Preparation method of high-temperature-resistant super-strong and super-tough fiber with adjustable mechanical properties

Abstract

The application relates to a preparation method of a high-temperature-resistant super-strong super-tough fiber with adjustable mechanical properties, and belongs to the technical field of functional fiber material preparation. The steps comprise the following: preparation of aromatic polyamide nanofiber spinning solution, spinning of the spinning solution, construction of a nanoscale curling structure and the like. In the application, the aromatic polyamide nanofiber is used as a matrix, and one-dimensional hydrogel fibers are obtained through wet spinning. The nanoscale curling is further introduced into the one-dimensional fibers, the high stretchability is realized while the super-high strength is maintained, and thus the aromatic polyamide one-dimensional fiber material with super-high toughness is obtained. Meanwhile, the functional fiber can still maintain the super-high toughness and stretchability under high temperature and extreme environment.

Description

Technical Field

[0001] This invention belongs to the technical field of functional fiber material preparation, specifically relating to a method for preparing high-temperature resistant, ultra-strong, and ultra-tough fibers with adjustable mechanical properties. Background Technology

[0002] Strength and toughness are contradictory properties in the mechanical properties of materials. A key challenge in the manufacture of high-performance fibers is achieving a combination of high tensile strength and high toughness. Common methods to improve tensile strength include stretching and subsequent annealing. Stretching can induce fiber orientation, and annealing can further increase crystallinity and reduce internal stress. However, these ultimately come at the cost of sacrificing the fiber's tensile strain, thus limiting the achievement of ultra-high toughness. For example, Kevlar exhibits high tensile strength due to its rigid molecular chains, strong intermolecular forces, and high crystallinity; however, its toughness is typically low due to limited tensile strain. Amorphous and semi-crystalline polymer fibers are more malleable. When combined with rigid or high-strength materials, they can achieve high toughness. However, they cannot achieve heat resistance and tolerance to harsh environments, and are prone to embrittlement and decomposition under extreme conditions, completely losing their malleability. Polymer fibers that combine high toughness, heat resistance, and chemical resistance are difficult to achieve, but hold great promise, especially for applications in defense, aerospace, and numerous other fields. Summary of the Invention

[0003] To overcome the shortcomings of existing processes in the background art, the present invention provides a method for preparing high-temperature resistant, ultra-strong, and ultra-tough fibers with adjustable mechanical properties.

[0004] The technical solution of the present invention is as follows:

[0005] A method for preparing a high-temperature resistant, ultra-strong, and ultra-tough fiber with adjustable mechanical properties includes the following steps:

[0006] 1) Preparation of spinning solution for aromatic polyamide nanofibers:

[0007] Aromatic polyamide is chopped or crushed and then washed and dried. The aromatic polyamide is either fully aromatic polyamide or aliphatic polyamide containing aromatic rings. The dried powder or chopped fibers are then dissolved in an organic solvent, which is an aprotic strong polar solvent. After thorough stirring, a uniform dark red solution is obtained through deprotonation, which is the aromatic polyamide nanofiber solution.

[0008] The mass ratio of the aromatic polyamide to the alkali is 1:1 to 3; the volume ratio of the deionized water to the organic solvent is 0 to 5:100; and the amount ratio of the aromatic polyamide to the organic solvent is 0.1 to 3 g:100 ml.

[0009] 2) Spinning with spinning solution:

[0010] The obtained aromatic polyamide nanofiber spinning solution was subjected to wet spinning, and aromatic polyamide nanofiber hydrogels were obtained through reprotonation and solvent exchange. The coagulation bath for wet spinning was one or more of the following: deionized water, ethanol, acetone, and 0.01–0.1M HCl aqueous solution. The inner diameter of the spinning needle was 0.1–2 mm, the spinning speed was 0.005–0.8 mm / s, and the capacity of the spinning syringe was 2.5–100 ml.

[0011] 3) Construction of nanoscale curled structures:

[0012] The obtained hydrogel fibers were dried. During the drying process, the degree of curling of the nanofibers in the hydrogel was controlled by loading different weights of axial load on the hydrogel fibers. The weight range of the loading load was 0.0001 to 50g. The smaller the weight, the greater the degree of curling of the nanofibers and the greater the tensile strain of the fibers. The greater the weight, the greater the degree of axial orientation of the nanofibers and the stronger the tensile strength of the fibers.

