Flexible conductive drivable composite fiber and preparation method, system and application thereof

Abstract

The invention discloses a flexible conductive drivable composite fiber and a preparation method, system and application thereof. The preparation method comprises the following steps: uniformly mixing a polymer solution with a large thermal expansion coefficient, a curing agent and a diluent to form a diluted polymer solution; the preparation method comprises the following steps: immersing conductive fibers in a diluted polymer solution, and then enabling a polymer to enter a conductive carbon fiber tow under the extrusion action through a rolling mechanism, and carrying out first-time immersion and homogenization; then dipping in a pure polymer solution, and carrying out capillary homogeneous extrusion again through the rolling mechanism; the operation is repeated for more than two times, so that the pure polymer solution is uniformly distributed in the conductive fiber tows; and finally, curing and twisting to prepare the flexible conductive drivable composite fiber with the uniform spiral structure. The composite fiber with a uniform structure is prepared through a rolling-assisted step-by-step impregnation process, has certain flexibility, retains good mechanical properties of the fiber, and still has good mechanical properties after knotting and spiral deformation.

Description

Technical Field

[0001] The invention relates to a flexible conductive drivable composite fiber and a preparation method, a preparation system and application thereof, belonging to the technical field of material science. Background Art

[0002] Conductive fibers have good Joule heating effect and can be used for convenient and fast electrothermal energy conversion. At the same time, they have excellent mechanical properties and flexibility. Flexible conductive fibers that can be woven and integrated have broad application prospects in the fields of flexible driving, soft robots, strain sensing, wearable electronics, human-computer interaction, etc., and have received widespread attention from academia and industry in recent years. On the one hand, flexible conductive fibers can be coated with various inorganic (carbon black, nanosilver, graphene, etc.) and organic conductive fillers (conductive polymers and ionic conductors, etc.) through coating, spinning, hot stretching and other processes to give them conductivity; on the other hand, they can also be introduced by introducing spiral, serpentine and other structures to amplify the strain of the fiber and reduce local stress to obtain flexibility. Lightweight fiber materials with good flexibility and conductivity are ideal choices for intelligent driving materials. Under thermal stimulation, materials and devices can be integrated to achieve energy conversion and movement in a single component. However, when subjected to deformation, the fiber has good mechanical properties, conductivity and flexibility at the same time, which is an urgent problem to be solved in engineering applications.

[0003] In recent years, commercial high-performance fibers such as poly(p-phenylene benzobisoxazole) (PBO) fibers, polyimide (PI) fibers, and aramid fibers are regarded as ideal materials for preparing flexible conductive fibers with high mechanical properties. For example, PBO and aramid fibers can obtain conductivity by coating conductive carbon nanotube narrow ribbons. PI fibers can achieve conductivity by copper plating. However, non-conductive high-performance fibers such as PBO, PI, and aramid fibers cannot rely on themselves but rely on the addition of conductive components to achieve conductivity and electrothermal conversion. They require conductive layers such as copper or silver plating, metal wire wrapping, and co-winding with carbon nanotube ribbons to complete electrothermal conversion, which increases the cost of raw materials, structural complexity, and stability. Therefore, it is particularly important to prepare fibers that have excellent mechanical properties, conductivity, and flexibility, and can quickly and easily achieve electrothermal conversion.

[0004] Carbon fiber (CF) is a high-performance fiber material with light weight, high strength, high modulus, high temperature resistance and good chemical stability. It has excellent conductivity. Its graphite microcrystalline structure is preferentially oriented along the fiber axis, so it has high strength and modulus in the axial direction, but its elongation at break is low, only 1.5% for T300, and its shear strength is low. It is a high modulus brittle material, which greatly limits the application of carbon fiber in the field of flexible intelligence. In order to obtain flexible carbon fiber, Xing Gao et al. extracted poplar lignin and microcrystalline cellulose, connected them through bionic covalent bonds, and mixed them with polyacrylonitrile as a precursor for electrospinning. The prepared fibers have good thermal stability and high flexibility, with an average elongation at break of 51.84%, but this preparation method is difficult to prepare in large quantities to meet the needs of engineering applications. In order to meet the demand for quantity in engineering applications, high-performance carbon fiber tows have become an ideal source of materials. The C Lamuta team and the Hu Xinghao team impregnated carbon fiber (CF) with polydimethylsiloxane (PDMS) to obtain CF / PDMS composite carbon fiber, but the preparation process is manual, with low efficiency, relatively low stability and uniformity, and long curing time. It is difficult to obtain large batches of samples, and the internal structure, uniformity, and flexibility of the fiber have not been characterized and confirmed. Because the strain of the fiber is amplified by forming a spiral structure, local stress is reduced and flexibility is enhanced, for fiber bundles of thousands of fibers, manual impregnation is difficult to ensure that each carbon fiber filament is evenly coated with PDMS, resulting in uneven composite of CF and PDMS, and thus it is difficult to ensure the structural uniformity of CF / PDMS composite carbon fiber. In deformations such as torsion, carbon fiber is easily broken due to lack of flexible protection, resulting in broken wires. Therefore, it is difficult to obtain flexible composite fibers with stable performance in continuous batches using manual processes. Summary of the invention

