Chitosan-modified boron nitride and graphene fiber composite material, its preparation method and application

Abstract

The present invention discloses a chitosan-modified boron nitride and graphene fiber composite material, its preparation method and application. The preparation method includes the following steps: Step 1, preparation of chitosan-modified boron nitride; Step 2, preparation of graphene fibers; Step 3, compounding of modified boron nitride and graphene fibers. The present invention uses chitosan to modify boron nitride nanoparticles, which, as an interfacial compatibilizer, improves the contact interface between boron nitride and the epoxy resin matrix, not only greatly improving the mechanical properties of the epoxy resin matrix, but also enhancing the thermal stability of the epoxy resin matrix and the stability of the thermal conduction network, thereby greatly improving the thermal conductivity of the epoxy resin. The composite thermal conductive material based on epoxy resin of the present invention can be used as a heat dissipation coating for electronic devices, providing an effective solution for improving the heat dissipation problem of electronic devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of materials, and specifically relates to a chitosan-modified boron nitride and graphene fiber composite material, a preparation method thereof, and an application thereof. Background Art

[0002] Epoxy resin is a kind of polymer. Its excellent physical and mechanical properties, electrical insulation properties, adhesion properties with various materials, and the flexibility of its use process are not possessed by other thermosetting plastics. Epoxy resin can be made into coatings, composite materials, casting materials, adhesives, molding materials and injection molding materials, and is widely used in various fields. However, due to the low thermal conductivity of epoxy resin (less than 0.2 W / m·K), heat accumulation is likely to occur during the operation of devices, increasing the internal stress and leading to a series of problems such as cracking of products. To effectively improve the thermal conductivity, adding high thermal conductivity fillers to the epoxy system is a common method.

[0003] Metal powder is the most commonly used thermal conductivity filler for epoxy resin. However, metal powder thermal conductivity fillers are particularly sensitive to the environment, with poor stability, which will affect the impact toughness of epoxy resin, resulting in easy cracking of epoxy resin and a decrease in thermal conductivity. The invention patent with the application number CN202110776950.3 and the patent name "A CNTs@CC Thermal Conductivity Filler and a Thermal Conductivity Composite Material Based on It" discloses carbon nanotubes obtained by high-temperature calcination of bimetallic Co / Zn-ZIF crystals, and a process for obtaining a thermal conductivity composite material after coating epoxy resin on both sides of the filler and curing. This invention patent uses carbon fiber cloth as a prefabricated skeleton, relying on the carbon nanotubes grown in-situ on its surface to connect between carbon fibers, reducing the contact thermal resistance between carbon fibers radially, and at the same time relying on the plain woven carbon fiber cloth skeleton to form a long-range ordered thermal conductivity network structure, which can significantly improve the thermal conductivity of the composite material. However, the preparation process of this method is complex, the yield of the thermal conductivity filler is not high, the process stability is poor, and the preparation cost is high, making it difficult to achieve industrial application. Summary of the Invention

[0004] To solve the above technical problems, the technical solution adopted by the present invention is: a preparation method of a chitosan-modified boron nitride and graphene fiber composite material, including the following steps:

[0005] Step 1, preparation of chitosan-modified boron nitride: Dissolve a certain amount of chitosan in an acetic acid solution, add a certain amount of deionized water, add a certain amount of phytic acid solution containing choline chloride, then add a certain amount of boron nitride, perform ultrasonic treatment on it using a cell crusher, then perform centrifugation several times, respectively take the supernatant, and finally wash with deionized water until the product is neutral, and dry the product in a vacuum environment to obtain chitosan-modified boron nitride;

[0006] Step 2: Preparation of graphene fibers. A certain amount of natural graphite and sodium nitrate are put into concentrated sulfuric acid to obtain a black solution. After continuously stirring in an ice bath for a period of time, a certain amount of potassium permanganate is slowly added, and stirring continues in the ice bath. Then, a certain amount of distilled water is slowly added to obtain a brownish-yellow solution. Subsequently, the brownish-yellow solution is diluted with a certain amount of warm water, and a certain amount of hydrogen peroxide is added to obtain a bright yellow solution. The bright yellow solution is filtered, and the filtered product is rinsed with dilute hydrochloric acid and distilled water until the solution is neutral. The filtered product is dried and ground to obtain graphene oxide. The graphene oxide is centrifugally washed with hydrochloric acid and distilled water until it is nearly neutral, and then the graphene oxide is dispersed in deionized water;