[0013] Preferably, the aromatic polyamide in step 1) is poly(p-phenylene terephthalamide), poly(m-phenylene isophthalamide), or poly(p-phenylene terephthalamide).

[0014] Preferably, the base is sodium hydroxide, potassium hydroxide, potassium ethoxide, sodium ethoxide, sodium methoxide, or sodium hydride; the organic solvent is an aprotic strongly polar solvent and includes at least dimethyl sulfoxide.

[0015] Preferably, the mass ratio of the aromatic polyamide to the alkali is 1:1.5; the volume ratio of the deionized water to the organic solvent is 1:50; and the amount ratio of the aromatic polyamide to the organic solvent is 0.5g:100ml.

[0016] Beneficial effects:

[0017] 1. Strength and toughness are contradictory in the mechanical properties of materials. A key challenge in the manufacture of high-performance fibers is achieving a combination of high tensile strength and high toughness. This invention uses aromatic polyamide nanofibers as a matrix and obtains one-dimensional hydrogel fibers through wet spinning. Furthermore, nanoscale crimping is introduced into the one-dimensional fibers, achieving high tensile strength while maintaining ultra-high strength, thus obtaining an aromatic polyamide one-dimensional fiber material with ultra-high toughness.

[0018] 2. This invention precisely controls the structural relaxation of aromatic polyamide nanofibers, which serve as building blocks, by adjusting the axial load of the hydrogel fibers during the drying process, thereby achieving different curled structures of the nanofibers. This allows for precise control of the tensile strength and tensile strain of the macroscopic fibers to meet the application requirements in different scenarios.

[0019] 3. This invention uses aromatic polyamide as the fiber matrix. Because aromatic polyamide has excellent properties such as high temperature resistance, chemical corrosion resistance, and flame retardancy, the high tensile strain of the fiber achieved through the nanoscale crimping structure can be maintained for a long time in high temperature and harsh working environments without embrittlement or reduction of tensile strain. Attached Figure Description

[0020] Figure 1 These are SEM surface comparison images of the samples prepared in implementation cases 1, 2, and 3.

[0021] Figure 2 These are infrared comparison spectra of the samples prepared in implementation cases 1, 2, and 3.

[0022] Figure 3 These are the XRD comparison spectra of the samples prepared in implementation cases 1, 2, and 3.

[0023] Figure 4 These are the stress-strain comparison curves of the samples prepared in Case Studies 1, 2, and 3. Detailed Implementation

[0024] Example 1:

[0025] 1. Cut 1g of poly(p-phenylene terephthalamide) fibers into short pieces, and ultrasonically clean them in anhydrous ethanol for 10–20 min. Remove them and place them in a drying oven at 40–60℃ for 1–3 h. Dissolve the dried chopped fibers in a mixture of 1.5g sodium hydroxide and 200mL dimethyl sulfoxide, stir thoroughly, and through deprotonation, obtain a uniform dark red solution, which is the poly(p-phenylene terephthalamide) nanofiber solution.

[0026] 2. The obtained poly(p-phenylene terephthalamide) nanofiber solution was wet-spun. The spinning solution was placed in a 2.5 mL syringe and injected into deionized water through a spinning head with an inner diameter of 0.1 mm at a spinning speed of 0.015 mm / s to obtain poly(p-phenylene terephthalamide) nanofiber hydrogel fibers.

[0027] 3. The obtained hydrogel fibers were loaded with an axial load of 0.08g and dried. After drying, a one-dimensional poly(p-phenylene terephthalamide) fiber material with ultra-high strength was obtained.

[0028] Example 2:

[0029] 1. Cut 1g of poly(p-phenylene terephthalamide) fibers into short pieces, and ultrasonically clean them in anhydrous ethanol for 10–20 min. Remove them and place them in a drying oven at 40–60℃ for 1–3 h. Dissolve the dried chopped fibers in 1.5g of sodium hydroxide and 200mL of dimethyl sulfoxide, stir thoroughly, and through deprotonation, obtain a uniform dark red solution, which is the poly(p-phenylene terephthalamide) nanofiber solution.

