A method for preparing highly oriented fiber

Abstract

The present invention discloses a method for preparing highly oriented fibers. This method primarily utilizes the synergistic effects of double diffusion and gel interface motion to achieve alignment of two-dimensional elements within the fiber, thereby producing highly oriented fibers. Specifically, the fibers, initially oriented by shearing, are extruded into a solution containing charged particles. The initially oriented two-dimensional elements further align due to double diffusion of the solvent and coagulant, as well as the motion of the gel interface formed by the charged particles. When thermally conductive elements are employed, the highly oriented two-dimensional elements provide a uniaxial heat conduction path, promoting the effective unidirectional transfer of phonons and achieving efficient heat transfer.

Description

Technical Field

[0001] The present invention relates to a new material, in particular to a method for preparing high-orientation fiber. Background Art

[0002] Currently, the main methods for preparing fibers composed of two-dimensional nanosheets include direct ink writing, wet spinning, melt deposition, and electrospinning. The fibers produced by these methods often rely on shear forces during extrusion to orient the two-dimensional nanosheets along the extrusion direction. However, due to the limited range of shear force and the loss of flow confinement after extrusion, it is difficult for the nanosheets to maintain a regular vertical orientation. Furthermore, methods that utilize only shear force for orientation require ensuring appropriate extrusion speeds and extrudate viscosities, resulting in a narrow operating range.

[0003] Thermally conductive fibers assembled from two-dimensional thermally conductive elements have promising practical applications in areas such as thermal management and wearable fabrics. Straightening and bundling individual thermally conductive fibers can create thermal interface materials with highly upright thermal networks. Weaving these fibers into highly conductive fabrics can effectively manage localized thermal conditions within the human body. When the two-dimensional thermally conductive elements within a single fiber are highly oriented along the axial direction, they are fully connected, significantly reducing interfacial thermal resistance and forming a continuous thermal network. As heat passes through the fiber, the fiber provides a uniaxial thermal pathway, enabling efficient phonon transfer and, consequently, effective heat transfer. However, if the two-dimensional thermally conductive elements within the fiber are disordered, significant interfacial thermal resistance exists between the elements, making it difficult to construct a continuous thermal pathway and effectively preventing heat transfer, significantly reducing their practical application value. Therefore, a new method for preparing highly oriented fibers with a wider operating range and the ability to produce them in a controlled, large-scale, and cost-effective manner is urgently needed to effectively address issues such as thermal conductivity efficiency in high-power electronic devices and personal localized thermal management. Summary of the Invention

[0004] The present invention addresses the shortcomings of existing technologies and provides a method for preparing highly oriented fibers. Specifically, dual orientation, achieved through shear and electrostatic gelation, is employed to further enhance orientation. A spinning solution containing two-dimensional primitives is extruded into a coagulation bath containing charged particles using shear forces. The two-dimensional primitives on the fiber's surface are preferentially oriented under the action of shear forces. During the coagulation process in the coagulation bath, the charged particles in the bath move inward from the outermost layer of the spun fiber, thereby inducing further orientation correction of the internal two-dimensional primitives. After washing and drying, a high-performance fiber formed from the highly oriented assembly of two-dimensional primitives is obtained.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a two-dimensional element spinning solution with a volume fraction of 0.5 to 15 vol% (thickness of 1 nm to 1 μm) is extruded into a coagulation bath containing 0.1 to 10 mol / L of charged particles through a spinning nozzle with a diameter of 0.25 to 2.0 mm at a speed of 0.1 to 20 mL / min, and after coagulation for 1 to 60 minutes, it is washed with water and dried to obtain the highly oriented fiber.

[0006] The double diffusion effect that occurs during the coagulation process is an important factor in inducing the orientation correction of the two-dimensional primitives in this application, which includes the double diffusion effect of the solvent in the nascent silk diffusing into the coagulation bath, and the coagulant, i.e., the charged particles diffusing into the nascent silk. The gelation induction of the charged particles will further cooperate with the above-mentioned double diffusion force, so that the two-dimensional primitives are highly oriented along the fiber axis. Therefore, in this application, the concentration of the two-dimensional primitive spinning solution, the extrusion speed, the fiber diameter and the degree of gelation induction are particularly critical. Among them, after 0.5-15vol% of the two-dimensional primitive spinning solution is extruded at a speed of 0.1-20mL / min under a spinning diameter of 0.25-2.0mm, the two-dimensional primitives on the surface are highly oriented under the shear force generated by the confinement of the spinning mouth, and a nascent silk with moderate density is formed, which provides a channel for the double diffusion and gelation interface movement occurring in the coagulation bath, and provides a suitable correction space for the correction of the two-dimensional primitives. In the coagulation bath, 0.1 to 10 mol / L charged particles will affect the double diffusion rate and gelation movement rate. After the surface two-dimensional primitives are preferentially solidified with high orientation, the inner two-dimensional primitives will undergo orientation correction under the constraint of the surface primitives.

[0007] Among them, an extrusion speed that is too fast or too slow will lead to poor shear orientation or even the extruded fiber has no oriented structure, which will affect the subsequent correction effect; experiments have shown that when the extrusion speed is as low as 0.1mL / min, the shear force is insufficient, and the two-dimensional elements on the surface of the primary silk have no oriented structure, and cannot provide effective orientation constraints in the coagulation bath of this application; when the extrusion speed is as high as 20mL / min or above, there is not enough shear field action time, and the disordered state is restored in the coagulation bath with charged particles in this application.

