Carbon nanotube master batch, polyethylene composite material and preparation method and application thereof

Abstract

The invention discloses a carbon nanotube master batch, a polyethylene composite material and a preparation method and application thereof, and belongs to the technical field of high polymer materials, the carbon nanotube master batch has a core-shell structure, the core comprises a carbon nanotube and iron barium oxide, and the shell is polyethylene grafted maleic anhydride; the mass ratio of the core to the shell is 1: (0.25-5); the mass ratio of the carbon nanotubes to the iron barium oxide is (1-9): 1. According to the invention, by coating the carbon nanotubes and the iron-barium-oxygen bodies, the dispersibility of the carbon nanotubes and the iron-barium-oxygen bodies in polyethylene is effectively improved, the agglomeration phenomenon is avoided, the interface bonding force with polyethylene is improved, the carbon nanotubes and the iron-barium-oxygen bodies are taken as cores, a tough composite reinforced core is formed, external loads can be effectively absorbed and dispersed, and the tensile strength of polyethylene is improved. The strength, the self-repairing property and the scratch resistance of the composite material are improved, and the carbon nanotube master batch is suitable for the fields of aerospace, electronics and electrics, medical equipment and 5G communication.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a carbon nanotube masterbatch, a polyethylene composite material, and a preparation method and application thereof. Background Art

[0002] The popularization of electronic products has led to a large amount of electromagnetic wave pollution in our daily life, which not only harms the environment and human health, but also greatly affects the normal operation of electronic devices due to the high integration development of electronic devices. Therefore, the design and preparation of high-efficiency wave-absorbing materials have received extensive attention from researchers.

[0003] Carbon nanotubes (CNTs) have received extensive attention due to their light weight, high aspect ratio, high electrical conductivity, and high specific surface area, and are a very promising wave-absorbing agent. However, due to their high electrical conductivity, it is difficult to obtain ideal impedance matching performance, resulting in a large amount of electromagnetic waves being reflected on their surface, limiting their wave-absorbing performance and restricting their wide application in the wave-absorbing field. At the same time, due to the strong electrostatic adsorption between CNTs, they are extremely easy to agglomerate in the matrix, which is also an important factor affecting their obtaining ideal wave-absorbing performance. Therefore, how to improve the impedance matching performance and dispersibility of CNTs to effectively exert their high dielectric loss performance is the key and difficulty in the preparation of CNT wave-absorbing materials at present.

[0004] Currently, researchers mainly improve the impedance matching performance of CNTs by compounding with magnetic materials having strong magnetic loss or materials with relatively good impedance matching. Based on CNTs, wave-absorbing materials that meet the requirements of aerospace are prepared by designing and regulating the structure of the composite material, providing a relevant research basis for the preparation of high-performance wave-absorbing materials, and having important social significance and theoretical guiding role. In addition, during the use process, micropores, microcracks and other damage defects will inevitably occur on the surface and inside of the polyethylene wave-absorbing composite material. These tiny defects will gradually develop under the multiple actions of external stress and internal stress. If not controlled, the continuously developing damage defects may cause accidents, seriously threatening the safe operation of the wave-absorbing material.

[0005] In view of this, the present application is proposed. Summary of the Invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a carbon nanotube masterbatch, a polyethylene composite material, and a preparation method and application thereof, which have excellent strength, self-healing performance, and scratch resistance.

[0007] To achieve the above object, the first aspect of the present application provides a carbon nanotube masterbatch having a core-shell structure, wherein the core includes carbon nanotubes and barium ferrite (BaFe 12 O 19, hereinafter the same), the shell is polyethylene grafted maleic anhydride;

[0008] The mass ratio of the core to the shell is 1:(0.25 - 5), for example, it can be 1:0.25, 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5 or the range composed of any two of these values.

[0009] The mass ratio of the carbon nanotubes to the barium ferrite is (1 - 9):1, for example, it can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or the range composed of any two of these values.

[0010] Preferably, the mass ratio of the core to the shell is 1:(0.5 - 2).

