Preparation method of anti-fragment material with negative Poisson's ratio effect

Abstract

The invention provides a preparation method of an anti-fragment material with a negative Poisson's ratio effect, and relates to the field of bulletproof materials, and the preparation method comprises the following steps: S1, preparing a negative Poisson's ratio fiber fabric: selecting any two of ultra-high molecular weight polyethylene, aramid fiber and carbon fiber to prepare the negative Poisson's ratio fiber fabric; s2, preparation of shear thickening gel: firstly preparing a carbon nanotube dispersion liquid, and then preparing a matrix solution; then, mixing the carbon nanotube dispersion liquid with the matrix solution, and sequentially adding silicon dioxide, a reinforced phase and an additive to obtain shear reinforced gel; and S3, preparing the anti-fragment material. According to the method, through superposition of the negative Poisson's ratio fiber fabric and the shear thickening gel, the anti-penetration advantage of the negative Poisson's ratio fiber fabric is reserved, the inherent mechanical shortages of the negative Poisson's ratio fiber fabric are made up, and the anti-fragment material which is light in weight, high in efficiency and high in stability is obtained.

Description

Technical Field

[0001] This invention relates to the field of bulletproof materials technology, and in particular to a method for preparing a fragmentation-resistant material with a negative Poisson's ratio effect. Background Technology

[0002] Fragmentation resistant materials are functional materials specifically designed to block, decelerate, or absorb the kinetic energy of high-speed fragments. Their core objective is to reduce penetrating injuries to personnel, equipment, or facilities. Due to the characteristics of high speed, irregular shape, and concentrated energy in fragments, fragmentation resistant materials typically possess high strength, high toughness, strong energy absorption, and lightweight properties. Currently, most existing fragmentation resistant materials utilize one of the following: ultra-high molecular weight polyethylene (UHMWPE), aramid fiber, or carbon fiber. UHMWPE fibers have high specific strength (strength / density) and excellent flexibility, enabling them to reduce localized stress concentration by utilizing the elastic deformation of the fibers before breakage and the overall dispersion of energy transmission through the fabric structure during high-speed fragment impact. Aramid fibers possess high temperature resistance and impact toughness, achieving energy dissipation through "rigid load-bearing and fabric interweaving friction," effectively hindering fragment penetration. Carbon fiber has ultra-high elastic modulus and resistance to deformation, relying on "rigid blocking and delamination energy dissipation," dispersing the impact force of fragments through matrix cracking, fiber breakage, and interlayer delamination. However, fragment impact is a complex process involving energy absorption, stress dispersion, and adaptability to multiple scenarios. The energy absorption mechanism of a single fiber material is limited, which not only fails to meet the requirements of complex environments (e.g., UHMWPE fiber has poor temperature resistance and is prone to softening at high temperatures, leading to a sharp drop in strength; aramid fiber is prone to moisture absorption after long-term use, resulting in a decrease in modulus; carbon fiber is brittle and prone to "brittle fracture"), but also fails to meet the requirements of lightweight and low cost.

[0003] The negative Poisson's ratio effect refers to the phenomenon that when a material is stretched, it expands both laterally and longitudinally, and when compressed, it contracts both laterally and longitudinally. Based on this effect and considering the differences in modulus between different fibers, a fiber fabric structure with a negative Poisson's ratio is obtained. When subjected to impact, this fiber fabric structure can effectively improve the overall tensile strength and enhance energy absorption. However, the energy absorption of negative Poisson's ratio fiber fabrics mainly relies on the elastic deformation of the structure. Under high-energy fragment impacts, it is prone to failure due to irreversible structural damage, thus affecting the overall fragmentation resistance performance. At the same time, the poor uniformity of the negative Poisson's ratio fiber fabric structure (such as loose weave nodes and inconsistent rebound of crimped fibers) creates stress concentration points during impact, leading to localized failure. In addition, to improve penetration resistance, negative Poisson's ratio fiber fabrics often need to increase their thickness, resulting in increased material weight, which violates the requirement for lightweight protective equipment. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide a method for preparing a fragmentation-resistant material with a negative Poisson's ratio effect. This method involves superimposing a negative Poisson's ratio fiber fabric with a shear-thickening gel, utilizing complementary energy absorption mechanisms, filling structural defects, and synergistic dynamic performance. This method retains the anti-penetration advantage of the negative Poisson's ratio fiber fabric while compensating for its inherent mechanical shortcomings, thereby obtaining a fragmentation-resistant material that is "lightweight, high-efficiency, and highly stable".

