A hydrogel coating for continuous zirconium oxide fiber weaving and its preparation method

Abstract

This invention relates to a hydrogel coating for continuous zirconia fiber weaving and its preparation method. The hydrogel of this invention is reinforced with surface-modified cellulose nanocrystals. First, a CNC suspension is obtained using acid hydrolysis; then, CNC-g-PAM is synthesized by grafting acrylamide onto the CNC surface using cerium ammonium nitrate-initiated polymerization; this is then added to a chemically cross-linked polyacrylic acid network to obtain a doubly cross-linked CNC-g-PAM / PAA nanocomposite hydrogel; simultaneously, zirconia fibers modified with a coupling agent are bonded to the hydrogel by abundant covalent bonds, uniformly forming a hydrogel coating on the fiber surface with stable covalent bonds and reversible hydrogen bonds. The hydrogel coating of this invention exhibits good mechanical properties and self-healing capabilities, while also being resistant to peeling from the fibers, improving the abrasion resistance of the zirconia fibers and enhancing the stability of the product in three-dimensional weaves.

Description

Technical Field

[0001] This invention relates to the field of materials preparation technology, and in particular to a hydrogel coating for improving the weaveability of continuous zirconia fibers and its preparation method. Background Technology

[0002] Zirconia fiber possesses properties such as high temperature resistance, oxidation resistance, low heat capacity, lightweight, and good insulation, making it highly sought after in aerospace, military defense, and modern advanced industries. For structural reinforcement in the aerospace and military fields, continuous zirconia fiber three-dimensional fabric reinforced composites, due to their excellent mechanical properties, can be used in high-temperature layered thermal insulation materials, radomes at the nose of missiles, and antenna windows of hypersonic vehicles. However, continuous zirconia fiber, being a polycrystalline fiber, suffers from poor bundle cohesion, high brittleness of single filaments, and poor flexibility. During its three-dimensional weaving process, frequent mechanical friction between multiple layers of yarn causes yarn damage, leading to fuzzing, splitting, and even breakage of the zirconia fiber bundles. This results in a decrease in the overall mechanical properties of the zirconia fiber three-dimensional texture and reduces its weaving efficiency. Therefore, performance damage and defects during the continuous zirconia fiber weaving process affect its processability and limit its application range.

[0003] Hydrogel coatings possess tunable mechanical properties and excellent adhesion, effectively improving the lubricity and durability of traditional substrates and medical device surfaces. However, existing hydrogel coating technologies face stringent requirements. Techniques such as surface bridging, initiation, or direct coating are either limited by specific substrates, rely on specific reaction systems, or require UV irradiation. These drawbacks result in poor universality for most current hydrogel coating technologies. Furthermore, existing strategies often involve lengthy preparation processes, such as stepwise crosslinking, soaking, and repeated heating / cooling cycles, extending hydrogel preparation time from several hours to several days—sacrificing preparation speed for improved mechanical properties. Therefore, achieving rapid preparation and high mechanical properties remains a key scientific challenge and a bottleneck in the field of hydrogels.

[0004] Currently, there is no domestic technology for preparing hydrogel coatings to improve the weaveability of continuous zirconia fibers. Therefore, it is of great significance to develop a controllable hydrogel coating to modify the surface of long, narrow-diameter / low-surface-energy zirconia fibers to improve their bundleability and antistatic properties, reduce their coefficient of friction, decrease the amount of fuzz generated during processing, and meet the performance requirements of zirconia fibers in subsequent three-dimensional texture forming processes such as weaving, lay-up, and winding. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a hydrogel coating for improving the weaveability of continuous zirconia fibers and its preparation method. The hydrogel coating prepared by this invention exhibits strong adhesion to the surface of zirconia fibers, high strength and toughness, and good lubricity, effectively solving the problem of risk of detachment during repeated friction. Simultaneously, the wear resistance and breaking strength of the zirconia fibers are improved, and the phenomena of fuzzing and fiber breakage are reduced, thereby comprehensively enhancing the stability of the product in three-dimensional weaving.

