Method for regulating and controlling conductivity of composite material based on dynamic electromagnetic field

Abstract

The invention discloses a method for regulating and controlling the conductivity of a composite material based on a dynamic electromagnetic field, and the method comprises the following steps: applying dynamic electromagnetic fields with different frequencies and powers to the composite material, causing the contact network structure of a conductive filler in the composite material to change, and obtaining the resistivity change of the composite material. According to the method, the conductive filler in the composite material is subjected to Maxwell stress and electrostatic force effects caused by the electromagnetic field through the dynamic electromagnetic field effect, so that the mutual contact network structure of the conductive filler in the composite material is regulated and controlled. The resistivity of the composite material can be changed from 1 * 10 < 8 > omega.cm to 1 * 10 < 7 > omega.cm according to different effects of regulating and controlling the conductive network.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for regulating the conductivity of a composite material, and more particularly to a method for regulating the conductivity of a composite material based on dynamic electromagnetic field. BACKGROUND

[0002] Conductive composite material is a kind of composite material obtained by blending conductive filler and matrix material, which aims to combine the conductive function of conductive filler and the mechanical properties of matrix material. The essence of the conductivity of the composite material lies in the fact that the conductive fillers contact each other to form a conductive network, thereby endowing the composite material with conductive functionality.

[0003] Based on the above-mentioned network formed by mutual contact, the following methods are often used to increase the probability of mutual contact in order to improve the conductivity when preparing conductive composite materials:

[0004] (1) Increasing the filling amount of conductive filler. According to the percolation threshold theory of conductive filler, increasing the amount of conductive filler beyond the percolation threshold can make the composite material complete the mutation from insulator to electrical conductor. However, increasing the filling amount of conductive filler inevitably damages other properties of the composite material, for example, increasing the amount of carbon-based conductive filler in the polymer matrix will cause the viscosity of the system to rise sharply, thereby causing processing difficulties. More unfortunately, in some conductive filler-matrix systems, the maximum filling amount of conductive filler cannot reach the percolation threshold of the system due to the influence of rheological factors, so that the conductivity of such composite systems cannot be obtained.

[0005] (2) Using fibrous, flaky or other fillers with larger specific surface area to increase the probability of mutual contact. Such as silver nanowires, carbon fibers or flaky graphene materials. However, the preparation of these fillers usually involves complex methods such as photolithography, hydrothermal or polyol, which is difficult to mass-produce, high in cost and complex in preparation process.

[0006] (3) Surface modification of conductive filler to increase the dispersibility of the filler and obtain better contact between the fillers. In conductive polymer composites, coupling agents are used to modify the surface of conductive fillers to increase the interfacial interaction between them. In metal-ceramic composites, a metal transition layer is sputtered on the ceramic matrix to improve the bonding force between the metal and the ceramic matrix. However, these modification methods usually involve additional steps and materials, which increases the time and financial cost of preparing the composite material.

[0007] (4) Improving the processing technology or dispersing more uniformly. In carbon-rubber composite systems, carbon-based conductive fillers are more uniformly dispersed in the rubber matrix by repeatedly opening the mill. Similarly, improving the processing technology will also increase the production cost and cause low efficiency.

[0008] (5) By using mechanical external force / laser sintering method to improve the conductivity of the composite material with poor conductivity. Obviously, these post-processing methods will cause irreversible damage to the composite material and are slow.

[0009] Therefore, in the field of research on conductive composites, it is particularly important to find a fast, simple, non-destructive and low-cost method to regulate the contact network of conductive fillers in the composite material, and then to realize the regulation of the conductivity of the composite material. SUMMARY

[0010] The purpose of the present application is to provide a method for regulating the conductivity of a composite material based on a dynamic electromagnetic field.

[0011] Technical solution: The method for regulating the conductivity of a composite material based on a dynamic electromagnetic field of the present application comprises the following steps:

[0012] (1) applying a dynamic electromagnetic field to the composite material, wherein the composite material is a conductive composite material composed of conductive fillers and matrix materials;

[0013] (2) the contact network structure of the conductive fillers in the composite material changes under the action of the electromagnetic field, causing the resistivity of the composite material to change from 1x10 8 Ω·cm to 1x10 -7 Ω·cm.

[0014] In step (1), the conductive network in the composite material is one or both of a conductor and a semiconductor. Preferably, the conductive network material is carbon nanotubes, carbon black, graphene, metal, alloy, ionic conductor and oxide conductor.

