CN109776832B

CN109776832B - Three-layer structure resin-based composite material and application thereof

Info

Publication number: CN109776832B
Application number: CN201910037232.7A
Authority: CN
Inventors: 顾嫒娟; 赵丹; 梁国正; 袁莉
Original assignee: Suzhou University
Current assignee: Suzhou University
Priority date: 2019-01-15
Filing date: 2019-01-15
Publication date: 2021-03-02
Anticipated expiration: 2039-01-15
Also published as: CN109776832A

Abstract

The invention discloses a three-layer structure resin matrix composite material and application thereof. The invention prepares the oriented carbon nanotube bundle/epoxy resin composite material (marked as a layer B) by a microwave curing method, prepares the barium titanate nanofiber/epoxy resin composite material (marked as a layer E) by a blade coating-thermosetting method, and constructs the B-E-B three-layer structure composite material by a layer-by-layer curing technology. Compared with the conductor-insulating layer/polymer laminated structure composite material prepared by the prior art, the three-layer structure composite material provided by the invention has the advantages of high dielectric constant (> 1000, @100 Hz), low dielectric loss and high energy storage density, and the preparation process is controllable and easy, short in production period and suitable for large-scale application.

Description

Three-layer structure resin-based composite material and application thereof

Technical Field

The invention relates to a resin-based composite material with high energy storage density, high dielectric constant (> 1000, 100 Hz) and low dielectric loss (< 0.6, 100 Hz) and application thereof, in particular to a resin-based composite material with a three-layer structure and application thereof, belonging to the technical field of dielectric functional composite materials.

Background

With the proliferation of pulsed power devices, electronic power systems, and compact, low cost electrical appliances, there is a pressing need for electrical energy storage elements that can store and instantaneously deliver energy. The dielectric capacitor does not relate to electrochemical reaction during charging and discharging, is generally solid, does not generate morphological change, has high service temperature, and is beneficial to ensuring the stable operation and service reliability of pulse power equipment and an electronic power system. The high-performance dielectric energy storage material is a core material of a dielectric capacitor, wherein the high-dielectric constant polymer-based composite material has the advantages of light weight, easy processing, adjustable dielectric property and the like, and is recognized as the most promising candidate material for the high-performance dielectric capacitor.

Linear dielectric energy storage density: (U _e) Proportional to the dielectric constant of dielectric (ε _r) And breakdown strength: (E _b) Square of (d). Heretofore, polymer-based composites have generally not been able to combine high dielectric constant with high breakdown strength. For example, in the ceramic/polymer composite material, even if the ceramic content is as high as 50vol% or more, the dielectric constant is less than 100, and the ceramic/polymer composite material has many structural defects and low breakdown strength. In the conductor/polymer composite material, a high dielectric constant is obtained by utilizing a seepage phenomenon, but the dielectric property of the conductor/polymer composite material is very sensitive to the content of the conductor, the dielectric loss is high (> 1, @100 Hz), the breakdown is easy to occur, and the dielectric constant is also lower than 350.

In order to solve the above problems, in recent years, various types of multilayer structure composite materials have been prepared, but the dielectric constant of the multilayer structure composite materials reported in the prior literature is generally low (< 350 @100 Hz), and the process is complicated and the cycle is long.

Therefore, how to prepare the low dielectric loss and the high dielectric loss by adopting a simple processE _bAnd heightU _eThe high dielectric constant polymer matrix composites of (a) remain a very challenging task. In the functional filling body, the oriented carbon nanotube bundle consisting of a plurality of single carbon nanotubes interacting in a certain direction has excellent mechanical property, conductivity andand compared with other one-dimensional materials, the dispersibility can more effectively improve the dielectric property of the nano composite material. However, when the content of the oriented carbon nanotube bundle is high, the dielectric constant (265 @100 Hz) of the prepared polymer-based composite material still needs to be further improved; meanwhile, the oriented carbon nanotube bundle/resin composite material also has the problems of high dielectric loss, low breakdown strength and low energy storage density.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide the novel resin-based composite material with high energy storage density, low dielectric loss and high dielectric constant, and the preparation method has the advantages of controllable and feasible preparation process, short production period and suitability for large-scale application.

The technical scheme for realizing the purpose of the invention is as follows:

a three-layer structure resin-based composite material is prepared by the following steps:

(1) mixing the curable resin system with the oriented carbon nanotube bundle to obtain an oriented carbon nanotube bundle prepolymer; then dividing the prepolymer into a first prepolymer and a second prepolymer; then, pre-curing the first prepolymer to obtain an oriented carbon nanotube bundle pre-cured sheet;

(2) mixing a curable resin system with the polydopamine-coated barium titanate nanofiber to obtain a barium titanate nanofiber prepolymer; then preparing a barium titanate nanofiber prepolymer into a membrane and then precuring to obtain a barium titanate nanofiber precured sheet;

(3) soaking the barium titanate nanofiber pre-cured sheet in a second prepolymer and then spreading the second prepolymer on an oriented carbon nanotube bundle pre-cured sheet; then pouring the second prepolymer on a barium titanate nanofiber pre-cured sheet; and curing to obtain the three-layer structure resin-based composite material.

The invention also discloses a preparation method of the three-layer structure resin matrix composite material, which comprises the following steps:

In the invention, in the step (1), the amount of the oriented carbon nanotube bundle is 0.1-2% of the mass of the curable resin system, preferably 0.3-1%; the first prepolymer and the second prepolymer are equal in quantity, can be equal in quantity or equal in mass, and the three-layer structure resin matrix composite material prepared in the way is uniform in structure and beneficial to performance of all directions; in the step (2), the dosage of the polydopamine-coated barium titanate nanofiber is 10-40% of the mass of the curable resin system, preferably 15-25%, the addition amount of the inorganic material is far lower than that of the inorganic material in the prior art, but the technical effect that the breakdown strength is 4.92 is achieved, and the method is not obvious.

In the present invention, the curable resin system comprises a resin or a resin and a curing agent; the curable resin system comprises a resin or a resin and a curing agent; the curable resin system and the curable resin system can be the same or different, and the invention adopts two names for distinguishing, namely the resin system can be cured under certain conditions (heating, illumination, microwave and the like) to reach the curing degree of nearly 100 percent. The resin system can be single resin, a composition of a plurality of resins, or a combination of the resin and a corresponding curing agent, wherein the resin comprises one or more of bismaleimide resin, cyanate ester resin, epoxy resin and polyimide resin, and the curing agent is selected conventionally according to the type of the resin; the term "resin" and "curing agent" used in the present invention is a term common in the art.

In the invention, the preparation method of the polydopamine-coated barium titanate nanofiber comprises the following steps:

firstly, mixing barium salt and titanate compound in a solvent, and then adding a viscosity regulator to obtain a precursor solution; performing electrostatic spinning and calcining on the precursor solution to obtain barium titanate nanofibers;

dissolving dopamine hydrochloride and tris hydrochloride in water, and then adjusting the pH value to 8-9 by using alkali liquor; and then adding barium titanate nanofiber to react to obtain polydopamine-coated barium titanate nanofiber.

In the technical scheme, barium salt is barium acetate, titanate compound is tetrabutyl titanate, solvent is acetic acid, and viscosity regulator is polyvinylpyrrolidone; the electrostatic spinning parameter is 1.7 kV/cm; the calcination is carried out for 3 hours at 700 ℃ under the conditions of the heating rate of 10 ℃/min and air atmosphere; the alkali liquor is sodium hydroxide aqueous solution; the reaction was carried out at room temperature for 24h with shaking. The molar ratio of the barium salt to the titanate compound is 1; the mass ratio of the dopamine hydrochloride, the trihydroxymethyl aminomethane hydrochloride, the water and the barium titanate nanofiber is 0.2: 0.1: 100: 2.

