Composite material with self-repairing function as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of functional polymer materials, and particularly discloses a composite material with a self-repairing function and a preparation method and application thereof. Specific functional groups are respectively introduced to the surfaces of the carbon nanotubes and the boron nitride, so that interface bonding between the carbon nanotubes and the boron nitride and a matrix is enhanced, the mechanical strength of the composite material is improved, the composite material has a certain effect of preventing generation of cracks, and meanwhile, when the cracks are generated in cooperation with the core-shell structure capsule in the composite material, the core-shell structure capsule has a good anti-cracking effect. The self-repairing effect of cracks is effectively improved, so that the composite material has an efficient self-repairing function and good mechanical properties, and the service life of the composite material is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional polymer materials, and in particular relates to a composite material with self-repairing function and a preparation method and application thereof. Background Art

[0002] In the prior art, polypropylene (PP) or polyethylene (PE) materials are widely used in industry due to their excellent mechanical properties, processing properties and economy. However, PP / PE materials are prone to microcracks during use, which will gradually expand and eventually lead to material failure, seriously affecting the service life of the product. At present, in order to improve the failure of PP / PE materials due to cracks, functional additives such as toughening agents, reinforcing agents, antioxidants, etc. are often added to PP / PE. Although they can improve certain properties of the material to a certain extent and play a role in reducing the occurrence of cracks, they cannot fundamentally solve the problem of material cracking and failure. In addition, in order to improve the strength and other properties of the material, it is often necessary to add inorganic fillers to PP / PE. The compatibility of inorganic fillers with the matrix is ​​poor, and the interface between the filler and the matrix is ​​also a hard-hit area for cracks.

[0003] Self-healing materials can repair cracks by stimulating the repair mechanism after cracks are generated, prevent cracks from further expanding, and even completely repair them to their original state. Self-healing materials are one of the effective methods to solve the problem of microcracks that are easy to generate in materials during use. In the field of self-healing of materials, the existing technology mainly focuses on materials such as thermosetting resins and hydrogels. These materials usually have low mechanical strength, complex processing technology, high cost, and are difficult to meet the needs of industrial applications. For thermoplastic plastics PP / PE, the molecular chain has high crystallinity and low activity, which makes it difficult to achieve self-healing function. Therefore, additional self-healing materials need to be added. However, at present, due to the small contact and poor compatibility between the additional self-healing materials and the matrix and filler, the matching effect is poor, and its self-healing effect cannot be significantly improved. Especially in systems with fillers, by adding conventional repair materials, it is impossible to accurately and efficiently improve the self-healing effect of the interface between the PP / PE matrix and the filler. In addition, in the PP / PE material system with fillers, cracks are easily generated at the interface between the filler and the matrix, increasing the difficulty of self-repair, and often leading to a decrease in the mechanical properties of the overall material, which seriously restricts the development of PP / PE materials in high-end application fields.

[0004] Therefore, how to develop a simple and efficient method to give PP / PE materials self-healing function and good mechanical properties is a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of the problems in the above-mentioned prior art, such as poor self-healing effect and mechanical properties of PP / PE materials, the present invention provides a composite material with self-healing function, its preparation method and application.

[0006] To achieve the above object, the specific technical solutions include the following:

[0007] A composite material with self-healing function, comprising the following components in parts by weight: 95-110 parts of matrix, 4-16 parts of core-shell structure capsules, 0.4-2.5 parts of surface-modified carbon nanotubes, 0.9-3.1 parts of silane coupling agent-modified boron nitride, and 2-9 parts of compatibilizer;

[0008] The matrix includes at least one of PP and PE;

[0009] In the core-shell structure capsules, the shell layer includes glycidyl methacrylate modified with maleic anhydride, and the core layer includes dicyclopentadiene and Grubbs catalyst;

[0010] The surface-modified carbon nanotubes are carbon nanotubes wrapped with acrylic acid-glycidyl methacrylate copolymer.

