Composite fibrid and method for making same
By mixing nylon 66 with para-aramid chopped fibers and combining it with modified carbon nanotubes, a high-performance aramid/PA66/CNTs composite precipitation fiber was prepared, solving the problem of uneven material bonding in the prior art and realizing a composite material with high conductivity and mechanical properties, suitable for gas-sensitive detection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHONGFANG NEW MATERIAL CO LTD
- Filing Date
- 2023-12-20
- Publication Date
- 2026-06-26
AI Technical Summary
Existing technologies struggle to effectively combine aramid fibers, nylon, and carbon nanotubes, leading to macromolecular chain aging or uneven dispersion of additives during high-temperature shearing of composite materials, which affects the conductivity and mechanical properties of the materials.
The process involves dissolving nylon 66 chips and mixing them with para-aramid chopped fibers, then dropping the mixture into a coagulation bath to shear and form composite precipitated fibers. These fibers are then ultrasonically dispersed and loaded with modified carbon nanotubes to form aramid/PA66/CNTs composite precipitated fibers.
A composite material with high mechanical properties and electrical conductivity was prepared, exhibiting good gas-sensing properties and suitable for the detection of organic gases.
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Figure CN117702303B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of composite material technology, specifically relating to a composite precipitated fiber and its preparation method. Background Technology
[0002] Aramid, short for aromatic polyamide fiber, is mainly divided into para-aramid and meta-aramid. Para-aramid has excellent mechanical properties, including high strength, high modulus, and good toughness. In addition, para-aramid also has good high-temperature resistance and chemical stability, and is widely used in composite materials, safety protection, optical cable reinforcement and other fields.
[0003] With the rapid development of science and technology, new requirements and challenges are constantly being put forward for materials. For example, wearable electronic products, biosensors and other fields require materials to have properties such as thinness, high strength, conductivity and flexibility. However, it remains a challenge in the field of materials engineering to develop a conductive material that has both high strength and toughness, can achieve charge transport, and has a simple preparation method.
[0004] Nylon fiber is a nanomaterial with high specific surface area, low density, and high length, width, and density. Carbon nanotubes are widely used in composite materials due to their excellent electrical conductivity, mechanical properties, and chemical stability. Research on combining aramid fiber, nylon, and carbon nanotubes to prepare high-performance conductive composite materials is relatively limited. Existing technologies include melt-compositing of nylon and aramid fibers. However, this method can cause aging and thermal degradation of the material's macromolecular chains under high-temperature shear conditions, and some surface treatments can also compromise the bulk strength of the aramid fibers. Another approach is in-situ polymerization reinforcement. While this method achieves good composite effects, the added additives face difficulties in dispersion, leading to agglomeration and hindering the achievement of ideal results. Summary of the Invention
[0005] To address the problems existing in the background technology, the present invention provides a composite precipitation fiber and its preparation method. The preparation method provided by the present invention achieves an effective combination of aramid fiber, nylon and carbon nanotubes. The prepared composite precipitation fiber can produce paper-based composite materials with high mechanical properties, certain electrical conductivity, and good performance in gas-sensitive detection.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] A composite precipitation fiber and its preparation method, comprising the following:
[0008] (1) Add nylon 66 (PA66) slices to m-cresol, heat and stir until completely dissolved to obtain PA66 solution;
[0009] (2) Add para-aramid short fibers to PA66 solution, heat and stir to obtain aramid / nylon 66 mixed solution;
[0010] (3) The aramid / PA66 mixed solution was dropped into the coagulation bath for shearing. After shearing, it was washed with deionized water to obtain aramid / PA66 composite precipitated fiber.
[0011] (4) Place the aramid / PA66 composite precipitation fiber into a modified carbon nanotube (CNT) dispersion and use ultrasonic dispersion to load the modified carbon nanotubes onto the aramid / PA66 composite precipitation fiber. After removal, wash with deionized water and vacuum dry to finally obtain the aramid / PA66 / CNTs composite precipitation fiber.
[0012] Preferably, the specific operation steps of step (1) are as follows: dissolve nylon 66 slices in m-cresol, add triethylamine and epichlorohydrin, and heat and stir at 40-70°C for 2-6 hours to obtain the nylon 66 solution, wherein the mass ratio of nylon 66 to m-cresol is 5-15:85-95, and the mass ratio of nylon 66 to triethylamine and epichlorohydrin is 20-30:1:3.