[0005] The objective of this invention is achieved through the following technical solution: A method for preparing a fragment-resistant material with a negative Poisson's ratio effect, comprising: Step S1: Preparation of negative Poisson's ratio fiber fabric: Select any two of ultra-high molecular weight polyethylene (UHMWPE), aramid, and carbon fiber, use low modulus fiber as core fiber and high modulus fiber as winding fiber, spirally wind high modulus fiber onto low modulus fiber to obtain negative Poisson's ratio fiber preform, and finally weave the resulting fiber preform into negative Poisson's ratio fiber fabric. Step S2, preparation of shear-thickening gel: First, prepare a carbon nanotube dispersion, then prepare a matrix solution; then, mix the carbon nanotube dispersion and the matrix solution, and add silica, reinforcing phase and additives in sequence to obtain a shear-enhanced gel; Step S3, Preparation of anti-fragmentation material: First, the negative Poisson's ratio fiber fabric woven in step S1 is screened and pre-processed. Then, the pre-processed negative Poisson's ratio fiber fabric is impregnated in shear gel and vacuum degassed. Finally, the impregnated negative Poisson's ratio fiber fabric is dried and cured to obtain the anti-fragmentation material.

[0006] Based on further optimization of the above scheme, the diameter ratio of the high-modulus fiber to the low-modulus fiber is 0.1 to 2:1, and the winding angle θ is 10° to 80°.

[0007] Based on further optimization of the above scheme, the specific preparation steps of the carbon nanotube dispersion are as follows: First, 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-4-methylpyridine tetrafluoroborate are stirred in a constant temperature water bath at 40-50℃ for 28-32 min to achieve uniform mixing and obtain a mixed ionic liquid; then, hydroxypropyl-β-cyclodextrin is added, and the mixture is kept in a constant temperature water bath at 40-50℃ and stirred continuously for 1-2 h until the hydroxypropyl-β-cyclodextrin is completely dissolved; after that, pretreated carbon nanotubes with a diameter of 5-10 nm and an aspect ratio of 10 are added. 4 ~10 5 First, mechanically stir for 28–32 minutes, then sonicate to obtain a carbon nanotube dispersion.

[0008] Based on further optimization of the above scheme, the mass ratio of 1-butyl-3-methylimidazolium tetrafluoroborate to 1-butyl-4-methylpyridine tetrafluoroborate is 6-7:3-4; the mass ratio of hydroxypropyl-β-cyclodextrin to carbon nanotubes is 1-3:1; and the concentration of carbon nanotubes in the carbon nanotube dispersion is 0.5-3.0 wt%.

[0009] Based on further optimization of the above scheme, the carbon nanotube pretreatment is specifically as follows: First, carbon nanotubes are added to a mixture of concentrated nitric acid and concentrated sulfuric acid, with a solid-liquid ratio of 0.8–1.2 g: 18–22 mL and a volume ratio of concentrated nitric acid to concentrated sulfuric acid of 1:3. The mixture is then magnetically stirred at 55–65 °C for 1.8–2.2 h. Next, the mixture is centrifuged and washed with deionized water at 7500–8500 rpm for 8–12 min each time, until the pH of the filtrate is 6–7. Finally, the mixture is vacuum dried at 55–65 °C and a vacuum degree of -0.08 MPa to -0.09 MPa for 10–12 h, and then ground into powder to obtain the pretreated carbon nanotubes.