In the invention, the thickness of the barium titanate nanofiber pre-cured sheet is 50-1000 μm, preferably 150-300 μm; and preparing the barium titanate nanofiber prepolymer into a membrane by adopting a coating method. The resin-based composite material with the three-layer structure prepared in the way can ensure a high dielectric constant to the maximum extent, so that the high dielectric constant is maintained and even slightly increased, and the breakdown strength is obviously improved.

In the invention, the curing degree of the oriented carbon nanotube bundle pre-curing sheet is 30-60%; the curing degree of the barium titanate nanofiber pre-cured sheet is 30-60%. The curing degree is a general term in the field, the raw materials are pre-cured, the dispersibility of inorganic components (carbon nanotube bundles and barium titanate nanofibers) can be increased under low viscosity, the problem of unstable three-layer structure caused by overlarge fluidity in the final curing process can be avoided, and meanwhile, the pre-polymerization curing degree is limited, and the interlayer curing effect can be improved.

In the invention, in the step (1), a first prepolymer is pre-cured by adopting a microwave intermittent curing mode; and (3) curing in a microwave intermittent curing mode. Preferably, the time of each curing of the microwave intermittent curing is 10-30 s, and the intermittent time is 5-15 s. The invention does not adopt the conventional thermosetting mode in the field of resin curing, but adopts microwave intermittent curing, namely microwave curing is suspended for a period of time after being suspended for a period of time, then microwave curing-suspending is carried out, and the cycle is continued, and the total curing time is determined according to a resin system, so that the curing degree of the obtained resin-based composite material with the three-layer structure is over 97 percent.

The invention also discloses an application of the three-layer structure resin-based composite material in preparation of a dielectric functional composite material.

The invention discloses a preparation method of a three-layer structure resin-based composite material, which specifically comprises the following steps: by mass, the amount of the solvent to be added,

(1) mixing and uniformly mixing 100 parts of a microwave-curable resin system and 0.1-2 parts of an oriented carbon nanotube bundle, and carrying out prepolymerization to obtain a prepolymer A;

(2) dividing the prepolymer A prepared in the step (1) into two parts, and pre-curing one half of the prepolymer A to obtain an oriented carbon nanotube bundle/resin pre-cured sheet B;

(3) uniformly mixing 100 parts of a thermocurable resin system and 10-40 parts of polydopamine-coated barium titanate nanofiber, and carrying out prepolymerization to obtain a prepolymer C; scraping and coating the prepolymer C into a prepolymer film D with the thickness of 50-1000 microns by using a film coater;

(4) pre-curing the prepolymer film D prepared in the step (3) to obtain a barium titanate nanofiber/thermosetting resin pre-cured sheet E;

(5) soaking the pre-cured sheet E prepared in the step (4) in the prepolymer A prepared in the step (1), and then spreading the pre-cured sheet E on the oriented carbon nanotube bundle/resin pre-cured sheet B prepared in the step (2) to obtain a double-layer structure composite material B-E;

(6) and (3) pouring the other half of the prepolymer A prepared in the step (1) onto one surface of the barium titanate nanofiber/thermosetting resin pre-cured sheet E of the double-layer structure composite material B-E prepared in the step (5), and curing to obtain a three-layer structure resin-based composite material B-E-B.

In the present invention, the aligned carbon nanotube bundles may be either not surface-treated or surface-treated.

The preparation method of the polydopamine-coated barium titanate nanofiber comprises the following steps:

firstly, dissolving 1 part of barium acetate and 1 part of tetrabutyl titanate in 10 parts of acetic acid by molar ratio, uniformly mixing, adding a proper amount of polyvinylpyrrolidone to adjust viscosity, and forming a stable precursor solution F; taking the precursor solution F, carrying out electrostatic spinning under 1.7kV/cm, and drying at 40 ℃ for 4h after the electrostatic spinning is finished to obtain a primary-spun composite nanofiber G; and (3) putting the primary-spun composite nanofiber G in a muffle furnace, heating to 700 ℃ at a heating rate of 10 ℃/min in the air atmosphere, carrying out heat preservation and calcination for 3h, and naturally cooling to obtain the barium titanate nanofiber, wherein the barium titanate nanofiber is recorded as BTnf.

Dissolving 0.2 part of dopamine hydrochloride and 0.1 part of tris (hydroxymethyl) aminomethane hydrochloride in 100 parts of water by mass to obtain solution H; dissolving 0.5 part of sodium hydroxide in 100 parts of water to obtain a sodium hydroxide aqueous solution; adjusting the pH value of the solution H to 8.5 by using an aqueous solution of sodium hydroxide to obtain a solution I; immersing 2 parts of barium titanate nanofiber in the solution I, and oscillating for 24 hours at room temperature; and after the reaction is finished, taking out, cleaning and drying to obtain the polydopamine-coated barium titanate nanofiber which is marked as PDA @ BTnf.

The prepolymerization process, the precuring process and the curing process of the invention depend on the adopted resin system, the prepolymerization degree is not particularly limited, and the precuring degree is controlled to be 30-60 percent and the curing degree is more than 97 percent.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention designs a novel resin-based composite material with a three-layer structure by taking an oriented carbon nanotube bundle and barium titanate nanofibers as functional bodies, and the resin-based composite material has high energy storage density, high dielectric constant (> 1000, @100 Hz) and low dielectric loss (< 0.6, @100 Hz).

2. The invention takes the oriented carbon nanotube bundle as a conductor and adopts a microwave curing mode for curing, and the formed dielectric layer has unique high dielectric constant. Firstly, the unique tube bundle structure enables more micro-capacitor structures to be formed inside the composite material, and a higher dielectric constant is achieved. Secondly, the curing time required for microwave curing is short, and the functional body can be well dispersed in the resin. Thirdly, in the microwave irradiation process, the magnetic susceptibility and the polarizability in the direction parallel to the axis of the oriented carbon nanotube bundle are different from the magnetic susceptibility and the polarizability in the direction perpendicular to the axis of the oriented carbon nanotube bundle, so that the carbon nanotube bundle is oriented in the direction of an electromagnetic field, that is, the functional body is oriented in a certain direction in the resin matrix, and therefore, the obtained carbon nanotube bundle resin-based material layer generates higher electric polarization and has high dielectric constant.

3. Barium titanate has excellent dielectric energy storage performance, wherein the barium titanate nanofibers arranged in parallel can achieve high breakdown strength at low addition amount. The resin composite material with the barium titanate nanofibers arranged in parallel is used as the high breakdown strength layer, so that the high breakdown strength of the three-layer composite material is ensured. In addition, the dielectric constant of the barium titanate layer is low, the dielectric constant of the carbon nanotube bundle layer is high, when an external electric field is applied, the difference of the dielectric constants between the two layers is increased, and the low dielectric constant layer bears a higher local electric field, so that the electric field intensity of the high dielectric constant layer is relieved, and the material is prevented from being completely broken down; and due to local electric field redistribution, the three-layer structure composite material has higher dielectric constant.

4. The barium titanate layer exists between the two carbon nanotube bundle layers, and can remarkably limit the migration of charges in the material, thereby playing a good role in reducing dielectric loss.

5. The preparation process of the resin-based composite material with the three-layer structure is controllable, large-scale production is easy, the period is short, and the resin-based composite material is suitable for large-scale application; the three-layer structure composite material has high dielectric constant and high breakdown strength, so that the three-layer structure composite material is endowed with excellent energy storage density.

Drawings

FIG. 1 is a Scanning Electron Microscope (SEM) photograph of a resin-based composite material with a three-layer structure, provided in example 1 of the present invention, taken in the direction of X, Y, Z.

Fig. 2 is a scanning electron microscope photograph of a barium titanate nanofiber/epoxy resin composite material in a three-layer structure resin-based composite material provided in embodiment 1 of the present invention and a layer interface of the three-layer composite material layer.

FIG. 3 is a scanning electron micrograph of the interface between the three layers of the resin-based composite material with three-layer structure provided in example 1 of the present invention.