[0013] Preferably, the mass ratio of aramid short-cut fibers to nylon 66 in the nylon 66 solution in step (2) is 1:3 to 5, and the heating and stirring time is 6 to 12 hours.
[0014] Preferably, the coagulation bath in step (3) is composed of glycerol and anhydrous ethanol, and the volume ratio of glycerol to anhydrous ethanol is 1:1 to 3.
[0015] Preferably, the stirring rate when the mixed solution described in step (3) is dropped into the coagulation bath for shearing is 3000-4000 rpm, the dropping speed is 1-3 mL / min, and stirring continues for 30-60 min after the dropping is completed.
[0016] Preferably, the concentration of the modified carbon nanotube dispersion in step (4) is 0.05-0.5 wt%, wherein the modified carbon nanotube is a carbon nanotube obtained by non-covalent functionalization modification of the polymer sodium polystyrene sulfonate, and the modified carbon nanotube dispersion is prepared by adding sodium polystyrene sulfonate to an ethanol dispersion of carbon nanotubes and performing graft modification of carbon nanotubes under ultrasonic conditions to obtain the modified carbon nanotube dispersion, wherein the mass ratio of sodium polystyrene sulfonate to carbon nanotube is 1:10, and the ultrasonic time is 15-30 min.
[0017] Preferably, the conditions for ultrasonic treatment in step (4) are: ultrasonic temperature of 0-5℃ and ultrasonic time of 5-15min.
[0018] Preferably, the vacuum drying conditions in step (4) are: vacuum degree of -0.1MPa to -0.03MPa, temperature of 60 to 90℃, and time of 2 to 6h.
[0019] The composite precipitation fiber prepared by this invention can be applied to the detection of organic gases, and can be used to distinguish the types of organic gases or detect the content of gases.
[0020] This application has the following beneficial effects:
[0021] 1. In this invention, a mixed solution of para-aramid short-cut fibers and PA66 is dropped into a high-speed shearing coagulation bath. Under the action of shear force, the mixed liquid droplets are gradually stretched and solidified into aramid / PA66 composite precipitated fibers with a certain aspect ratio. Since aramid and PA66 have a large number of amide bonds and polar groups in their structure, they have extremely strong surface interaction forces, which enable the two to be effectively combined together. In addition, the composite precipitated fibers obtained after high-speed shearing have a high specific surface area, providing a large adhesion surface for carbon nanotubes, thereby achieving an effective combination of aramid, PA66 and carbon nanotubes.
[0022] 2. The aramid / PA66 / CNTs composite precipitated fiber prepared by the preparation method provided by the present invention can produce paper-based composite materials with high mechanical properties, certain electrical conductivity, and good gas-sensing properties, providing a new design idea for the preparation of multifunctional sensing materials. Attached Figure Description
[0023] Figure 1 The tensile strength curve of the aramid / PA66 / CNTs composite precipitated fiber prepared in Example 1 of this invention;
[0024] Figure 2 Performance tests of the gas-sensitive properties of the aramid / PA66 / CNTs composite precipitation fibers prepared in Example 1 and Comparative Example 6 of this invention. Detailed Implementation
[0025] The present application will be further described in detail below with reference to the embodiments.
[0026] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available.
[0027] Example 1
[0028] 10g of PA66 slices were added to 90g of m-cresol, along with triethylamine and epichlorohydrin. The mixture was heated to 60℃ and stirred for 3 hours until completely dissolved, yielding a PA66 solution. 2g of para-aramid chopped fibers were added to the PA66 solution and stirred for 8 hours to obtain an aramid / nylon 66 mixed solution. This aramid / PA66 mixed solution was then dropped into a coagulation bath at a rate of 1mL / min. The coagulation bath consisted of 500mL glycerol and 1000mL anhydrous ethanol, and the stirring rate was 3600rpm. After the addition was complete, shearing continued for 30 minutes. After shearing, the solution was used... The aramid / PA66 composite precipitated fiber was obtained by washing with deionized water. A 0.1% wt modified carbon nanotube dispersion was prepared, in which anhydrous ethanol was used as the dispersant. The dispersion was ultrasonically dispersed for 30 min in the range of 0-5℃. The aramid / PA66 composite precipitated fiber was placed in the modified carbon nanotube dispersion and ultrasonically dispersed for 10 min while maintaining the temperature at 0-5℃. The carbon nanotubes were loaded onto the aramid / PA66 composite precipitated fiber. After removal, the fiber was washed with deionized water and placed in a vacuum drying oven with a vacuum degree of -0.08 MPa and a temperature of 80℃ for 2 h to dry. Finally, the aramid / PA66 / CNTs composite precipitated fiber was obtained.