[0008] In certain embodiments of the present invention, the two-dimensional element solution contains a gel component. While its addition will affect the orientation of the two-dimensional elements in the spun silk to a certain extent, this gel component can undergo gelation under the action of the charged particles. Therefore, the gel component content should be appropriately controlled to ensure continuous extrusion while controlling the movement of the gelled interface to coordinate with the double diffusion force. In certain specific embodiments of the present invention, this gel component can also play a role in anchoring the two-dimensional thermally conductive elements, enabling extrusion of thinner extrudates that would not form under shear alone.

[0009] When the aforementioned two-dimensional elements are thermally conductive elements, the highly oriented fibers exhibit extremely high thermal conductivity. The thermally conductive elements include, but are not limited to, at least one of boron nitride nanosheets, graphene oxide nanosheets, graphene nanosheets, and aluminum oxide nanosheets. Boron nitride nanosheets, graphene nanosheets, and aluminum oxide nanosheets are typically added to a gel component for gelation-assisted orientation induction.

[0010] Furthermore, the charged particles are selected from Na + , Ca 2+ 、Zn 2+ 、Ba 2+ 、Cu 2+ 、Fe 3+ 、Al 3+ 、Zr 4+ , citrate, and tripolyphosphate.

[0011] Furthermore, the gel component is selected from at least one of polyurethane, sodium alginate, pectin, cellulose, sodium polygalacturonate, chitosan, and branched polyethyleneimine.

[0012] The present invention achieves the following beneficial effects: it utilizes shearing to initially orient two-dimensional primitives, and then further orients these primitives in a coagulation bath through coordinated double diffusion and gelation. This results in highly oriented fibers composed of two-dimensional primitives, with an orientation factor reaching 0.8. Compared to conventional shearing, this coordinated orientation method offers a wider operating range, enabling improvements in both the orientation region and degree of orientation.

[0013] When using thermal conductive elements, highly oriented two-dimensional elements can provide uniaxial heat conduction paths, promote the effective unidirectional transmission of phonons, and the thermal conductivity of the fiber reaches 14.0W / (m*K). BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the principle of ordinary shear orientation and shear combined with double diffusion gelation induced orientation correction proposed by the present invention.

[0015] Figure 2 Edge electron micrographs of fibers prepared using different volume fractions of boron nitride as a two-dimensional primitive. The boron nitride volume fraction in a is 2%, in b it is 15%, and in c it is 20%.

[0016] Figure 3 Electron micrographs of fibers prepared using different mass fractions of sodium alginate as the gel component. The mass fraction of sodium alginate in a is 0.5%, in b it is 3%, and in c it is 6%.

[0017] Figure 4Electron micrographs of fibers prepared using different concentrations of calcium chloride solution as the charged particle solution. The concentration of the calcium chloride solution in a is 0.1 mol / L, the concentration in b is 1 mol / L, and the concentration in c is 5 mol / L.

[0018] Figure 5 The electron micrographs of fibers prepared using different needle apertures are shown in Figure a (0.4 mm), b (0.8 mm), c (1.2 mm), d (1.6 mm), and e (2.2 mm).

[0019] Figure 6 The electron micrographs of fibers prepared at different extrusion speeds are shown in Figure a (0.05 mL / min), Figure b (0.1 mL / min), Figure c (5 mL / min), and Figure d (25 mL / min).

[0020] Figure 7 Electron microscope image of fibers prepared using alumina as thermal conductive elements

[0021] Figure 8 Electron micrograph of fibers prepared using sodium carboxymethyl cellulose as a gel component

[0022] Figure 9 Electron microscope image of pure disordered fiber prepared in Comparative Example 1

[0023] Figure 10 This is the electron microscope image of the shear-oriented fiber prepared in Comparative Example 2.

[0024] Figure 11 Electron microscope image of the gelation-induced oriented fiber prepared in Comparative Example 3 DETAILED DESCRIPTION

[0025] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0026] Since the concentration of the assembly unit, the viscosity of the assembly liquid, and the concentration of charged particles in the solution adsorbed on the substrate can all be adjusted according to needs through simple experiments, in the following embodiments, unless otherwise specified, the concentration of the assembly unit is calculated to be 0.5-15 vol%, the viscosity of the assembly liquid is tested to meet the conditions for extrusion molding, and the concentration of charged particles adsorbed on the substrate is 0.1-10 mol / L to achieve gelation.

[0027] In the following examples, commercially available products are used, and the two-dimensional elements are all commercially available sheet materials with a thickness of 1 nm to 1 μm.

[0028] In the following examples, it can be observed that the two-dimensional primitives present a highly oriented layered concentric structure in the circumferential direction. According to the aforementioned theory, the double diffusion effect and the movement of the gel interface will correct the orientation of the nanosheets perpendicular to the direction of movement. For a single fiber, the double diffusion effect and the movement of the gel interface from the outermost radially inward can be expected to cause the two-dimensional primitives to present a highly oriented layered concentric structure in the circumferential direction. At the same time, it promotes the two-dimensional primitives to present a highly upright orientation in the axial direction under the action of the parallel interface. The cross-section of the two-dimensional primitives observed in the thickness direction of the fiber cross-section in the electron microscope image shows that the two-dimensional primitives are highly perpendicular to the observed cross-section, verifying that the highly layered concentric structure in the circumferential direction is bound to cause a highly upright orientation in the axial direction.