[0005] The main purpose of the present invention is to provide a flexible conductive drivable composite fiber and a preparation method thereof, so as to overcome the deficiencies in the prior art.

[0006] Another object of the present invention is to provide a system for preparing the flexible, conductive and drivable composite fiber.

[0007] Another object of the present invention is to provide an application of the flexible, conductive and drivable composite fiber.

[0008] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0009] An embodiment of the present invention provides a method for preparing a flexible conductive drivable composite fiber, which comprises:

[0010] Mixing the polymer solution with a large thermal expansion coefficient, the curing agent and the diluent uniformly to form a diluted polymer solution;

[0011] The conductive fiber is immersed in a diluted polymer solution, and then the polymer with a large thermal expansion coefficient is squeezed into the conductive fiber bundle through a roller pressing mechanism for the first homogenization.

[0012] The conductive fibers that have been homogenized for the first time are immersed in a pure polymer solution, and then subjected to capillary homogenization extrusion through an extrusion mechanism; the capillary homogenization extrusion operation is repeated for more than two times, so that the pure polymer solution is evenly distributed in the conductive fiber bundles;

[0013] Finally, the fiber is cured and twisted to obtain a flexible, conductive and actuatable composite fiber with a uniform spiral structure.

[0014] In some embodiments, the polymer with a large thermal expansion coefficient includes any one of polydimethylsiloxane, nylon, and polytetrafluoroethylene, or a combination of two or more thereof.

[0015] The embodiment of the present invention also provides a flexible conductive drivable composite fiber with a uniform spiral structure obtained by the aforementioned preparation method, which includes conductive fibers and a polymer with a large thermal expansion coefficient, wherein the conductive fibers are uniformly distributed in the polymer with a large thermal expansion coefficient.

[0016] The embodiment of the present invention further provides a system for preparing a flexible conductive and drivable composite fiber, which is applied to the aforementioned preparation method, and the preparation system comprises:

[0017] An introduction mechanism, at least used to introduce the conductive fibers into the diluted polymer solution and the pure polymer solution respectively;

[0018] A first rolling mechanism, at least for rolling the conductive fibers that have been impregnated for the first time;

[0019] A second rolling mechanism, at least used to roll the conductive fibers that have been impregnated for the second time;

[0020] A collecting mechanism, at least used to collect the cured composite conductive fibers;

[0021] The twisting mechanism is at least used to twist the collected composite conductive fibers to form a uniform spiral structure.

[0022] The embodiments of the present invention also provide applications of the aforementioned flexible conductive drivable composite fiber in the fields of flexible driving, flexible sensing, aerospace, electronic equipment, intelligent robots, intelligent wearables or human-computer interaction.

[0023] Compared with the prior art, the advantages of the present invention are at least:

[0024] 1) The preparation method of the flexible conductive drivable composite fiber provided by the present invention does not require the addition of other conductive components, but relies on the conductivity of the composite fiber to achieve electrothermal energy conversion through the Joule heat effect, so that its structure-function-drive-energy conversion is integrated; the prepared composite fiber has a uniform structure and no holes, overcomes the brittleness of the conductive fiber itself and has good flexibility, and can still withstand a large load even after being knotted or twisted, retaining the good mechanical properties of the conductive fiber;