[0029] Example 2
[0030] 5g of PA66 slices were added to 95g of m-cresol, along with triethylamine and epichlorohydrin. The mixture was heated to 50℃ and stirred for 4 hours until completely dissolved, yielding a PA66 solution. 1.5g of para-aramid chopped fibers were added to the PA66 solution and stirred for 6 hours to obtain an aramid / nylon 66 mixed solution. This aramid / PA66 mixed solution was then dropped into a coagulation bath at a rate of 3mL / min. The coagulation bath consisted of 500mL glycerol and 500mL anhydrous ethanol, and the stirring rate was 4000rpm. After the addition was complete, shearing continued for 60 minutes. After shearing, the solution was used... The aramid / PA66 composite precipitated fiber was obtained by washing with deionized water. A 0.05 wt% modified carbon nanotube dispersion was prepared, in which anhydrous ethanol was used as the dispersant. The dispersion was ultrasonically dispersed for 20 min in the range of 0–5 °C. The aramid / PA66 composite precipitated fiber was placed in the modified carbon nanotube dispersion and ultrasonically dispersed for 5 min while maintaining the temperature at 0–5 °C. The carbon nanotubes were loaded onto the aramid / PA66 composite precipitated fiber. After removal, the fiber was washed with deionized water and placed in a vacuum drying oven at a vacuum degree of -0.1 MPa and a temperature of 60 °C for drying for 6 h. Finally, the aramid / PA66 / CNTs composite precipitated fiber was obtained.
[0031] Example 3
[0032] 15g of PA66 slices were added to 85g of m-cresol, followed by triethylamine and epichlorohydrin. The mixture was heated to 70℃ and stirred for 2 hours until completely dissolved, yielding a PA66 solution. 3g of para-aramid chopped fibers were added to the PA66 solution and stirred for 12 hours to obtain an aramid / nylon 66 mixed solution. This aramid / PA66 mixed solution was then dropped into a coagulation bath at a rate of 2mL / min. The coagulation bath consisted of 300mL glycerol and 900mL anhydrous ethanol, and the stirring rate was 3000rpm. After the addition was complete, shearing continued for 45 minutes. After shearing, the solution was... The aramid / PA66 composite precipitated fiber was obtained by washing with deionized water. A 0.2 wt% modified carbon nanotube dispersion was prepared, in which anhydrous ethanol was used as the dispersant. The dispersion was ultrasonically dispersed for 15 min in the range of 0–5 °C. The aramid / PA66 composite precipitated fiber was placed in the carbon nanotube dispersion and ultrasonically dispersed for 15 min while maintaining the temperature at 0–5 °C. The carbon nanotubes were loaded onto the aramid / PA66 composite precipitated fiber. After removal, the fiber was washed with deionized water and placed in a vacuum drying oven at a vacuum degree of -0.08 MPa and a temperature of 90 °C for 2 h to dry, finally obtaining the aramid / PA66 / CNTs composite precipitated fiber.
[0033] Example 4
[0034] 10g of PA66 slices were added to 90g of m-cresol, along with triethylamine and epichlorohydrin. The mixture was heated to 40℃ and stirred for 6 hours until completely dissolved, yielding a PA66 solution. 3g of para-aramid chopped fibers were added to the PA66 solution, and the mixture was stirred for 9 hours to obtain an aramid / nylon 66 mixed solution. This aramid / PA66 mixed solution was then dropped into a coagulation bath at a rate of 1mL / min. The coagulation bath consisted of 500mL glycerol and 500mL anhydrous ethanol, and the stirring rate was 4000rpm. After the addition was complete, shearing continued for 30 minutes. After shearing, a deionization agent was used. The aramid / PA66 composite precipitated fiber was obtained by washing with deionized water. A 0.5 wt% modified carbon nanotube dispersion was prepared, in which anhydrous ethanol was used as the dispersant. The dispersion was ultrasonically dispersed for 20 min in the range of 0-5℃. The aramid / PA66 composite precipitated fiber was placed in the modified carbon nanotube dispersion and ultrasonically dispersed for 10 min while maintaining the temperature at 0-5℃. The carbon nanotubes were loaded onto the aramid / PA66 composite precipitated fiber. After removal, the fiber was washed with deionized water and placed in a vacuum drying oven with a vacuum degree of -0.05 MPa and a temperature of 70℃ for 4 h to dry. Finally, the aramid / PA66 / CNTs composite precipitated fiber was obtained.