[0006] The technical solution of the present invention is as follows:

[0007] The first aspect of this invention protects a method for preparing a CNC-reinforced nanocomposite hydrogel, comprising the following steps:

[0008] S1: Mix microcrystalline cellulose with acid, stir and react, quench, centrifuge, remove supernatant and dialyze to obtain CNC suspension;

[0009] S2: Dilute the CNC suspension, sonicate it, add acid to adjust the pH to obtain the CNC reaction solution, stir with nitrogen gas, then add cerium ammonium nitrate and acrylamide in sequence to react, dialyze the reaction product, precipitate, dry, and pulverize to obtain CNC-g-PAM powder, add water to prepare CNC-g-PAM suspension for later use.

[0010] S3: CNC-g-PAM suspension, acrylic acid, N,N-methylenebisacrylamide were mixed with water and ultrasonically treated in an ice-water bath to obtain a homogeneous solution. Potassium persulfate was then added to react and obtain CNC-g-PAM-reinforced nanocomposite hydrogel.

[0011] Preferably, in step S1, the particle size of the microcrystalline cellulose is 20-200 μm; the acid is at least one of sulfuric acid, hydrochloric acid, and formic acid; the mass concentration of the acid is 60 wt%-70 wt%; the mass-volume ratio of the microcrystalline cellulose to the acid is 6-12 g: 45-100 mL; the temperature of the stirring reaction is 45℃-65℃, and the time is 0.5-1.5 h.

[0012] Preferably, in step S2, the dilution involves diluting the CNC suspension with water to 0.5–2 wt%; the acid is nitric acid with a mass concentration of 15%–45%; the pH adjustment refers to adjusting the pH to 1–4; the nitrogen purging and stirring time is 10–30 min; the mass-to-volume ratio of cerium ammonium nitrate to the CNC reaction solution is 0.1–0.6 g: 30–100 mL; the mass ratio of cerium ammonium nitrate to acrylamide is 0.1–0.6: 1.5–7; the reaction temperature is 45–65 °C, and the reaction time is 2–4 h; the mass fraction of the CNC-g-PAM suspension is 0.7%–3.5%.

[0013] Preferably, in step S3, the amount of CNC-g-PAM suspension added is 0% to 2% of the mass of acrylic acid; the amount of N,N-methylenebisacrylamide added is 0.1% to 0.6% of the mass of acrylic acid; the mass ratio of acrylic acid to water is 30 to 42:100; the amount of potassium persulfate added is 1% to 4% of the mass of acrylic acid; and the reaction time is 30 min to 90 min.

[0014] A second aspect of this invention protects a hydrogel prepared by the preparation method described in the first aspect above.

[0015] A third aspect of this invention protects an application of the hydrogel described in the second aspect above, wherein the hydrogel is used to prepare coatings, including textile coatings, medical device coatings, and composite material coatings.

[0016] A fourth aspect of this invention protects a method for preparing a hydrogel coating for continuous zirconia fiber weaving, the method comprising the following steps:

[0017] S2-1: After immersing the zirconium oxide fiber in the coupling agent solution for a certain period of time, remove it and dry it;

[0018] S2-2: Prepare CNC-g-PAM suspension, acrylic acid, and N,N-methylenebisacrylamide by the method according to any one of claims 1-4, add water and sonicate to obtain solution A, and then impregnate the zirconium oxide fiber treated in step S2-1 in solution A and take it out for later use.

[0019] S2-3: The initiator solution is sprayed onto the surface of the zirconia fiber treated in step S2-2. After standing at room temperature for a period of time, the zirconia fiber with hydrogel coating can be obtained.