[0029] From a mechanistic perspective, the highly layered, concentric-circular structure exhibited along the circumference also confirms the aforementioned double diffusion and gelation-induced theories. This highly layered, concentric-circular structure demonstrates the high perpendicularity of the two-dimensional elements to the fiber cross-section. This also confirms that the double diffusion of solvent into the coagulation bath and coagulant into the spun silk, combined with the gelation-induced action of charged particles, effectively orients the two-dimensional elements along the fiber axis.

[0030] Example 1:

[0031] This example mainly explores the effect of the content of two-dimensional thermal conductive elements (here, boron nitride nanosheets) on the degree of fiber orientation and thermal conductivity.

[0032] (1) Sodium alginate was added to deionized water and stirred to prepare a sodium alginate aqueous solution. Boron nitride nanosheets and the sodium alginate aqueous solution were mixed and stirred until no boron nitride particles were present to obtain an extrusion slurry. The volume fraction of the boron nitride nanosheets, the concentration of sodium alginate, and the viscosity of the extrusion slurry are shown in Table 1.

[0033] (2) The extruded slurry is filled into a syringe, sealed at the top and bottom, and centrifuged for 15 minutes at a certain speed to remove bubbles in the slurry. The centrifugal speed is 1000-8000 rpm / min according to the viscosity.

[0034] (3) Place the syringe filled with the centrifuged slurry on the syringe pump, install a multi-channel extruder at the front end of the syringe, and install a needle at the front end of the multi-channel extruder. Extrude the boron nitride fiber into the calcium chloride solution at a certain speed and soak it in the calcium chloride solution for 30 minutes. The needle diameter, extrusion speed, and calcium chloride solution concentration are shown in Table 1. Then, take out the fully gelled fiber and soak it in deionized water for more than 12 hours to remove excess calcium ions from the fiber. Place the fiber fully soaked in deionized water in a 60°C oven and dry it for 12 hours.

[0035] (4) Scanning electron microscopy was used to observe the edge morphology of the gelled fibers. Figure 2 .

[0036] (5) SAXS was used to characterize the degree of nanosheet orientation along the fiber axis and to calculate the orientation factor. The thermal conductivity of a single fiber was tested using the transient electrothermal method. The orientation factors and thermal conductivities of samples 1 to 5 are shown in Table 1.

[0037] Table 1 Experimental and performance parameters of Example 1

[0038]

[0039] Combine Figure 2 As can be seen from the results in Table 1, when the volume fraction of boron nitride is between 5% and 15% (samples 2, 3, and 4), as the volume fraction increases, more two-dimensional thermal conductive elements are present in the extrudate. Double diffusion and gelation lead to a highly ordered arrangement of more elements, improving the degree of fiber orientation and the thermal conductivity. When the volume fraction is 2% (sample 1), the extrudate contains too few two-dimensional thermal conductive elements, the arrangement is not dense enough, and there is a large space for movement. The correction effect has a side effect on some elements, and the degree of fiber orientation and thermal conductivity are significantly reduced. When the volume fraction is 20% (sample 5), the extrudate contains too many two-dimensional elements and the arrangement is too dense. There is insufficient space for double diffusion and gel interface diffusion to occur, and the degree of orientation and thermal conductivity are reduced.

[0040] Example 2: This example mainly explores the effect of the gel component content (here, the sodium alginate concentration) on the fiber orientation degree and thermal conductivity.

[0041] (1) Sodium alginate was added to deionized water and stirred to prepare a sodium alginate aqueous solution. Boron nitride nanosheets and the sodium alginate aqueous solution were mixed and stirred until no boron nitride particles were present to obtain an extrusion slurry. The volume fraction of the boron nitride nanosheets, the concentration of sodium alginate, and the viscosity of the extrusion slurry are shown in Table 2.

[0042] (2) The extruded slurry is filled into a syringe, sealed at the top and bottom, and centrifuged for 15 minutes at a certain speed to remove bubbles in the slurry. The centrifugal speed is 1000-8000 rpm / min according to the viscosity.

[0043] (3) Place the syringe filled with the centrifuged slurry on the syringe pump, install a multi-channel extruder at the front end of the syringe, and install a needle at the front end of the multi-channel extruder. Extrude the boron nitride fiber into the calcium chloride solution at a certain speed and soak it in the calcium chloride solution for 30 minutes. The needle diameter, extrusion speed, and calcium chloride solution concentration are shown in Table 2. Then, take out the fully gelled fiber and soak it in deionized water for more than 12 hours to remove excess calcium ions from the fiber. Place the fiber fully soaked in deionized water in a 60°C oven and dry it for 12 hours.

[0044] (4) Scanning electron microscopy was used to observe the fiber morphology after gelation. Figure 3 .

[0045] (5) SAXS was used to characterize the degree of nanosheet orientation along the fiber axis and to calculate the orientation factor. The thermal conductivity of a single fiber was tested using the transient electrothermal method. The orientation factors and thermal conductivities of samples 6 to 12 are shown in Table 2.

[0046] Table 2 Experimental and performance parameters of Example 2

[0047]

[0048] Combine Figure 3 As can be seen from the results in Table 2, when the sodium alginate concentration is 2wt% to 5wt% (samples 8, 9, 10, and 11), a relatively suitable viscosity can be maintained, and the double diffusion effect and gelation successfully correct the further orientation of the two-dimensional primitives; when the sodium alginate concentration is 0.5wt% and 1wt% (samples 6 and 7), the gel component content is insufficient, the gelation process is weak, and it is difficult to further orient the primitives by double diffusion alone; when the sodium alginate concentration is 6wt% (sample 12), the gel component content is too much, the viscosity is too high, the double diffusion effect is weakened, and it is also difficult to correct the further orientation of the two-dimensional primitives.