[0025] 2) The flexible conductive drivable composite fiber provided by the present invention can be prepared continuously and automatically, reducing the low efficiency and unevenness caused by human factors, and can be prepared in large quantities, providing a new solution for solving the flexible structure application of existing fibers in the fields of aerospace, intelligent robots, and intelligent wearables;

[0026] 3) The preparation method of the flexible conductive drivable composite fiber provided by the present invention does not require complicated equipment. The problem of uniform composite of the conductive fiber and the polymer can be effectively solved by the rolling method, so that almost every conductive fiber is evenly coated with the polymer, thereby improving its shear and deformation resistance and having good flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 Schematic diagram of the preparation of CF / PDMS composite helical carbon fiber in a typical embodiment of the present invention;

[0029] Figure 2 This is a physical picture of the CF / PDMS composite carbon fiber prepared in batches and continuously in Example 1 of the present invention;

[0030] Figure 3a This is a surface morphology of the CF / PDMS composite carbon fiber prepared in Example 1 of the present invention;

[0031] Figure 3b and Figure 3c They are cross-sectional morphology diagrams of the CF / PDMS composite carbon fibers prepared in Example 1 of the present invention;

[0032] Figure 4a The figure is a physical picture of a pure carbon fiber tow (CF) and the CF / PDMS composite carbon fiber prepared in Example 1 of the present invention in a knotted state;

[0033] Figure 4bGraph showing the tensile mechanical test results of pure carbon fiber tow (CF) and CF / PDMS composite carbon fiber prepared in Example 1 of the present invention in a knotted state;

[0034] Figure 5a-5e They are respectively the uniform spiral structure diagrams of the CF / PDMS composite carbon fibers prepared in Example 1 of the present invention under loads of 10 g, 70 g, 130 g, 190 g, and 210 g;

[0035] Figure 6 This is a tensile fracture diagram of the spiral CF / PDMS composite carbon fiber prepared in Example 1 of the present invention;

[0036] Figure 7 This is a diagram of the electrothermal conversion effect of the spiral CF / PDMS composite carbon fiber prepared in Example 1 of the present invention;

[0037] Figure 8 Schematic diagram of the spiral CF / PDMS composite carbon fiber prepared in Example 1 of the present invention driving a 1.5 kg dumbbell. DETAILED DESCRIPTION

[0038] In view of the problems in the prior art of low preparation efficiency, difficulty in uniformly compounding thousands of conductive fiber bundles with polymers, and easy breakage of conductive fibers during deformation due to their brittleness, the inventors of this case have proposed the technical solution of the present invention after long-term research and extensive practice. It mainly adopts a roller-assisted step-by-step infiltration process to produce composite fibers with uniform structure, which overcomes the brittleness of the fibers themselves and has a certain flexibility, while retaining the good mechanical properties of the fibers and still having good mechanical properties after knotting and spiral deformation.

[0039] The technical solution, its implementation process and principle are further explained as follows. However, it should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described in the following (embodiments) can be combined with each other to form a new or preferred technical solution. Due to space limitations, they will not be described one by one here.

[0040] Explanation of terms that need to be given:

[0041] CF:Carbon fiber, carbon fiber;

[0042] PDMS: Polydimethylsiloxane.

[0043] As one aspect of the technical solution of the present invention, a method for preparing a flexible conductive drivable composite fiber involves:

[0044] The polymer with a large thermal expansion coefficient, the curing agent and the diluent are mixed uniformly to form a diluted polymer solution;

[0045] The conductive fiber is immersed in a diluted polymer solution, and then the polymer with a large thermal expansion coefficient is squeezed into the conductive fiber bundle through a roller pressing mechanism for the first homogenization.

[0046] The conductive fibers that have been homogenized for the first time are immersed in a pure polymer solution, and then subjected to capillary homogenization extrusion through an extrusion mechanism; the capillary homogenization extrusion operation is repeated for more than two times, so that the pure polymer solution is evenly distributed in the conductive fiber bundles;

[0047] Finally, the fiber is cured and twisted to obtain a flexible, conductive and actuatable composite fiber with a uniform spiral structure.

[0048] In some specific embodiments, the polymer with a large thermal expansion coefficient may be PDMS (polydimethylsiloxane), and may also be compounded with other polymers with a large thermal expansion coefficient (such as nylon, polytetrafluoroethylene, etc.), but is not limited thereto.