[0007] The solution containing graphene oxide is injected into a glass syringe, and a spinning needle is used to control the spinning speed with a flow pump. The graphene oxide fibers are rapidly shrunk and solidified in a high-temperature nitrogen gas stream. The obtained graphene oxide fibers are reduced in a sodium citrate aqueous solution for a period of time, and repeatedly washed with deionized water until neutral. Finally, they are dried in a vacuum environment to obtain graphene fibers;

[0008] Step 3: Composite of modified boron nitride and graphene fibers. A certain amount of the chitosan-modified boron nitride prepared in Step 1 and a certain amount of the graphene fibers prepared in Step 2 are respectively added to deionized water, heated and kept warm for a period of time, and then rapidly cooled in an ice bath environment. After filtration, the filtered product is dried in a vacuum environment to obtain a black powder. Under a nitrogen atmosphere, it is kept at a high temperature for a period of time, and then the product is washed with concentrated hydrochloric acid and water multiple times until neutral. Finally, the product is dried in a vacuum to obtain a composite material of chitosan-modified boron nitride and graphene fibers.

[0009] As a preference of the above technical solution, in Step 1, 2 g of chitosan is dissolved in 1 ml of acetic acid solution with a concentration of 1%, 25 ml of deionized water is added, and then 5 g of choline chloride and 50% phytic acid with a total mass are added. The molar ratio of choline chloride to phytic acid is 4:1. 80 mg of boron nitride is weighed and dispersed in the solution, and it is ultrasonically treated with a cell crusher.

[0010] As a preference of the above technical solution, when ultrasonically treating with a cell crusher in Step 1, the power is adjusted to 150 W, and the ultrasonic time is set to 90 min; during the centrifugation process, the rotation speed is 1000 - 1500 r / min, and the centrifugation time is 10 min respectively; the drying temperature in the vacuum environment is 90 °C.

[0011] Preferably, in step two, 1 g of natural graphite and 1 g of sodium nitrate are put into a beaker, and 46 ml of 98% concentrated sulfuric acid is slowly added to obtain a black solution, which is continuously stirred in an ice bath for 4 h. Subsequently, 6 g of potassium permanganate is slowly added in the ice bath environment, and stirring in the ice bath is continued for 2 h. Then, 92 ml of distilled water is slowly added to obtain a brownish solution. Subsequently, the mixed solution is diluted with 350 ml of warm water at about 50 °C, and 20 ml of 30% hydrogen peroxide is used to remove the residual potassium permanganate to obtain a bright yellow solution. Finally, the solution is filtered, and the obtained product is rinsed with dilute hydrochloric acid and distilled water until the solution is neutral, dried at 50 °C, and ground to obtain graphite oxide. The product is centrifugally washed with 10% HCl and distilled water until it is nearly neutral, and then graphene oxide is dispersed in 500 ml of deionized water.

[0012] Preferably, in step two, the spinning needle has a specification of 1.6 μm, the spinning speed is 1.5 ml / h, the temperature of the nitrogen gas flow is 250 °C, the graphene oxide fiber is reduced with a 70% aqueous solution of sodium citrate at 90 °C for 8 h, and the drying temperature in a vacuum environment is 100 °C.

[0013] Preferably, in step three, 8 g of modified boron nitride and graphene fiber are added to 200 ml of deionized water according to a mass ratio of 1:1, heated to 100 °C and kept warm for 1 h, quickly cooled in an ice bath environment, filtered and dried in a vacuum environment to obtain a black powder; under a nitrogen atmosphere, it is kept warm at 700 °C for 3 h, and then the product is washed with concentrated hydrochloric acid and water for many times until it is neutral. Finally, the product is dried in a vacuum drying oven at 80 °C for 24 h.

[0014] The chitosan-modified boron nitride and graphene fiber composite material is prepared by the above preparation method.

[0015] Application of the chitosan-modified boron nitride and graphene fiber composite material, using the chitosan-modified boron nitride and graphene fiber composite material for thermal conductivity modification of epoxy resin.

[0016] Preferably, epoxy resin, the chitosan-modified boron nitride and graphene fiber composite material are put into a planetary vacuum mixer and kneaded for 5 min, and then the material is taken out and pressurized and kept warm at 50 °C for 2 h, thus obtaining an epoxy resin material with the chitosan-modified boron nitride and graphene fiber composite material as a thermal conductivity filler.