[0049] Example 3:

[0050] This example mainly explores the effect of charged particle concentration (here, calcium ion concentration) on the degree of fiber orientation and thermal conductivity.

[0051] (1) Sodium alginate was added to deionized water and stirred to prepare a sodium alginate aqueous solution. Boron nitride nanosheets and the sodium alginate aqueous solution were mixed and stirred until no boron nitride particles were present to obtain an extrusion slurry. The volume fraction of the boron nitride nanosheets and the concentration of the sodium alginate were shown in Table 3.

[0052] (2) The extruded slurry was filled into a syringe, sealed at the top and bottom, and centrifuged at 6000 rpm for 15 minutes to remove bubbles in the slurry.

[0053] (3) Place the syringe filled with the centrifuged slurry on the syringe pump, install a multi-channel extruder at the front end of the syringe, and install a needle at the front end of the multi-channel extruder. Extrude the boron nitride fiber into the calcium chloride solution at a certain speed and soak it in the calcium chloride solution for 30 minutes. The needle diameter, extrusion speed, and calcium chloride solution concentration are shown in Table 3. Then, take out the fully gelled fiber and soak it in deionized water for more than 12 hours to remove excess calcium ions from the fiber. Place the fiber fully soaked in deionized water in a 60°C oven and dry it for 12 hours.

[0054] (4) Scanning electron microscopy was used to observe the fiber morphology after gelation. Figure 4 .

[0055] (5) SAXS was used to characterize the degree of nanosheet orientation along the fiber axis and to calculate the orientation factor. The thermal conductivity of a single fiber was tested using the transient electrothermal method. The orientation factors and thermal conductivities of samples 13 to 17 are shown in Table 3.

[0056] Table 3 Experimental and performance parameters of Example 3

[0057]

[0058] Combine Figure 4 It can be seen from the results in Table 3 that when the concentration of the calcium chloride solution is 1-5 mol / L (samples 16 and 17), the charged particle concentration is moderate, and the fiber maintains a high degree of orientation and high thermal conductivity; when the concentration of the calcium chloride solution is less than 1 mol / L (samples 13, 14, and 15), the charged particle content is insufficient, and the diffusion of charged particles into the fiber and the formation of gelation are not sufficient to correct the further orientation of a large number of two-dimensional thermal conductive elements. In this case, a certain degree of orientation is maintained only by shearing.

[0059] Example 4:

[0060] This example mainly explores the effect of needle aperture on fiber orientation and thermal conductivity.

[0061] (1) Sodium alginate was added to deionized water and stirred to prepare a sodium alginate aqueous solution. Boron nitride nanosheets and the sodium alginate aqueous solution were mixed and stirred until no boron nitride particles were present to obtain an extrusion slurry. The volume fraction of the boron nitride nanosheets and the concentration of the sodium alginate were shown in Table 4.

[0062] (2) The extruded slurry was filled into a syringe, sealed at the top and bottom, and centrifuged at 6000 rpm for 15 minutes to remove bubbles in the slurry.

[0063] (3) Place the syringe filled with the centrifuged slurry on the syringe pump, install a multi-channel extruder at the front end of the syringe, and install a needle at the front end of the multi-channel extruder. Extrude the boron nitride fiber into the calcium chloride solution at a certain speed and soak it in the calcium chloride solution for 30 minutes. The needle diameter, extrusion speed, and calcium chloride solution concentration are shown in Table 4. Then, take out the fully gelled fiber and soak it in deionized water for more than 12 hours to remove excess calcium ions from the fiber. Place the fiber fully soaked in deionized water in a 60°C oven and dry it for 12 hours.

[0064] (4) Scanning electron microscopy was used to observe the fiber morphology after gelation. Figure 5 .

[0065] (5) SAXS was used to characterize the degree of nanosheet orientation along the fiber axis and to calculate the orientation factor. The thermal conductivity of a single fiber was tested using the transient electrothermal method. The orientation factors and thermal conductivities of samples 18 to 27 are shown in Table 4.

[0066] Table 4 Experimental and performance parameters of Example 4

[0067]

[0068] Combine Figure 5 It can be seen from the results in Table 4 that when the needle aperture is 0.6 mm to 2.0 mm (samples 19 to 26), the shearing effect allows the two-dimensional elements to be initially oriented better. At the same time, the appropriate diameter provides suitable space for double diffusion and gelation in the coagulation bath, and the fiber maintains a high degree of orientation and high thermal conductivity. When the needle aperture is 0.4 mm (sample 18), the fiber is too dense, and there is insufficient space for double diffusion and gelation interface movement, and the orientation cannot be further corrected. When the needle aperture is 2.2 mm (sample 27), the internal space of the fiber is too large, and the corrected orientation does not necessarily lead to a regular arrangement of the elements.

[0069] Example 5:

[0070] This example mainly explores the effect of extrusion speed on fiber orientation and thermal conductivity.

[0071] (1) Sodium alginate was added to deionized water and stirred to prepare a sodium alginate aqueous solution. Boron nitride nanosheets and the sodium alginate aqueous solution were mixed and stirred until no boron nitride particles were present to obtain an extrusion slurry. The volume fraction of the boron nitride nanosheets and the concentration of the sodium alginate were shown in Table 5.