[0049] Furthermore, the curing agent may be a commercially available curing agent, which is not limited herein.

[0050] In some specific embodiments, the diluent includes a non-polar organic solvent, preferably ethyl acetate, and other organic solvents such as n-hexane may also be used, but are not limited thereto.

[0051] In some specific embodiments, the mass ratio of the combination of the polymer with a large thermal expansion coefficient and the curing agent to the diluent is 3:1 to 1:1.

[0052] In some specific embodiments, the conductive fiber can be a carbon fiber, wherein the carbon fiber can also be replaced by any one or a combination of two or more of other conductive fiber bundles (such as metal fibers, polymer fibers with conductive fillers added, etc.), or non-conductive fiber bundles coated with a conductive layer (such as copper-coated polyimide fibers, etc.), and is not limited thereto. The method of the present invention is prepared using commercial carbon fibers with excellent mechanical properties and good electrical conductivity, and does not require the addition of other conductive components. It relies on the electrical conductivity of the composite carbon fiber to achieve electrothermal energy conversion through the Joule heating effect, so that its structure-function-drive-energy conversion is integrated.

[0053] The metal fiber may be a copper fiber, and the conductive filler added to the polymer fiber may be at least any one of graphene, carbon nanotubes, etc., but is not limited thereto.

[0054] Furthermore, the carbon fiber used in the present invention has a wide source and a simple preparation method, which can meet the problem of batch engineering application of flexible conductive materials.

[0055] In some specific embodiments, the preparation method comprises:

[0056] The conductive fiber is introduced into the diluted polymer solution for a first dipping;

[0057] The conductive fibers that have been impregnated for the first time are squeezed by a roller mechanism, so that the polymer with a large thermal expansion coefficient enters the conductive fiber bundle through the extrusion effect, and the first homogenization is performed.

[0058] Furthermore, the rolling mechanism may be a mechanical component with a smooth surface, preferably including a homogenizing roller, but not limited thereto.

[0059] Furthermore, the device used for introducing the conductive fiber includes a guide roller, but is not limited thereto.

[0060] In some specific embodiments, the preparation method comprises:

[0061] The conductive fibers homogenized for the first time are introduced into the pure polymer solution for a second dipping, and the conductive fibers dipped for the second time are squeezed by a roller pressing mechanism to perform capillary homogenization extrusion;

[0062] The conductive fibers that have been homogenously extruded by capillary extrusion are introduced again into a pure polymer solution for a third immersion, so that each conductive fiber bundle is evenly coated with the polymer, which can solve the problem of brittle fracture of the conductive fibers during complex deformation processes.

[0063] In some specific embodiments, the curing temperature is 155-185° C. and the curing time is 0.5-1 min.

[0064] Furthermore, the preparation method further comprises: collecting the cured composite conductive fibers, wherein the collection speed is 30 to 40 m / h.

[0065] In summary, the present invention adopts a three-step impregnation method, and the polymer solution is fully impregnated through the capillary extrusion effect of rolling and the concentration difference of the solution, so that the polymer is evenly dispersed in the conductive fiber bundle, so as to achieve the purpose of uniform compounding and fully covering the conductive fiber monofilament, and obtain a composite fiber with uniform structure and good flexibility and mechanical properties after curing. This preparation process has the advantages of continuous, automated, high-efficiency and large-scale preparation, reduces the low efficiency and unevenness caused by human factors, and can be prepared in large quantities, providing a new solution for solving the flexible structure application of fibers in aerospace, intelligent robots, and intelligent wearable fields.

[0066] As another aspect of the technical solution of the present invention, it also relates to a flexible conductive drivable composite fiber with a uniform spiral structure obtained by the aforementioned preparation method, wherein the flexible conductive drivable composite fiber comprises a conductive fiber and a polymer with a large thermal expansion coefficient, and the conductive fiber is uniformly distributed in the polymer with a large thermal expansion coefficient.

[0067] In summary, the composite fiber prepared by the present invention has a uniform structure and no holes, overcomes the brittleness of the conductive fiber itself and has good flexibility. It can still withstand a large load even after being knotted or twisted into a spiral, and retains the good mechanical properties of the conductive fiber.