[0011] The carbon nanotube masterbatch of the present invention has a core - shell structure. Among them, the core includes carbon nanotubes and barium ferrite, and the shell is polyethylene grafted maleic anhydride; by coating the carbon nanotubes and barium ferrite, the dispersibility of the carbon nanotubes and barium ferrite in polyethylene is effectively improved, avoiding agglomeration, and the interfacial bonding force with polyethylene is improved. With the carbon nanotubes and barium ferrite as the core, a strong and tough composite reinforcement core is formed, which can effectively absorb and disperse external loads. The carbon nanotubes absorb electromagnetic waves through the mechanisms of conductive loss and multiple reflections, while the barium ferrite absorbs magnetic field energy through magnetic loss and resonance effects. The synergistic effect of the two, combined with the uniform distribution of the core - shell structure, significantly improves the strength, self - repairability and scratch resistance of the composite material, and at the same time has certain wave - absorbing properties. The described carbon nanotube masterbatch is applicable to the fields of aerospace, electronics and electrical, medical equipment, and 5G communication.

[0012] Among them, when being scratched by external force or having micro - cracks, the PE - g - MAH in the core - shell structure has certain fluidity and re - plasticity, providing a thermoplastic self - repair mechanism. The carbon nanotubes and barium ferrite reduce the generation of cracks and scratches, and reduce the area of cracks and scratches. At the same time, the carbon nanotubes have high mechanical strength and high thermal conductivity, and can transfer stress and heat near the cracks and scratches, promoting the repair process. The barium ferrite has magnetic response characteristics, enhancing the repair ability at the cracks and scratches. Thus, under the synergistic effect of the three, the self - repair effect and scratch resistance performance are effectively improved.

[0013] Preferably, the grafting rate of maleic anhydride in the polyethylene grafted maleic anhydride is 0.2 - 2%, for example, it can be 0.2%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2% or the range composed of any two of these values.

[0014] Preferably, the grafting rate of maleic anhydride in the polyethylene grafted maleic anhydride is 0.8 - 1.5%.

[0015] Among them, the polyethylene grafted maleic anhydride mentioned in the present invention can be obtained by purchasing through regular commercial channels, or the polyethylene grafted maleic anhydride can be prepared by existing methods.

[0016] Exemplarily, the preparation method of the polyethylene grafted maleic anhydride is: mixing polyethylene, maleic anhydride and an initiator, and extruding to obtain the polyethylene grafted maleic anhydride.

[0017] It should be noted that by adjusting the ratio of polyethylene to maleic anhydride, polyethylene grafted maleic anhydrides with different grafting rates can be obtained.

[0018] Among them, the grafting rate of maleic anhydride can be measured by infrared spectroscopy: using a Fourier transform infrared spectrometer to test a sample with a fixed thickness to obtain the characteristic absorption peak of the infrared spectrum, and the grafting rate of maleic anhydride can be calculated by comparing the ratio of the absorbance intensities of the carbonyl group and the methylene group.

[0019] Exemplarily, the temperature of the extrusion is 170 - 250 °C.

[0020] Exemplarily, the rotation speed of the extrusion is 20 - 500 rpm.

[0021] Exemplarily, the weight parts of the polyethylene are 95 - 99 parts; the weight parts of the maleic anhydride are 1 - 5 parts; the weight parts of the initiator are 0.1 - 1 part.

[0022] There are no special requirements for the melt flow rate of the polyethylene. For example, when measured according to ASTM D1238 - 10 under a load of 2.16 kg and a temperature of 190 °C, the melt flow rate of the polyethylene is 0.1 g / 10 min - 60.0 g / 10 min.

[0023] Exemplarily, the initiator includes one of dicumyl peroxide, benzoyl peroxide, di - tert - butyl peroxide, and diisopropylbenzene hydroperoxide.

[0024] Preferably, the length of the carbon nanotubes is 1 - 50 μm, for example, it can be 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm or the range composed of any two of these values.

[0025] Preferably, the diameter of the carbon nanotubes is 1 - 15 nm, for example, it can be 1 nm, 2 nm, 5 nm, 8 nm, 10 nm, 12 nm, 15 nm or the range composed of any two of these values.