[0072] (2) The extruded slurry was filled into a syringe, sealed at the top and bottom, and centrifuged at 6000 rpm for 15 minutes to remove bubbles in the slurry.

[0073] (3) Place the syringe filled with the centrifuged slurry on the syringe pump, install a multi-channel extruder at the front end of the syringe, and install a needle at the front end of the multi-channel extruder. Extrude the boron nitride fiber into the calcium chloride solution at a certain speed and soak it in the calcium chloride solution for 30 minutes. The needle diameter, extrusion speed, and calcium chloride solution concentration are shown in Table 5. Then, take out the fully gelled fiber and soak it in deionized water for more than 12 hours to remove excess calcium ions from the fiber. Place the fiber fully soaked in deionized water in a 60°C oven and dry it for 12 hours.

[0074] (4) Scanning electron microscopy was used to observe the fiber morphology after gelation. Figure 6 .

[0075] (5) SAXS was used to characterize the degree of nanosheet orientation along the fiber axis and to calculate the orientation factor. The thermal conductivity of a single fiber was tested using the transient electrothermal method. The orientation factors and thermal conductivities of samples 28 to 34 are shown in Table 5.

[0076] Table 5 Experimental and performance parameters of Example 5

[0077]

[0078] Combine Figure 6 It can be seen from the results in Table 5 that when the extrusion speed is between 0.083 mL / min (5 mL / h) and 20 mL / min (samples 29 to 33), the extrusion speed is appropriate, good shear orientation can be maintained, and the fiber maintains high orientation and high thermal conductivity; when the extrusion speed is 0.05 mL / min (sample 28), the extrusion speed is too slow and the shear orientation is poor; when the extrusion speed is 25 mL / min, the extrusion speed is too fast and the shear orientation is poor.

[0079] Example 6:

[0080] This embodiment aims to verify that the aforementioned double diffusion and gelation processes can still occur when the volume fraction of the two-dimensional elements is as low as 0.5 vol%, so that the orientation of the two-dimensional elements can be further corrected.

[0081] (1) 50 g of a 10 mg / g graphene oxide solution and 50 g of deionized water were mixed and stirred to obtain an extrusion slurry, wherein the volume fraction of the graphene oxide nanosheets was 0.5 vol%, and the viscosity of the extrusion slurry was 200 mPa·s.

[0082] (2) The extruded slurry was filled into a syringe, sealed at the top and bottom, and centrifuged at 2000 rpm for 15 minutes to remove bubbles in the slurry.

[0083] (3) The syringe filled with the centrifuged slurry is placed on a syringe pump, a multi-channel extrusion head is installed at the front end of the syringe, a 0.8 mm needle is installed at the front end of the multi-channel extrusion head, and graphene oxide fibers are extruded into a 5 mol / L calcium chloride solution at a speed of 5 mL / min. The extruded graphene oxide fibers are soaked in the calcium chloride solution for 30 minutes and then taken out.

[0084] (4) Take out the fiber that has been fully gelled in the calcium chloride solution and soak it in deionized water for more than 12 hours to remove excess calcium ions from the fiber.

[0085] (5) The cleaned graphene oxide fibers were immersed in a 1% sodium ascorbate aqueous solution, heated to 80° C. for reduction for 12 hours, and then washed again with deionized water.

[0086] (6) Place the cleaned fiber in a 60°C oven and dry for 12 hours.

[0087] (7) SAXS was used to characterize the degree of orientation of the nanosheets along the fiber axis, and the orientation factor was calculated to be 0.68. The thermal conductivity of a single fiber was tested using the transient electrothermal method, and the thermal conductivity of a single fiber was 4.82 W / (m*K) at room temperature.

[0088] Example 7:

[0089] This example aims to verify that the aforementioned double diffusion and gelation processes can still occur when the charged particle concentration is as low as 0.1 mol / L, thereby further correcting the orientation of the two-dimensional element.

[0090] (1) 3 g of sodium alginate was added to 97 g of deionized water and stirred to prepare a 3 wt% sodium alginate aqueous solution. 54 g of alumina nanosheets and 46 g of the sodium alginate aqueous solution were mixed and stirred until no alumina particles were present to obtain an extrusion slurry. The volume fraction of the alumina nanosheets was 15 vol%, and the viscosity of the extrusion slurry was 1500 mPa·s.

[0091] (2) The extruded slurry was filled into a syringe, sealed at the top and bottom, and centrifuged at 6000 rpm for 15 minutes to remove bubbles in the slurry.

[0092] (3) Place the syringe filled with the centrifuged slurry on the syringe pump, install a multi-channel extrusion head at the front end of the syringe, and install a 0.8 mm needle at the front end of the multi-channel extrusion head. Extrude the alumina fibers into a 0.1 mol / L calcium chloride solution at a speed of 5 mL / min. Soak the extruded alumina fibers in the calcium chloride solution for 30 minutes and then take them out.

[0093] (4) Take out the fiber that has been fully gelled in the calcium chloride solution and soak it in deionized water for more than 12 hours to remove excess calcium ions from the fiber. The SEM photo of the fiber after drying is as follows: Figure 7 shown.

[0094] (5) Place the cleaned fiber in a 60°C oven and dry for 12 hours.

[0095] (6) SAXS was used to characterize the degree of nanosheet orientation along the fiber axis, and the orientation factor was calculated to be 0.70; the thermal conductivity of a single fiber was tested using the transient electrothermal method, and the thermal conductivity of a single fiber was 10.72 W / (m*K) at room temperature.