[0068] As another aspect of the technical solution of the present invention, it also relates to a preparation system of a flexible conductive drivable composite fiber, which is applied to the aforementioned preparation method, and the preparation system comprises:

[0069] An introduction mechanism, at least used to introduce the conductive fibers into the diluted polymer solution and the pure polymer solution respectively;

[0070] A first rolling mechanism, at least for rolling the conductive fibers that have been impregnated for the first time;

[0071] A second rolling mechanism, at least used to roll the conductive fibers that have been impregnated for the second time;

[0072] A collecting mechanism, at least used to collect the cured composite conductive fibers;

[0073] The twisting mechanism is at least used to twist the collected composite conductive fibers to form a uniform spiral structure.

[0074] Furthermore, the rolling mechanism may be a mechanical component with a smooth surface, preferably including a homogenizing roller, but not limited thereto.

[0075] Furthermore, the introduction mechanism includes guide rollers, but is not limited thereto.

[0076] In summary, the present invention does not require complicated equipment and can effectively solve the problem of uniform compounding of conductive fibers and polymers through a rolling method, so that almost every conductive fiber is evenly coated with the polymer, thereby improving its shear and deformation resistance and having good flexibility.

[0077] As another aspect of the technical solution of the present invention, it also relates to the application of the flexible conductive drivable composite fiber in the fields of flexible driving, flexible sensing, aerospace, electronic equipment, intelligent robots, intelligent wearables or human-computer interaction.

[0078] In summary, the present invention uses conductive fibers to prepare uniform spiral fibers with conductivity, flexibility, good mechanical properties and electrothermal conversion effects, so as to further improve flexibility and successfully apply them in flexible driving. The composite fibers obtained by this preparation method are expected to have engineering application prospects in the fields of soft robots, strain sensing, wearable electronics, aerospace, intelligent robots, intelligent wearables, human-computer interaction, etc.

[0079] The technical scheme of the present invention is further described in detail below in conjunction with several preferred embodiments and the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. It should be pointed out that the embodiments described below are intended to facilitate the understanding of the present invention, and do not have any limiting effect on it. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present invention. The experimental methods for which specific conditions are not specified in the following embodiments are usually carried out under conventional conditions or under the conditions recommended by the manufacturer.

[0080] Example 1

[0081] In this embodiment, the high-performance flexible conductive drivable composite carbon fiber is obtained by impregnating commercial 1K carbon fiber tow with polydimethylsiloxane, and curing to obtain CF / PDMS composite spiral carbon fiber. Figure 1 As shown, the specific preparation steps are as follows:

[0082] Step (1): Prepare PDMS solution: Mix silicone rubber resin, curing agent and non-polar solvent ethyl acetate in a ratio of 2:1, remove bubbles and prepare a diluted silicone rubber resin solution to become a diluted PDMS solution. The solution without diluent is pure PDMS solution.

[0083] Step (2): The 1K carbon fiber bundle is introduced into a diluted PDMS solution for the first impregnation and pulled out from the die. The use of a low-viscosity diluted PDMS solution helps it to penetrate into the interior of the carbon fiber bundle. The main purpose of the first impregnation is to wet the fiber bundle so that it is easier to impregnate the pure PDMS into the fiber bundle later. The carbon fiber bundle is passed around the first roller, and the excess PDMS on the surface of the bundle is squeezed into the interior of the fiber bundle by the squeezing action between the fiber bundle and the roller for the first homogenization. The fiber bundle is then introduced into a pure PDMS solution for a second impregnation and pulled out from the membrane pores. The wetted carbon fiber bundle is continued to be squeezed through the second roller for capillary homogenization. Finally, the wetted bundle is introduced into a pure PDMS solution for a third impregnation and pulled out from the die so that the PDMS solution is evenly distributed in the carbon fiber bundle.

[0084] Step (3): The filament bundle is cured in a furnace at 180° C. for 0.8 min and collected on a reel at a certain speed. The preparation speed of CF / PDMS composite carbon fiber is about 32 m / h.

[0085] Step (4): The cured CF / PDMS composite carbon fiber is twisted to form a CF / PDMS composite carbon fiber with a uniform spiral structure, which has good flexibility.