[0026] In the present invention, the diameter and length of the carbon nanotubes are measured by a microscopy method: a plurality of carbon nanotube samples (at least 10) are placed under a microscope for observation, and the diameters and lengths of all the carbon nanotubes in the samples are calculated, and the average value is calculated to obtain the diameter and length of the carbon nanotubes.

[0027] Preferably, the length of the carbon nanotubes is 10-20 μm and the diameter is 4-8 nm.

[0028] Preferably, the average particle size of the barium ferrite is 40-400 nm, for example, it can be 40 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm or the range composed of any two of these values.

[0029] The average particle size of the barium ferrite is measured according to GB / T19077-2016.

[0030] The second aspect of the present application provides a method for preparing a carbon nanotube masterbatch, including the following steps: mixing carbon nanotubes and barium ferrite evenly to obtain a mixture, and putting the mixture and polyethylene grafted maleic anhydride into a twin-screw extruder for melt mixing, and extruding and pelletizing to obtain a carbon nanotube masterbatch.

[0031] In the present application, by mixing carbon nanotubes and barium ferrite evenly and then putting the mixture and polyethylene grafted maleic anhydride into a twin-screw extruder for melt mixing, in the melt mixing process, the polyethylene grafted maleic anhydride is a dienophile and the carbon nanotube / barium ferrite is a diene. Through the DA reaction (Diels-Alder reaction), the coating of carbon nanotube / barium ferrite by PE-g-MAH is successfully realized, and a carbon nanotube masterbatch with carbon nanotubes and barium ferrite as the core and polyethylene grafted maleic anhydride as the shell is prepared.

[0032] The third aspect of the present application provides an application of the carbon nanotube masterbatch in the fields of aerospace, electronic and electrical, medical equipment, and 5G communication.

[0033] The fourth aspect of the present application provides a polyethylene composite material, including polyethylene and a carbon nanotube masterbatch; the mass ratio of the polyethylene to the carbon nanotube masterbatch is (90-99):(1-10); for example, it can be 90:10, 92:8, 94:6, 95:5, 98:2, 99:1 or the range composed of any two of these values.

[0034] In the polyethylene composite material of the present application, the mass percentage content of polyethylene is not less than 90%.

[0035] Preferably, in the polyethylene composite material of the present application, the mass percentage content of polyethylene is 90-99%, for example, it can be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or the range composed of any two of these values.

[0036] The carbon nanotube masterbatch includes the carbon nanotube masterbatch described above.

[0037] Among them, the preparation method of the polyethylene composite material includes the following steps: uniformly mixing the carbon nanotube masterbatch and polyethylene, then putting them into a twin-screw extruder for melt mixing, and extruding and pelletizing to obtain the carbon nanotube masterbatch.

[0038] It should be noted that the polyethylene composite material of the present invention may further include at least one of mineral powder, lubricant, colorant, weathering agent, antistatic agent, flame retardant, ultraviolet absorber, antioxidant.

[0039] The polyethylene composite material of the present invention may include mineral powder, and suitable mineral powders include but are not limited to calcium carbonate, mica, kaolin, magnesium hydroxide, boehmite, talc powder and their combinations.

[0040] The polyethylene composite material of the present invention may include colorant, and suitable colorants include but are not limited to carbon black, titanium dioxide, zinc sulfide, iron oxide red, titanium yellow and their combinations.

[0041] The polyethylene composite material of the present invention may include lubricant, and suitable lubricants include but are not limited to polyethylene wax, fatty acid esters, hyperbranched amides and their combinations.

[0042] The polyethylene composite material of the present invention may include weathering agent, and suitable weathering agents include but are not limited to hindered amine light stabilizers and their combinations.

[0043] The polyethylene composite material of the present invention may include antistatic agent, and suitable antistatic agents include but are not limited to zinc oxide, manganese dioxide, chromium trioxide and their combinations.

[0044] The polyethylene composite material of the present invention may include flame retardant, and suitable flame retardants include but are not limited to brominated polymers (such as brominated polystyrene), metal dialkyl phosphites (such as tris(diethyl phosphite)aluminum), metal hydroxides (such as magnesium hydroxide), aromatic phosphates (such as resorcinol bis(diphenyl phosphate) and bisphenol A bis(diphenyl phosphate)) and their combinations.