[0011] In the composite material of the present invention, on the one hand, the carbon nanotubes are grafted and modified with acrylic acid and glycidyl methacrylate, and the boron nitride is modified with a silane coupling agent, introducing specific functional groups on the surfaces of the carbon nanotubes and boron nitride respectively, enhancing the interfacial bonding between the carbon nanotubes and boron nitride and the matrix, improving the dispersibility and compatibility of the carbon nanotubes and boron nitride in the matrix, effectively preventing the agglomeration of the carbon nanotubes and boron nitride, and reducing in advance at the preparation source the crack risk caused by poor interfacial bonding due to poor dispersibility and compatibility between the filler and the matrix. In addition, the surface-modified carbon nanotubes and the silane coupling agent-modified boron nitride synergistically improve the tensile strength of the composite material, enabling the composite material to have good mechanical properties. On the other hand, there are core-shell structure capsules in the composite material of the present invention. Among them, the shell layer contains maleic anhydride-modified polyglycidyl methacrylate, which has both epoxy groups and anhydride groups at the same time. When the core-shell structure capsules are melt-blended with the rest of the raw materials, their epoxy groups and anhydride groups can form chemical bonds with the matrix, improving the interfacial bonding strength and overall uniformity between the core-shell structure capsules and the matrix, which is conducive to improving the self-healing performance of the material subsequently. The core layer contains dicyclopentadiene and Grubbs catalyst. When the material is in a stable state, the Grubbs catalyst is in a passivated state. When the material is damaged by external force and cracks occur, the environment changes, the Grubbs catalyst is activated, and the core-shell structure capsules rupture in time to release dicyclopentadiene, which acts as a repair agent. Under the action of the Grubbs catalyst, dicyclopentadiene acts as a monomer and quickly polymerizes to form a cross-linked network structure, effectively repairing the cracks. In addition, both the carbon nanotubes and boron nitride in the present invention are modified. Their specific functional groups on the surface will not only reduce the repair effect of the material, but also provide more interfacial bonding sites, enhancing the compatibility between the matrix and the core-shell structure capsules, improving the thermal conductivity of the material, promoting the heat conduction during the repair process, and enhancing the interfacial bonding strength after repair. Moreover, the network structure of the modified carbon nanotubes and boron nitride fillers helps the directional flow and diffusion of the repair agent. The modified carbon nanotubes and boron nitride in the present invention can improve the self-healing effect of the material. Therefore, the present invention reduces the cracks in the composite material from two aspects: effectively preventing crack generation at the preparation source and achieving efficient self-healing after crack generation, improving the mechanical strength of the composite material, comprehensively enabling the composite material to have good mechanical properties and self-healing functions, and improving the service life of the composite material.

[0012] Preferably, the composite material with self-healing function comprises the following components in parts by weight: 100 parts of matrix, 5-15 parts of core-shell structure capsules, 0.5-2 parts of surface-modified carbon nanotubes, 1-3 parts of silane coupling agent-modified boron nitride, and 3-8 parts of compatibilizer.

[0013] Preferably, in the composite material with self-healing function, the mass percentage of the matrix in the composite material with self-healing function is not less than 60%, and more preferably not less than 70%.

[0014] Preferably, the matrix comprises the following components in parts by weight: 60-80 parts of PP and 20-40 parts of PE.

[0015] Preferably, the melt mass flow rate (MFR) of the PP tested according to ISO1133-2011 under the conditions of 230 °C and 2.16 Kg load is 0.1-30 g / 10 min. Specifically, it can be 0.1 g / 10 min, 0.5 g / 10 min, 2.5 g / 10 min, 5 g / 10 min, 10 g / 10 min, 15 g / 10 min, 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, etc., as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0016] Preferably, the melt mass flow rate (MFR) of the PE tested according to ISO1133-2011 under the conditions of 190 °C and 2.16 Kg load is 0.5-30 g / 10 min. Specifically, it can be 0.5 g / 10 min, 2.5 g / 10 min, 5 g / 10 min, 10 g / 10 min, 15 g / 10 min, 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, etc., as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0017] Preferably, the PE comprises at least one of HDPE, LDPE, and LLDPE.

[0018] Preferably, the core-shell structure capsule comprises the following components in parts by weight: 1.5-3.5 parts of dicyclopentadiene, 0.5-1.8 parts of maleic anhydride-modified polyglycidyl methacrylate, and 0.015-0.035 parts of Grubbs catalyst.

[0019] More preferably, the Grubbs catalyst comprises the first-generation Grubbs catalyst, the second-generation Grubbs catalyst, and the third-generation Grubbs catalyst. Among them, the second-generation Grubbs catalyst is benzylidene[1,3-bis(trimethylphenyl)-2-imidazolinylidene]dichloride(tricyclohexylphosphine)ruthenium.

[0020] Further preferably, the mass ratio of the dicyclopentadiene and maleic anhydride modified polyglycidyl methacrylate is (1.5 - 2.5):(0.5 - 1.5), and specifically it can be 1.5:0.5, 1.5:1, 1.5:1.5, 2:0.5, 2:1, 2:1.5, 1.5:0.5, 2.5:1, 2.5:1.5, etc., as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0021] Preferably, the average particle size of the core layer in the core - shell structure capsule is 200 - 500 nm, and the shell layer thickness is 20 - 50 nm. The size of the core - shell structure capsule and its core - shell structure is obtained by scanning electron microscope testing.

