High-temperature oxidized dopamine modified fiber resin composite material and preparation method thereof

Abstract

The invention relates to the technical field of materials, and discloses a high-temperature oxidized dopamine modified fiber resin composite material, which comprises a plurality of layers of dopamine modified fiber cloth, and mixed slurry is compounded between the adjacent layers of dopamine modified fiber cloth; the mixed slurry is composed of a reinforcing phase, epoxy resin and a curing agent; the dopamine modified fiber cloth at least contains carbon fibers and dopamine deposited on the carbon fibers, and a dopamine coating on the carbon fibers is used for increasing the surface roughness, hydrophilicity and the number of active functional groups of the carbon fibers; the invention further discloses a preparation method of the high-temperature oxidized dopamine modified fiber resin composite material. The carbon fiber modification time is shortened, the operation method is simple, the combination effect of the carbon fiber and dopamine is effectively improved, and the performance of the fiber resin composite material is improved.

Description

Technical Field

[0001] The invention relates to the technical field of materials, and in particular to a high-temperature oxidized dopamine-modified fiber resin composite material and a preparation method thereof. Background Art

[0002] Resin-based composite materials have the advantages of high strength, low density, strong designability, and good dimensional stability, and are widely used in aerospace, wind power, rail transportation, automobiles and other fields. Fiber-reinforced composite materials have the characteristics of light weight, high strength, high temperature resistance and corrosion resistance. After the combination of these two types of materials, the addition of fibers can greatly improve the strength of the material, reduce the weight of the final product, and extend the service life of the product. At the same time, the resin matrix gives the material excellent properties such as high strength, heat resistance, and corrosion resistance.

[0003] At present, the most widely used resin matrix in fiber-reinforced resin-based composites is epoxy resin. Epoxy resin materials have the characteristics of high mechanical strength, high stiffness, and chemical resistance, providing good mechanical properties for composite materials. However, in practical applications, fiber-resin composites will have poor interface bonding due to the different chemical compositions between the fiber and the resin matrix, thereby reducing the material interface strength and limiting the overall excellent performance of the composite material.

[0004] Therefore, the prior art proposes that physical or chemical means can be used to modify the fiber, and by changing the fiber surface properties, a more compatible interface can be constructed between the resin and the fiber, and the stress transfer between the fiber and the resin can be strengthened to achieve the purpose of improving the interface strength of the composite material. At present, the research on fiber-resin composite materials is mostly focused on adding reinforcing phases to the materials to improve the mechanical properties, flame retardant properties, etc. of the materials, and there are few studies on introducing materials on the fibers to improve the interface bonding between the fibers and the resin, thereby improving the overall performance of the composite materials.

[0005] At the same time, the carbon fiber needs to be pretreated before the material is introduced on the fiber. At present, the pretreatment of carbon fiber mostly uses the Soxhlet extraction method to remove the sizing agent and pollutants on the fiber surface. This method requires the carbon fiber to be placed in a Soxhlet extractor and refluxed with acetone at 75°C for 72 hours. The extraction process is complicated, the use of chemical reagents causes damage to the fiber surface, and the extraction takes a long time, which limits the research and development and production of resin-based composite materials. Therefore, a new carbon fiber desizing method with short time consumption and simple operation is urgently needed to produce resin-based composite materials. Summary of the invention

[0006] The object of the present invention is to provide a high-temperature oxidized dopamine modified fiber resin composite material and a preparation method thereof, so as to solve the technical problem of long desizing time of existing carbon fibers in the prior art.

[0007] In order to solve the above technical problems, the present invention specifically provides the following technical solutions:

[0008] The present invention provides a high-temperature oxidized dopamine-modified fiber resin composite material, comprising a plurality of layers of dopamine-modified fiber cloths, wherein a mixed slurry is compositely arranged between adjacent layers of the dopamine-modified fiber cloths;

[0009] The mixed slurry consists of a reinforcing phase, an epoxy resin and a curing agent;

[0010] The dopamine-modified fiber cloth contains at least carbon fibers and dopamine deposited on the carbon fibers, wherein the dopamine coating on the carbon fibers is used to increase the surface roughness, hydrophilicity and number of active functional groups of the carbon fibers.