FIG. 4 shows a three-layer structure resin-based composite material provided in example 1 of the present invention, an oriented carbon nanotube bundle/epoxy resin composite material provided in comparative example 1, a barium titanate nanofiber/epoxy resin composite material provided in comparative example 2, an oriented carbon nanotube bundle/barium titanate nanofiber/epoxy resin composite material provided in comparative example 3, and a two-layer structure composite material ([ ACB/EP)]₂) Conductivity-frequency curve of (a).

FIG. 5 shows a three-layer structure resin-based composite material provided in example 1 of the present invention, an oriented carbon nanotube bundle/epoxy resin composite material provided in comparative example 1, a barium titanate nanofiber/epoxy resin composite material provided in comparative example 2, an oriented carbon nanotube bundle/barium titanate nanofiber/epoxy resin composite material provided in comparative example 3, and a two-layer structure composite material ([ ACB/EP)]₂) Dielectric constant versus frequency curve of (a).

FIG. 6 shows a three-layer structure resin-based composite material provided in example 1 of the present invention, an oriented carbon nanotube bundle/epoxy resin composite material provided in comparative example 1, a barium titanate nanofiber/epoxy resin composite material provided in comparative example 2, an oriented carbon nanotube bundle/barium titanate nanofiber/epoxy resin composite material provided in comparative example 3, and a two-layer structure composite material ([ ACB/EP)]₂) Dielectric loss versus frequency curve of (a).

FIG. 7 shows a three-layer structure resin-based composite material provided in example 1 of the present invention, an oriented carbon nanotube bundle/epoxy resin composite material provided in comparative example 1, an oriented carbon nanotube bundle/barium titanate nanofiber/epoxy resin composite material provided in comparative example 3, and a two-layer structure composite material provided in comparative example 4Composite material ([ ACB/EP)]₂) Breakdown strength of (d).

FIG. 8 shows a three-layer structure resin-based composite material provided in example 1 of the present invention, an oriented carbon nanotube bundle/epoxy resin composite material provided in comparative example 1, an oriented carbon nanotube bundle/barium titanate nanofiber/epoxy resin composite material provided in comparative example 3, and a two-layer structure composite material ([ ACB/EP)]₂) The energy storage density of (1).

Detailed Description

The technical solution of the present invention will be further described with reference to the accompanying drawings, examples and comparative examples.

Example 1

(1) Mixing 0.12g of non-surface-treated oriented carbon nanotube bundle (length 20-100 μm, diameter 2-5 μm) and 20g of bisphenol A type epoxy resin (trade name E-51), stirring at 60 ℃ for 10min by ultrasonic oscillation, adding 0.8g of 2-ethyl-4-methylimidazole, continuing stirring for 10min, and then carrying out vacuum defoaming at 60 ℃ for 20min to obtain prepolymer A; and (3) dividing the prepolymer A into two parts, namely a first prepolymer and a second prepolymer, pouring the first prepolymer into a preheated mold, then putting the mold into a microwave oven, circularly irradiating for 5 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain the oriented carbon nanotube/epoxy cured resin composite material pre-cured sheet B with the curing degree of 60%.

(2) Under magnetic stirring at 50 ℃, 4.38g of barium acetate and 5.84g of tetrabutyl titanate were added to acetic acid (20 mL) and mixed uniformly, and 5g of polyvinylpyrrolidone was added to adjust the viscosity, forming a stable precursor solution F. And (3) carrying out electrostatic spinning on the precursor solution F under the voltage of 1.7kV/cm, wherein the spinning environment is constant temperature and humidity, the temperature is 30 ℃, and the relative humidity is 50%. The sample injection rate of electrostatic spinning is 0.8 mL/h. And drying the primary spinning composite nanofiber G obtained by electrostatic spinning at 40 ℃. And then, putting the barium titanate nano-fiber into a muffle furnace in an air atmosphere, heating to 700 ℃ at a heating rate of 10 ℃/min, carrying out heat preservation calcination for 3h, and naturally cooling to obtain the barium titanate nano-fiber, which is recorded as BTnf.

(3) Dissolving 0.4g of dopamine hydrochloride and 0.2g of tris (hydroxymethyl) aminomethane hydrochloride in 200mL of water to obtain a solution H; dissolving 1g of sodium hydroxide in 200mL of water to obtain a sodium hydroxide aqueous solution; adjusting the pH value of the solution H to 8.5 by using an aqueous solution of sodium hydroxide to obtain a solution I; adding 4g of BTnf into the solution I, and stirring and reacting at room temperature for 24 h; and after the reaction is finished, taking out, cleaning and drying to obtain the polydopamine-coated barium titanate nanofiber which is marked as PDA @ BTnf.

(4) Mixing 4g of PDA @ BTnf and 20g of bisphenol A type epoxy resin (brand number E-51), ultrasonically vibrating and stirring for 10min at the temperature of 60 ℃, adding 0.8g of 2-ethyl-4-methylimidazole, and continuously ultrasonically vibrating and stirring for 10min to obtain a prepolymer C; and (3) coating a prepolymer film D with the thickness of 200 mu m on a preheated polytetrafluoroethylene plate in a scraping way, curing for 1h at the temperature of 80 ℃, and naturally cooling to obtain a barium titanate nanofiber/epoxy resin composite material pre-cured sheet E with the curing degree of 60%.

(5) Soaking the pre-cured sheet E prepared in the step (4) in the prepolymer A (second prepolymer) prepared in the step (1), and then spreading the pre-cured sheet E on the pre-cured sheet B prepared in the step (1) to remove bubbles, so as to obtain a double-layer structure composite material B-E; and (2) pouring the other half of the prepolymer A prepared in the step (1) to one side of a pre-cured sheet E of the double-layer structure composite material B-E, then placing the mold into a microwave oven, circularly irradiating for 15 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain the three-layer structure resin-based composite material with the curing degree of more than 97%, which is marked as B-E-B. A scanning electron microscope photo of the distribution of the oriented carbon nanotube bundles, a scanning electron microscope photo of the distribution of the barium titanate nanofibers, a scanning electron microscope photo of an interface between layers, a conductivity-frequency curve, a dielectric constant-frequency curve, a dielectric loss-frequency curve, breakdown strength and energy storage density in the B-E-B are respectively shown in the attached

drawings

1, 2, 3, 4, 5, 6, 7 and 8.

Referring to the attached figure 1, it is a scanning electron micrograph of the distribution of the oriented carbon nanotube bundles in the epoxy resin matrix in the B-E-B three-layer structure resin-based composite material provided by the embodiment 1 of the invention, wherein X, Y, Z in the figure represents the scanning electron micrograph in the X, Y, Z direction respectively. It can be seen that the distribution of the bundles of oriented carbon nanotubes in the epoxy resin is not random, but is uniformly dispersed, regularly arranged, and more prone to arrangement along the Z-direction.

Referring to the attached figure 2, it is a scanning electron microscope photograph of barium titanate nano-fibers distributed in epoxy resin in the B-E-B three-layer structure resin-based composite material provided in embodiment 1 of the present invention. The barium titanate nanofibers are uniformly dispersed, but the arrangement of the barium titanate nanofibers is more likely to be arranged in the horizontal direction.

Referring to the attached figure 3, it is a scanning electron microscope photograph of the interface between the layers of the B-E-B three-layer structure resin-based composite material provided by the embodiment 1 of the invention. As can be seen, the interlayer bonding is good, and no defects such as voids exist.

Comparative example 1 preparation of oriented carbon nanotube bundle/epoxy resin composite

Mixing 0.12g of non-surface-treated oriented carbon nanotube bundle (length 20-100 μm, diameter 2-5 μm) and 20g of bisphenol A type epoxy resin (trade name E-51), stirring at 60 ℃ for 10min by ultrasonic oscillation, adding 0.8g of 2-ethyl-4-methylimidazole, continuing stirring for 10min, and then carrying out vacuum defoaming at 60 ℃ for 20min to obtain prepolymer A; pouring the prepolymer A into a preheated mold, then placing the mold into a microwave oven, circularly irradiating for 15 periods (the irradiation process in each period is medium fire, heating for 30s and cooling for 10 s), and cooling to obtain an oriented carbon nanotube/epoxy resin composite material with the curing degree of more than 97%, which is recorded as ACB/EP; the conductivity-frequency curve, the dielectric constant-frequency curve, the dielectric loss-frequency curve, the breakdown strength and the energy storage density are respectively shown in the attached figures 4, 5, 6, 7 and 8.