[0022] Preferably, in the surface - modified carbon nanotubes, the acrylic acid - glycidyl methacrylate copolymer accounts for 5 - 12 wt% of the total mass of the surface - modified carbon nanotubes. Specifically, it can be 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, 10 wt%, 10.5 wt%, 11 wt%, 11.5 wt%, 12 wt%, etc., as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0023] Preferably, the average length of the surface - modified carbon nanotubes is 100 - 500 nm, and the average diameter of the surface - modified carbon nanotubes is 10 - 30 nm. The size of the surface - modified carbon nanotubes is obtained by scanning electron microscope testing.

[0024] Preferably, in the maleic anhydride - modified polyglycidyl methacrylate, the mass ratio of maleic anhydride to polyglycidyl methacrylate is (0.05 - 0.15):1, and specifically it can be 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, 0.11:1, 0.12:1, 0.13:1, 0.14:1, 0.15:1, etc., as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0025] Preferably, in the silane coupling agent-modified boron nitride, the modification degree is 8-15 wt%, which can specifically be 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, 10 wt%, 10.5 wt%, 11 wt%, 11.5 wt%, 12 wt%, 12.5 wt%, 13 wt%, 13.5 wt%, 14 wt%, 14.5 wt%, 15 wt%, etc., as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0026] Preferably, the average sheet diameter of the silane coupling agent-modified boron nitride is 50-200 nm, and the average thickness of the silane coupling agent-modified boron nitride is 3-8 nm. The size of the silane coupling agent-modified boron nitride is obtained by scanning electron microscope testing.

[0027] Preferably, the mass ratio of the surface-modified carbon nanotubes to the silane coupling agent-modified boron nitride is (0.5-2.5):(1-3), which can specifically be 0.5:1, 0.5:1.5, 0.5:2, 0.5:2.5, 0.5:3, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 2:1, 2:1.5, 2:2, 2:2.5, 3:1, 3:1.5, 3:2, 3:2.5, 3:3, etc., as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0028] Preferably, the silane coupling agent of the silane coupling agent-modified boron nitride includes at least one of γ-methacryloxypropyltrimethoxysilane, γ-glycidyletheroxypropyltrimethoxysilane, and vinyltriethoxysilane.

[0029] Preferably, the compatibilizer includes at least one of maleic anhydride grafted polypropylene, maleic anhydride grafted polyethylene, and ethylene-vinyl acetate copolymer.

[0030] Preferably, the composite material with self-healing function further includes 0.09-0.8 parts of additives.

[0031] Preferably, the additives include at least one of antioxidant and light stabilizer.

[0032] Preferably, the antioxidant includes at least one of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl) phosphite, and 2,2'-methylenebis(4-methyl-6-tert-butylphenol).

[0033] Preferably, the light stabilizer includes hindered amine light stabilizer.

[0034] The present invention provides a method for preparing the described composite material with self-healing function, comprising the following steps:

[0035] (1) Disperse carbon nanotubes in water, add acrylic acid, glycidyl methacrylate and an initiator, and carry out a reaction to obtain surface-modified carbon nanotubes;

[0036] (2) Disperse boron nitride in ethanol, add a silane coupling agent, and adjust the pH value of the solution system to 4-5, and carry out a reaction to obtain silane coupling agent-modified boron nitride;

[0037] (3) Dissolve polyglycidyl methacrylate in tetrahydrofuran, then sequentially add maleic anhydride and a catalyst, and carry out a modification reaction to obtain maleic anhydride-modified glycidyl methacrylate;

[0038] Mix water, an emulsifier and a stabilizer to obtain an aqueous phase;

[0039] Mix the maleic anhydride-modified polyglycidyl methacrylate, dicyclopentadiene, Grubbs catalyst and dichloromethane to obtain an oil phase;

[0040] Under stirring, add the oil phase to the aqueous phase for emulsification treatment, adjust the pH value and carry out drying treatment, and after separation, washing and freeze-drying, obtain core-shell structure capsules;

[0041] (4) Disperse the surface-modified carbon nanotubes, silane coupling agent-modified boron nitride and core-shell structure capsules in an organic solvent under ultrasonic assistance, and then sequentially carry out rotary evaporation and drying; obtain a mixture;

[0042] (5) Mix the mixture with the remaining raw materials, melt, extrude and granulate to obtain a composite material with self-healing function.