[0010] Based on further optimization of the above scheme, the specific preparation steps of the matrix solution are as follows: First, ethylene glycol, PEG400 and glycerol are mixed in proportion and mechanically stirred for 18-22 min to obtain a base liquid; then, KH550 (γ-aminopropyltriethoxysilane) and nano-montmorillonite with a particle size of 40-60 nm are added to the base liquid, and the mixture is stirred at high speed at 1400-1600 rpm for 28-32 min at a temperature of 30-40°C, and then ultrasonically treated at a power of 200-300 W for 18-22 min to obtain a matrix suspension.

[0011] Based on further optimization of the above scheme, the mass ratio of ethylene glycol, PEG400 and glycerol is 3.8-4.2:2.8-3.2:2.8-3.2, the amount of KH550 accounts for 1.3-1.7 wt% of the matrix solution, and the amount of nano-montmorillonite accounts for 2.8-3.2 wt% of the matrix solution.

[0012] Based on further optimization of the above scheme, the carbon nanotube dispersion and the matrix solution are mixed at a volume ratio of 0.8-1.2:4.8-5.2 and mechanically stirred at 800-1000 rpm for 50-70 min; the particle size of silica is 12-100 nm, and the amount of silica used is 5-10 wt% of the shear-thickening gel.

[0013] Based on further optimization of the above scheme, the reinforcing phase is a mixture of PNIPAM (poly-N-isopropylacrylamide) microgel with a particle size of 80-120 nm and nanocellulose with a diameter of 5 nm and a length of 180-220 nm; wherein, the amount of PNIPAM microgel is 1.5-2.5 wt% of the shear-thickening gel, and the amount of nanocellulose is 1.2-1.8 wt% of the shear-thickening gel.

[0014] Based on further optimization of the above scheme, the additive is FeCl3·6H2O, and the amount of FeCl3·6H2O is 0.15 to 0.25 wt% of the shear-thickening gel.

[0015] Based on further optimization of the above scheme, the screening and pre-processing of the negative Poisson's ratio fiber fabric in step S3 is as follows: First, fabrics with splices or missing yarns are removed and cut into blocks that meet the size requirements; then, the cut fiber fabric is pre-soaked in a dopamine and Tris (tris(hydroxymethyl)aminomethane)-HCl buffer solution (buffer pH is 8.5), with the dopamine dosage being 0.8-1.2 wt%, and left to stand at a temperature of 27-33°C for 3.5-4.5 hours. After removal, it is rinsed with deionized water until neutral and dried at 55-60°C.

[0016] Based on further optimization of the above scheme, in step S3, the impregnation time of the pre-processed negative Poisson's ratio fiber fabric in the shear gel is 1 to 1.5 hours; the vacuum degree of the vacuum degassing treatment is -0.08 MPa to -0.09 MPa, and the treatment time is 12 to 16 minutes.

[0017] Based on further optimization of the above scheme, the drying and curing in step S3 specifically involves drying in an oven at 45-55°C for 1-2 hours.

[0018] The following are the technical effects of this solution: This invention effectively suppresses the spontaneous aggregation of carbon nanotubes during the mixing process of shear-thickening gels by preparing a carbon nanotube dispersion. This avoids problems such as decreased mechanical properties of the gel, formation of weak points in the protective structure, and "hysteresis" or "local failure" in the shear-thickening response caused by uneven dispersion due to carbon nanotube aggregation. Through the combination of carbon nanotube dispersion, matrix solution, silica, reinforcing phase, and additives, it not only effectively enhances the interfacial bonding between fibers and gel and improves stress transfer efficiency, but also improves the shear-thickening response speed and network strength, thereby enhancing the resistance to high-speed fragmentation. In addition, it effectively improves the stability of the shear-thickening gel, avoiding problems such as easy crystallization or glass transition at low temperatures, easy volatilization or softening at high temperatures, and ensuring the overall long-term stability of the shear-thickening gel.