[0011] As a preferred embodiment of the present invention, the dopamine modified fiber cloth is composed of 20 parts of carbon fiber, 5 parts of dopamine hydrochloride and 3 parts of tris(hydroxymethyl)aminomethane (Tris) by weight.

[0012] As a preferred embodiment of the present invention, the mixed slurry contains at least 50-70 parts of epoxy resin, 2-6 parts of reinforcing phase and 15-21 parts of curing agent in parts by mass.

[0013] As a preferred solution of the present invention, the reinforcement phase includes at least one or more of carbon nanotubes and graphene.

[0014] As a preferred solution of the present invention, the reinforcing phase is carbon nanotubes.

[0015] As a preferred embodiment of the present invention, the epoxy resin is bisphenol A epoxy resin.

[0016] As a preferred solution of the present invention, the carbon fiber is polyacrylonitrile carbon fiber.

[0017] The present invention also provides a method for preparing a high-temperature oxidized dopamine-modified fiber resin composite material, comprising the following steps:

[0018] The carbon fiber is heat-treated at 250-350° C. for 1-3 hours and then naturally cooled to room temperature, then the carbon fiber is soaked in a 0.1 mol / L sodium hydroxide solution for 1-3 hours, and the carbon fiber is dried at 50-80° C. for 6-12 hours to obtain a desized carbon fiber;

[0019] 0.1 mol / L hydrochloric acid (HCl) is dripped into 0.01 mol / L tris(hydroxymethyl)aminomethane (Tris) to obtain a Tris-HCl buffer solution with a pH value of 8.5, dopamine hydrochloride is dissolved in the Tris-HCl buffer solution, mixed and stirred evenly to obtain a dopamine solution, the desized carbon fiber is immersed in the dopamine solution, reacted at room temperature for 12-24 hours, after the reaction is completed, washed with deionized water and anhydrous ethanol for multiple times, and dried at 50-80° C. for 6-12 hours to obtain dopamine modified fiber;

[0020] The carbon nanotubes, epoxy resin and curing agent are mixed and stirred at room temperature for 5-15 minutes to obtain a uniform mixed slurry. The mixed slurry is placed in a vacuum drying oven and kept warm for 5-10 minutes to remove bubbles. The mixed slurry is evenly applied layer by layer on the dopamine-modified carbon fiber cloth composed of the dopamine-modified carbon fiber, and pressurized and cured at 70-90°C, and the pressure is maintained for 0.5-1 hour to obtain a dopamine-modified fiber resin composite material.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention uses high-temperature oxidation to pretreat the carbon fiber. Compared with the existing Soxhlet extraction method, the high-temperature oxidation treatment method takes a short time and can significantly change the surface wettability of the carbon fiber. The material changes from hydrophobic to hydrophilic, which is beneficial to the combination of the fiber and the liquid, has little damage to the fiber surface, and has a good combination effect.

[0023] The present invention combines dopamine with carbon fiber so that the dopamine material is deposited on the surface of the carbon fiber to form a dopamine coating, thereby increasing the roughness of the fiber surface and the number of active functional groups, which not only increases the specific surface area of ​​the interface between the fiber and the resin matrix, but also increases the chemical bond between the fiber and the reinforcement phase, thereby achieving the performance of the composite material regulated on a multi-scale basis.

[0024] Dopamine and carbon nanotubes that can be chemically bonded with dopamine are added to the fiber-resin composite material disclosed in the present invention. Compared with pure carbon fiber-epoxy resin composite materials and single carbon nanotube-reinforced fiber-resin composite materials, the material has better strength and hydrophilicity, and effectively improves the performance of the material without damaging the material itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0026] Figure 1 A schematic flow chart of a method for preparing a high-temperature oxidized dopamine-modified fiber resin composite material is provided for the present invention;

[0027] Figure 2 The present invention provides a schematic diagram of the size of the fiber resin composite material sample shown in Example 1 and Comparative Examples 1-2;

[0028] Figure 3 The present invention provides a schematic diagram of the contact angle of the surface of the carbon fiber modified by high temperature oxidation dopamine as shown in Example 1;

[0029] Figure 4 A schematic diagram of the contact angle of the surface of carbon fiber directly modified by dopamine as shown in Comparative Example 1 is provided for the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The present invention provides a high-temperature oxidized dopamine modified fiber resin composite material, which is a composite of multiple layers of fiber cloth and resin-based materials. Specifically, the resin-based materials are applied between adjacent fiber cloths. Generally, the number of fiber cloth layers is 6, and the resin-based materials are arranged between the layers of the fiber cloth.