[0015] In step (1), the composite material is a ceramic matrix composite material, a polymer matrix composite material or a hybrid composite material. Preferably, the matrix material is one or more of silicon carbide, boron carbide, boron nitride, silicon carbon boron, alumina, aluminum oxycarbide, zirconia, silicate, silica, cement, wood, clay, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polymethyl methacrylate, polyether ether ketone, polyformaldehyde, polycarbonate, polybutylene, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate, polybutylene terephthalate, thermoplastic polyurethane, polytetrafluoroethylene, nylon, polyvinylidene fluoride, polyimide, polytrifluorochloroethylene, ethylene-propylene copolymer, ethylene-tetrafluoroethylene copolymer, polyvinyl alcohol, chlorinated polypropylene, polyacrylonitrile, polyphenylene ether ketone, polyphenylene sulfide, polyvinylidene chloride, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, hydrogenated styrene-butadiene copolymer, styrene-isoprene copolymer or hydrogenated styrene-isoprene copolymer, phenol formaldehyde resin, urea formaldehyde resin, melamine resin, epoxy resin, silicone resin, unsaturated polyester resin, alkyd resin, polybutadiene resin, vinyl resin, furan resin, silicone resin, thermosetting polyimide, thermosetting polyurethane resin, cellulose resin, aldehyde ketone resin or fluorocarbon resin, styrene butadiene rubber, chloroprene rubber, cis-butadiene rubber, butyl rubber, isoprene rubber, ethylene propylene rubber, ternary ethylene propylene rubber, natural rubber, nitrile rubber, silicone rubber, fluororubber, polyurethane rubber, polysulfide rubber, polyacrylate rubber, chloroether rubber, chlorosulfonated polyethylene, chlorinated polyethylene or butyl pyrrole rubber.

[0016] In step (1), the frequency of the dynamic electric field is in the range of 1 Hz to 10 GHz. Preferably, it is in the range of 10 kHz to 1 GHz.

[0017] In step (1), the rising edge and falling edge time of the electric field of the dynamic electromagnetic field is in the range of 1 ns to 100 s.

[0018] In step (1), the power of the dynamic electromagnetic field is in the range of 1 mW to 10 kW, preferably in the range of 1 W to 1 kW.

[0019] In step (1), the electromagnetic field can act in the form of electromagnetic waves, which can be non-contact transmission or contact action on the composite material.

[0020] Preferably, the dynamic electromagnetic field is applied to the surrounding of the composite material by an electromagnetic generating device, and the distance between the electromagnetic generating device and the composite material is 0-200 meters.

[0021] In step (1), the action time of the electromagnetic field on the material is in the range of 1 ns to 1 h, preferably in the range of 0.1 s to 600 s.

[0022] In step (2), the change of the conductive filler network structure in the composite material is caused by the dynamic electromagnetic field.

[0023] In step (2), the change of the resistance is caused by the change of the conductive filler network structure.

[0024] In another aspect, the present application provides a composite material prepared according to the above method.

[0025] Principle: According to classical electromagnetic theory, moving charged particles will produce changing electric and magnetic fields. This changing electric and magnetic field propagates in the form of a wave, forming an electromagnetic wave. Electromagnetic waves transfer energy and momentum in the form of waves in space, and their propagation direction is perpendicular to the oscillation direction of the electric field and the magnetic field. In the invention, different types of dynamic electric fields can be generated by using electromagnetic generating devices, which in turn generate dynamic magnetic fields, and then lead to the generation of dynamic electric fields, resulting in alternating "electric field-magnetic field" (i.e. electromagnetic wave). When the electromagnetic wave spreads into the composite material, the conductive filler in it will form induced current and polarized charge distribution due to the changing electromagnetic field, so that it is subjected to Maxwell stress, electrostatic force and vibrates, twists, rotates or moves in the electromagnetic field, causing the structure of the conductive network to change. By adjusting the dynamic electromagnetic field, the structure of the conductive network in the composite material can be remotely controlled, and the electrical conductivity of the composite material can be controlled.

[0026] Advantages: Compared with the prior art, the present application has the following remarkable effects: (1) simple and easy to operate, fast in action, the dynamic electromagnetic field propagates at the speed of light and acts on the material to achieve the control effect instantly; (2) the material is not damaged, and the dynamic electromagnetic field can be used to remotely control the material; (3) good control effect, the resistivity of the composite material can be changed from 1×10 8 Ω·cm to 1×10 -7 Ω·cm; (4) good versatility, the conductive filler contact network of conductor, semiconductor or mixed type can be effectively controlled. BRIEF DESCRIPTION OF DRAWINGS

[0027] Fig. 1 Schematic diagram of the invention: the alternating electric field E and the alternating magnetic field B perpendicular to each other form a dynamic electromagnetic field, under the action of the dynamic electromagnetic field, the conductive filler in the composite material is displaced and deformed, causing the structure of the conductive network to change.