Comparative example 2 preparation of barium titanate nanofiber/epoxy resin composite

Mixing 4g of polydopamine-coated barium titanate nanofiber PDA @ BTnf prepared in example 1 and 20g of bisphenol A type epoxy resin (brand E-51), ultrasonically shaking, stirring and stirring at 60 ℃ for 10min, adding 0.8g of 2-ethyl-4-methylimidazole, continuously ultrasonically shaking, stirring for 10min, and then carrying out vacuum defoaming at 60 ℃ for 20min to obtain prepolymer A; pouring the prepolymer A into a preheated mold, putting the mold into an oven, curing the prepolymer A according to the process of 80 ℃/2h +100 ℃/2h +120 ℃, post-treating the prepolymer A for 4h at 150 ℃, and naturally cooling the prepolymer A to obtain a barium titanate nanofiber/epoxy resin composite material with the curing degree of more than 97%, which is recorded as BTnf/EP; the conductivity-frequency curve, the dielectric constant-frequency curve and the dielectric loss-frequency curve are respectively shown in the attached figures 4, 5 and 6.

Comparative example 3 preparation of oriented carbon nanotube bundle/barium titanate nanofiber/epoxy resin composite

0.12g of non-surface-treated aligned carbon nanotubes (length 20-100 μm, diameter 2-5 μm), 4g of the polydopamine-coated barium titanate nanofibers prepared in example 1 and 20g of bisphenol A epoxy resin (trade name E-51) were mixed, stirred with ultrasonic agitation at 60 ℃ for 10 min; then adding 0.8g of 2-ethyl-4-methylimidazole, continuing ultrasonic oscillation and stirring for 10min, and then carrying out vacuum defoaming at 60 ℃ for 20min to obtain a prepolymer A; pouring the prepolymer A into a preheated mould, putting the mould into an oven, curing the prepolymer A according to the process of 80 ℃/2h +100 ℃/2h +120 ℃, post-treating the prepolymer A for 4h at 150 ℃, and naturally cooling the prepolymer A to obtain an oriented carbon nanotube/barium titanate nanofiber/epoxy resin composite material with the curing degree of more than 97%, which is recorded as ACB/BTnf/EP; the conductivity-frequency curve, the dielectric constant-frequency curve, the dielectric loss-frequency curve, the breakdown strength and the energy storage density are respectively shown in the attached figures 4, 5, 6, 7 and 8.

Comparative example 4 two-layer Structure composite ([ ACB/EP)]₂) Preparation of

Mixing 0.12g of non-surface-treated oriented carbon nanotube bundle (length 20-100 μm, diameter 2-5 μm) and 20g of bisphenol A type epoxy resin (trade name E-51), stirring at 60 ℃ for 10min by ultrasonic oscillation, adding 0.8g of 2-ethyl-4-methylimidazole, continuing stirring for 10min, and then carrying out vacuum defoaming at 60 ℃ for 20min to obtain prepolymer A; and (3) dividing the prepolymer A into two parts, pouring one part into a preheated mold, then placing the mold into a microwave oven, circularly irradiating for 5 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain the oriented carbon nanotube/epoxy cured resin composite material pre-cured sheet B with the curing degree of 60%. Pouring the other half of the prepolymer A prepared in the step (1) onto the pre-cured sheet B, then placing the mold into a microwave oven, and circularly irradiating for 15 cycles (each cycle)The irradiation process is middle fire heating for 30s and cooling for 10 s), and the curing degree is obtained after natural cooling>97% of a two-layer composite material, designated [ ACB/EP]₂(ii) a The conductivity-frequency curve, the dielectric constant-frequency curve, the dielectric loss-frequency curve, the breakdown strength and the energy storage density are respectively shown in the attached figures 4, 5, 6, 7 and 8.

Referring to FIG. 4, there are provided a three-layer structure resin-based composite material B-E-B composite material provided in example 1 of the present invention, an oriented carbon nanotube bundle/epoxy resin composite material (ACB/EP) provided in comparative example 1, a barium titanate nanofiber/epoxy resin (BTnf/EP) composite material provided in comparative example 2, an oriented carbon nanotube bundle/barium titanate nanofiber/epoxy resin (ACB/BTnf/EP) composite material provided in comparative example 3, and a two-layer structure composite material ([ ACB/EP) ("B/EP)]₂) Conductivity-frequency curve of (a). From these results, the ACB/EP composite material provided in comparative example 1, the BTnf/EP composite material provided in comparative example 2, the ACB/BTnf/EP composite material provided in comparative example 3, and the two-layer structure composite material ([ ACB/EP) provided in comparative example 4 were found]₂) The electrical conductivity of the B-E-B composite material provided in example 1 respectively reaches 10^-7、10^-11、10^-9、10^-9、10^-10Of order (@ 1 Hz). The B-E-B composite provided in example 1 has the lowest electrical conductivity, because the presence of the polydopamine coated barium titanate nanofiber/epoxy composite layer has a blocking effect on the conductive path inside the composite, and reduces the electrical leakage phenomenon of the composite.

Referring to FIG. 5, there are provided a three-layer structure resin-based composite material B-E-B composite material provided in example 1 of the present invention, an oriented carbon nanotube bundle/epoxy resin composite material (ACB/EP) provided in comparative example 1, a barium titanate nanofiber/epoxy resin (BTnf/EP) composite material provided in comparative example 2, an oriented carbon nanotube bundle/barium titanate nanofiber/epoxy resin (ACB/BTnf/EP) composite material provided in comparative example 3, and a two-layer structure composite material ([ ACB/EP) ("B/EP) (" B/EP ")]₂) Dielectric constant versus frequency curve of (a). It can be seen that the B-E-B composite material provided in example 1 has the highest dielectric constant. Comparative example at 100Hz1, comparative example 2, comparative example 3, and comparative example 4 ([ ACB/EP ] s]₂) The dielectric constants of the B-E-B composite material provided by the embodiment 1 are 797.6, 21.1, 350.4, 828 and 1080.9 respectively. Among them, the dielectric constant value of the B-E-B composite material provided in example 1 is the optimum value, higher than the hitherto reported value of the conductor/polymer multilayer composite material containing the insulating layer; the BTnf/EP composite material provided in comparative example 2 had a worst value of 21.1 (@ 100 Hz), and had a dielectric constant of 16.9 (@ 100 Hz) if barium titanate nanofibers were used directly instead of the polydopamine-coated barium titanate nanofibers.

The barium titanate nanofiber is a ceramic functional body, and the dielectric constant of the BTnf/EP composite material provided in comparative example 2 was the lowest when the amount of the barium titanate nanofiber added was 20 wt%. The presence of barium titanate nanofibers in the ACB/BTnf/EP composite provided in comparative example 3 blocked the formation of a conductive network of aligned carbon nanotube bundles, compared to the ACB/EP composite provided in comparative example 1, and therefore its dielectric constant was much lower than that of comparative example 1.