[0020] Preferably, in step S2-1, the coupling agent solution is obtained by mixing the coupling agent, water, and ethanol to obtain a mixture and then adjusting the pH to 3.0-5.8. The mixture, by mass percentage, includes 1%-8% coupling agent, 2%-9% water, and the remainder is ethanol. The coupling agent is a silane coupling agent. Preferably, the coupling agent is selected from at least one of vinyltriacetoxysilane, vinyltrimethoxysilane, vinyltri(ethoxymethoxy)silane, γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropylmethoxydiethoxysilane, and γ-methacryloyloxypropylmethyldimethoxysilane. The impregnation time is 12h-24h, and the drying temperature is 45℃-75℃.

[0021] Preferably, in step S2-2, the amount of N,N-methylenebisacrylamide added is 0.1-0.6% of the mass of acrylic acid; the amount of CNC-g-PAM suspension added is 0-5% of the mass of acrylic acid; and the mass ratio of acrylic acid to water is 30-42:100.

[0022] Preferably, in steps S2-3, the initiator solution is obtained by ultrasonically mixing an initiator with water; the initiator is potassium persulfate; the amount of potassium persulfate used is 1% to 4% of the mass of acrylic acid; the standing time is 30 to 90 minutes; the spraying distance is 10 to 15 cm, and the number of spraying times is 1 to 3.

[0023] The fifth aspect of this invention protects a continuous zirconia fiber with a hydrogel coating prepared by the preparation method described in the fourth aspect above, wherein the thickness of the hydrogel coating is 0.09 mm to 0.15 mm.

[0024] The beneficial technical effects of this invention are as follows:

[0025] (1) This invention synthesizes polyacrylamide-grafted cellulose nanocrystals by using cerium salt-initiated acrylamide graft polymerization on the surface of CNC, and then adds them to a chemically crosslinked polyacrylic acid network to obtain a double-crosslinked CNC-g-PAM / PAA nanocomposite hydrogel. CNC-g-PAM acts as both an interfacially compatible nanofiller and a physical crosslinking agent through hydrogen bonding between polyacrylic acid (PAA) and polyacrylamide (PAM) on the CNC surface. Simultaneously, the presence of hydrogen bonds improves the interfacial compatibility between the CNC and the PAA matrix. The synergistic effect of the nanofiller enhancing and disrupting hydrogen bonds dissipates energy, giving the CNC-g-PAM / PAA nanocomposite hydrogel high mechanical properties. Furthermore, reversible hydrogen bonding endows the CNC-g-PAM / PAA nanocomposite hydrogel with excellent self-healing capabilities.

[0026] (2) Due to its smooth surface and poor activity, zirconia fiber has insufficient adhesion to other materials. To improve the adhesion of the hydrogel coating to zirconia fiber, this invention modifies the zirconia fiber with a silane coupling agent, improving the wettability of the fiber surface and increasing its activity. Furthermore, the double bonds on the coupling agent on the fiber surface are covalently bonded to the CNC-g-PAM / PAA nanocomposite hydrogel, making the coating less prone to peeling or detachment during use.

[0027] (3) The hydrogel coating and its preparation method for improving the weaveability of continuous zirconia fibers described in this invention reduce the coefficient of friction of the fibers by uniformly forming a hydrogel coating on the surface of modified zirconia fibers, thereby effectively improving the wear resistance of brittle continuous zirconia fibers and giving them certain lubrication characteristics. At the same time, it improves the fuzzing and breakage phenomena that occur after fiber friction, and improves the mechanical properties and processing performance of the fibers, thereby improving the weaveability, weaving efficiency and product quality of zirconia fabrics.

[0028] (4) The hydrogel coating for improving the weaveability of continuous zirconia fibers described in this invention has good film-forming properties, is simple to synthesize, and has good mechanical properties and self-healing ability. In addition, the synthesis process does not require ultraviolet light, oxygen-free environment, heating, molds, etc., which breaks through the limitations of hydrogel polymerization and crosslinking conditions on traditional hydrogel coatings and can be applied to large-area coatings. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the preparation of the CNC-g-PAM / PAA nanocomposite hydrogel of the present invention and a schematic diagram of its network microstructure.