[0035] Example 5
[0036] 12g of PA66 slices were added to 88g of m-cresol, followed by triethylamine and epichlorohydrin. The mixture was heated to 60℃ and stirred for 5 hours until completely dissolved, yielding a PA66 solution. 2.5g of para-aramid chopped fibers were added to the PA66 solution and stirred for 8 hours to obtain an aramid / nylon 66 mixed solution. This aramid / PA66 mixed solution was then dropped into a coagulation bath at a rate of 1mL / min. The coagulation bath consisted of 400mL glycerol and 800mL anhydrous ethanol, and the stirring rate was 3600rpm. After the addition was complete, shearing continued for 30 minutes. After shearing, the solution was... The aramid / PA66 composite precipitated fiber was obtained by washing with deionized water. A 0.3 wt% modified carbon nanotube dispersion was prepared, in which anhydrous ethanol was used as the dispersant. The dispersion was ultrasonically dispersed for 30 min in the range of 0–5 °C. The aramid / PA66 composite precipitated fiber was placed in the modified carbon nanotube dispersion and ultrasonically dispersed for 8 min while maintaining the temperature at 0–5 °C. The carbon nanotubes were loaded onto the aramid / PA66 composite precipitated fiber. After removal, the fiber was washed with deionized water and placed in a vacuum drying oven at a vacuum degree of -0.03 MPa and a temperature of 90 °C for 3 h to dry, finally obtaining the aramid / PA66 / CNTs composite precipitated fiber.
[0037] Comparative Example 1
[0038] The only difference between this comparative example and Example 1 is that:
[0039] The prepared composite precipitation fibers contained only aramid fibers and modified carbon nanotubes, but no nylon 66 fibers.
[0040] 2g of para-aramid short-cut fibers were added to 90g of m-cresol, along with triethylamine and epichlorohydrin. The mixture was heated to 60℃ and stirred for 8 hours to obtain an aramid solution. The aramid solution was then dropped into a coagulation bath at a rate of 1mL / min for shearing. The coagulation bath consisted of 500mL glycerol and 1000mL anhydrous ethanol, and the stirring rate was 3600rpm. After the addition was complete, shearing continued for 30 minutes. After shearing, the mixture was washed with deionized water to obtain aramid precipitated fibers. A 0.1% wt modified carbon nanotube dispersion was prepared, wherein the dispersant was anhydrous ethanol. The dispersion was ultrasonically dispersed for 30 min in the range of 0-5℃. The aramid precipitated fiber was placed in the modified carbon nanotube dispersion and ultrasonically dispersed for 10 min while maintaining the temperature at 0-5℃. The carbon nanotubes were loaded onto the aramid precipitated fiber. After removal, the fiber was washed with deionized water and placed in a vacuum drying oven with a vacuum degree of -0.08 MPa and a temperature of 80℃ for 2 h to dry, finally obtaining aramid / CNTs composite precipitated fiber.
[0041] Comparative Example 2
[0042] The only difference between this comparative example and Example 1 is that:
[0043] The prepared composite precipitation fiber contained only nylon 66 fiber and modified carbon nanotubes, without the addition of aramid fiber.
[0044] 10g of PA66 slices were added to 90g of m-cresol, followed by triethylamine and epichlorohydrin. The mixture was heated to 60℃ and stirred for 3 hours until completely dissolved, yielding a PA66 solution. The PA66 solution was then added dropwise to a coagulation bath at a rate of 1mL / min. The coagulation bath consisted of 500mL glycerol and 1000mL anhydrous ethanol, and the stirring rate was 3600rpm. After the addition was complete, shearing continued for 30 minutes. The solution was then washed with deionized water to obtain PA66 precipitate. Fibers; a 0.1% wt modified carbon nanotube dispersion was prepared, wherein the dispersant was anhydrous ethanol. The dispersion was ultrasonically dispersed for 30 min in the range of 0-5℃. PA66 precipitated fibers were placed in the modified carbon nanotube dispersion and ultrasonically dispersed for 10 min while maintaining the temperature at 0-5℃. The carbon nanotubes were loaded onto the PA66 precipitated fibers. After removal, the fibers were washed with deionized water and placed in a vacuum drying oven with a vacuum degree of -0.08 MPa and a temperature of 80℃ for 2 h to dry, finally obtaining PA66 / CNTs composite precipitated fibers.