[0045] The polyethylene composite material described in the present invention may include an ultraviolet light absorber. Suitable ultraviolet light absorbers include, but are not limited to, hydroxybenzophenones, benzotriazoles, hydroxybenzotriazines, cyanoacrylates, nano-scale inorganic materials (such as titanium oxide, cerium oxide, and zinc oxide), and combinations thereof.

[0046] The polyethylene composite material described in the present invention may include an antioxidant. Suitable antioxidants include, but are not limited to, at least one of thioester antioxidants, hindered phenol antioxidants, hydroxylamine antioxidants, phosphite antioxidants, and phosphate antioxidants.

[0047] The fifth aspect of the present application provides an application of a polyolefin composite material in the fields of aerospace, electronics and electrical engineering, medical equipment, and 5G communication.

[0048] The beneficial effects of the present invention are as follows: The carbon nanotube masterbatch described in the present invention has a core-shell structure. Among them, the core includes carbon nanotubes and barium ferrite, and the shell is polyethylene grafted maleic anhydride; by coating the carbon nanotubes and barium ferrite, the dispersion of carbon nanotubes and barium ferrite in polyethylene is effectively improved, avoiding agglomeration, and improving the interfacial bonding force with polyethylene. With carbon nanotubes and barium ferrite as the core, a strong and tough composite reinforcement core is formed, which can effectively absorb and disperse external loads. Carbon nanotubes absorb electromagnetic waves through conductive loss and multiple reflection mechanisms, while barium ferrite absorbs magnetic field energy through magnetic loss and resonance effects. The synergistic effect of the two, combined with the uniform distribution of the core-shell structure, significantly improves the strength, self-repairability, and scratch resistance of the composite material, and at the same time has certain wave absorption performance. The described carbon nanotube masterbatch is applicable to the fields of aerospace, electronics and electrical engineering, medical equipment, and 5G communication. Detailed Embodiments

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0050] In the present application, among the technical features described in an open-ended manner, a closed technical solution composed of the listed features is included, as well as an open technical solution including the listed features.

[0051] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when the range refers to integers, it includes each integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0052] The raw materials used in the examples and comparative examples are described as follows:

[0053] Carbon nanotube - 1: length 10 - 20 μm, diameter 4 - 8 nm, Zhongke Times Company, TNM0.

[0054] Carbon nanotube - 2: length 10 - 20 μm, diameter 4 - 6 nm, Xianfeng Nano, XFM67.

[0055] Carbon nanotube - 3: length 1 - 3 μm, diameter 1 - 2 nm, Zhongke Times Company, TNSS.

[0056] Carbon nanotube - 4: length 30 - 50 μm, diameter 8 - 15 nm, Chengdu Organic Chemistry, TNIM2.

[0057] Barium ferrite (BaFe 12 O 19 ), purchased from Daojin Technology, model DK - BaFeO - 01, after grinding and sieving, barium ferrite (BaFe 12 O 19 ) with different particle size distributions was obtained.

[0058] Barium ferrite - 1 (BaFe 12 O 19 ): 40 nm.

[0059] Barium ferrite - 2 (BaFe 12 O 19 ): 100 nm.

[0060] Barium ferrite - 3 (BaFe 12 O 19 ): 200 nm.

[0061] Barium ferrite - 4 (BaFe 12 O 19 ): 400 nm.

[0062] Polyethylene: sourced from Sinopec, model LLDPE M2320.

[0063] Polyethylene grafted maleic anhydride - 1: The grafting rate of maleic anhydride is 0.8%, and the polyethylene model is LLDPE M2320.

[0064] Polyethylene grafted maleic anhydride - 2: The grafting rate of maleic anhydride is 1.5%, and the polyethylene model is LLDPE M2320.

[0065] Polyethylene grafted maleic anhydride - 3: The grafting rate of maleic anhydride is 0.2%, and the polyethylene model is LLDPE M2320.

[0066] Polyethylene grafted maleic anhydride - 4: The grafting rate of maleic anhydride is 2%, and the polyethylene model is LLDPE M2320.

[0067] The following examples are provided to facilitate the understanding of the present invention. These examples are not provided to limit the scope of the claims.