[0030] Figure 2 This is a schematic diagram illustrating the preparation of the continuous zirconia fiber composite hydrogel coating of the present invention. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] To address the conflict between the mechanical properties and processability of hydrogels in existing technologies, as well as the problems of yarn damage, fuzzing, splitting, and breakage that easily occur during the weaving of continuous zirconia fibers, this invention provides a hydrogel coating for improving the weaveability of continuous zirconia fibers and its preparation method. The resulting hydrogel coating has a strong bond with the surface of zirconia fibers, high strength and toughness, and is lubricating, effectively solving the problem of the risk of detachment during repeated friction. Simultaneously, the abrasion resistance and breaking strength of zirconia fibers are improved, and the phenomena of fuzzing and breakage are reduced, thereby comprehensively improving the stability of the product in three-dimensional weaving.

[0033] This invention first modifies zirconia fibers with a coupling agent to improve the activity and wettability of the fiber surface. Then, an in-situ polymerization method is used to uniformly form a CNC (cellulose nanocrystal) reinforced nanocomposite hydrogel coating on the fiber surface, which is doubly cross-linked by stable covalent bonds and reversible hydrogen bonds, exhibiting good mechanical properties and self-healing capabilities. The double bonds on the coupling agent on the fiber surface are richly covalently bonded to the CNC-g-PAM / PAA nanocomposite hydrogel, preventing peeling and shedding during use. The synergistic effect between the two reduces the coefficient of friction of the fiber, effectively improving the wear resistance of brittle zirconia fibers. At the same time, it improves the fuzzing and fiber breakage phenomena that occur after zirconia fiber friction, enhances the mechanical and processing properties of the fiber, and comprehensively improves the stability of the product in three-dimensional texture.

[0034] In this invention, the amorphous regions of cellulose can be removed by acid-catalyzed hydrolysis, while the densely packed crystalline regions are not easily hydrolyzed and are thus retained.

[0035] It is understood that the initiator cerium ammonium nitrate used in this invention can form a redox initiation system with the hydroxyl groups on the cellulose surface, so that chain initiation and growth can both occur on the CNC surface, resulting in high initiation selectivity and grafting efficiency.

[0036] CNC can be directly used as a filler in the preparation of nanocomposite hydrogels. However, the physical interaction between CNC and the hydrogel matrix is ​​weak. In this invention, polyacrylamide-grafted cellulose nanocrystals are incorporated into a chemically cross-linked PAA network. The polyacrylamide-grafted cellulose nanocrystals (CNC-g-PAM) can act as both a nanofiller and a physical cross-linking agent through hydrogen bonds between PAA and PAM on the CNC surface. Chemical cross-linking improves the elastic properties of the material, while non-covalent hydrogen bonds improve the viscoelasticity and recovery properties of the material.

[0037] It is understood that in this invention, the dual crosslinking of the dual crosslinked CNC-g-PAM / PAA nanocomposite hydrogel is specifically as follows: (1) chemical crosslinking: PAA is crosslinked by covalent bonds; (2) physical crosslinking: reversible hydrogen bonds between PAA and PAM on the CNC surface.

[0038] It is understood that this invention modifies zirconia fibers with a silane coupling agent, improving the wettability of the fiber surface and enhancing its activity. Furthermore, the double bonds on the coupling agent on the fiber surface are covalently bonded to the CNC-g-PAM / PAA nanocomposite hydrogel, preventing peeling or detachment during use. Without modification of the zirconia, a hydrogel coating would form directly on its surface, resulting in weak adhesion and easy detachment.

[0039] For the coupling agent, the molecular structure of the silane coupling agent used in this invention is YR-Si(OR)3, wherein Si-OR is a silaneoxy group. The Si-OR structure in the coupling agent hydrolyzes into a Si-OH structure and forms three active hydroxyl groups. After hydrolysis, the silanol groups can bind to the pretreated fiber surface and form covalent bonds with the fiber during the heating and drying process, so that the coupling agent is grafted onto the fiber surface. At the same time, the silane coupling agent is bound to the CNC-g-PAM / PAA nanocomposite hydrogel by abundant covalent bonds.