[0043] Preferably, in step (1), the mass ratio of the water to the carbon nanotubes is (50-150):1.

[0044] Preferably, in step (1), the mass ratio of the carbon nanotubes, acrylic acid and glycidyl methacrylate is carbon nanotubes:acrylic acid:glycidyl methacrylate = 1:(0.2-0.6):(0.2-0.6).

[0045] Preferably, in step (1), the initiator includes ammonium persulfate.

[0046] Preferably, in step (1), the temperature of the reaction is 60-85°C, and the reaction time is 3-12 h.

[0047] Preferably, in step (2), the mass of the ethanol to the boron nitride is (50-150):1.

[0048] Preferably, in step (2), the mass ratio of the silane coupling agent to the boron nitride is (0.08 - 0.15):1.

[0049] Preferably, in step (2), the reaction temperature is 55 - 80°C, and the reaction time is 3 - 12 h.

[0050] Preferably, in step (3), the mass ratio of maleic anhydride to glycidyl methacrylate is (0.05 - 0.15):(0.5 - 1.5).

[0051] Preferably, in step (3), the modification reaction temperature is 60 - 80°C, and the modification reaction time is 5 - 12 h.

[0052] Preferably, in step (3), the catalyst includes triethylamine.

[0053] Preferably, in step (3), the mass ratio of the catalyst to maleic anhydride is 1:(0.5 - 1.5).

[0054] Preferably, in step (3), the emulsifier includes sodium dodecyl sulfate.

[0055] Preferably, in step (3), the stabilizer includes polyvinyl alcohol.

[0056] Preferably, in step (3), the mass ratio of the emulsifier, the stabilizer to water is (0.1 - 1):(0.1 - 0.5):100.

[0057] Preferably, in step (3), after glycidyl methacrylate is dissolved in tetrahydrofuran, the concentration of glycidyl methacrylate is 5 - 15 wt%.

[0058] Preferably, in step (3), the temperature of the drying treatment is 65 - 75°C.

[0059] Preferably, in step (3), the pH value is adjusted to 6.5 - 7.5.

[0060] Preferably, in step (3), the emulsification treatment time is 4 - 6 h.

[0061] Preferably, in step (4), the organic solvent includes tetrahydrofuran.

[0062] Preferably, in step (4), the temperature of the rotary evaporation is 45 - 65°C, and the drying is carried out under vacuum at 45 - 65°C for 10 - 18 h.

[0063] Preferably, in step (5), the melting temperature is 170 - 200°C.

[0064] The present invention provides an application of the described composite material with self-healing function in the preparation of automotive parts, electronic and electrical housings, pipeline components, and packaging materials.

[0065] In addition, the present invention also provides a plastic part with self-healing function, which contains the described composite material with self-healing function.

[0066] Compared with the prior art, the present invention has the following beneficial effects: specific functional groups are introduced on the surfaces of carbon nanotubes and boron nitride respectively, which not only enhances the interfacial bonding between carbon nanotubes and boron nitride and the matrix, improves the mechanical strength of the composite material, but also has a certain effect of preventing crack generation. At the same time, in combination with the core-shell structure capsules in the composite material, when cracks occur, the self-healing effect of the cracks is effectively improved, enabling the composite material to have both high-efficiency self-healing function and good mechanical properties, and improving the service life of the composite material. Detailed Embodiments

[0067] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described through specific embodiments below. The test methods used in the embodiments and / or comparative examples are all conventional methods unless otherwise specified; the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0068] PP-1: PP-R4220, MFR = 0.3 g / 10 min, Sinopec;

[0069] PP-2: E800BHM, MFR = 8 g / 10 min, Sinopec;

[0070] PE: HDPE 5000S, MFR = 1 g / 10 min, Sinopec;

[0071] LDPE: 2426H, MFR = 2 g / 10 min, Sinopec;

[0072] Carbon nanotubes: NC7000 series multi-walled carbon nanotubes produced by Nanocyl, USA;

[0073] Boron nitride nanosheets: GP-BN type hexagonal boron nitride powder, DENKA, Japan;

[0074] Compatibilizer: maleic anhydride grafted polypropylene, Fusabond P353, DuPont;

[0075] Second-generation Grubbs catalyst: benzylidene[1,3-bis(trimethylphenyl)-2-imidazolinylidene]dichloride(tricyclohexylphosphine)ruthenium, Sigma-Aldrich;

[0076] Antioxidant: Irganox 1010, commercially available;

[0077] Light stabilizer: Tinuvin 770, commercially available;

[0078] Acrylic acid, commercially available;

[0079] Dicyclopentadiene (DCPD), commercially available;