[0096] Example 8:

[0097] This example aims to verify that the aforementioned double diffusion and gelation processes can still occur when the charged particle concentration is as high as 10 mol / L, thereby further correcting the orientation of the two-dimensional element.

[0098] (1) 3 g of sodium alginate was added to 97 g of deionized water and stirred to prepare a 3 wt% sodium alginate aqueous solution. 34.05 g of boron nitride nanosheets and 65.95 g of the sodium alginate aqueous solution were mixed and stirred until no boron nitride particles were present to obtain an extrusion slurry. The volume fraction of the boron nitride nanosheets was 15 vol%, and the viscosity of the extrusion slurry was 1500 mPa·s.

[0099] (2) The extruded slurry was filled into a syringe, sealed at the top and bottom, and centrifuged at 6000 rpm for 15 minutes to remove bubbles in the slurry.

[0100] (3) Place the syringe filled with the centrifuged slurry on the syringe pump, install a multi-channel extrusion head at the front end of the syringe, and install a 0.8 mm needle at the front end of the multi-channel extrusion head. Extrude the boron nitride fiber into a 10 mol / L zinc chloride solution at a speed of 5 mL / min. The extruded boron nitride fiber is soaked in the zinc chloride solution for 30 minutes and then taken out.

[0101] (4) Take out the fiber that has been fully gelled in the zinc chloride solution and soak it in deionized water for more than 12 hours to remove excess zinc ions from the fiber.

[0102] (5) Place the cleaned fiber in a 60°C oven and dry for 12 hours.

[0103] (6) SAXS was used to characterize the degree of nanosheet orientation along the fiber axis, and the orientation factor was calculated to be 0.74; the thermal conductivity of a single fiber was tested using the transient electrothermal method, and the thermal conductivity of a single fiber was 12.46 W / (m*K) at room temperature.

[0104] Example 9:

[0105] This example aims to verify that the aforementioned double diffusion and gelation processes can still occur when the spinning nozzle diameter is as low as 0.25 mm and the coagulation time is only 1 mm, so that the two-dimensional elements can be further oriented.

[0106] (1) 2 g of sodium alginate was added to 98 g of deionized water and stirred to prepare a 2 wt% sodium alginate aqueous solution. 54 g of alumina nanosheets and 46 g of the sodium alginate aqueous solution were mixed and stirred until no alumina particles were present to obtain an extrusion slurry. The volume fraction of the alumina nanosheets was 15 vol%, and the viscosity of the extrusion slurry was 1000 mPa·s.

[0107] (2) The extruded slurry was filled into a syringe, sealed at the top and bottom, and centrifuged at 4000 rpm for 15 minutes to remove bubbles in the slurry.

[0108] (3) Place the syringe filled with the centrifuged slurry on the syringe pump, install a multi-channel extrusion head at the front end of the syringe, install a 0.25 mm needle at the front end of the multi-channel extrusion head, extrude the alumina fibers into a 5 mol / L calcium chloride solution at a speed of 5 mL / min, and soak the extruded alumina fibers in the calcium chloride solution for 1 minute before taking them out.

[0109] (4) Take out the fiber that has been fully gelled in the calcium chloride solution and soak it in deionized water for more than 12 hours to remove excess calcium ions from the fiber.

[0110] (5) Place the cleaned fiber in a 60°C oven and dry for 12 hours.

[0111] (6) SAXS was used to characterize the degree of nanosheet orientation along the fiber axis, and the orientation factor was calculated to be 0.72; the thermal conductivity of a single fiber was tested using the transient electrothermal method, and the thermal conductivity of a single fiber was 11.12 W / (m*K) at room temperature.

[0112] Example 10:

[0113] This example aims to verify that the aforementioned double diffusion and gelation process can still occur when the gel component is replaced, so that the orientation of the two-dimensional element can be further corrected.

[0114] (1) 34.05 g of boron nitride nanosheets and 65.95 g of a 35% aqueous polyurethane solution were stirred until no boron nitride particles were present, to obtain an extrusion slurry. The volume fraction of the boron nitride nanosheets was 15 vol%, and the viscosity of the extrusion slurry was 1500 mPa·s.

[0115] (2) The extruded slurry was filled into a syringe, sealed at the top and bottom, and centrifuged at 6000 rpm for 15 minutes to remove bubbles in the slurry.

[0116] (3) The syringe filled with the centrifuged slurry is placed on the syringe pump, and a multi-channel extrusion head is installed at the front end of the syringe. A 0.8 mm needle is installed at the front end of the multi-channel extrusion head, and the boron nitride fiber is extruded into a 5 mol / L calcium chloride solution at a speed of 5 mL / min. The extruded boron nitride fiber is soaked in the calcium chloride solution for 30 minutes and then taken out.

[0117] (4) Take out the fiber that has been fully gelled in the calcium chloride solution and soak it in deionized water for more than 12 hours to remove excess calcium ions from the fiber.

[0118] (5) Place the cleaned fiber in a 60°C oven and dry for 12 hours.

[0119] (6) SAXS was used to characterize the degree of nanosheet orientation along the fiber axis, and the orientation factor was calculated to be 0.72; the thermal conductivity of a single fiber was tested using the transient electrothermal method, and the thermal conductivity of a single fiber was 11.57 W / (m*K) at room temperature.