[0040] All fibers used in this invention are single-strand fibers.

[0041] All raw materials described in this invention are commercially available. Specific information about the raw materials is as follows:

[0042] Microcrystalline cellulose (MCC), acrylic acid (AA), and cerium ammonium nitrate (CAN) were purchased from China National Pharmaceutical Chemical Reagent Co., Ltd.; sulfuric acid (98%), nitric acid, and acrylamide (AM) were purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; N,N'-methylenebisacrylamide (MBA) was purchased from Nanjing Chemical Reagent Co., Ltd.; coupling agent was from Hangzhou Jessica Chemical Co., Ltd.; and ammonium persulfate (APS) was purchased from Wujiang Nanfeng Fine Chemical Co., Ltd.

[0043] Example 1

[0044] A CNC-reinforced nanocomposite hydrogel with stable covalent bonds and reversible hydrogen bonds is prepared by means of the following steps:

[0045] S1: CNC fabrication:

[0046] 7.5 g of microcrystalline cellulose (MCC) was mixed with 100 mL of 68 wt% H₂SO₄ solution and stirred at 50 °C for 1.5 h. After the reaction, the product was poured into 1000 mL of deionized water to quench the hydrolysis. The resulting suspension was centrifuged, the supernatant was removed, and the remaining suspension was dialyzed with deionized water until pH = 7 to obtain the CNC suspension.

[0047] S2: Preparation of CNC-g-PAM:

[0048] The CNC suspension was first diluted and sonicated to obtain 100 mL of 1 wt% aqueous CNC suspension. This suspension was transferred to a three-necked flask, and the pH was adjusted to 2 with nitric acid. The mixture was stirred for 30 min under nitrogen purging. 0.35 g of cerium ammonium nitrate (CAN) was added at 45 °C, and the mixture was stirred for 15 min. Then, 2.2 g of acrylamide (AM) was added, and the mixture was stirred for 3.5 h under nitrogen purging. After the reaction was complete, the product was placed in a dialysis bag and dialyzed at room temperature for 4 days to separate unreacted acrylamide and other impurities. A CNC-g-PAM aqueous suspension was obtained after dialysis. This suspension was then poured into ethanol to form a precipitate, which was vacuum dried and pulverized to obtain CNC-g-PAM powder. Water was added to obtain a 3% (w / w) CNC-g-PAM suspension.

[0049] S3: Preparation of CNC-g-PAM reinforced nanocomposite hydrogels:

[0050] CNC-g-PAM suspension (0.5% of AA by mass), AA, MBA (0.3% of AA by mass), and deionized water were mixed and sonicated in an ice-water bath to obtain a homogeneous solution with a mass ratio of AA to deionized water of 34%. APS (3% of AA by mass) was added to the resulting solution, and the mixture was reacted at room temperature for 30 min to form a hydrogel.

[0051] Example 2

[0052] Example 2 is the same as Example 1, except that CNC-g-PAM suspension was not added in step S3.

[0053] Example 3

[0054] Example 3 is the same as Example 1, except that the amount of CNC-g-PAM suspension in step S3 is changed. In this example, the mass fraction of CNC-g-PAM suspension is 3%, and the suspension accounts for 1% of the mass of AA.

[0055] Example 4

[0056] Example 4 is the same as Example 1, except that the amount of CNC-g-PAM suspension in step S3 is changed. In this example, the mass fraction of CNC-g-PAM suspension is 3%, and the suspension accounts for 2% of the mass of AA.

[0057] The elastic modulus, elongation at break, and tensile strength of the hydrogels in Examples 1-4 were measured, and the results are shown in Table 1.