[0028] Fig. 2For the effect picture: a) in the circuit of 12V DC power supply, the composite material is connected in series with the small bulb LED. In the initial state, the resistance of the composite material is large (3MΩ), and the current of the LED bulb in the circuit is small, which is in the state of being off or dim; b) when the spectrum electromagnetic field of 0.06W and 1kHz-5GHz is applied outside 40cm, the resistance of the composite material will immediately become small to 5Ω, the current in the circuit becomes large, and the small bulb in the circuit is lit. DETAILED DESCRIPTION

[0029] The application will be further described in detail below.

[0030] As Figs. 1-2 shown, the embodiment of the application provides a method for regulating the conductivity of a composite material, comprising the following steps:

[0031] (1) arranging the distance between an electromagnetic generating device (a dynamic electromagnetic wave emitting source) and the composite material, wherein the electromagnetic generating device can provide a dynamic electromagnetic field around the composite material; adjusting the voltage and current of the electromagnetic generating device to realize the setting of the frequency and power of the dynamic electromagnetic wave;

[0032] (2) the contact network structure of the conductive filler in the composite material changes under the action of the electromagnetic field, causing the resistivity of the composite material to change from 1×10 8 Ω·cm to 1×10 -7 Ω·cm.

[0033] In the following examples, the 5% carbon nanotube-polyethylene composite material refers to the mass ratio of carbon nanotubes to polyethylene in the carbon nanotube-polyethylene composite material being 5:95.

[0034] Example 1

[0035] The application discloses a method for regulating the conductive network in a composite material based on a dynamic electromagnetic field, comprising the following steps:

[0036] (1) melting and co-extruding carbon nanotubes and polyethylene to form a 5% carbon nanotube-polyethylene composite material;

[0037] (2) measuring and recording the initial resistivity of the carbon nanotube-polyethylene composite material;

[0038] (3) adjusting the waveform emitter parameters and experimental conditions according to the parameters in Table 1 to perform experiments;

[0039] (4) terminating the emission of the waveform emitter, and measuring and recording the final resistivity of the composite material.

[0040] Example 2

[0041] The basic steps are the same as those in Example 1, and the specific parameters are shown in Table 1.

[0042] Example 3

[0043] The basic steps are the same as Example 1, and the specific parameters are shown in Table 1.

[0044] Example 4

[0045] The basic steps are the same as Example 1, and the specific parameters are shown in Table 1.

[0046] Table 1

[0047]

[0048] Example 5

[0049] The application discloses a method for regulating a conductive network in a composite material based on a dynamic electromagnetic field, comprising the following steps:

[0050] (1) melt-extruding carbon nanotubes and polyethylene to form a 5% carbon nanotube-polyethylene composite material;

[0051] (2) measuring and recording the initial resistivity of the carbon nanotube-polyethylene composite material;

[0052] (3) adjusting the waveform emitter parameters and experimental conditions according to the parameters in Table 2 to perform experiments;

[0053] (4) terminating the emission of the waveform emitter, and measuring and recording the final resistivity of the composite material.

[0054] Example 6

[0055] The basic steps are the same as Example 5, and the specific parameters are shown in Table 2.

[0056] Example 7

[0057] The basic steps are the same as Example 5, and the specific parameters are shown in Table 2.

[0058] Example 8

[0059] The basic steps are the same as Example 5, and the specific parameters are shown in Table 2.

[0060] Table 2

[0061]

[0062] Example 9

[0063] The application discloses a method for regulating a conductive network in a composite material based on a dynamic electromagnetic field, comprising the following steps:

[0064] (1) melt-extruding carbon nanotubes and polyethylene to form a 5% carbon nanotube-polyethylene composite material;

[0065] (2) Measure and record the initial resistivity of the composite carbon nanotube-polyethylene;

[0066] (3) Conduct the experiment with the parameters in Table 3, adjusting the waveform emitter parameters and experimental conditions;

[0067] (4) Terminate the waveform emitter emission, measure and record the final resistivity of the composite.

[0068] Example 10

[0069] The basic steps are the same as in Example 9, as shown in Table 3.

[0070] Example 11

[0071] The basic steps are the same as in Example 9, as shown in Table 3.

[0072] Example 12

[0073] The basic steps are the same as in Example 9, as shown in Table 3.