[0030] 2. The obtained poly(p-phenylene terephthalamide) nanofiber solution was wet-spun. The spinning solution was placed in a 2.5 mL syringe and injected into deionized water through a spinning head with an inner diameter of 0.1 mm at a spinning speed of 0.015 mm / s to obtain poly(p-phenylene terephthalamide) nanofiber hydrogel fibers.

[0031] 3. The obtained hydrogel fibers were loaded with an axial load of 0.01g and dried. After drying, a one-dimensional poly(p-phenylene terephthalamide) fiber material with high strength and high strain was obtained.

[0032] Example 3:

[0033] 1. Cut 1g of poly(p-phenylene terephthalamide) fibers into short pieces, and ultrasonically clean them in anhydrous ethanol for 10–20 min. Remove them and place them in a drying oven at 40–60℃ for 1–3 h. Dissolve the dried chopped fibers in 1.5g of sodium hydroxide and 200mL of dimethyl sulfoxide, stir thoroughly, and through deprotonation, obtain a uniform dark red solution, which is the poly(p-phenylene terephthalamide) nanofiber solution.

[0034] 2. The obtained poly(p-phenylene terephthalamide) nanofiber solution was wet-spun. The spinning solution was placed in a 2.5 mL syringe and injected into deionized water through a spinning head with an inner diameter of 0.1 mm at a spinning speed of 0.015 mm / s to obtain poly(p-phenylene terephthalamide) nanofiber hydrogel fibers.

[0035] 3. The obtained hydrogel fibers were loaded with an axial load of 0.0025g and dried. After drying, a one-dimensional poly(p-phenylene terephthalamide) fiber material with ultra-high toughness and ultra-high strain was obtained.

[0036] SEM surface comparison images of the samples prepared in Examples 1-3 above are shown below. Figure 1 As shown, the infrared contrast spectrum is as follows: Figure 2 As shown, the XRD contrast patterns are as follows: Figure 3 As shown, the stress-strain comparison curves of the samples are as follows: Figure 4 As shown, by Figures 1-4It can be seen that the smaller the load, the greater the crimp of the nanofibers, the greater the tensile strain of the fibers, and the greater the weight, the greater the orientation of the nanofibers, and the stronger the tensile strength of the fibers.

[0037] Example 4:

[0038] 1. Cut 2g of poly(p-phenylene terephthalamide) fibers into short pieces and ultrasonically clean them in anhydrous ethanol for 10–20 min. Remove them and place them in a drying oven at 40–60℃ for 1–3 h. Dissolve the dried chopped fibers in 2g potassium hydroxide, 10ml deionized water, and 200mL dimethyl sulfoxide. Stir thoroughly and, through deprotonation, obtain a uniform dark red solution, which is the poly(p-phenylene terephthalamide) nanofiber solution.

[0039] 2. The obtained poly(p-phenylene terephthalamide) nanofiber solution was wet-spun. The spinning solution was placed in a 20 mL syringe and injected into ethanol through a spinning head with an inner diameter of 0.3 mm at a spinning speed of 0.05 mm / s to obtain poly(p-phenylene terephthalamide) nanofiber hydrogel fibers.

[0040] 3. The obtained hydrogel fibers were loaded with an axial load of 0.1g and dried. After drying, a one-dimensional poly(p-phenylene terephthalamide) fiber material with high toughness was obtained.

[0041] Example 5:

[0042] 1. Ultrasonically clean 4g of poly(p-phenylene terephthalamide) powder in anhydrous ethanol for 10–20 min; remove and dry in a drying oven at 40–60℃ for 1–3 h. Dissolve the dried chopped fibers in 6g of methyl hydroxide, 15ml of deionized water and 200mL of dimethyl sulfoxide, stir thoroughly, and obtain a uniform dark red solution through deprotonation, which is the poly(p-phenylene terephthalamide) nanofiber solution.

[0043] 2. The obtained poly(p-phenylene terephthalamide) nanofiber solution was wet-spun. The spinning solution was placed in a 20 mL syringe and injected into a 0.05 M hydrochloric acid aqueous solution through a spinning head with an inner diameter of 0.5 mm at a spinning speed of 0.2 mm / s to obtain poly(p-phenylene isophthalamide) nanofiber hydrogel fibers.