[0058] Table 1. Hydrogel properties with different CNC-g-PAM solid contents

[0059] Sample Elastic modulus (kPa) Fracture strength (kPa) Elongation at break (%) Example 1 60 200 433 Example 2 30 30 156 Example 3 70 247 354 Example 4 85 300 318

[0060] Table 1 shows that without the addition of CNC-g-PAM, the E value of the hydrogel is 30 kPa, and the σ value is... b The E value is 30 kPa and the ε value is 156%, indicating the brittleness of purely chemically cross-linked hydrogels. When the CNC-g-PAM addition is 2%, the E value of the hydrogel is 85 kPa and the σ value is... b The value was 300 kPa and the ε value was 318%, which were 2.83 times, 10 times, and 2 times that of the unadded CNC-g-PAM hydrogel, respectively.

[0061] Example 5

[0062] A hydrogel coating for continuous zirconium oxide fiber weaving, the preparation method of which includes the following steps:

[0063] S1: Zirconia fibers were immersed in a vinyltrimethoxysilane solution for 12 hours. The acidic solution of the silane coupling agent was prepared by mixing 1 wt% vinyltrimethoxysilane, 2 wt% deionized water, and 97 wt% anhydrous ethanol until homogeneous, and adding 0.5 mol / L hydrochloric acid solution dropwise while stirring to adjust the pH of the solution to 3.0. After the reaction was complete, the fibers were washed with deionized water to remove the adsorbed silane coupling agent and ethanol, and then dried at 50°C.

[0064] S2: CNC-g-PAM was prepared according to the method in Example 1, and diluted with water to obtain a CNC-g-PAM suspension. The CNC-g-PAM suspension (2% of the mass of AA), AA, MBA (0.3% of the mass of AA) and deionized water (the mass ratio of AA to water is 34:100) were ultrasonically mixed to obtain solution A. The grafted modified zirconia fiber was immersed in solution A for 20 min.

[0065] S3: After ultrasonically mixing the initiator APS (3% of the mass of AA) and deionized water, a solution B with a mass fraction of 4% is obtained. Solution B is uniformly sprayed onto the surface of continuous zirconia fiber and reacted at room temperature for 30 minutes to form a hydrogel coating.

[0066] In this embodiment, when repeatedly rubbed under a 1N load, the wear occurs after approximately 350 cycles, resulting in scratches and debris.

[0067] Example 6

[0068] Example 6 is the same as Example 5, except that the method of preparing the vinyltrimethoxysilane solution is as follows: 2 wt% vinyltrimethoxysilane, 5 wt% deionized water and 93 wt% anhydrous ethanol are mixed evenly, and 0.5 mol / L hydrochloric acid solution is added dropwise while stirring to adjust the pH of the solution to 3.0.

[0069] In this embodiment, the coating begins to peel off after approximately 387 rubs when repeatedly rubbed under a 1N load.

[0070] Example 7

[0071] Example 7 is the same as Example 5, except that the preparation method of the vinyltrimethoxysilane solution is as follows: 3 wt% vinyltrimethoxysilane, 3 wt% deionized water and 94 wt% anhydrous ethanol are mixed evenly, and 0.5 mol / L hydrochloric acid solution is added dropwise while stirring to adjust the pH of the solution to 3.0.

[0072] In this embodiment, the hydrogel coating showed no obvious damage or peeling when repeatedly rubbed 400 times under a 1N load.

[0073] Example 8

[0074] Example 8 is the same as Example 5, except for the silane coupling agent and its preparation method. In this example, the silane coupling agent is γ-methacryloxypropyltrimethoxysilane. The solution is prepared by mixing 3.5wt% γ-methacryloxypropyltrimethoxysilane, 5wt% deionized water and 91.5wt% anhydrous ethanol evenly, and adding 0.5mol / L hydrochloric acid solution dropwise while stirring to adjust the pH of the solution to 3.0.

[0075] In this embodiment, the hydrogel coating showed no obvious damage or peeling when repeatedly rubbed 400 times under a 1N load.