[0080] Glycidyl methacrylate, commercially available;

[0081] Poly(glycidyl methacrylate) (PGMA): 705314, Sigma - Aldrich;

[0082] Examples 1 - 16 and Comparative Examples 1 - 6

[0083] A composite material with self - healing function, including the following preparation steps:

[0084] (1) According to Table 1, disperse carbon nanotubes in water, add acrylic acid, glycidyl methacrylate and initiator ammonium persulfate, and carry out a free - radical polymerization (in - situ grafting) reaction at 65 °C for 6 h. After the reaction, the product is filtered, washed and dried to obtain surface - modified carbon nanotubes; during the reaction process, monomers will form graft polymer chains on the surface of carbon nanotubes, thus realizing surface modification;

[0085] (2) According to Table 2, disperse boron nitride in 95 wt% ethanol, add silane coupling agent KH - 570, and adjust the pH value of the solution system to 4 - 5. React at 60 °C for 6 h. After the reaction is completed, the product is centrifuged, washed and dried to obtain silane - coupling - agent - modified boron nitride; during the reaction process, the methoxy group of KH - 570 hydrolyzes and then undergoes a condensation reaction with the hydroxyl groups on the surface of boron nitride, thus realizing surface modification;

[0086] (3 - 1) According to Table 3, dissolve poly(glycidyl methacrylate) (PGMA) in tetrahydrofuran to prepare a 10 wt% solution, then successively add maleic anhydride (MAH), stir and react at 70 °C for 4 h, and then add triethylamine as a catalyst and continue to react for 2 h to obtain maleic - anhydride - modified glycidyl methacrylate (PGMA - g - MAH); during the reaction process, the anhydride group of MAH will undergo a ring - opening reaction with the epoxy group of PGMA, and at the same time, part of the unreacted epoxy groups are retained, and finally, both epoxy groups and anhydride groups are present on the surface of PGMA;

[0087] (3 - 2) Mix water, sodium dodecyl sulfate emulsifier and polyvinyl alcohol stabilizer to obtain an aqueous phase;

[0088] (3-3) Mix the maleic anhydride-modified poly(glycidyl methacrylate) (PGMA-g-MAH), dicyclopentadiene (DCPD), Grubbs second-generation catalyst, and dichloromethane to obtain an oil phase;

[0089] Slowly add the oil phase to the water phase under mechanical stirring at 800 - 1000 rpm for emulsification treatment to form an O / W type emulsion, and raise the temperature of the system to 70 °C. Control the pH value of the system to be 6.5 - 7.5. As the temperature rises, dichloromethane volatilizes, and PGMA-g-MAH deposits at the oil-water interface to form a shell layer. Inside the shell layer is a core layer containing cyclopentadiene and Grubbs second-generation catalyst. After 5 h of emulsification treatment, the product is centrifuged, washed, and freeze-dried to obtain core-shell structured capsules; the particle size of the core-shell structured capsules is in the nanoscale range, the average particle size of the core layer is 200 - 500 nm, and the shell layer thickness is 20 - 50 nm;

[0090] (4) According to Table 4-5, ultrasonically disperse the surface-modified carbon nanotubes or carbon nanotubes, and silane-coupling-agent-modified boron nitride or boron nitride for 15 min, disperse them in 100 parts by weight of tetrahydrofuran, add the core-shell structured capsules, and continue ultrasonication for 10 min; then carry out rotary evaporation under reduced pressure at 50 °C to remove the solvent, and vacuum-dry at 60 °C for 12 h to obtain a mixture;

[0091] (5) According to Table 4-5, feed the mixture and the remaining raw materials into a modular twin-screw extruder for melt blending. The screw adopts a "shearing - mixing - shearing" combination, and the temperature control is in a five-stage manner. The screw combination from the feeding section to the discharging section is: conveying section - first shearing section - first mixing section - second shearing section - second mixing section - exhaust section - conveying section; among them, the temperature control adopts a five-stage manner: feeding section 170 °C, first shearing section 185 °C, mixing section 200 °C, second shearing section 190 °C, discharging section 175 °C, screw speed 350 - 450 rpm, vacuum degree -0.06 to -0.08 MPa, the screw diameter of the twin-screw extruder is 30 mm, the length-diameter ratio is 40:1, and the residence time is about 2 - 3 min. Then, through extrusion and pelletizing, a composite material with self-healing function is obtained.

