 44.61 23.61 17.79 2θ (100) 20.15 20.18 20.21 20.44 20.21 (010)/(110) 23.51 23.32 23.24 23.28 23.57 FWHM (100) 0.5 0.5 0.67 0.96 2.13 (010)/(110) 2.86 2.74 1.79 2.03 2.1 Accumulation
burglar (100) 0.81 0.50 0.31 0.29 0.25 (010)/(110) 1.28 1.95 2.22 1.01 0.32 (100)/(010) 0.63 0.26 0.14 0.3 0.77 Microcrystalline
Size (nm) H ₍₁₀₀₎ 2.79 2.79 2.1 1.47 0.66 H _(010)/(110) 0.49 0.52 0.79 0.7 0.68

Referring to FIGS. 11 and 6, crystallization characteristics of the (100) crystal plane and the (010)/(110) crystal plane are shown. In the case of the (100) crystal plane, the size of the crystallites continues to decrease. On the other hand, in the case of the (010)/(110) crystal plane, the size of the microcrystal increases until the content of SRGO reaches 1 wt%, and the largest value is increased when the content of SRGO is 1 wt%. And decreased thereafter. These results are in good agreement with the results of Fig. 10. Fig. 12 is a scan for a case of applying a PA-SRGO bond on various carbon fibers in order to analyze the surface shape of a carbon fiber composite according to an embodiment of the present invention. These are electron microscope pictures.

Referring to FIG. 12, (a) is a carbon fiber, (b) is a carbon fiber implanted with SRGO, (c) is a carbon fiber subjected to polyamide sizing treatment, and (d) sizing treatment with a PA-SRGO bond. One carbon fiber, (e) is a carbon fiber grafted with SRGO and polyamide sizing is performed, and (f) a carbon fiber grafted with SRGO is sized with a PA-SRGO bond.

The technical idea of the present invention described above is not limited to the above-described embodiments and the accompanying drawings, and that various substitutions, modifications and changes are possible within the scope not departing from the technical idea of the present invention. It will be apparent to those of ordinary skill in the art to which this belongs.

Claims (20)

Dissolving the shellac in a polar solvent to form a shellac solution;
Forming a shellac solution layer by applying the shellac solution to the surface of the carbon fiber;
Heat-treating the shellac solution layer to form a shellac-induced reduced graphene oxide layer including a shellac-induced reduced graphene oxide;
Forming a sizing layer by applying a sizing material on the shellac-induced reduced graphene oxide layer; And
Forming a bonding layer in which the shellac-induced reduced graphene oxide and the sizing material are chemically bonded between the shellac-induced reduced graphene oxide layer and the sizing layer; including, a method for producing a carbon fiber composite material . The method according to claim 1,
The step of preparing the shellac solution is performed by dissolving the shellac in a polar solvent. The method according to claim 2,
The polar solvent comprises ethanol, methanol, or isopropyl alcohol, a method for producing a carbon fiber composite. The method according to claim 1,
Before performing the step of forming the shellac solution layer, the surface of the carbon fiber is plasma-treated, a method of manufacturing a carbon fiber composite material. The method according to claim 1,
The step of heat-treating the shellac solution layer to form a shellac-induced reduced graphene oxide layer is performed at a temperature in the range of 500°C to 900°C. The method according to claim 1,
The sizing material comprises polyamide, a method for producing a carbon fiber composite. The method according to claim 1,
The shellac-induced reduced graphene oxide and the sizing material form a hydrogen bond, a method of manufacturing a carbon fiber composite. The method according to claim 1,
The shellac-induced reduced graphene oxide and the carbon fiber form a covalent bond, a method of manufacturing a carbon fiber composite. The method according to claim 1,
The content of the shellac-induced reduced graphene oxide with respect to the sizing material is in the range of more than 0 wt% to 2 wt% or less, a method for producing a carbon fiber composite. Mixing the sizing material and deionized water to form a mixed solution;
Mixing by adding a surfactant to the mixed solution;
Mixing by adding a shellac-induced reduced graphene oxide to the mixed solution;
Removing the surfactant from the mixed solution;
Applying the mixed solution to the surface of carbon fibers; And
Drying the carbon fiber to form a bonding layer in which the shellac-induced reduced graphene oxide and the sizing material are chemically bonded to each other on the surface of the carbon fiber. The method of claim 10,
The sizing material comprises polyamide, a method for producing a carbon fiber composite. The method of claim 10,
The surfactant includes sodium dodecylbenzene sulfonate, a method for producing a carbon fiber composite. The method of claim 10,
In the step of forming the mixed solution, the content of the sizing material with respect to the deionized water is in the range of 1 wt% to 5 wt%, a method of manufacturing a carbon fiber composite material. The method of claim 10,
The step of removing the surfactant is made by using ethyl acetate, a method of producing a carbon fiber composite. The method of claim 14,
The step of removing the surfactant is performed by heating the mixed solution to vaporize the ethyl acetate. Carbon fiber;
A shellac-induced reduced graphene oxide layer comprising a shellac-induced reduced graphene oxide and covering the surface of the carbon fiber;
A sizing layer covering the shellac-induced reduced graphene oxide layer and including a sizing material; And
The shellac-induced reduced graphene oxide layer and interposed between the sizing layer, the shellac-induced reduced graphene oxide and a bonding layer chemically bonded to the sizing material; containing, carbon fiber composite material. The method of claim 16,
The content of the shellac-induced reduced graphene oxide with respect to the sizing material is in the range of more than 0 wt% to 2 wt% or less, a carbon fiber composite material. The method of claim 16,
The shellac-induced reduced graphene oxide layer is derived from shellac, a carbon fiber composite. The method of claim 16,
The sizing layer comprises a polyamide, carbon fiber composite. The method of claim 16,
The carbon fiber includes a woven carbon fiber, a carbon fiber composite.

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