[0076] Example 9

[0077] Example 9 is the same as Example 5, except for the silane coupling agent and its preparation method. The silane coupling agent in this example is vinyltris(ethoxymethoxy)silane. The solution is prepared by mixing 4 wt% vinyltris(ethoxymethoxy)silane, 4 wt% deionized water and 92 wt% anhydrous ethanol evenly, and adding 0.5 mol / L hydrochloric acid solution dropwise while stirring to adjust the pH of the solution to 3.0.

[0078] In this embodiment, when repeatedly rubbed under a 1N load, the wear occurs after approximately 390 wear cycles, resulting in scratches and debris.

[0079] Comparative Example 1

[0080] Comparative Example 1 is the original zirconium oxide monofilament fiber from Example 5.

[0081] Comparative Example 2

[0082] Comparative Example 2 is the same as Example 5, except that the zirconia fiber is not modified in step S1, and the rest is the same as Example 5.

[0083] In this comparative example, since the zirconium oxide fiber was not modified, the hydrogel coating was difficult to graft onto the fiber surface. Under repeated friction under a 1N load, the coating could be peeled off after 280 friction cycles.

[0084] Comparative Example 3

[0085] The difference between Comparative Example 3 and Example 5 is that only the zirconium oxide fiber was modified in step S1.

[0086] The mechanical properties, wear rate, and coefficient of friction of the coated zirconia fibers prepared in the examples and comparative examples were measured, and the results are shown in Table 2.

[0087] The tensile breaking strength test was conducted according to GB / T3362-2005; the stiffness test was conducted according to GB / T7690.4-2013 Test Methods for Reinforcing Materials Yarns Part 4: Determination of Stiffness; the abrasion rate test was conducted according to FZ / T01058-1999 Test Methods for Yarn Abrasion Resistance - Reciprocating Roller Method; the coefficient of friction (COF) test was conducted using a UMT-Tribolab tribolab friction and wear tester. The fibers were fixed in place by a self-made clamp, and the fibers were subjected to contact friction in a cross-shaped manner (perpendicular to each other) before the results were read.

[0088] Table 2. Performance test results before and after zirconia fiber composite hydrogel coating.

[0089]

[0090]

[0091] As shown in Table 2, compared with the original continuous zirconia fiber, under the condition of a coating thickness of about 0.12 mm, the wear rate of the fiber is reduced by 3.5% to 11.9%, the coefficient of friction is reduced by 11.2% to 20.8%, the wear resistance is significantly improved, and the self-lubricating property is achieved to a certain extent; the tensile properties of the fiber are improved by 2.9% to 8.6%, and the stiffness is reduced, which helps to improve the fiber damage and breakage caused by bending deformation during continuous zirconia fiber weaving.

[0092] Compared to Comparative Example 2, which did not modify the zirconia fibers, the continuous zirconia composite hydrogel coatings prepared in Examples 5-9, which were modified with coupling agents, showed significantly reduced wear rate and coefficient of friction, while improved adhesion and abrasion resistance. This helps to mitigate fiber damage and even breakage caused by frequent friction during continuous zirconia fiber weaving. Therefore, the CNC-reinforced nanocomposite hydrogel coating with stable covalent bonds and reversible hydrogen bonds used in this invention can effectively protect the fibers while maintaining their thinness, uniform thickness, and flexibility, and simultaneously imparts a certain degree of self-lubricating properties to the fibers. This reduces frictional damage to continuous zirconia fibers during weaving, thereby improving the weavability of the fibers.

[0093] This invention modifies continuous zirconia fibers by using coupling agents with different formulations, and then uses in-situ polymerization to uniformly form a CNC-reinforced nanocomposite hydrogel coating on the fiber surface, which is doubly cross-linked by stable covalent bonds and reversible hydrogen bonds, thereby improving the wear and fiber breakage of continuous zirconia fibers during production and processing.