[0019] This invention combines a negative Poisson's ratio structure with a shear-enhancing gel, and strengthens the interface between the two to obtain a lightweight, high-speed impact-resistant, and highly stable anti-fragmentation material, which has broad application prospects in areas such as individual soldier protection against blast impact fragments and armored vehicle protection against secondary fragments. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the winding of a negative Poisson's ratio fiber preform in an embodiment of the present invention.

[0021] Among them, 1. core fiber; 2. winding fiber; 3. winding angle. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0023] Example 1: A method for preparing a fragment-resistant material with a negative Poisson's ratio effect, comprising: Step S1: Preparation of negative Poisson's ratio fiber fabric: Select ultra-high molecular weight polyethylene (UHMWPE) fiber and carbon fiber (UHMWPE modulus approximately 150 GPa, carbon fiber modulus approximately 295 GPa), using UHMWPE fiber as the core fiber and carbon fiber as the winding fiber, and use a fiber winding machine to spirally wind the carbon fiber onto the UHMWPE fiber to obtain a negative Poisson's ratio fiber preform (e.g. Figure 1 As shown), the diameter ratio of carbon fiber to UHMWPE fiber is 0.1:1, and the winding angle θ is 45°; finally, the resulting fiber preform is woven into a negative Poisson's ratio fiber fabric.

[0024] Step S2, Preparation of Shear-Thickening Gel: First, prepare a carbon nanotube dispersion. Specifically, 1-Butyl-3-methylimidazolium tetrafluoroborate (CAS No.: 174501-65-6) and 1-Butyl-4-methylpyridine tetrafluoroborate (CAS No.: 343952-33-0) are stirred in a 40°C water bath for 32 min (stirring speed 300 rpm) to achieve uniform mixing and obtain a mixed ionic liquid. The mass ratio of 1-Butyl-3-methylimidazolium tetrafluoroborate to 1-Butyl-4-methylpyridine tetrafluoroborate is 6:4. Then, hydroxypropyl-β-cyclodextrin (CAS No.: 128446-5-5) is added, and the mixture is kept in a 40°C water bath and stirred continuously for 2 h (stirring speed 400 rpm) until the hydroxypropyl-β-cyclodextrin is completely dissolved. The mass ratio of hydroxypropyl-β-cyclodextrin to carbon nanotubes is 1:1. Then, pretreated carbon nanotubes with a diameter of 5–10 nm and an aspect ratio of 10 are added. 4 ~105 The carbon nanotube dispersion had a carbon nanotube concentration of 0.5 wt%. The dispersion was first mechanically stirred for 32 min (600 rpm) and then ultrasonically treated (400 W, ultrasonic for 50 min) to obtain the carbon nanotube dispersion. The carbon nanotube pretreatment involved adding carbon nanotubes to a mixture of concentrated nitric acid and concentrated sulfuric acid at a solid-liquid ratio of 0.8 g:18 mL and a volume ratio of 1:3. The mixture was magnetically stirred at 55℃ for 2.2 h (stirring speed 200 rpm). The mixture was then centrifuged and washed with deionized water at 7500 rpm for 12 min each time until the pH of the filtrate was 6–7. Finally, the mixture was vacuum dried at 55℃ and a vacuum degree of -0.08 MPa for 12 h, then ground into powder to obtain the pretreated carbon nanotubes.

[0025] The matrix solution was then prepared as follows: First, ethylene glycol, PEG400, and glycerol were mixed in a ratio of 3.8:2.8:2.8 by mass, and mechanically stirred for 22 minutes (stirring speed 300 rpm) to obtain a matrix solution. Then, KH550 (γ-aminopropyltriethoxysilane) and nano-montmorillonite with a particle size of 40-60 nm were added to the matrix solution. The amount of KH550 accounted for 1.3 wt% of the matrix solution, and the amount of nano-montmorillonite accounted for 2.8 wt% of the matrix solution. At a temperature of 30°C, the mixture was first stirred at a high speed of 1400 rpm for 32 minutes, and then ultrasonically treated at a power of 200 W for 22 minutes to obtain a matrix suspension.