[0044] 3. The obtained hydrogel fibers were loaded with an axial load of 0.5g and dried. After drying, a one-dimensional poly(m-phenylene isophthalamide) fiber material with high toughness was obtained.

[0045] Example 6:

[0046] 1. Clean 0.5g of poly(p-phenylene terephthalamide) powder with anhydrous ethanol using ultrasonic cleaning for 10–20 min; remove and place in a drying oven at 40–60℃ for 1–3 h. Dissolve the dried chopped fibers in 1g sodium hydroxide and 200mL dimethyl sulfoxide, stir thoroughly, and obtain a uniform dark red solution through deprotonation, which is the poly(p-phenylene terephthalamide) nanofiber solution.

[0047] 2. The obtained poly(p-benzoamide) nanofiber solution was wet-spun. The spinning solution was placed in a 10 mL syringe and injected into the acetone solution through a spinning head with an inner diameter of 0.2 mm at a spinning speed of 0.3 mm / s to obtain poly(p-benzoamide) nanofiber hydrogel fibers.

[0048] 3. The obtained hydrogel fibers were each loaded with an axial load of 0.001g and dried. After drying, a one-dimensional poly(p-benzoamide) fiber material with high toughness was obtained.

[0049] This invention offers advantages such as simple process, low cost, high repeatability, high yield, and suitability for large-scale industrial production. The resulting fibers exhibit high mechanical properties and excellent environmental stability. Achieving polymer fibers that combine high toughness with heat resistance and chemical corrosion resistance is difficult, making this a promising technology with indispensable applications, particularly in defense, aerospace, and numerous other fields.

[0050] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by using the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for preparing a high-temperature resistant, ultra-strong, and ultra-tough fiber with adjustable mechanical properties, comprising the following steps: 1) Preparation of spinning solution for aromatic polyamide nanofibers: Aromatic polyamide is chopped or pulverized, then washed and dried. The aromatic polyamide is poly(p-phenylene terephthalamide), poly(m-phenylene isophthalamide), or poly(p-phenylene terephthalamide). The dried powder or chopped fibers are then dissolved in an organic solvent, which is an aprotic, strongly polar solvent. After thorough stirring, a uniform dark red solution is obtained through deprotonation, which is the aromatic polyamide nanofiber solution. The mass ratio of the aromatic polyamide to the alkali is 1:1 to 3; the volume ratio of the deionized water to the organic solvent is 0 to 5:100; and the amount ratio of the aromatic polyamide to the organic solvent is 0.1 to 3 g:100 ml. 2) Spinning with spinning solution: The obtained aromatic polyamide nanofiber spinning solution was subjected to wet spinning, and aromatic polyamide nanofiber hydrogel was obtained through reprotonation and solvent exchange. The coagulation bath for wet spinning was one or more of the following: deionized water, ethanol, acetone, and 0.01~0.1 M HCl aqueous solution. The inner diameter of the spinning needle was 0.1~2 mm, the spinning speed was 0.005~0.8 mm / s, and the capacity of the spinning syringe was 2.5~100 ml. 3) Construction of nanoscale curled structures: The obtained hydrogel fibers were dried. During the drying process, the degree of curling of the nanofibers in the hydrogel was controlled by loading different weights of axial loads onto the hydrogel fibers. The weight range of the loading load was 0.0001~50 g. The smaller the weight, the greater the degree of curling of the nanofibers and the greater the tensile strain of the fibers. The greater the weight, the greater the degree of axial orientation of the nanofibers and the stronger the tensile strength of the fibers.

2. The method for preparing a high-temperature resistant, ultra-strong, and ultra-tough fiber with adjustable mechanical properties according to claim 1, characterized in that, The alkali is sodium hydroxide, potassium hydroxide, potassium ethoxide, sodium ethoxide, sodium methoxide, or sodium hydride; the organic solvent is an aprotic strong polar solvent and includes at least dimethyl sulfoxide.

3. The method for preparing a high-temperature resistant, ultra-strong, and ultra-tough fiber with adjustable mechanical properties according to claim 1, characterized in that, The mass ratio of the aromatic polyamide to the alkali is 1:1.5; the volume ratio of the deionized water to the organic solvent is 1:50; and the amount ratio of the aromatic polyamide to the organic solvent is 0.5 g:100 ml.

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