[0094] The above description is merely a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It is understood that other improvements and variations that are directly derived or conceived by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included within the protection scope of the present invention.

Claims

1. A method for preparing a hydrogel coating for continuous zirconia fiber weaving, characterized in that, The preparation method includes the following steps: S2-1: After immersing the zirconium oxide fiber in the coupling agent solution for a certain period of time, remove it and dry it; S2-2: Add water to CNC-g-PAM suspension, acrylic acid, N,N-methylenebisacrylamide and sonicate to obtain solution A. Impregnate the zirconium oxide fiber treated in step S2-1 in solution A and then take it out for later use. S2-3: The initiator solution is sprayed onto the surface of the zirconia fiber treated in step S2-2. After standing at room temperature for a period of time, the zirconia fiber with hydrogel coating can be obtained. In step S2-2, the preparation method of the CNC-g-PAM suspension includes the following steps: S1: Mix microcrystalline cellulose with acid, stir and react, quench, centrifuge, remove supernatant and dialyze to obtain CNC suspension; S2: Dilute the CNC suspension, sonicate it, add acid to adjust the pH to obtain the CNC reaction solution, stir with nitrogen gas, then add cerium ammonium nitrate and acrylamide to react, dialyze the reaction product, precipitate, dry, pulverize to obtain CNC-g-PAM powder, add water to prepare CNC-g-PAM suspension; In step S2-1, the coupling agent solution is obtained by mixing coupling agent, water and ethanol to obtain a mixture and then adjusting the pH to 3.0~5.

8. The mixture, by mass percentage, includes 1%~8% coupling agent, 2%~9% water, and the balance is ethanol. The coupling agent is a silane coupling agent.

2. The preparation method according to claim 1, characterized in that, In step S1, the particle size of the microcrystalline cellulose is 20~200μm; the acid is at least one of sulfuric acid, hydrochloric acid, and formic acid; and the mass concentration of the acid is 60wt%~70wt%. The mass-to-volume ratio of the microcrystalline cellulose to the acid is 6~12g:45~100mL; the stirring reaction temperature is 45℃~65℃, and the time is 0.5~1.5h.

3. The preparation method according to claim 1, characterized in that, In step S2, the dilution involves diluting the CNC suspension with water to 0.5-2 wt%; the acid is nitric acid with a mass concentration of 15%-45%; the pH adjustment refers to adjusting the pH to 1-4; the stirring time with nitrogen gas is 10-30 min; the mass-to-volume ratio of cerium ammonium nitrate to the CNC reaction solution is 0.1-0.6 g : 30-100 mL; the mass ratio of cerium ammonium nitrate to acrylamide is 0.1-0.6 : 1.5-7; the reaction temperature is 45-65℃, and the reaction time is 2-4 h; the mass fraction of the CNC-g-PAM suspension is 0.7%-3.5%.

4. The preparation method according to claim 1, characterized in that, In step S2-1, the coupling agent is selected from at least one of vinyltriacetoxysilane, vinyltrimethoxysilane, vinyltri(ethoxymethoxy)silane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethoxydiethoxysilane, and γ-methacryloxypropylmethyldimethoxysilane; the impregnation time is 12h~24h, and the drying temperature is 45℃~75℃.

5. The preparation method according to claim 1, characterized in that, In step S2-2, the amount of N,N-methylenebisacrylamide added is 0.1~0.6% of the mass of acrylic acid; the amount of CNC-g-PAM suspension added is 2~5% of the mass of acrylic acid; and the mass ratio of acrylic acid to water is 30~42:

100. In steps S2-3, the initiator solution is obtained by ultrasonically mixing an initiator with water; the initiator is potassium persulfate; the standing time is 30-90 minutes; the spraying distance is 10-15 cm, and the number of spraying times is 1-3.

6. A continuous zirconia fiber with a hydrogel coating prepared by the preparation method according to any one of claims 1-5, characterized in that, The thickness of the hydrogel coating is 0.09 mm to 0.15 mm.

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