[0045] Comparative Example 3
[0046] The only difference between this comparative example and Example 1 is that:
[0047] The prepared composite precipitation fiber contained only nylon 66 fiber and aramid fiber, without the addition of modified carbon nanotubes.
[0048] 10g of PA66 slices were added to 90g of m-cresol, along with triethylamine and epichlorohydrin. The mixture was heated to 60℃ and stirred for 3 hours until completely dissolved to obtain a PA66 solution. 2g of para-aramid chopped fibers were added to the PA66 solution and stirred for 8 hours to obtain an aramid / nylon 66 mixed solution. The aramid / PA66 mixed solution was then dropped into a coagulation bath at a rate of 1mL / min for shearing. The coagulation bath consisted of 500mL of glycerol and 1000mL of anhydrous ethanol, and the stirring rate was 3600rpm. After the addition was complete, shearing continued for 30 minutes. After shearing, the solution was washed with deionized water and placed in a vacuum drying oven at -0.08MPa and 80℃ for 2 hours to obtain aramid / PA66 composite precipitated fibers.
[0049] Comparative Example 4
[0050] The only difference between this comparative example and Example 1 is that:
[0051] The nylon 66 used to prepare the composite precipitated fiber was commercially available, and the PA66 solution was not treated.
[0052] 10g of PA66 slices were added to 90g of m-cresol and stirred at 60℃ for 3 hours until completely dissolved to obtain a PA66 solution. 2g of para-aramid chopped fibers were added to the PA66 solution and stirred for 8 hours to obtain an aramid / nylon 66 mixed solution. The aramid / PA66 mixed solution was then sheared dropwise into a coagulation bath at a rate of 1mL / min. The coagulation bath consisted of 500mL glycerol and 1000mL anhydrous ethanol, and the stirring rate was 3600rpm. After the addition was complete, shearing continued for 30 minutes. After shearing, the solution was washed with deionized water to obtain... Aramid / PA66 composite precipitated fibers were obtained; a 0.1% wt modified multi-walled carbon nanotube dispersion was prepared, wherein the dispersant was anhydrous ethanol. The dispersion was ultrasonically dispersed for 30 min in the range of 0-5℃. The aramid / PA66 composite precipitated fibers were placed in the modified carbon nanotube dispersion and ultrasonically dispersed for 10 min while maintaining the temperature at 0-5℃. The carbon nanotubes were loaded onto the aramid / PA66 composite precipitated fibers. After removal, the fibers were washed with deionized water and placed in a vacuum drying oven with a vacuum degree of -0.08 MPa and a temperature of 80℃ for 2 h to dry, finally obtaining aramid / PA66 / CNTs composite precipitated fibers.
[0053] Comparative Example 5
[0054] The only difference between this comparative example and Example 1 is that:
[0055] The nylon 66 and carbon nanotubes used to prepare the composite precipitated fibers were both commercially available. The nylon 66 solution was not treated and the carbon nanotubes were not modified.
[0056] 10g of PA66 slices were added to 90g of m-cresol and stirred at 60℃ for 3 hours until completely dissolved to obtain a PA66 solution. 2g of para-aramid chopped fibers were added to the PA66 solution and stirred for 8 hours to obtain an aramid / nylon 66 mixed solution. The aramid / PA66 mixed solution was then dropped into a coagulation bath at a rate of 1mL / min for shearing. The coagulation bath consisted of 500mL glycerol and 1000mL anhydrous ethanol, and the stirring rate was 3600rpm. After the addition was complete, shearing continued for 30 minutes. After shearing, the solution was washed with deionized water. Aramid / PA66 composite precipitated fibers were obtained. A 0.1% wt ordinary carbon nanotube dispersion was prepared, wherein the dispersant was anhydrous ethanol. The dispersion was ultrasonically dispersed for 30 min in the range of 0-5℃. The aramid / PA66 composite precipitated fibers were placed in the ordinary carbon nanotube dispersion and ultrasonically dispersed for 10 min while maintaining the temperature at 0-5℃. The carbon nanotubes were loaded onto the aramid / PA66 composite precipitated fibers. After removal, the fibers were washed with deionized water and placed in a vacuum drying oven with a vacuum degree of -0.08 MPa and a temperature of 80℃ for 2 h to dry. Finally, aramid / PA66 / CNTs composite precipitated fibers were obtained.