[0092] In the surface-modified carbon nanotubes of the present invention, two monomers, acrylic acid and glycidyl methacrylate, are used to modify the carbon nanotubes, and acrylic acid and glycidyl methacrylate are copolymerized on the surface of the carbon nanotubes. The test method for the percentage of the acrylic acid-glycidyl methacrylate copolymer in the total mass of the surface-modified carbon nanotubes is as follows:

[0093] (1) The mass of the un-surface-modified carbon nanotubes is m0;

[0094] (2) Surface modify the carbon nanotubes with a mass of m0 according to the method in step (1) above to obtain surface-modified carbon nanotubes with a mass of m1;

[0095] (3) Soxhlet extract the surface-modified carbon nanotubes with a mass of m1 with an excessive amount of tetrahydrofuran solvent for 24 h to remove the unreacted monomers, and dry to a constant weight to obtain surface-modified carbon nanotubes with a mass of m2. Calculate the percentage of the acrylic acid-glycidyl methacrylate copolymer in the total mass of the surface-modified carbon nanotubes based on the mass difference before and after modification;

[0096] The calculation formula is: percentage of the acrylic acid-glycidyl methacrylate copolymer in the total mass of the surface-modified carbon nanotubes (%) = [(m2 - m0) / m2] × 100%;

[0097] (4) Use thermogravimetric analysis (TGA) to test and verify the calculation results.

[0098] The modification degree in the silane coupling agent-modified boron nitride of the present invention is calculated based on the weight parts of the silane coupling agent and boron nitride added during the preparation of the silane coupling agent-modified boron nitride. The calculation formula is as follows:

[0099] Modification degree in the silane coupling agent-modified boron nitride (%) = m A / (m B ) × 100%, where in the formula, m A , m B are the weight parts of the silane coupling agent and boron nitride, respectively.

[0100] Table 1 (in weight parts)

[0101]

[0102] Table 2 (in weight parts)

[0103]

[0104] Table 3

[0105]

[0106] Table 4 (in weight parts)

[0107]

[0108]

[0109] Table 5 (in weight parts)

[0110] Raw material / Group Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 PP-1 70 70 70 70 70 70 PE 30 30 30 30 30 30 Core-shell structure capsule 1 - 8 8 8 8 8 Surface-modified carbon nanotube 1 1 - 1 - - 1 (Unmodified) carbon nanotube - - - - 1 - Silane coupling agent-modified boron nitride 1 2 2 - - 2 - (Unmodified) boron nitride nanosheet - - - - - 2 Compatibilizer 4 4 4 4 4 4 Antioxidant 0.2 0.2 0.2 0.2 0.2 0.2 Light stabilizer 0.2 0.2 0.2 0.2 0.2 0.2

[0111] Performance test

[0112] The properties of the self-healing composite materials obtained from the above examples and comparative examples were characterized. The specific test items, test methods and results are as follows:

[0113] Mechanical properties and healing effect: The self-healing composite materials prepared in the above examples and comparative examples were injection molded into specimens by conventional processes, and the specimens were cut into dumbbell shapes for testing. The tensile strength was tested according to the standard of GB / T1040.2-2006, and the tensile strength Rm0 (tensile strength before healing) before healing was measured. Then, a crack with a length of 10±0.5 mm, a width of 0.2±0.02 mm and a depth of 0.5±0.05 mm was made in the middle of the specimen. The specimen was placed in an environment of 80 °C for healing. When the healing at the crack was observed to be completed, the time taken for healing was recorded, and the tensile strength Rm1 (after healing) after healing was tested, and the healing rate was calculated. Healing rate (%) = Rm1 / Rm0×100%; the passing standard is: healing rate ≥ 85%, healing time ≤ 4 h.

[0114] The test results are shown in Table 6 below.

[0115] Table 6

[0116]

[0117]

[0118] Note: The tensile strength of pure PP (without adding any modifiers) is 30.0 MPa.

[0119] *Example 2 is a pure PE matrix system, and its tensile strength is lower than that of pure PP, but this is due to the mechanical properties of PE itself and does not affect the modification effect of the composite material.

[0120] As can be seen from the above examples, the composite materials of the present invention have high self-healing ability and good mechanical properties.

[0121] In Examples 1-3, the matrices are pure PP, pure PE, and a mixed matrix of PP and PE, respectively. The results show that all three matrix materials can achieve good self-healing effects. Among them, due to the synergistic effect of PP and PE, the compatibility and interfacial bonding force of the material during healing are improved. Therefore, the healing rate of the PP / PE mixed matrix is the highest, reaching 95%.