[0120] Example 11:

[0121] This example aims to verify that the aforementioned double diffusion and gelation process can still occur when the gel component is replaced, so that the orientation of the two-dimensional element can be further corrected.

[0122] (1) 3 g of chitosan was added to 96 g of deionized water, and 1 g of glacial acetic acid was added and stirred to prepare a 3 wt% chitosan aqueous solution. 34.05 g of boron nitride nanosheets and 65.95 g of the chitosan aqueous solution were mixed and stirred until no boron nitride particles were present to obtain an extrusion slurry. The volume fraction of the boron nitride nanosheets was 15 vol%, and the viscosity of the extrusion slurry was 1500 mPa·s.

[0123] (2) The extruded slurry was filled into a syringe, sealed at the top and bottom, and centrifuged at 6000 rpm for 15 minutes to remove bubbles in the slurry.

[0124] (3) Place the syringe filled with the centrifuged slurry on the syringe pump, install a multi-channel extrusion head at the front end of the syringe, and install a 0.8 mm needle at the front end of the multi-channel extrusion head. Extrude the boron nitride fiber into a 5 mol / L sodium citrate solution at a speed of 5 mL / min. The extruded boron nitride fiber is soaked in the sodium citrate solution for 30 minutes and then taken out.

[0125] (4) The fiber that has been fully gelled in the sodium citrate solution is taken out and immersed in deionized water for more than 12 hours to remove excess citrate ions from the fiber.

[0126] (5) Place the cleaned fiber in a 60°C oven and dry for 12 hours.

[0127] (6) SAXS was used to characterize the degree of nanosheet orientation along the fiber axis, and the orientation factor was calculated to be 0.75; the thermal conductivity of a single fiber was tested using the transient electrothermal method, and the thermal conductivity of a single fiber was 12.45 W / (m*K) at room temperature.

[0128] Example 12:

[0129] This example aims to verify that the aforementioned double diffusion and gelation process can still occur when the gel component is replaced, so that the orientation of the two-dimensional element can be further corrected.

[0130] (1) 3 g of sodium carboxymethyl cellulose was added to 97 g of deionized water and stirred to prepare a 3 wt% sodium carboxymethyl cellulose aqueous solution. 34.05 g of boron nitride nanosheets and 65.95 g of the sodium carboxymethyl cellulose aqueous solution were mixed and stirred until no boron nitride particles were present to obtain an extrusion slurry. The volume fraction of the boron nitride nanosheets was 15 vol%, and the viscosity of the extrusion slurry was 1500 mPa·s.

[0131] (2) The extruded slurry was filled into a syringe, sealed at the top and bottom, and centrifuged at 6000 rpm for 15 minutes to remove bubbles in the slurry.

[0132] (3) The syringe filled with the centrifuged slurry is placed on the syringe pump, and a multi-channel extrusion head is installed at the front end of the syringe. A 0.8 mm needle is installed at the front end of the multi-channel extrusion head, and the boron nitride fiber is extruded into a 5 mol / L calcium chloride solution at a speed of 5 mL / min. The extruded boron nitride fiber is soaked in the calcium chloride solution for 30 minutes and then taken out.

[0133] (4) Take out the fiber that has been fully gelled in the calcium chloride solution and soak it in deionized water for more than 12 hours to remove excess calcium ions from the fiber. The SEM photo of the fiber after drying is as follows: Figure 8 shown.

[0134] (5) Place the cleaned fiber in an oven at 60°C.

[0135] (6) SAXS was used to characterize the degree of nanosheet orientation along the fiber axis, and the orientation factor was calculated to be 0.75; the thermal conductivity of a single fiber was tested using the transient electrothermal method, and the thermal conductivity of a single fiber was 12.65 W / (m*K) at room temperature.

[0136] Comparative Example 1:

[0137] This comparative example aims to explore the orientation factor and thermal conductivity of the fiber when shearing, double diffusion and gelation do not occur.

[0138] (1) 3 g of sodium alginate was added to 97 g of deionized water and stirred to prepare a 3 wt% sodium alginate aqueous solution. 34.05 g of boron nitride nanosheets and 65.95 g of the sodium alginate aqueous solution were mixed and stirred until no boron nitride particles were present to obtain an extrusion slurry. The volume fraction of the boron nitride nanosheets was 15 vol%, and the viscosity of the extrusion slurry was 1500 mPa·s.

[0139] (2) The extruded slurry was filled into a syringe, sealed at the top and bottom, and centrifuged at 6000 rpm for 15 minutes to remove bubbles in the slurry.

[0140] (3) The syringe filled with the centrifuged slurry is placed on a syringe pump, a multi-channel extrusion head is installed at the front end of the syringe, a 0.8 mm needle is installed at the front end of the multi-channel extrusion head, and the slurry is extruded into the air at a speed of 0.05 mL / min.

[0141] (4) The fibers extruded into the air were placed in a 60°C oven and dried for 12 hours. Figure 9 shown.

[0142] (5) SAXS was used to characterize the degree of orientation of the nanosheets along the fiber axis, and the orientation factor was calculated to be 0.32. The thermal conductivity of a single fiber was tested using the transient electrothermal method, and the thermal conductivity of a single fiber was 3.709 W / (m*K) at room temperature.

[0143] Comparative Example 2:

[0144] This comparative example aims to investigate the orientation factor and thermal conductivity of fibers when only shearing action occurs.