[0017] The beneficial effects of the present invention are as follows: The present invention uses chitosan to modify boron nitride nanoparticles, which are used as an interfacial compatibilizer to improve the contact interface between boron nitride and the epoxy resin matrix. This not only greatly improves the mechanical properties of the epoxy resin matrix, but also enhances the thermal stability of the epoxy resin matrix and the stability of the thermal conduction network, thereby significantly improving the thermal conductivity of the epoxy resin. Boron nitride nanoparticles have characteristics such as high thermal stability and good thermal conductivity, and have broad application prospects in the field of insulating thermal management. Boron nitride nanoparticles can not only significantly increase its thermal conductivity, but also its large aspect ratio and specific surface area are beneficial to the formation of a thermal conduction path in the polymer matrix. Graphene fiber materials have excellent flexibility and high thermal conductivity. When used as the main thermal conductive filler for the modification of epoxy resin, a three-dimensional thermal conduction network can be formed in the epoxy resin matrix, opening up a path for the transmission of thermal phonons, thereby greatly improving the thermal conduction ability of the epoxy resin matrix. The composite thermal conductive material based on epoxy resin in the present invention can be used as a heat dissipation coating for electronic devices, providing an effective solution to improve the heat dissipation problem of electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the SEM image of the epoxy resin material in each embodiment. SPECIFIC EMBODIMENTS

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0021] Example 1

[0022] 1. Modification of boron nitride with chitosan

[0023] Dissolve 2 g of chitosan in 1 ml of acetic acid solution with a concentration of 1%, and add 25 ml of deionized water. Then add 5 g of choline chloride (analytical grade) and 50% phytic acid with a total mass into a beaker, where the molar ratio of choline chloride to phytic acid is 4:1. Weigh 80 mg of boron nitride and disperse it in the solution. Use a cell crusher to perform ultrasonic treatment on it, adjust the power to 150 W, set the ultrasonic time to 90 min, then centrifuge at a speed of 1500 r / min for 10 min, take the supernatant and centrifuge again (10000 r / min, 10 min), and then wash with deionized water until the product is neutral. Dry the product in a vacuum environment at 90 °C to obtain chitosan-modified boron nitride.

[0024] 2. Preparation of Graphene Fibers

[0025] Put 1 g of natural graphite and 1 g of sodium nitrate into a beaker, slowly add 46 ml of 98% concentrated sulfuric acid (concentrated H2SO4) to obtain a black solution, continuously stir in an ice bath for 4 h, then slowly add 6 g of potassium permanganate in the ice bath environment, continue to stir in the ice bath for 2 h, and then slowly add 92 ml of distilled water (this process is also an exothermic process, must be slow) to obtain a brownish-yellow solution. Subsequently, dilute the mixed solution with 350 ml of warm water at about 50 °C, and use 20 ml of 30% hydrogen peroxide to remove the residual potassium permanganate to obtain a bright yellow solution. Finally, filter the solution, and rinse the obtained product with dilute hydrochloric acid and distilled water until the solution is neutral, and dry and grind it at 50 °C to obtain graphite oxide. Centrifuge and wash the product with 10% HCl and distilled water until it is nearly neutral, and then disperse the solution in 500 ml of deionized water.

[0026] Inject the graphene oxide solution into a glass syringe, use a 1.6 μm spinning needle, control the spinning speed with a flow pump at 1.5 ml / h, and rapidly contract and solidify the nascent graphene oxide fiber in a nitrogen gas stream at 250 °C. Reduce the above-prepared graphene oxide fiber with 70% sodium citrate aqueous solution at 90 °C for 8 h, repeatedly wash with deionized water until it is neutral, and finally dry it in a vacuum environment at 100 °C to obtain graphene fibers.

[0027] 3. Composite of Modified Boron Nitride and Graphene Fibers

[0028] Add 8 g of modified boron nitride and graphene fibers according to a mass ratio of 1:1 to 200 ml of deionized water, heat to 100 °C and keep warm for 1 h, quickly cool in an ice bath environment, filter and dry in a vacuum environment to obtain a black powder. Under a nitrogen atmosphere, keep warm at 700 °C for 3 h, and then wash the product with concentrated hydrochloric acid and water for many times until it is neutral. Finally, dry the product in a vacuum drying oven at 80 °C for 24 h.

[0029] 4. Modified Epoxy Resin

[0030] Put the epoxy resin and the chitosan-modified boron nitride and graphene fiber composite material into a planetary vacuum mixer at a weight ratio of 5% and knead for 5 minutes, then take it out and press and heat it at 50 °C for 2 hours to obtain an epoxy resin material with the chitosan-modified boron nitride and graphene fiber composite material as the filler.