[0032] In particular, the resin-based material is a mixed slurry composed of a reinforcing phase, epoxy resin, and a curing agent, which is applied to a fiber cloth and cured. The fiber cloth specifically refers to a dopamine-modified fiber cloth, which contains at least carbon fiber and dopamine (also referred to as a dopamine coating) compositely arranged on the carbon fiber, and the dopamine coating can increase the surface roughness, hydrophilicity, and number of active functional groups of the carbon fiber.

[0033] When the surface roughness of the carbon fiber increases, the contact area between the resin-based material and the dopamine-modified fiber cloth increases, thereby improving the connection strength. At the same time, the active functional groups on the dopamine-modified fiber cloth are chemically bonded to the reinforcing phase in the resin-based material. The increase in the number of active functional groups can improve the chemical bonding between the fiber material and the reinforcing phase, thereby improving the performance of the composite material under multi-scale regulation.

[0034] In order to improve the interface strength between the fiber and the resin matrix, in a preferred embodiment of the present invention, the reinforcing phase includes at least one or more of carbon nanotubes and graphene. Further, the reinforcing phase is carbon nanotubes.

[0035] In a preferred embodiment of the present invention, the epoxy resin is bisphenol A epoxy resin, and the carbon fiber is polyacrylonitrile carbon fiber.

[0036] The present invention further provides a method for preparing the above-mentioned high-temperature oxidized dopamine-modified fiber resin composite material. In particular, the present invention replaces the commonly used Soxhlet extraction method with a high-temperature oxidation treatment to remove the sizing agent on the fiber surface, then deposits dopamine on the fiber surface, and composites the fiber with the dopamine coating with a resin to obtain the above-mentioned dopamine-modified fiber resin composite material.

[0037] The preparation method disclosed by the invention can shorten the process time and introduce dopamine material at the same time, thereby improving the performance of the fiber resin composite material.

[0038] Specifically, Figure 1 As shown, the preparation of the dopamine modified fiber resin composite material includes the following steps:

[0039] 1. High temperature oxidation treatment (carbon fiber pretreatment):

[0040] The carbon fiber is placed in a heating furnace, and after heat treatment at 250-350°C for 1-3 hours, it is taken out and naturally cooled to room temperature. The carbon fiber is then soaked in a 0.1 mol / L sodium hydroxide solution for 1-3 hours. The carbon fiber is placed in an oven at 50-80°C and dried for 6-12 hours to obtain de-sizing carbon fiber.

[0041] 2. Preparation of dopamine solution:

[0042] Tris (hydroxymethylaminomethane) was mixed to a concentration of 0.01 mol / L, and the pH value of the solution was calibrated to 8.5 with 0.1 mol / L hydrochloric acid. Dopamine hydrochloride was dissolved in Tris-HCl buffer and mixed and stirred to obtain a dopamine solution.

[0043] 3. Preparation of dopamine modified carbon fiber:

[0044] The desized carbon fiber is immersed in the prepared dopamine solution, and reacted at room temperature for 12-24 hours. After the reaction, the fiber is washed with deionized water and anhydrous ethanol for multiple times, and then placed in an oven for drying at 50-80°C for 6-12 hours to obtain dopamine modified fiber, which is then laid as dopamine modified fiber cloth.

[0045] 4. Preparation of fiber resin composite materials:

[0046] Take the reinforcing phase, epoxy resin and curing agent, mix the three in proportion and stir them thoroughly at room temperature for 5-15 minutes to obtain a mixed slurry, place the mixed slurry in a vacuum drying oven and keep it warm for 5-10 minutes to remove bubbles, then evenly apply the mixed slurry layer by layer on the dopamine modified carbon fiber cloth, place the dopamine modified fiber cloth (usually 6 layers) on the equipment and pressurize and cure it at 70-90°C, and keep the pressure for 0.5-1 hour to obtain a dopamine modified fiber resin composite material.