Comparative example 4 provides a two-layer structure composite ([ ACB/EP) as compared to the ACB/EP composite provided in comparative example 1]₂) One more interface layer has stronger interface polarization effect, so the dielectric constant is slightly higher. Example 1 provides a B-E-B composite with a higher dielectric constant due to space charge polarization in the presence of two interfacial layers. In addition, the electrical conductivities of the aligned carbon nanotube bundle/epoxy resin composite layer (layer a) and the barium titanate nanofiber/epoxy resin composite layer (layer B) were 10, respectively^-7And 10^-11(@ 1 Hz), the ratio between the layers being formed [ ACB/EP]₂More charge accumulates between the layers, resulting in more pronounced interfacial polarization. Therefore, the dielectric constant of the B-E-B composite material provided by the embodiment 1 is greatly improved. On the other hand, the difference of the dielectric constants of the oriented carbon nanotube bundle/epoxy resin composite layer and the barium titanate nanofiber/epoxy resin composite layer causes the local electric field intensity redistribution when the composite material is in an electric field, and the barium titanate with low dielectric constantThe nanofiber/epoxy composite layer (21.1 @100 Hz) is polarized under a higher electric field, the degree of electric polarization is higher, and therefore the dielectric constant of the B-E-B composite material is increased.

Referring to FIG. 6, there are provided a three-layer structure resin-based composite material B-E-B composite material provided in example 1 of the present invention, an oriented carbon nanotube bundle/epoxy resin composite material (ACB/EP) provided in comparative example 1, a barium titanate nanofiber/epoxy resin (BTnf/EP) composite material provided in comparative example 2, an oriented carbon nanotube bundle/barium titanate nanofiber/epoxy resin (ACB/BTnf/EP) composite material provided in comparative example 3, and a two-layer structure composite material ([ ACB/EP) ("B/EP) (" B/EP ")]₂) Dielectric loss versus frequency curve of (a). It can be seen that the dielectric loss of the B-E-B resin-based composite material provided in example 1 is reduced compared to the ACB/EP composite material provided in comparative example 1, and the barium titanate nanofiber/epoxy resin composite material layer in the B-E-B composite material provided in example 1 has the lowest dielectric loss (0.59 @100 Hz), so that the migration of charges inside the material can be significantly limited, and the function of reducing the dielectric loss is very good.

Referring to FIG. 7, there are provided a three-layer structure resin-based composite material B-E-B composite material provided in example 1 of the present invention, an oriented carbon nanotube bundle/epoxy resin composite material (ACB/EP) provided in comparative example 1, a barium titanate nanofiber/epoxy resin (BTnf/EP) composite material provided in comparative example 2, an oriented carbon nanotube bundle/barium titanate nanofiber/epoxy resin (ACB/BTnf/EP) composite material provided in comparative example 3, and a two-layer structure composite material ([ ACB/EP) ("B/EP) (" B/EP ")]₂) Breakdown strength map of (a). It can be seen that the breakdown strength of the B-E-B composite provided in example 1 reached 4.92, which is 2.5 times the breakdown strength of the ACB/BTnf/EP composite provided in comparative example 3, because the breakdown path in B-E-B is long, and due to the presence of the intermediate interface layer, the breakdown path is extended. In particular, when an electric field is applied, after the local electric field intensity is redistributed, the electric field intensity of the barium titanate nanofiber/epoxy resin composite layer with small dielectric constant (capable of bearing the electric field intensity higher than that of the oriented carbon nanotube bundle/epoxy resin composite layer) is larger, and the dielectric constant is highThe oriented carbon nanotube bundle/epoxy resin composite material layer has small local electric field intensity, reduces the probability of breakdown, thereby improving the breakdown strength of the B-E-B composite material and being beneficial to improving the energy storage density of the multilayer structure composite material. Therefore, the resin-based composite material with the three-layer structure has the advantage of adjusting the local electric field intensity distribution.

Referring to FIG. 8, there are provided a three-layer structure resin-based composite material B-E-B composite material provided in example 1 of the present invention, an oriented carbon nanotube bundle/epoxy resin composite material (ACB/EP) provided in comparative example 1, a barium titanate nanofiber/epoxy resin (BTnf/EP) composite material provided in comparative example 2, an oriented carbon nanotube bundle/barium titanate nanofiber/epoxy resin (ACB/BTnf/EP) composite material provided in comparative example 3, and a two-layer structure composite material ([ ACB/EP) ("B/EP) (" B/EP ")]₂) The energy storage density of (1). As can be seen from the results, the B-E-B composite material provided in example 1 has the highest energy storage density, and is the ACB/EP composite material provided in comparative example 1, the ACB/BTnf/EP composite material provided in comparative example 3, and the two-layer structure composite material ([ ACB/EP ] provided in comparative example 4, respectively]₂) 12.8, 18.8 and 7.7 times the storage density of (a). This is because the energy storage density of the linear material is proportional to the square of the dielectric constant and the breakdown strength of the composite material, and thus, the B-E-B three-layer structure composite material can obtain a high energy storage density with the highest dielectric constant and breakdown strength. These data demonstrate that the present invention, through structure and composition design, can produce composite materials with low dielectric loss, high dielectric constant and high breakdown strength, thereby obtaining materials with high energy storage density.

Example 2

(1) Mixing 0.02g of non-surface-treated oriented carbon nanotube bundle (length 20-100 μm, diameter 2-5 μm) and 20g of bisphenol A type epoxy resin (trade name E-51), stirring at 60 ℃ for 10min by ultrasonic oscillation, adding 0.8g of 2-ethyl-4-methylimidazole, continuing stirring for 10min, and then carrying out vacuum defoaming at 60 ℃ for 20min to obtain prepolymer A; and (3) dividing the prepolymer A into two parts, pouring one part into a preheated mold, then placing the mold into a microwave oven, circularly irradiating for 5 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain the oriented carbon nanotube/epoxy cured resin composite material pre-cured sheet B with the curing degree of 60%.

(2) Mixing 2g of polydopamine-coated barium titanate nanofiber PDA @ BTnf prepared in example 1 and 20g of bisphenol A type epoxy resin (brand E-51), ultrasonically shaking and stirring at 60 ℃ for 10min, adding 0.8g of 2-ethyl-4-methylimidazole, and continuously ultrasonically shaking and stirring for 10min to obtain prepolymer C; and (3) coating a prepolymer film D with the thickness of 160 mu m on a preheated polytetrafluoroethylene plate in a scraping way, curing for 1h at the temperature of 80 ℃, and naturally cooling to obtain a barium titanate nanofiber/epoxy resin composite material pre-cured sheet E with the curing degree of 60%.

(3) Soaking the pre-cured sheet E prepared in the step (2) in the prepolymer A prepared in the step (1), and then spreading the pre-cured sheet E on the pre-cured sheet B prepared in the step (1) to remove bubbles, so as to obtain a double-layer structure composite material B-E; and (2) pouring the other half of the prepolymer A prepared in the step (1) to one side of a pre-cured sheet E of the double-layer structure composite material B-E, then placing the mold into a microwave oven, circularly irradiating for 15 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain the three-layer structure resin-based composite material with the curing degree of more than 97%, which is marked as B-E-B.

Example 3

(1) Mixing 0.12g of non-surface-treated oriented carbon nanotube bundle (length 20-100 μm, diameter 2-5 μm) and 20g of bisphenol A type epoxy resin (trade name E-51), stirring at 60 ℃ for 10min by ultrasonic oscillation, adding 0.8g of 2-ethyl-4-methylimidazole, continuing stirring for 10min, and then carrying out vacuum defoaming at 60 ℃ for 20min to obtain prepolymer A; and (3) dividing the prepolymer A into two parts, pouring one part into a preheated mold, then placing the mold into a microwave oven, circularly irradiating for 5 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain the oriented carbon nanotube/epoxy cured resin composite material pre-cured sheet B with the curing degree of 60%.

(2) Mixing 6g of polydopamine-coated 0 acid barium nanofiber PDA @ BTnf prepared in example 1 and 20g of bisphenol A type epoxy resin (brand E-51), ultrasonically shaking and stirring at 60 ℃ for 10min, adding 0.8g of 2-ethyl-4-methylimidazole, and continuously ultrasonically shaking and stirring for 10min to obtain prepolymer C; and (3) coating a prepolymer film D with the thickness of 180 mu m on a preheated polytetrafluoroethylene plate in a scraping way, curing for 1h at the temperature of 80 ℃, and naturally cooling to obtain a barium titanate nanofiber/epoxy resin composite material pre-cured sheet E with the curing degree of 60%.