[0145] (1) 3 g of sodium alginate was added to 97 g of deionized water and stirred to prepare a 3 wt% sodium alginate aqueous solution. 34.05 g of boron nitride nanosheets and 65.95 g of the sodium alginate aqueous solution were mixed and stirred until no boron nitride particles were present to obtain an extrusion slurry. The volume fraction of the boron nitride nanosheets was 15 vol%, and the viscosity of the extrusion slurry was 1500 mPa·s.

[0146] (2) The extruded slurry was filled into a syringe, sealed at the top and bottom, and centrifuged at 6000 rpm for 15 minutes to remove bubbles in the slurry.

[0147] (3) The syringe filled with the centrifuged slurry is placed on a syringe pump, a multi-channel extrusion head is installed at the front end of the syringe, a 0.8 mm needle is installed at the front end of the multi-channel extrusion head, and the slurry is extruded into the air at a speed of 5 mL / min.

[0148] (4) The fibers extruded into the air were placed in a 60°C oven and dried for 12 hours. Figure 10 shown.

[0149] (5) SAXS was used to characterize the degree of nanosheet orientation along the fiber axis, and the orientation factor was calculated to be 0.60. The thermal conductivity of a single fiber was tested using the transient electrothermal method, and the thermal conductivity of a single fiber was 8.89 W / (m*K) at room temperature.

[0150] Comparative Example 3:

[0151] This comparative example aims to explore the orientation factor and thermal conductivity of the fiber when only double diffusion and gelation occur.

[0152] (1) 3 g of sodium alginate was added to 97 g of deionized water and stirred to prepare a 3 wt% sodium alginate aqueous solution. 34.05 g of boron nitride nanosheets and 65.95 g of the sodium alginate aqueous solution were mixed and stirred until no boron nitride particles were present to obtain an extrusion slurry. The volume fraction of the boron nitride nanosheets was 15 vol%, and the viscosity of the extrusion slurry was 1500 mPa·s.

[0153] (2) The extruded slurry was filled into a syringe, sealed at the top and bottom, and centrifuged at 6000 rpm for 15 minutes to remove bubbles in the slurry.

[0154] (3) The syringe filled with the centrifuged slurry is placed on the syringe pump, and a multi-channel extrusion head is installed at the front end of the syringe. A 0.8 mm needle is installed at the front end of the multi-channel extrusion head, and the boron nitride fiber is extruded into a 5 mol / L calcium chloride solution at a speed of 0.05 mL / min. The extruded boron nitride fiber is soaked in the calcium chloride solution for 30 minutes and then taken out.

[0155] (4) Take out the fiber that has been fully gelled in the calcium chloride solution and soak it in deionized water for more than 12 hours to remove excess calcium ions from the fiber. The SEM photo of the fiber after drying is as follows: Figure 11 shown.

[0156] (5) Place the cleaned fiber in a 60°C oven and dry for 12 hours.

[0157] (7) SAXS was used to characterize the degree of nanosheet orientation along the fiber axis, and the orientation factor was calculated to be 0.63; the thermal conductivity of a single fiber was tested using the transient electrothermal method, and the thermal conductivity of a single fiber at room temperature was 9.72 W / (m*K).

[0158] Comparative Example 4:

[0159] This comparative example aims to investigate the orientation factor and thermal conductivity of fibers without gel components.

[0160] (1) 34.05 g of boron nitride nanosheets and 65.95 g of deionized water were mixed and stirred until no boron nitride particles were present to obtain an extrusion slurry. The volume fraction of the boron nitride nanosheets was 15 vol%, and the viscosity of the extrusion slurry was 50 mPa·s.

[0161] (2) The extruded slurry was filled into a syringe, sealed at the top and bottom, and centrifuged at 1000 rpm for 15 minutes to remove bubbles in the slurry.

[0162] (3) The syringe filled with the centrifuged slurry was placed on the syringe pump, and a multi-channel extrusion head was installed at the front end of the syringe. A 0.8 mm needle was installed at the front end of the multi-channel extrusion head, and the boron nitride fiber was extruded into a 5 mol / L calcium chloride solution at a speed of 5 mL / min. Since the boron nitride nanosheets and the charged particles had almost no electrostatic interaction, the fibers dissolved in the calcium chloride solution and could not be formed, and high-orientation fibers could not be obtained.

[0163] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing highly oriented fibers, characterized in that: The method at least comprises: extruding a two-dimensional elementary spinning solution with a volume fraction of 0.5 to 15 vol% into a coagulation bath containing 0.1 to 10 mol / L charged particles at a speed of 0.1 to 20 mL / min through a spinning nozzle with a diameter of 0.25 to 2.0 mm, coagulating for 1 to 60 minutes, washing with water, and drying to obtain the highly oriented fiber; The two-dimensional primitive is a heat-conducting primitive, and the heat-conducting primitive is at least one or more combinations of boron nitride nanosheets, graphene nanosheets, and aluminum oxide nanosheets; The two-dimensional elementary spinning solution contains gel components, which can be gelled under the action of the charged particles.

2. The preparation method according to claim 1, characterized in that The gel component is selected from at least one of polyurethane, sodium alginate, pectin, cellulose, sodium polygalacturonate, chitosan, and branched polyethyleneimine.

3. The preparation method according to claim 1, characterized in that The charged particles are selected from Na + , Ca 2+ 、Zn 2+ 、Ba 2+ 、Cu 2+ 、Fe 3+ 、Al 3+ 、Zr 4+ , citrate, and tripolyphosphate.

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