[0068] Unless otherwise specified, the component raw materials used in the examples and comparative examples of the present invention are all commercially available raw materials, and the component raw materials used in each parallel experiment are of the same kind.

[0069] Example 1

[0070] A method for preparing a carbon nanotube masterbatch, comprising the following steps:

[0071] Mix carbon nanotube - 1 and barium ferrite - 1 evenly according to a mass ratio of 3:1 to obtain a mixture, and put the mixture and polyethylene grafted maleic anhydride - 1 into a twin - screw extruder according to a mass ratio of 1:1 for melt mixing. The temperatures of the 1 - 4 zones of the twin - screw extruder are set at 180°C, 200°C, 220°C, and the head temperature is 200°C. Extrude and pelletize to obtain carbon nanotube masterbatch - 1.

[0072] The core - shell and mass ratio of the carbon nanotube masterbatch are shown in Table 1.

[0073] Example 2

[0074] The difference between Examples 2 - 4 and Example 1 is that the mass ratio of carbon nanotube - 1 and barium ferrite - 1 is changed to obtain carbon nanotube masterbatches 2 - 4 respectively.

[0075] Examples 5 - 7

[0076] The difference between Examples 5 - 7 and Example 1 is that the type of carbon nanotube is changed to obtain carbon nanotube masterbatches 5 - 7 respectively.

[0077] Examples 8 - 10

[0078] The difference between Examples 8 - 10 and Example 1 is that the type of barium ferrite is changed to obtain carbon nanotube masterbatches 8 - 10 respectively.

[0079] Examples 11 to 13

[0080] Examples 11 to 13 are different from Example 1 in that the types of polyethylene grafted maleic anhydride are changed to obtain carbon nanotube masterbatches 11 to 13 respectively.

[0081] Examples 14 to 15, Comparative Examples 1 to 2

[0082] Examples 14 to 15, Comparative Examples 1 to 2 are different from Example 1 in that the mass ratios of the core - shell are changed to obtain carbon nanotubes 14 to 15 and comparative carbon nanotube masterbatches 1 to 2 respectively.

[0083] Comparative Example 3

[0084] Comparative Example 3 is carbon nanotube - 1 without any treatment.

[0085] Comparative Example 4

[0086] Comparative Example 4 is different from Example 1 in that it is a mixture of carbon nanotube - 1 and barium ferrite - 1 without coating treatment.

[0087] Carbon nanotube - 1 and barium ferrite - 1 are mixed evenly according to the mass ratio of 3:1 to obtain comparative carbon nanotube - 4.

[0088] Comparative Example 5

[0089] Comparative Example 5 is different from Example 1 in that no barium ferrite is added in Comparative Example 5.

[0090] A method for preparing a carbon nanotube masterbatch includes the following steps:

[0091] Carbon nanotube - 1 and polyethylene grafted maleic anhydride - 1 are put into a twin - screw extruder according to the mass ratio of 1:1 for melt mixing. The temperatures of the 1 - 4 zones of the twin - screw extruder are set to 180°C, 200°C, 220°C, and the head temperature is 200°C. Extrusion granulation is carried out to obtain comparative carbon nanotube masterbatch - 5. Table 1

[0092]

[0093]

[0094] Among them, Examples 1 to 15 and Comparative Examples 1 to 5 in Table 1 correspond to carbon nanotube masterbatches 1 to 15 and comparative carbon nanotube masterbatches 1 to 5 respectively.

[0095] Examples 16 to 33, Comparative Examples 6 to 10

[0096] The polyethylene composites of Examples 16 to 33 and Comparative Examples 6 to 10 are shown in Table 2 and Table 3.

[0097] The preparation methods of the polyethylene composites of Examples 16 to 33 and Comparative Examples 6 to 10 all include the following steps:

[0098] Mix the carbon nanotube masterbatch and polyethylene (LLDPE M2320) evenly according to the ratio, put them into a twin-screw extruder for melt mixing, set the temperatures of the 1st to 4th zones of the twin-screw extruder at 180 °C, 200 °C, 220 °C, and the head at 200 °C, and extrude and pelletize to obtain the polyethylene composite.