Example 4

(2) 8g of polydopamine-coated barium titanate nanofiber PDA @ BTnf prepared in example 1 and 20g of bisphenol A type epoxy resin (brand E-51) are mixed, stirred for 10min under ultrasonic oscillation at 60 ℃, 0.8g of 2-ethyl-4-methylimidazole is added, and stirring for 10min under ultrasonic oscillation is continued to obtain prepolymer C; and (3) coating a prepolymer film D with the thickness of 210 mu m on a preheated polytetrafluoroethylene plate in a scraping way, curing for 1h at the temperature of 80 ℃, and naturally cooling to obtain a barium titanate nanofiber/epoxy resin composite material pre-cured sheet E with the curing degree of 60%.

Example 5

(1) Mixing 0.18g of non-surface-treated oriented carbon nanotube bundle (length 20-100 μm, diameter 2-5 μm) and 20g of bisphenol A type epoxy resin (trade name E-51), stirring at 60 ℃ for 10min by ultrasonic oscillation, adding 0.8g of 2-ethyl-4-methylimidazole, continuing stirring for 10min, and then carrying out vacuum defoaming at 60 ℃ for 20min to obtain prepolymer A; and (3) dividing the prepolymer A into two parts, pouring one part into a preheated mold, then placing the mold into a microwave oven, circularly irradiating for 5 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain the oriented carbon nanotube/epoxy cured resin composite material pre-cured sheet B with the curing degree of 60%.

(2) Mixing 3g of polydopamine-coated barium titanate nanofiber PDA @ BTnf prepared in example 1 and 20g of bisphenol A type epoxy resin (brand E-51), ultrasonically shaking and stirring at 60 ℃ for 10min, adding 0.8g of 2-ethyl-4-methylimidazole, and continuously ultrasonically shaking and stirring for 10min to obtain prepolymer C; and (3) coating a prepolymer film D with the thickness of 200 mu m on a preheated polytetrafluoroethylene plate in a scraping way, curing for 1h at the temperature of 80 ℃, and naturally cooling to obtain a barium titanate nanofiber/epoxy resin composite material pre-cured sheet E with the curing degree of 60%.

Example 6

(1) Mixing 0.11g of non-surface-treated oriented carbon nanotube bundle (length 20-100 μm, diameter 2-5 μm) and 20g of bisphenol A type epoxy resin (trade name E-51), stirring at 60 ℃ for 10min by ultrasonic oscillation, adding 0.8g of 2-ethyl-4-methylimidazole, continuing stirring for 10min, and then carrying out vacuum defoaming at 60 ℃ for 20min to obtain prepolymer A; and (3) dividing the prepolymer A into two parts, pouring one part into a preheated mold, then placing the mold into a microwave oven, circularly irradiating for 5 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain the oriented carbon nanotube/epoxy cured resin composite material pre-cured sheet B with the curing degree of 60%.

(2) Mixing 4g of polydopamine-coated barium titanate nanofiber PDA @ BTnf prepared in example 1 and 20g of bisphenol A type epoxy resin (brand E-51), ultrasonically shaking and stirring at 60 ℃ for 10min, adding 0.8g of 2-ethyl-4-methylimidazole, and continuously ultrasonically shaking and stirring for 10min to obtain prepolymer C; and (3) coating a prepolymer film D with the thickness of 400 mu m on a preheated polytetrafluoroethylene plate in a scraping way, curing for 1h at the temperature of 80 ℃, and naturally cooling to obtain a barium titanate nanofiber/epoxy resin composite material pre-cured sheet E with the curing degree of 60%.

Example 7

(1) Mixing 0.15g of non-surface-treated oriented carbon nanotube bundle (length 20-100 μm, diameter 2-5 μm) and 20g of bisphenol A type epoxy resin (trade name E-51), stirring at 60 ℃ for 10min by ultrasonic oscillation, adding 0.8g of 2-ethyl-4-methylimidazole, continuing stirring for 10min, and then carrying out vacuum defoaming at 60 ℃ for 20min to obtain prepolymer A; and (3) dividing the prepolymer A into two parts, pouring one part into a preheated mold, then placing the mold into a microwave oven, circularly irradiating for 5 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain the oriented carbon nanotube/epoxy cured resin composite material pre-cured sheet B with the curing degree of 60%.

(2) Mixing 5g of polydopamine-coated barium titanate nanofiber PDA @ BTnf prepared in example 1 and 20g of bisphenol A type epoxy resin (brand E-51), ultrasonically shaking and stirring at 60 ℃ for 10min, adding 0.8g of 2-ethyl-4-methylimidazole, and continuously ultrasonically shaking and stirring for 10min to obtain prepolymer C; and (3) coating a prepolymer film D with the thickness of 280 mu m on a preheated polytetrafluoroethylene plate in a scraping way, curing for 1h at the temperature of 80 ℃, and naturally cooling to obtain a barium titanate nanofiber/epoxy resin composite material pre-cured sheet E with the curing degree of 60%.

Example 8

(2) Mixing 3.5g of polydopamine-coated barium titanate nanofiber PDA @ BTnf prepared in example 1 and 20g of bisphenol A type epoxy resin (brand E-51), ultrasonically shaking and stirring at 60 ℃ for 10min, adding 0.8g of 2-ethyl-4-methylimidazole, and continuously ultrasonically shaking and stirring for 10min to obtain prepolymer C; and (3) coating a prepolymer film D with the thickness of 200 mu m on a preheated polytetrafluoroethylene plate in a scraping way, curing for 1h at the temperature of 80 ℃, and naturally cooling to obtain a barium titanate nanofiber/epoxy resin composite material pre-cured sheet E with the curing degree of 60%.

Example 9

(1) Mixing 0.13g of oriented carbon nanotube bundle (with the length of 20-100 mu m and the diameter of 2-5 mu m) with the surface of which is hydroxylated and 20g of bisphenol A type epoxy resin (brand E-51), stirring the mixture at 60 ℃ for 10min by ultrasonic vibration, adding 0.8g of 2-ethyl-4-methylimidazole, continuing stirring the mixture for 10min, and then carrying out vacuum defoaming at 60 ℃ for 20min to obtain a prepolymer A; and (3) dividing the prepolymer A into two parts, pouring one part into a preheated mold, then placing the mold into a microwave oven, circularly irradiating for 5 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain the oriented carbon nanotube/epoxy cured resin composite material pre-cured sheet B with the curing degree of 60%.

(2) Mixing 4g of polydopamine-coated barium titanate nanofiber PDA @ BTnf prepared in example 1 and 20g of bisphenol A type epoxy resin (brand E-51), ultrasonically shaking and stirring at 60 ℃ for 10min, adding 0.8g of 2-ethyl-4-methylimidazole, and continuously ultrasonically shaking and stirring for 10min to obtain prepolymer C; and (3) coating a prepolymer film D with the thickness of 300 mu m on a preheated polytetrafluoroethylene plate in a scraping way, curing for 1h at the temperature of 80 ℃, and naturally cooling to obtain a barium titanate nanofiber/epoxy resin composite material pre-cured sheet E with the curing degree of 60%.

(3) Soaking the pre-cured sheet E prepared in the step (2) in the prepolymer A prepared in the step (1), and then spreading the pre-cured sheet E on the pre-cured sheet B prepared in the step (1) to remove bubbles, so as to obtain a double-layer structure composite material B-E; and (2) pouring the other half of the prepolymer A prepared in the step (1) to one side of a pre-curing sheet E of the double-layer structure composite material B-E, then placing the mold into a microwave oven, circularly irradiating for 15 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain the three-layer structure resin-based composite material with the curing degree of more than 97%, wherein the three-layer structure resin-based composite material is marked as B-E-B, the dielectric constant is 1072.1 (@ 100 Hz), and the breakdown strength reaches 4.76. If the other half of the prepolymer A in the step (3) is poured on the side of the pre-cured sheet B of the B-E, and other conditions are not changed, the dielectric constant of the obtained three-layer structure resin-based composite material B-B-E is 798.6 (@ 100 Hz), and the breakdown strength is 3.03.