[0086] The CF / PDMS composite carbon fibers prepared in this embodiment, the rolled-up portion of the composite fibers are as follows: Figure 2 As shown, the length of the composite fiber shown is about 300 meters. In the present invention, each carbon fiber filament is evenly coated with PDMS to improve the brittleness of the carbon fiber and make the CF / PDMS composite carbon fiber flexible. First, different solution concentrations and multiple impregnations are used to ensure that enough PDMS solution is fully immersed in the carbon fiber bundle. Secondly, a certain capillary friction force is provided by rolling to squeeze the PDMS solution into the gaps between the fiber filaments, so that almost every carbon fiber obtains the flexible protection of PDMS. The surface morphology of this uniform structure of the CF / PDMS composite carbon fiber is shown in Figure 3a As shown in the figure, the surface of the composite carbon fiber is smooth and undamaged. Figure 3b and Figure 3c As shown, the cross section clearly shows that the carbon fibers are evenly distributed in the PDMS. This uniform composite structure makes the brittle carbon fibers flexible and has good toughness.

[0087] The CF / PDMS composite carbon fiber prepared in this example has good flexibility. After being knotted, it was subjected to a tensile mechanical test and compared with a pure carbon fiber tow. The knotted state is as follows: Figure 4a shown. Figure 4b The results of the tensile performance test are shown in Figure 1, which show that the breaking load of pure carbon fiber after knotting is 1.2N, and the breaking load of CF / PDMS composite carbon fiber after knotting is 6.2N, which is 5 times higher than the former. Inserting a certain twist into the CF / PDMS composite carbon fiber can form a uniform spiral structure to amplify its flexibility. It can withstand a certain load without breaking. Its uniform spiral structure under different loads is shown in Figure 2. Figure 5a-5e As shown in Figure 1, the uniform spiral structure of CF / PDMS composite carbon fiber under loads of 10g, 70g, 130g, 190g, and 210g respectively. The tensile fracture properties of the spiral CF / PDMS composite carbon fiber are shown in Figure 1. Figure 6As shown in the figure, its elongation at break is 110.0% and its breaking load is 3.12N. Its elongation at break is more than 70 times higher than that of carbon fiber at 1.5%, and is nearly twice that of the 51.84% of flexible carbon fiber prepared by electrospinning after covalent bonding of poplar lignin and microcrystalline cellulose and mixing with polyacrylonitrile. It can be seen that this flexible composite carbon fiber still has good mechanical properties in the knotted and spiral state.

[0088] The CF / PDMS composite carbon fiber prepared in this embodiment has good flexibility and conductivity. Figure 7 As shown in the figure, when voltage is applied, the excellent Joule heat effect of carbon fiber can rapidly heat up the composite fiber, and the electrical energy can be quickly converted into thermal energy, so that the spiral composite carbon fiber can achieve axial contraction through the untwisting caused by radial expansion, which can increase the weight of a 1.5kg dumbbell by 20%. Figure 8 The composite carbon fiber obtained by the method of the present invention will have good application prospects in the fields of flexible driving, flexible sensing, aerospace, and electronic equipment.

[0089] Furthermore, the curing temperature of the present invention can be within the range of 155 to 185° C. and the curing time can be within the range of 0.5 to 1 minute.

[0090] Comparative Example 1

[0091] The difference between this comparative example and Example 1 is that the first dipping and rolling are not performed in step (2).

[0092] Since the first impregnation was not performed, the uniformity of the polymer in the carbon fiber bundle in the final composite fiber was not as good as that in Example 1. This was because the dilute polymer solution used in the first impregnation had a low viscosity and was easier to flow into the carbon fiber bundle.

[0093] Comparative Example 2

[0094] The difference between this comparative example and Example 1 is that the third dipping and rolling are not performed in step (2).

[0095] The uniformity of the polymer in the carbon fiber bundle in the final composite fiber is not as good as that in Example 1.

[0096] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification. For example, replacing carbon fiber with metal fiber such as copper fiber or copper-plated polyimide fiber, replacing polydimethylsiloxane with nylon, polytetrafluoroethylene, etc., replacing the diluent with n-hexane, etc., and obtained relatively ideal results.