[0099] Table 2

[0100]

[0101] Table 3

[0102]

[0103]

[0104] Performance testing

[0105] Tensile strength: According to ISO 527-2, the tensile speed is 50 mm / min.

[0106] Self-healing efficiency: Among them, the scratch resistance performance test is carried out through the PV3952-2019 Volkswagen scratch resistance test; among them, the scratch self-healing performance is tested by injection molding the prepared polypropylene material into a 100 mm * 100 m * 3 mm Volkswagen K31 leather grain board and then conducting a scratch test, and the scratch force used in the test is 10 N. The color difference before scratching and after scratching (tested immediately after scratching) is recorded as ΔL1, the automatic repair temperature after scratching is 25 °C, and the time is 60 min. Calculate the color difference before scratching and after repair and record it as ΔL2.

[0107] Among them, the smaller the value of ΔL1, the closer the scratched material is to the state before scratching, and the better the scratch resistance performance.

[0108] Among them, the smaller the value of ΔL2, the closer the repaired material is to the state before scratching, and the better the self-healing performance.

[0109] Table 1

[0110]

[0111]

[0112] As can be seen from Table 4, the carbon nanotube masterbatch of the present invention can improve the strength, self-repairability and scratch resistance of the polyethylene composite material. The carbon nanotube masterbatch is applicable to the fields of aerospace, electronics and electrical, medical equipment, and 5G communication. Among them, the tensile strength of the polyethylene composite material containing the carbon nanotube masterbatch of the present invention is ≥27 MPa, ΔL1≤1.3, and ΔL2≤0.8.

[0113] By comparing the examples and comparative examples, it can be seen that the carbon nanotube masterbatch with a core-shell structure of the present invention can significantly improve the strength, self-repairability and scratch resistance of the polyethylene composite material.

[0114] By comparing the examples with Comparative Examples 1-2, it can be seen that the present invention significantly improves the strength, self-repairability and scratch resistance of the polyethylene composite material by controlling the mass ratio of the core to the shell to be 1:(0.25-4).

[0115] 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 carbon nanotube masterbatch, characterized in that, It has a core-shell structure, where the core includes carbon nanotubes and barium ferrite, and the shell is polyethylene grafted with maleic anhydride; The mass ratio of the core to the shell is 1:(0.25 - 5); The mass ratio of the carbon nanotubes to the barium ferrite is (1 - 9):

1.

2. The carbon nanotube masterbatch according to claim 1, characterized in that, The mass ratio of the core to the shell is 1:(0.5 - 2).

3. The carbon nanotube masterbatch according to claim 1, characterized in that, The grafting rate of maleic anhydride in the polyethylene grafted with maleic anhydride is 0.2 - 2%.

4. The carbon nanotube masterbatch according to claim 3, characterized in that The grafting rate of maleic anhydride in the polyethylene grafted with maleic anhydride is 0.8 - 1.5%.

5. The carbon nanotube masterbatch according to claim 1, wherein The length of the carbon nanotubes is 1 - 50 μm, and the diameter is 1 - 15 nm.

6. The carbon nanotube masterbatch according to claim 1, characterized in that, The average particle size of the barium ferrite is 40 - 400 nm.

7. The preparation method of the carbon nanotube masterbatch according to any one of claims 1 to 6, characterized in that, It includes the following steps: mixing the carbon nanotubes and barium ferrite evenly to obtain a mixture, and putting the mixture and the polyethylene grafted with maleic anhydride into a twin-screw extruder for melt mixing, and then extruding and pelletizing to obtain carbon nanotube masterbatch.

8. Application of the carbon nanotube masterbatch according to any one of claims 1 - 6 in the fields of aerospace, electronic and electrical, medical equipment, and 5G communication.

9. A polyethylene composite material, characterized in that, It includes polyethylene and carbon nanotube masterbatch; the mass ratio of the polyethylene to the carbon nanotube masterbatch is (90 - 99):(1 - 10); the carbon nanotube masterbatch includes the carbon nanotube masterbatch according to any one of claims 1 - 6.

10. Application of the polyolefin composite material according to claim 9 in the fields of aerospace, electronic and electrical, medical equipment, and 5G communication.

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