[0122] In Examples 3, 4, and 5, the weight parts of the core-shell structure capsules are 8 parts, 5 parts, and 15 parts, respectively. The results show that as the amount of the core-shell structure capsules increases, the healing rate of the material increases, the healing time shortens, and the tensile strength also increases. However, considering the comprehensive factors of cost and processing performance, the amount of the core-shell structure capsules is 8 parts, which has better comprehensive performance.

[0123] In Examples 3, 6, and 7, the mass ratios of surface-modified carbon nanotubes to silane-coupling-agent-modified boron nitride are (1:2), (0.5:2.5), and (2:1), respectively. The results show that the optimal mass ratio of surface-modified carbon nanotubes to silane-coupling-agent-modified boron nitride is 1:2, at which time the material has the best comprehensive properties. When the mass ratio of the two is 0.5:2.5, compared with Example 3, the repair effect is slightly improved but the mechanical properties decrease; when the mass ratio of the two is 2:1, compared with Example 3, the mechanical properties and repair effect of the material show a downward trend.

[0124] In the core-shell structure capsules of Examples 3, 10, and 11, the mass ratios of DCPD to PGMA-g-MAH are (2:1), (1.5:1.5), and (2.5:0.5), respectively. The results show that the optimal mass ratio of DCPD to PGMA-g-MAH in the core-shell structure capsules is 2:1, at which time it has the best repair effect, stability, and mechanical properties. When the mass ratio of the two is 1.5:1.5, compared with the material of Example 3, the repair effect and mechanical properties slightly decrease. When the mass ratio of the two is 2.5:0.5, the repair effect and mechanical properties decrease, and the thinner shell layer may affect the stability of the capsule.

[0125] In the modified carbon nanotubes of Examples 3, 12, and 13, the percentages of acrylic acid-glycidyl methacrylate copolymer in the total mass of surface-modified carbon nanotubes are 8wt%, 5wt%, and 12wt%, respectively. The results show that the optimal percentage of acrylic acid-glycidyl methacrylate copolymer in the total mass of surface-modified carbon nanotubes for the modified carbon nanotubes is 8wt%, at which time it has the best dispersibility and interfacial bonding force. Compared with Example 3, when the percentage of acrylic acid-glycidyl methacrylate copolymer in the total mass of surface-modified carbon nanotubes is 5wt%, the dispersibility and interfacial bonding force of the carbon nanotubes slightly decrease, resulting in a slight decrease in the mechanical properties of the material; when the percentage of acrylic acid-glycidyl methacrylate copolymer in the total mass of surface-modified carbon nanotubes is 15wt%, the percentage is too high, which instead affects the intrinsic properties of the carbon nanotubes and further decreases the mechanical properties of the material.

[0126] In Examples 3, 14, and 15 of the silane coupling agent-modified boron nitride, the modification degrees are 10 wt%, 8 wt%, and 15 wt% respectively. The results show that the optimal modification degree of the silane coupling agent-modified boron nitride is 10 wt%. At this time, the boron nitride has the best dispersibility and interfacial bonding force. Compared with Example 3, when the modification degree is 8 wt%, the dispersibility and interfacial bonding force of the boron nitride decrease slightly, resulting in a slight decrease in the mechanical properties of the material; when the modification degree is 15 wt%, the modification degree is too high, which will affect the thermal conductivity of the boron nitride and reduce the mechanical properties and modification effect.

[0127] Compared with Example 3, Comparative Examples 1-3 lack core-shell structure capsules, surface-modified carbon nanotubes, and silane coupling agent-modified boron nitride respectively. Comparative Example 4 lacks both surface-modified carbon nanotubes and silane coupling agent-modified boron nitride at the same time. Comparative Examples 5-6 use unmodified carbon nanotubes and unmodified boron nitride respectively. The results show that: compared with Example 3, the lack of any one functional component in Comparative Examples 1-4 will significantly reduce the self-healing performance of the material. Among them, the self-healing function cannot be achieved at all when the core-shell structure capsules are missing. The lack of two functional components at the same time will further reduce the material performance. The use of unmodified carbon nanotubes or boron nitride will lead to poor dispersibility and weak interfacial bonding force, thus affecting the overall self-healing effect and mechanical properties of the material; the addition of unmodified fillers in Comparative Examples 5-6 has a worse repair effect than the case without fillers in Comparative Example 4, indicating that the unmodified ones cannot improve the self-healing effect of the material, but are adverse to the self-healing of the material. It can be seen that in the PE and / or PP system, adding specific modified carbon nanotubes and boron nitride can not only improve the mechanical properties of the material, but also significantly improve the self-healing effect of the material.