[0047] In the above preparation process, the proportions of the main materials are as follows: 50-70 parts of epoxy resin, 20 parts of carbon fiber, 2-6 parts of reinforcing phase, 5 parts of dopamine hydrochloride, 15-21 parts of curing agent, and 3 parts of tris(hydroxymethyl)aminomethane, calculated by weight.

[0048] The reinforcing phase is mainly carbon nanotubes.

[0049] The following provides an example of a high temperature oxidized dopamine modified fiber resin composite material and a preparation method thereof, Example 1:

[0050] Pretreatment: Place the carbon fiber in a heating furnace, keep it at 300°C for 2 hours, take it out, cool it naturally to room temperature, and then soak it in a 0.1 mol / L sodium hydroxide solution for 1 hour. After taking it out, wash it with deionized water and anhydrous ethanol for multiple times, and then put it in an oven at 60°C for 12 hours to obtain high-temperature oxidized carbon fiber;

[0051] 6 g of dopamine hydrochloride was dissolved in a 3 L Tris-HCl solution with a pH value of 8.5 and stirred evenly. A carbon fiber with a cutting weight of about 24 g was immersed in the dopamine solution and reacted at room temperature for 24 hours. After the reaction was completed, the carbon fiber was washed with deionized water and anhydrous ethanol for multiple times and then dried in an oven at 60° C. for 12 hours to obtain dopamine-modified fiber.

[0052] 60g of epoxy resin was evenly mixed with 18g of curing agent and 2.34g of carbon nanotubes, and the mixture was applied layer by layer onto six layers of vertically cross-arranged dopamine-modified carbon fiber cloth. The carbon fiber cloth was placed in a mold of a press, pressurized and cured at 70°C, and the pressure was maintained for 0.5 hours to obtain a dopamine-modified fiber resin composite material product.

[0053] Comparative Example 1:

[0054] The preparation steps are the same as those of Example 1, and the difference from Example 1 is that the carbon fibers in Comparative Example 1 are not subjected to high-temperature oxidation pretreatment.

[0055] Comparative Example 2:

[0056] The preparation steps are the same as those of Example 1, and the difference from Example 1 is that the carbon fibers in Comparative Example 2 are not modified with dopamine.

[0057] Performance Testing

[0058] The fiber resin composite material samples prepared in Example 1, Comparative Example 1 and Comparative Example 2 were used for performance testing to detect the effects of high temperature oxidation pretreatment and dopamine modification treatment on the mechanical properties and surface contact angle of the fiber resin composite material. The detection method is as follows:

[0059] Bending performance test: Determine the shape and size of the sample according to GB / T 1449-2005 Test method for bending performance of fiber reinforced plastics, such as Figure 2 As shown, the test equipment is a universal material testing machine CMT-5105GL, and the test speed is 10mm / min.

[0060] The experimental results are shown in Table 1:

[0061] Table 1

[0062]

[0063] Table 1 shows that the samples prepared by compounding dopamine-modified carbon fibers with epoxy resin have higher flexural strength and flexural modulus, and the flexural strength of the composite materials prepared by high-temperature oxidative pretreated carbon fibers after dopamine modification is significantly improved by 29% compared with the unmodified carbon fibers.

[0064] In addition, compared with direct modification by dopamine, the bending performance of the composite material prepared by dopamine-modified carbon fiber treated by high-temperature oxidation is more significantly improved. High-temperature oxidation treatment can replace the common modification methods in the prior art, save time, and cause less damage to the fiber surface. Experiments have shown that the composite material of Example 1 has the best bending performance.

[0065] Contact angle analysis: The static contact angle between carbon fiber and deionized water was measured by micro-droplet method, see Figure 3 and Figure 4 , Figure 3 is a static contact angle diagram between the carbon fiber and deionized water in Example 1, wherein the static contact angle is 45.83°, Figure 4 Graph showing the static contact angle between the carbon fiber of Comparative Example 1 and deionized water, wherein the static contact angle is 112.88°.