[0074] Table 3

[0075]

[0076] Example 13

[0077] A method for regulating the conductive network in a composite material based on dynamic electromagnetic field is disclosed, comprising the following steps:

[0078] (1) Melt-extrude carbon nanotubes and polyethylene to form a 5% carbon nanotube-polyethylene composite material;

[0079] (2) Measure and record the initial resistivity of the composite carbon nanotube-polyethylene;

[0080] (3) Conduct the experiment with the parameters in Table 4, adjusting the waveform emitter parameters and experimental conditions;

[0081] (4) Terminate the waveform emitter emission, measure and record the final resistivity of the composite.

[0082] Example 14

[0083] The basic steps are the same as in Example 13, as shown in Table 4.

[0084] Example 15

[0085] The basic steps are the same as in Example 13, as shown in Table 4.

[0086] Example 16

[0087] The basic steps are the same as in Example 13, as shown in Table 4.

[0088] Table 4

[0089]

[0090] Example 17

[0091] A method for regulating conductive network in composite material based on dynamic electromagnetic field is disclosed, comprising the following steps:

[0092] (1) melt co-extrusion of conductive network material and matrix material to form composite material (composition see Table 5), wherein the mass ratio of conductive network material and matrix material is 5:95;

[0093] (2) measure and record the initial resistivity of each type of composite material;

[0094] (3) adjust the waveform emitter parameters and experimental conditions according to the parameters in Table 5 to conduct experiments;

[0095] (4) terminate the emission of the waveform emitter, measure and record the final resistivity of the composite material.

[0096] Table 5

[0097]

[0098] Example 18

[0099] The basic steps are the same as those of Example 17, and the specific parameters are shown in Table 5.

[0100] Example 19

[0101] The basic steps are the same as those of Example 17, and the specific parameters are shown in Table 5.

[0102] Example 20

[0103] The basic steps are the same as those of Example 17, and the specific parameters are shown in Table 5.

[0104] Example 21

[0105] The basic steps are the same as those of Example 17, and the specific parameters are shown in Table 5.

[0106] Example 22

[0107] The basic steps are the same as those of Example 17, and the specific parameters are shown in Table 5.

Claims

1. A method for controlling the conductivity of composite materials based on dynamic electromagnetic fields, characterized in that, Includes the following steps: (1) Apply a dynamic electromagnetic field around the composite material, wherein the composite material is a composite material composed of conductive filler and matrix material; (2) The conductive filler contact network structure in the composite material changes under the action of electromagnetic field, causing the resistivity of the composite material to change.

2. The method for controlling the conductivity of composite materials based on dynamic electromagnetic field according to claim 1, characterized in that, The conductive filler in the composite material is one or more of a conductor or a semiconductor.

3. The method for controlling the conductivity of composite materials based on dynamic electromagnetic field according to claim 2, characterized in that, The conductive filler is carbon nanotube, carbon black, graphene, metal, alloy, ionic conductor or oxide conductor.

4. The method for controlling the conductivity of composite materials based on dynamic electromagnetic fields according to claim 1, characterized in that, The composite material is a ceramic matrix composite, a polymer matrix composite, a carbon matrix composite, or a hybrid composite.

5. The method for controlling the conductivity of composite materials based on dynamic electromagnetic field according to claim 1, characterized in that, In step (1), the frequency range of the dynamic electromagnetic field is 1Hz to 10G Hz.

6. The method for controlling the conductivity of composite materials based on dynamic electromagnetic field according to claim 1, characterized in that, In step (1), the time range of the rising and falling edges of the electric field of the dynamic electromagnetic field is 1ns to 100s.

7. The method for controlling the conductivity of composite materials based on dynamic electromagnetic field according to claim 1, characterized in that, In step (1), the power of the dynamic electromagnetic field is 1mW to 10kW.

8. The method for controlling the conductivity of composite materials based on dynamic electromagnetic field according to claim 1, characterized in that, In step (1), the dynamic electromagnetic field acts in the form of electromagnetic waves, and is either non-contact propagation or contact action on the composite material.

9. The method for controlling the conductivity of composite materials based on dynamic electromagnetic field according to claim 1, characterized in that, A dynamic electromagnetic field is applied around the composite material by an electromagnetic generator, with the distance between the electromagnetic generator and the composite material ranging from 0 to 200 meters.

10. The method for controlling the conductivity of composite materials based on dynamic electromagnetic field according to claim 1, characterized in that, In step (1), the electromagnetic field acts on the material for a period of 1 ns to 1 h.

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