Example 10

(1) Mixing 0.07g of oriented carbon nanotube bundle with hydroxylated surface (length is 20-100 μm, diameter is 2-5 μm) and 20g of bisphenol A type epoxy resin (trade name is E-51), stirring for 10min under ultrasonic oscillation at 60 ℃, adding 0.8g of 2-ethyl-4-methylimidazole, continuing stirring for 10min, and then carrying out vacuum defoaming at 60 ℃ for 20min to obtain prepolymer A; and (3) dividing the prepolymer A into two parts, pouring one part into a preheated mold, then placing the mold into a microwave oven, circularly irradiating for 4 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain the oriented carbon nanotube/epoxy cured resin composite material pre-cured sheet B with the curing degree of 40%.

(2) Mixing 2g of polydopamine-coated barium titanate nanofiber PDA @ BTnf prepared in example 1 and 20g of bisphenol A type epoxy resin (brand E-51), ultrasonically shaking and stirring at 60 ℃ for 10min, adding 0.8g of 2-ethyl-4-methylimidazole, and continuously ultrasonically shaking and stirring for 10min to obtain prepolymer C; and (3) coating a prepolymer film D with the thickness of 150 mu m on a preheated polytetrafluoroethylene plate in a scraping way, curing for 45min at 80 ℃, and naturally cooling to obtain a barium titanate nanofiber/epoxy resin composite material pre-cured sheet E with the curing degree of 40%.

Example 11

(1) Mixing 0.16g of oriented carbon nanotube bundle with hydroxylated surface (length is 20-100 mu m, diameter is 2-5 mu m) and 20g of bisphenol A type epoxy resin (trade name is E-51), stirring for 10min under ultrasonic oscillation at 60 ℃, adding 0.8g of 2-ethyl-4-methylimidazole, continuing stirring for 10min, and then carrying out vacuum defoaming at 60 ℃ for 20min to obtain prepolymer A; and (3) dividing the prepolymer A into two parts, pouring one part into a preheated mold, then placing the mold into a microwave oven, circularly irradiating for 5 periods (the irradiation process in each period is medium fire, heating for 10s and cooling for 10 s), and naturally cooling to obtain the oriented carbon nanotube/epoxy cured resin composite material pre-cured sheet B with the curing degree of 30%.

(2) Mixing 6g of polydopamine-coated barium titanate nanofiber PDA @ BTnf prepared in example 1 and 20g of bisphenol A type epoxy resin (brand E-51), ultrasonically shaking and stirring at 60 ℃ for 10min, adding 0.8g of 2-ethyl-4-methylimidazole, and continuously ultrasonically shaking and stirring for 10min to obtain prepolymer C; and (3) coating a prepolymer film D with the thickness of 275 mu m on a preheated polytetrafluoroethylene plate in a scraping way, curing for 1h at the temperature of 80 ℃, and naturally cooling to obtain a barium titanate nanofiber/epoxy resin composite material pre-cured sheet E with the curing degree of 30%.

Example 12

(1) Mixing 0.19g of non-surface-treated oriented carbon nanotube bundle (length 20-100 μm, diameter 2-5 μm) and 20g of bisphenol A type epoxy resin (trade name E-51), stirring at 80 ℃ for 10min by ultrasonic vibration, adding 5g of diaminodiphenylmethane, stirring for 10min, and removing bubbles at 80 ℃ for 20min in vacuum to obtain prepolymer A; and (3) dividing the prepolymer A into two parts, pouring one part into a preheated mold, then placing the mold into a microwave oven, circularly irradiating for 4 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain the oriented carbon nanotube/epoxy cured resin composite material pre-cured sheet B with the curing degree of 50%.

(2) 8g of polydopamine-coated barium titanate nanofiber PDA @ BTnf prepared in example 1 and 20g of bisphenol A type epoxy resin (brand E-51) are mixed, stirred for 10min under ultrasonic oscillation at 80 ℃, 5g of diaminodiphenylmethane is added, and stirring for 10min under ultrasonic oscillation is continued to obtain prepolymer C; and (3) coating a prepolymer film D with the thickness of 270 mu m on a preheated polytetrafluoroethylene plate in a scraping way, curing for 45min at 80 ℃, and naturally cooling to obtain a barium titanate nanofiber/epoxy resin composite material pre-cured sheet E with the curing degree of 50%.

Example 13

(1) Mixing 0.2g of non-surface-treated oriented carbon nanotube bundle (length 20-100 μm, diameter 2-5 μm) and 20g of bisphenol A type epoxy resin (trade name E-51), stirring at 80 ℃ for 10min by ultrasonic vibration, adding 5g of diaminodiphenylmethane, stirring for 10min, and removing bubbles at 80 ℃ for 20min in vacuum to obtain prepolymer A; and (3) dividing the prepolymer A into two parts, pouring one part into a preheated mold, then placing the mold into a microwave oven, circularly irradiating for 4 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain the oriented carbon nanotube/epoxy cured resin composite material pre-cured sheet B with the curing degree of 50%.

(2) Mixing 4g of polydopamine-coated barium titanate nanofiber PDA @ BTnf prepared in example 1 and 20g of bisphenol A type epoxy resin (brand E-51), ultrasonically shaking and stirring at 80 ℃ for 10min, adding 5g of diaminodiphenylmethane, and continuously ultrasonically shaking and stirring for 10min to obtain prepolymer C; and (3) coating a prepolymer film D with the thickness of 260 mu m on a preheated polytetrafluoroethylene plate in a scraping way, curing for 45min at 80 ℃, and naturally cooling to obtain a barium titanate nanofiber/epoxy resin composite material pre-cured sheet E with the curing degree of 50%.

Example 14

(1) Mixing 0.08g of non-surface-treated oriented carbon nanotube bundle (20-100 μm in length and 2-5 μm in diameter) and 20g of bisphenol A type epoxy resin (brand E-51), stirring at 80 ℃ for 10min by ultrasonic vibration, adding 5g of diaminodiphenylmethane, continuing stirring for 10min, and removing bubbles at 80 ℃ for 20min in vacuum to obtain prepolymer A; and (3) dividing the prepolymer A into two parts, pouring one part into a preheated mold, then placing the mold into a microwave oven, circularly irradiating for 4 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain the oriented carbon nanotube/epoxy cured resin composite material pre-cured sheet B with the curing degree of 50%.

(2) Mixing 6g of polydopamine-coated barium titanate nanofiber PDA @ BTnf prepared in example 1 and 20g of bisphenol A type epoxy resin (brand E-51), ultrasonically shaking and stirring at 80 ℃ for 10min, adding 5g of diaminodiphenylmethane, and continuously ultrasonically shaking and stirring for 10min to obtain prepolymer C; and (3) coating a prepolymer film D with the thickness of 2400 mu m on a preheated polytetrafluoroethylene plate in a scraping manner, curing for 45min at 80 ℃, and naturally cooling to obtain a barium titanate nanofiber/epoxy resin composite material pre-cured sheet E with the curing degree of 50%.

Example 15

(1) Stirring and heating 10g of bismaleimide diphenylmethane and 7.4g of diallyl bisphenol A compound at 130 ℃ to obtain a transparent solution, adding 0.14g of oriented carbon nanotube bundle (with the length of 20-100 mu m and the diameter of 2-5 mu m) without surface treatment, pre-polymerizing for 50min at 140 ℃, pouring into a preheated mold, and removing bubbles at 140 ℃ in vacuum for 30min to obtain a prepolymer A; and (3) dividing the prepolymer A into two parts, pouring one part into a preheated mold, then placing the mold into a microwave oven, circularly irradiating for 5 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain an oriented carbon nanotube/bismaleimide resin composite material pre-cured sheet B with the curing degree of 60%.