[0097] It should be understood that the above are only some embodiments of the present invention. It should be pointed out that for ordinary technicians in this field, other modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing a flexible conductive drivable composite fiber, characterized in that: include: The polymer with a large thermal expansion coefficient, the curing agent and the diluent are mixed uniformly to form a diluted polymer solution; The conductive fiber is immersed in a diluted polymer solution, and then the polymer with a large thermal expansion coefficient is squeezed into the conductive fiber bundle through a roller pressing mechanism to perform the first impregnation and the first homogenization; The conductive fibers that have been homogenized for the first time are immersed in a pure polymer solution, and then subjected to capillary homogenization extrusion through an extrusion mechanism; the pure polymer solution immersion and capillary homogenization extrusion operations are repeated for more than two times, so that the pure polymer solution is evenly distributed inside the conductive fiber bundle; Finally, the fiber is cured and twisted to obtain a flexible, conductive and actuatable composite fiber with a uniform spiral structure.

2. The preparation method according to claim 1, characterized in that: The polymer with a large thermal expansion coefficient includes any one of polydimethylsiloxane, nylon, and polytetrafluoroethylene, or a combination of two or more thereof; And / or, the diluent comprises a non-polar organic solvent, preferably any one of ethyl acetate and n-hexane or a combination of two thereof; And / or, the mass ratio of the combination of the polymer with a large thermal expansion coefficient and the curing agent to the diluent is 3:1 to 1:

1.

3. The preparation method according to claim 1, characterized in that: The conductive fiber comprises any one of carbon fiber, metal fiber, polymer fiber with added conductive filler, and non-conductive fiber coated with a conductive layer, or a combination of two or more thereof; preferably, the metal fiber comprises copper fiber; preferably, the conductive filler added to the polymer fiber comprises at least any one of graphene and carbon nanotube; preferably, the non-conductive fiber coated with a conductive layer comprises copper-plated polyimide fiber.

4. The preparation method according to claim 1, characterized in that: include: The conductive fiber is introduced into the diluted polymer solution for a first dipping; The conductive fibers that have been impregnated for the first time are squeezed by a roller pressing mechanism, so that the polymer with a large thermal expansion coefficient enters the conductive fiber bundle through the squeezing action, and the first homogenization is performed; Preferably, the rolling mechanism comprises a mechanical component with a smooth surface, preferably a homogenizing roller; Preferably, the device for introducing the conductive fibers comprises guide rollers.

5. The preparation method according to claim 4, characterized in that: include: The conductive fibers that have been impregnated and homogenized for the first time are introduced into the pure polymer solution for a second impregnation, and the conductive fibers that have been impregnated for the second time are squeezed by a roller pressing mechanism to perform capillary homogenization extrusion; The conductive fibers that have been homogenously extruded by capillary extrusion are introduced into the pure polymer solution again for a third immersion, so that each single fiber inside the conductive fiber bundle is evenly coated with the polymer.

6. The preparation method according to claim 1, characterized in that: The curing temperature is 155-185° C., the time is 0.5-1 min and / or, the preparation method further comprises: collecting the cured composite conductive fibers, preferably, the collection speed is 30-40 m / h.

7. A flexible conductive drivable composite fiber with a uniform spiral structure obtained by the preparation method according to any one of claims 1 to 6, wherein the flexible conductive drivable composite fiber comprises a conductive fiber and a polymer with a large thermal expansion coefficient, and the conductive fiber is uniformly distributed in the polymer with a large thermal expansion coefficient.

8. A system for preparing a flexible conductive and drivable composite fiber, characterized in that: Applicable to the preparation method according to any one of claims 1 to 6, and the preparation system comprises: An introduction mechanism, at least used to introduce the conductive fibers into the diluted polymer solution respectively; A first rolling mechanism, at least for rolling the conductive fibers impregnated for the first time and introducing them into a next stage of pure polymerization solution; A second rolling mechanism, at least used to roll the conductive fibers that have been impregnated for the second time; A collecting mechanism, at least used to collect the cured composite conductive fibers; The twisting mechanism is at least used to twist the collected composite conductive fibers to form a uniform spiral structure.

9. The preparation system according to claim 8, characterized in that: The introduction mechanism comprises a guide roller; and / or the rolling mechanism comprises a mechanical component with a smooth surface, preferably a homogenizing roller.

10. Application of the flexible conductive drivable composite fiber according to claim 7 in the fields of flexible driving, flexible sensing, aerospace, electronic equipment, intelligent robots, intelligent wearables or human-computer interaction.

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