[0066] from Figure 3 and Figure 4It can be seen that the surface wettability of the carbon fiber after high-temperature oxidation modification changes significantly, from 112.88° to 45.83°, and the material changes from hydrophobic to hydrophilic, which is conducive to the combination of fiber and liquid. The resin and fiber in the material are tightly combined, so that the bending strength of the final product is improved. It can be seen that the high-temperature oxidation treatment modification method provided by the embodiment of the present invention can effectively improve the combination effect of fiber and dopamine, and effectively modify the carbon fiber.

[0067] Through the high-temperature oxidized dopamine-modified fiber resin composite material and its preparation method of this embodiment, the carbon fiber modification time can be shortened, and the operation method is simple, which effectively improves the bonding effect between carbon fiber and dopamine, increases the roughness of the fiber surface and the number of active functional groups, and not only improves the interface bonding between the fiber and the resin matrix, but also can improve the chemical bond bonding between the fiber and the reinforcement phase, and the performance of the composite material is regulated on a multi-scale basis.

[0068] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present application.

Claims

1. A high temperature oxidized dopamine modified fiber resin composite material, characterized in that: It comprises several layers of dopamine modified fiber cloth, and a mixed slurry is compositely arranged between adjacent layers of the dopamine modified fiber cloth; The mixed slurry is composed of epoxy resin, reinforcing phase and curing agent; The dopamine-modified fiber cloth contains at least carbon fibers and a dopamine coating deposited on the carbon fibers, wherein the dopamine coating on the carbon fibers is used to increase the surface roughness, hydrophilicity and number of active functional groups of the carbon fibers.

2. The high temperature oxidized dopamine modified fiber resin composite material according to claim 1, characterized in that: In terms of weight, the dopamine modified fiber cloth consists of 30 parts of carbon fiber, 5 parts of dopamine hydrochloride and 3 parts of tris(hydroxymethyl)aminomethane.

3. The high temperature oxidized dopamine modified fiber resin composite material according to claim 1, characterized in that: Calculated by weight, the mixed slurry contains at least 50-70 parts of epoxy resin, 2-6 parts of reinforcing phase, and 15-21 parts of curing agent.

4. The high temperature oxidized dopamine modified fiber resin composite material according to claim 1, characterized in that: The reinforcement phase includes at least one or more of carbon nanotubes and graphene.

5. The high temperature oxidized dopamine modified fiber resin composite material according to claim 4, characterized in that: The reinforcement phase is carbon nanotubes.

6. The high temperature oxidized dopamine modified fiber resin composite material according to claim 1, characterized in that: The epoxy resin is bisphenol A type epoxy resin.

7. The high temperature oxidized dopamine modified fiber resin composite material according to claim 1, characterized in that: The carbon fiber is polyacrylonitrile carbon fiber.

8. A method for preparing a high temperature oxidized dopamine modified fiber resin composite material, used for preparing the high temperature oxidized dopamine modified fiber resin composite material according to any one of claims 1 to 7, characterized in that: The steps include: The carbon fiber is heat-treated at 250-350° C. for 1-3 hours and then naturally cooled to room temperature, then the carbon fiber is soaked in a 0.1 mol / L sodium hydroxide solution for 1-3 hours, and the carbon fiber is dried at 50-80° C. for 6-12 hours to obtain a desized carbon fiber; The hydrochloric acid with a concentration of 0.1 mol / L is dripped into the tris(hydroxymethyl)aminomethane with a concentration of 0.01 mol / L to obtain a Tris-HCl buffer with a pH value of 8.5, dopamine hydrochloride is dissolved in the Tris-HCl buffer, mixed and stirred evenly to obtain a dopamine solution, the desized carbon fiber is immersed in the dopamine solution, reacted at room temperature for 12-24 hours, after the reaction is completed, washed with deionized water and anhydrous ethanol for multiple times, and dried at 50-80° C. for 6-12 hours to obtain dopamine modified fiber; The carbon nanotubes, epoxy resin and curing agent are mixed and stirred at room temperature for 5-15 minutes to obtain a mixed slurry. The mixed slurry is placed in a vacuum drying oven and kept warm at 60°C for 5-10 minutes to remove bubbles. The mixed slurry is evenly applied layer by layer on the dopamine-modified carbon fiber cloth composed of the dopamine-modified carbon fiber, and pressurized and cured at 70-90°C, and the pressure is maintained for 0.5-1 hour to obtain a dopamine-modified fiber resin composite material.

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