(2) Stirring and heating 10g of bismaleimide diphenylmethane and 7.4g of diallyl bisphenol A compound at 130 ℃ to obtain a transparent solution, adding 8g of polydopamine-coated barium titanate nanofiber PDA @ BTnf prepared in example 1, pre-polymerizing for 50min at 140 ℃, pouring into a preheated mold, and removing bubbles at 140 ℃ in vacuum for 30min to obtain a prepolymer C; and (3) coating a prepolymer film D with the thickness of 250 mu m on a preheated polytetrafluoroethylene plate in a scraping way, curing for 50min at the temperature of 140 ℃, and naturally cooling to obtain a barium titanate nanofiber/bismaleimide resin composite material pre-cured sheet E with the curing degree of 60%.

Example 16

(1) Stirring and heating 10g of bismaleimide diphenylmethane and 8.6g of diallyl bisphenol A compound at 130 ℃ to obtain a transparent solution, adding 0.1g of oriented carbon nanotube bundle (with the length of 20-100 mu m and the diameter of 2-5 mu m) without surface treatment, pre-polymerizing for 50min at 140 ℃, pouring into a preheated mold, and removing bubbles at 140 ℃ in vacuum for 30min to obtain a prepolymer A; and (3) dividing the prepolymer A into two parts, pouring one part into a preheated mold, then placing the mold into a microwave oven, circularly irradiating for 5 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain an oriented carbon nanotube/bismaleimide resin composite material pre-cured sheet B with the curing degree of 60%.

(2) Stirring and heating 10g of bismaleimide diphenylmethane and 8.6g of diallyl bisphenol A compound at 130 ℃ to obtain a transparent solution, adding 8g of polydopamine-coated barium titanate nanofiber PDA @ BTnf prepared in example 1, pre-polymerizing for 50min at 140 ℃, pouring into a preheated mold, and removing bubbles in vacuum for 30min at 140 ℃ to obtain a prepolymer C; and (3) coating a prepolymer film D with the thickness of 250 mu m on a preheated polytetrafluoroethylene plate in a scraping way, curing for 50min at the temperature of 140 ℃, and naturally cooling to obtain a barium titanate nanofiber/bismaleimide resin composite material pre-cured sheet E with the curing degree of 60%.

(3) Soaking the pre-cured sheet E prepared in the step (2) in the prepolymer A prepared in the step (1), and then spreading the pre-cured sheet E on the pre-cured sheet B prepared in the step (1) to remove bubbles, so as to obtain a double-layer structure composite material B-E; and (2) pouring the other half of the prepolymer A prepared in the step (1) to one side of a pre-curing sheet E of the double-layer structure composite material B-E, then placing the mold into a microwave oven, circularly irradiating for 15 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain the three-layer structure resin-based composite material with the curing degree of more than 97%, wherein the three-layer structure resin-based composite material is marked as B-E-B, the dielectric constant is 1062.8 (@ 100 Hz), and the breakdown strength reaches 4.79. If the non-intermittent microwave irradiation is adopted in the steps (1) and (3) and other conditions are unchanged, the dielectric constant of the obtained three-layer structure resin-based composite material B-E-B is 882.6 (@ 100 Hz), and the breakdown strength is 3.62; if the heating mode (curing at 160 ℃ for 60 min) is adopted in the steps (1) and (3) instead of the intermittent microwave mode, and other conditions are unchanged, the dielectric constant of the obtained three-layer structure resin-based composite material B-E-B is 738.8 (@ 100 Hz), and the breakdown strength is 3.38.

Example 17

(1) Stirring and heating 10g of bismaleimide diphenylmethane and 8g of diallyl bisphenol A compound at 130 ℃ to obtain a transparent solution, adding 0.37g of oriented carbon nanotube bundle (with the length of 20-100 mu m and the diameter of 2-5 mu m) without surface treatment, pre-polymerizing for 50min at 140 ℃, pouring into a preheated mold, and removing bubbles in vacuum at 140 ℃ for 30min to obtain a prepolymer A; and (3) dividing the prepolymer A into two parts, pouring one part into a preheated mold, then placing the mold into a microwave oven, circularly irradiating for 5 periods (the irradiation process in each period is middle fire, heating for 30s and cooling for 10 s), and naturally cooling to obtain an oriented carbon nanotube/bismaleimide resin composite material pre-cured sheet B with the curing degree of 60%.

(2) Stirring and heating 10g of bismaleimide diphenylmethane and 8g of diallyl bisphenol A compound at 130 ℃ to obtain a transparent solution, adding 4g of polydopamine-coated barium titanate nanofiber PDA @ BTnf prepared in example 1, pre-polymerizing for 50min at 140 ℃, pouring into a preheated mold, and removing bubbles in vacuum at 140 ℃ for 30min to obtain a prepolymer C; and (3) coating a prepolymer film D with the thickness of 200 mu m on a preheated polytetrafluoroethylene plate in a scraping way, curing for 50min at the temperature of 140 ℃, and naturally cooling to obtain a barium titanate nanofiber/bismaleimide resin composite material pre-cured sheet E with the curing degree of 60%.

Claims

1. The three-layer structure resin matrix composite material is characterized in that the preparation method of the three-layer structure resin matrix composite material comprises the following steps:

(3) soaking the barium titanate nanofiber pre-cured sheet in a second prepolymer and then spreading the second prepolymer on an oriented carbon nanotube bundle pre-cured sheet; then pouring the second prepolymer on a barium titanate nanofiber pre-cured sheet; curing to obtain a three-layer structure resin matrix composite material;

in the step (1), the amount of the oriented carbon nanotube bundle is 0.1-2% of the mass of the curable resin system, and the first prepolymer and the second prepolymer are equivalent; in the step (2), the dosage of the polydopamine-coated barium titanate nanofiber accounts for 10-40% of the mass of the curable resin system;

the curable resin system comprises a resin or a resin and a curing agent; the curable resin system comprises a resin or a resin and a curing agent; the preparation method of the polydopamine-coated barium titanate nanofiber comprises the following steps:

2. The three-layer structure resin-based composite material according to claim 1, wherein the resin comprises one or more of bismaleimide resin, cyanate ester resin, epoxy resin and polyimide resin; barium salt is barium acetate, titanate compound is tetrabutyl titanate, solvent is acetic acid, and viscosity regulator is polyvinylpyrrolidone; the electrostatic spinning parameter is 1.7 kV/cm; the calcination is carried out for 3 hours at 700 ℃ under the conditions of the heating rate of 10 ℃/min and air atmosphere; the alkali liquor is sodium hydroxide aqueous solution; the reaction was carried out at room temperature for 24h with shaking.

3. The three-layer structure resin-based composite material according to claim 1, wherein the molar ratio of the barium salt to the titanate compound is 1; the mass ratio of the dopamine hydrochloride, the trihydroxymethyl aminomethane hydrochloride, the water and the barium titanate nanofiber is 0.2: 0.1: 100: 2.

4. The three-layer structure resin-based composite material according to claim 1, wherein the thickness of the barium titanate nanofiber pre-cured sheet is 50-1000 μm; and preparing the barium titanate nanofiber prepolymer into a membrane by adopting a coating method.

5. The three-layer structure resin-based composite material as claimed in claim 1, wherein the degree of curing of the oriented carbon nanotube-bundle pre-cured sheet is 30-60%; the curing degree of the barium titanate nanofiber pre-cured sheet is 30-60%.

6. The three-layer structure resin-based composite material according to claim 1, wherein in the step (1), the first prepolymer is pre-cured by microwave batch curing; and (3) curing in a microwave intermittent curing mode.

7. The three-layer structure resin-based composite material according to claim 6, wherein the microwave intermittent curing is performed for 10-30 s per curing, and the intermittent curing is performed for 5-15 s.

8. Use of the three-layer structure resin-based composite material according to claim 1 for the preparation of a dielectrically functional composite.