[0031] Example 2

[0032] The steps are the same as those in Example 1, except that in Step 4, the epoxy resin and the chitosan-modified boron nitride and graphene fiber composite material are kneaded in a planetary vacuum mixer at a weight ratio of 10% to obtain an epoxy resin material with the chitosan-modified boron nitride and graphene fiber composite material as the filler.

[0033] Example 3

[0034] The steps are the same as those in Example 1, except that in Step 4, the epoxy resin and the chitosan-modified boron nitride and graphene fiber composite material are kneaded in a planetary vacuum mixer at a weight ratio of 20% to obtain an epoxy resin material with the chitosan-modified boron nitride and graphene fiber composite material as the filler.

[0035] Comparative Example 1

[0036] Use the epoxy resin without any thermal conductive filler directly as the comparative example.

[0037] The SEM scanning images of the cross-sections of the epoxy resin materials of Examples 1-3 and Comparative Example 1 after thermosetting are as Figure 1 shown.

[0038] For the epoxy resin materials of Examples 1-3 and Comparative Example 1, performance test and analysis are carried out. The test methods are as follows:

[0039] For the impact performance, refer to the standard of GB / T 1451-2005, and use a HY-5J pendulum impact tester to test the mechanical properties of the samples;

[0040] The tensile performance is tested according to GBT2567-2008;

[0041] The thermal conductivity of the specimen is measured by a quasi-steady-state thermal conductivity meter.

[0042] The volume resistivity is tested by a high-resistance meter after preheating the specimen to 25 °C and applying an external voltage of 1000 V.

[0043] The test results are as follows:

[0044]

[0045] From the above test results, it can be seen that the chitosan-modified boron nitride and graphene fiber composite material prepared in this application can effectively improve the thermal conductivity of epoxy resin. This is because the modified boron nitride acts as an interfacial compatibilizer, improving the contact interface between boron nitride and the epoxy resin matrix, enhancing the mechanical properties of the epoxy resin matrix, as well as the thermal stability of the epoxy resin matrix and the stability of the thermal conduction network. The graphene fibers form a three-dimensional thermal conduction network in the epoxy resin matrix (as Figure 1 shown), opening up a path for the transmission of thermal phonons, thereby greatly improving the thermal conduction ability of the epoxy resin matrix.

[0046] It is worth mentioning that the technical features such as the cell crusher involved in this invention patent application should be regarded as prior art. The specific structures, working principles, and possible control methods and spatial arrangement methods of these technical features can be selected conventionally in the art and should not be regarded as the invention points of this invention patent. This invention patent will not be further specifically elaborated.

[0047] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention through logical analysis, reasoning, or limited experiments based on the concept of the present invention on the basis of the prior art shall fall within the protection scope determined by the claims.

Claims

1. A method for preparing a chitosan-modified boron nitride and graphene fiber composite material, characterized in that: The following steps are included: Step 1, preparation of chitosan-modified boron nitride, dissolving a certain amount of chitosan in an acetic acid solution, adding a certain amount of deionized water, adding a certain amount of phytic acid solution containing choline chloride, and then adding a certain amount of boron nitride, using a cell crusher to ultrasonically treat it, and then centrifuging it several times, taking the supernatant respectively, and finally washing it with deionized water until the product is neutral, and drying the product in a vacuum environment to obtain chitosan-modified boron nitride; Step 2, preparation of graphene fiber, a certain amount of natural graphite and sodium nitrate are placed in concentrated sulfuric acid to obtain a black solution, after continuous stirring in an ice bath for a period of time, a certain amount of potassium permanganate is slowly added, and the ice bath is continued to stir, and then a certain amount of distilled water is slowly added to obtain a brown solution, and then the brown solution is diluted with a certain amount of warm water, and a certain amount of hydrogen peroxide is added to obtain a bright yellow solution, the bright yellow solution is filtered, and the filtered solution is washed with dilute hydrochloric acid and distilled water respectively until the solution is neutral, the filtered solution is dried and ground to obtain graphene oxide, and the graphene oxide is centrifuged and washed with hydrochloric acid and distilled water respectively until it is nearly neutral, and then the graphene oxide is dispersed in deionized water; A solution containing graphene oxide is injected into a glass syringe, and a flow pump is used to control the spinning speed of the spinning needle. The graphene oxide fibers are rapidly shrunk and solidified in a high-temperature nitrogen flow. The obtained graphene oxide fibers are reduced in a sodium citrate aqueous solution for a period of time, repeatedly washed with deionized water until neutral, and finally dried in a vacuum environment to obtain graphene fibers. Step 3, composite of modified boron nitride and graphene fiber, add a certain amount of chitosan-modified boron nitride prepared in step 1 and a certain amount of graphene fiber prepared in step 2 into deionized water, heat and keep warm for a period of time, then quickly cool in an ice bath environment, filter and filter the product, dry in a vacuum environment to obtain a black powder, keep warm at high temperature for a period of time under a nitrogen atmosphere, then wash the product with concentrated hydrochloric acid and water several times until neutral, and finally vacuum dry the product to obtain a composite material of chitosan-modified boron nitride and graphene fiber. In the step 1, 2 g of chitosan was dissolved in 1 ml of 1% acetic acid solution, 25 ml of deionized water was added, and then 5 g of choline chloride and 50% phytic acid were added, wherein the molar ratio of choline chloride to phytic acid was 4:

1. 80 mg of boron nitride was weighed and dispersed in the solution, and the solution was subjected to ultrasonic treatment using a cell crusher. In the step three, 8 g of modified boron nitride and graphene fiber were added to 200 ml of deionized water in a mass ratio of 1:1, heated to 100°C for 1 hour, rapidly cooled in an ice bath, filtered, and dried in a vacuum environment to obtain a black powder; under a nitrogen atmosphere, the mixture was kept at 700°C for 3 hours, and then the product was washed several times with concentrated hydrochloric acid and water until neutral, and finally the product was dried in a vacuum drying oven at 80°C for 24 hours.

2. The method for preparing the chitosan-modified boron nitride and graphene fiber composite material according to claim 1, wherein: When using a cell crusher for ultrasonic treatment in step 1, the power is adjusted to 150 W and the ultrasonic time is set to 90 minutes; the speed during the centrifugal treatment is 1000-1500 r / min and the centrifugation time is 10 minutes; the temperature of the vacuum drying is 90°C.

3. The method for preparing the chitosan-modified boron nitride and graphene fiber composite material according to claim 1, wherein: In the second step, 1 g of natural graphite and 1 g of sodium nitrate are placed in a beaker, 46 ml of 98% concentrated sulfuric acid is slowly added to obtain a black solution, and the mixture is continuously stirred in an ice bath for 4 h. Subsequently, 6 g of potassium permanganate is slowly added in an ice bath environment, and the ice bath stirring is continued for 2 h. Then, 92 ml of distilled water is slowly added to obtain a brown solution. Subsequently, the mixed solution is diluted with 350 ml of 50°C warm water, and the residual potassium permanganate is removed with 20 ml of 30% hydrogen peroxide to obtain a bright yellow solution. Finally, the solution is filtered and washed with dilute hydrochloric acid and distilled water, respectively, until the solution is neutral. The solution is dried and ground at 50°C to obtain graphite oxide. The product is centrifuged and washed with 10% HCl and distilled water, respectively, until it is nearly neutral. Then, the graphene oxide is dispersed in 500 ml of deionized water.

4. The method for preparing the chitosan-modified boron nitride and graphene fiber composite material according to claim 3, wherein: In the step 2, the specification of the spinning needle is 1.6 μm, the spinning speed is 1.5 ml / h, the temperature of the nitrogen gas flow is 250° C., the graphene oxide fiber is reduced with a 70% sodium citrate aqueous solution at 90° C. for 8 hours, and the drying temperature in a vacuum environment is 100° C.

5. Chitosan modified boron nitride and graphene fiber composite material, characterized in that, The method is as described in any one of claims 1 to 4.

6. Application of chitosan modified boron nitride and graphene fiber composite material, characterized in that: The chitosan-modified boron nitride and graphene fiber composite material as claimed in claim 5 is used for thermal conductivity modification of epoxy resin.

7. The use of the chitosan-modified boron nitride and graphene fiber composite material according to claim 6, characterized in that: The epoxy resin, chitosan-modified boron nitride and graphene fiber composite material were placed together in a planetary vacuum mixer and mixed for 5 minutes. The materials were then taken out and pressurized and kept warm at 50°C for 2 hours to obtain an epoxy resin material with chitosan-modified boron nitride and graphene fiber composite material as thermal conductive filler.

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