[0057] Comparative Example 6
[0058] The only difference between this comparative example and Example 1 is that:
[0059] The carbon nanotubes in the prepared composite precipitated fibers were commercially available and had not been modified.
[0060] 10g of PA66 slices were added to 90g of m-cresol, along with triethylamine and epichlorohydrin. The mixture was heated to 60℃ and stirred for 3 hours until completely dissolved, yielding a PA66 solution. 2g of para-aramid chopped fibers were added to the PA66 solution and stirred for 8 hours to obtain an aramid / nylon 66 mixed solution. This aramid / PA66 mixed solution was then dropped into a coagulation bath at a rate of 1mL / min. The coagulation bath consisted of 500mL glycerol and 1000mL anhydrous ethanol, and the stirring rate was 3600rpm. After the addition was complete, shearing continued for 30 minutes. After shearing, the solution was... The aramid / PA66 composite precipitated fiber was obtained by washing with deionized water. A 0.1% wt ordinary carbon nanotube dispersion was prepared, in which anhydrous ethanol was used as the dispersant. The dispersion was ultrasonically dispersed for 30 min in the range of 0-5℃. The aramid / PA66 composite precipitated fiber was placed in the carbon nanotube dispersion and ultrasonically dispersed for 10 min while maintaining the temperature at 0-5℃. The carbon nanotubes were loaded onto the aramid / PA66 composite precipitated fiber. After removal, the fiber was washed with deionized water and placed in a vacuum drying oven with a vacuum degree of -0.08 MPa and a temperature of 80℃ for 2 h to dry. Finally, the aramid / PA66 / CNTs composite precipitated fiber was obtained.
[0061] Experimental Example 1
[0062] The mechanical properties of the composite precipitated fibers prepared in the examples and comparative examples were characterized. The composite precipitated fibers prepared in Examples 1-5 and Comparative Examples 1-6 were processed into paper-based composite materials of a certain thickness using wet papermaking and hot pressing. The paper-based composite materials were cut into test specimens of a certain size, and their tensile and bending properties were tested. The test results are shown in Table 1.
[0063] Table 1
[0064] Tensile strength (MPa) Number of bends Example 1 127 655 Example 2 124 631 Example 3 126 644 Example 4 121 671 Example 5 125 657 Comparative Example 1 80 395 Comparative Example 2 48 264 Comparative Example 3 96 516 Comparative Example 4 105 531 Comparative Example 5 102 525 Comparative Example 6 123 646
[0065] Results Analysis: Analysis of the data in Table 1 shows that the paper-based composite materials prepared by the aramid / PA66 / CNTs composite precipitated fibers in Examples 1-5 of this application have higher mechanical properties. In addition, the tensile strength and bending properties are significantly higher than those of Comparative Examples 1-5. The carbon nanotubes used in Comparative Example 6 were not modified, but the aramid / PA66 / CNTs composite precipitated fibers prepared still have high mechanical properties.
[0066] Experimental Example 2
[0067] This experiment tested the gas-sensitive properties of the aramid / PA66 / CNTs composite precipitated fibers prepared in Example 1 and Comparative Example 6. The prepared aramid / PA66 / CNTs composite precipitated fibers were formed into a paper-based composite material of a certain thickness using wet papermaking and hot pressing. The paper-based composite material was cut into strips 2 mm wide and 10 mm long. A multimeter and the paper-based composite material were connected in series to detect the change in resistance of the paper-based composite material. First, the circuit was connected, and the paper-based composite material was placed in the air. After the multimeter resistance reading stabilized, the paper-based composite material was placed in a sealed conical flask containing an organic solvent, and the resistance change was recorded in real time. After the reading stabilized, the paper-based composite material was removed and placed in the air, and the resistance change was recorded until a stable value was obtained. The results are as follows. Figure 2 As shown.