[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A composite material with self-healing function, characterized in that, It comprises components in the following parts by weight: 95 - 110 parts of matrix, 4 - 16 parts of core - shell structure capsule, 0.4 - 2.5 parts of surface - modified carbon nanotubes, 0.9 - 3.1 parts of silane - coupling - agent - modified boron nitride, and 2 - 9 parts of compatibilizer; The matrix comprises at least one of PP and PE; In the core - shell structure capsule, the shell layer comprises maleic - anhydride - modified polyglycidyl methacrylate, and the core layer comprises dicyclopentadiene and Grubbs catalyst; The surface - modified carbon nanotubes are carbon nanotubes wrapped with acrylic - glycidyl methacrylate copolymer.

2. The composite material with self-healing function according to claim 1, characterized in that, In the core - shell structure capsule, it comprises components in the following parts by weight: 1.5 - 3.5 parts of dicyclopentadiene, 0.5 - 1.8 parts of maleic - anhydride - modified polyglycidyl methacrylate, and 0.015 - 0.035 parts of Grubbs catalyst.

3. The composite material with self-repairing function according to claim 2, characterized in that, The mass ratio of dicyclopentadiene to maleic - anhydride - modified polyglycidyl methacrylate is (1.5 - 2.5):(0.5 - 1.5).

4. The composite material with self-healing function according to claim 1, characterized in that, In the surface - modified carbon nanotubes, the acrylic - glycidyl methacrylate copolymer accounts for 5 - 12 wt% of the total mass of the surface - modified carbon nanotubes.

5. The composite material with self-repairing function according to claim 1, wherein, In the silane - coupling - agent - modified boron nitride, the modification degree is 8 - 15 wt%.

6. The composite material with a self-healing function according to claim 1, wherein The mass ratio of the surface - modified carbon nanotubes to the silane - coupling - agent - modified boron nitride is (0.5 - 2.5):(1 - 3).

7. The composite material with self-healing function according to claim 1, characterized in that, It includes at least one of the following: In the matrix, it comprises components in the following parts by weight: 60 - 80 parts of PP and 20 - 40 parts of PE; The average length of the surface - modified carbon nanotubes is 100 - 500 nm, and the average diameter of the surface - modified carbon nanotubes is 10 - 30 nm; The average sheet diameter of the silane - coupling - agent - modified boron nitride is 50 - 200 nm, and the average thickness of the silane - coupling - agent - modified boron nitride is 3 - 8 nm; The silane coupling agent in the silane - coupling - agent - modified boron nitride includes at least one of γ - methacryloyloxypropyltrimethoxysilane, γ - glycidoxypropyltrimethoxysilane, and vinyltriethoxysilane; The compatibilizer includes at least one of maleic - anhydride - grafted polypropylene, maleic - anhydride - grafted polyethylene, and ethylene - vinyl acetate copolymer; It further includes 0.09 - 0.8 parts of additives, and the additives include at least one of antioxidant and light stabilizer.

8. A method for preparing a composite material with self-healing function according to any one of claims 1-7, characterized in that, It includes the following steps: (1) Disperse carbon nanotubes in water, add acrylic acid, glycidyl methacrylate and initiator, and carry out reaction to obtain surface - modified carbon nanotubes; (2) Disperse boron nitride in ethanol, add silane coupling agent, and adjust the pH value of the solution system to 4 - 5, and carry out reaction to obtain silane - coupling - agent - modified boron nitride; (3) Dissolve polyglycidyl methacrylate in tetrahydrofuran, then add maleic anhydride and catalyst in sequence, and carry out modification reaction to obtain maleic - anhydride - modified polyglycidyl methacrylate; Mix water, emulsifier and stabilizer to obtain an aqueous phase; Mix the maleic - anhydride - modified polyglycidyl methacrylate, dicyclopentadiene, Grubbs catalyst and dichloromethane to obtain an oil phase; Under stirring, the oil phase is added to the water phase for emulsification treatment, the pH value is adjusted and drying treatment is carried out. After separation, washing and freeze-drying, core-shell structure capsules are obtained; (4) The surface-modified carbon nanotubes, silane coupling agent-modified boron nitride and core-shell structure capsules are dispersed in an organic solvent under ultrasonic assistance, and then successively subjected to rotary evaporation and drying to obtain a mixture; (5) The mixture and the remaining raw materials are mixed, melted, extruded and granulated to obtain a composite material with self-healing function.

9. Use of the composite material with self-healing function according to any one of claims 1-7 in the preparation of automotive parts, electronic and electrical housings, pipe components, packaging materials.

10. A plastic part with self - repair function, characterized in that, Comprising the composite material with self-healing function according to any one of claims 1-7.

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