[0068] Results Analysis: Analysis Figure 2 It can be seen that the aramid / PA66 / CNTs composite precipitated fibers prepared in Example 1 and Comparative Example 6 of this application exhibited rapid increases in resistance when placed in conical flasks containing organic solvents, and gradually recovered their resistance when exposed to air, demonstrating certain gas-sensing properties. Experimental results show that the paper-based composite material obtained from the aramid / PA66 / CNTs composite precipitated fibers prepared in Example 1 has a relatively fast response and recovery speed to organic solvent gases, with response and recovery times of 13–22 s and 6–15 s, respectively. The response signal stabilizes quickly and exhibits good recovery performance. Furthermore, it shows different resistance response signals to different organic solvent gases, demonstrating a certain degree of differentiation and overall good gas-sensing performance. In contrast, the aramid / PA66 / CNTs composite precipitated fibers prepared in Comparative Example 6 exhibit some differentiation function for different organic solvents, but their response and recovery speeds are slower, with response and recovery times both exceeding 30 s. The response signal requires a longer time to stabilize, indicating poor recovery performance.
[0069] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.
[0070] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.
Claims
1. A method for preparing composite precipitation fibers, characterized in that, Includes the following steps: (1) Add PA66 slices to m-cresol, heat and stir until completely dissolved to obtain PA66 solution; (2) Add para-aramid short fibers to the PA66 solution, heat and stir to obtain an aramid / nylon 66 mixed solution; (3) The aramid / PA66 mixed solution was dropped into the coagulation bath for shearing. After shearing, it was washed with deionized water to obtain aramid / PA66 composite precipitated fiber. (4) Place the aramid / PA66 composite precipitated fiber into the modified carbon nanotube dispersion, and use ultrasonic dispersion to load the modified carbon nanotube onto the aramid / PA66 composite precipitated fiber. After removal, wash with deionized water and vacuum dry to finally obtain the aramid / PA66 / CNTs composite precipitated fiber. The specific operation steps of step (1) are as follows: dissolve nylon 66 slices in m-cresol, add triethylamine and epichlorohydrin, and heat and stir at 40-70°C for 2-6 hours to obtain the nylon 66 solution, wherein the mass ratio of nylon 66 to m-cresol is 5-15: 85-95, and the mass ratio of nylon 66 to triethylamine and epichlorohydrin is 20-30: 1:
3.
2. The method for preparing composite precipitation fibers according to claim 1, characterized in that, In step (2), the mass ratio of aramid short-cut fibers to nylon 66 in the nylon 66 solution is 1:3 to 5, and the heating and stirring time is 6 to 12 hours.
3. The method for preparing composite precipitation fibers according to claim 1, characterized in that, The coagulation bath described in step (3) is composed of glycerol and anhydrous ethanol, and the volume ratio of glycerol to anhydrous ethanol is 1:1 to 3.
4. The method for preparing composite precipitation fibers according to claim 1, characterized in that, When the mixed solution described in step (3) is dropped into the coagulation bath for shearing, the stirring rate is 3000-4000 rpm and the dropping speed is 1-3 mL / min. After the dropping is completed, stirring is continued for 30-60 min.
5. The method for preparing composite precipitation fibers according to claim 1, characterized in that, The modified carbon nanotube dispersion in step (4) has a concentration of 0.05-0.5 wt%, wherein the modified carbon nanotube is a carbon nanotube obtained by non-covalent functionalization of the polymer sodium polystyrene sulfonate. The modified carbon nanotube dispersion is prepared by adding sodium polystyrene sulfonate to an ethanol dispersion of carbon nanotubes and performing graft modification of the carbon nanotubes under ultrasonic conditions to obtain the modified carbon nanotube dispersion. The mass ratio of sodium polystyrene sulfonate to carbon nanotubes is 1:10, and the ultrasonic time is 15-30 min.
6. The method for preparing composite precipitation fibers according to claim 1, characterized in that, The conditions for ultrasonic dispersion in step (4) are: ultrasonic temperature of 0-5℃ and ultrasonic time of 5-15min.
7. The method for preparing composite precipitation fibers according to claim 1, characterized in that, The vacuum drying conditions described in step (4) are: vacuum degree of -0.1MPa to -0.03MPa, temperature of 60 to 90℃, and time of 2 to 6h.
8. A composite precipitation fiber, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 7.
9. A composite precipitation fiber according to claim 8, characterized in that: The composite precipitation fiber is used in the detection of organic gases to distinguish the types of organic gases or to detect the content of gases.