[0026] Subsequently, the carbon nanotube dispersion was mixed with the matrix solution at a volume ratio of 0.8:4.8, and mechanically stirred at 800 rpm for 70 min. Silica with a particle size of 12–100 nm, the reinforcing phase, and the additive were added sequentially to obtain a shear-reinforced gel. The amount of silica used was 5 wt% of the shear-thickening gel, and stirring was performed for 40 min (stirring speed 500 rpm) after adding silica. The reinforcing phase consisted of a mixture of PNIPAM (poly-N-isopropylacrylamide) microgel with a particle size of 80–120 nm and nanocellulose with a diameter of 5 nm and a length of 180–220 nm. The amount of PNIPAM microgel was 1.5 wt% of the shear-thickening gel, and the amount of nanocellulose was 1.2 wt%. The additive was FeCl3·6H2O, with an amount of 0.15 wt% of the shear-thickening gel.

[0027] Step S3, Preparation of anti-fragmentation material: First, the negative Poisson's ratio fiber fabric woven in step S1 is screened and pre-processed. Specifically, the fabric with splices or missing yarns is first removed and cut into blocks that meet the size requirements (e.g., cut into 300mm x 300mm squares). Then, the cut fiber fabric is pre-soaked in dopamine (CAS No.: 51-61-6) and Tris (tris(hydroxymethyl)aminomethane)-HCl buffer (buffer pH is 8.5), with the dopamine dosage being 0.8wt%. The mixture is left to stand at 27℃ for 4.5h, then rinsed with deionized water until neutral and dried at 55℃.

[0028] The pre-processed negative Poisson's ratio fiber fabric was then immersed in shear gel for 1 hour; vacuum degassing treatment: the vacuum degree of the vacuum degassing treatment was -0.08 MPa, and the treatment time was 16 minutes.

[0029] Finally, the impregnated negative Poisson's ratio fiber fabric is dried and cured, specifically by drying in an oven at 45°C for 2 hours to obtain the anti-fragmentation material.

[0030] Example 2: A method for preparing a fragment-resistant material with a negative Poisson's ratio effect, comprising: Step S1: Preparation of negative Poisson's ratio fiber fabric: Ultra-high molecular weight polyethylene (UHMWPE) and aramid fiber (UHMWPE modulus approximately 150 GPa, aramid fiber modulus approximately 90 GPa) are selected. Aramid fiber is used as the core fiber, and UHMWPE fiber as the winding fiber. A fiber winding machine is used to spirally wind the UHMWPE fiber onto the aramid fiber to obtain a negative Poisson's ratio fiber preform (e.g., ...). Figure 1 As shown), the diameter ratio of UHMWPE fiber to aramid fiber is 0.2:1, and the winding angle θ is 45°; finally, the resulting fiber preform is woven into a negative Poisson's ratio fiber fabric.

[0031] Step S2, Preparation of Shear-Thickening Gel: First, prepare a carbon nanotube dispersion. Specifically, 1-Butyl-3-methylimidazolium tetrafluoroborate (CAS No.: 174501-65-6) and 1-Butyl-4-methylpyridine tetrafluoroborate (CAS No.: 343952-33-0) are stirred in a 45°C water bath for 30 min (stirring speed 350 rpm) to achieve uniform mixing, obtaining a mixed ionic liquid. The mass ratio of 1-Butyl-3-methylimidazolium tetrafluoroborate to 1-Butyl-4-methylpyridine tetrafluoroborate is 6.5:3.5. Then, hydroxypropyl-β-cyclodextrin (CAS No.: 128446-5-5) is added, and the mixture is kept in a 45°C water bath and stirred continuously for 1.5 h (stirring speed 450 rpm) until the hydroxypropyl-β-cyclodextrin is completely dissolved. The mass ratio of hydroxypropyl-β-cyclodextrin to carbon nanotubes is 2:1. Then, pretreated carbon nanotubes with a diameter of 5–10 nm and an aspect ratio of 10 are added. 4 ~10 5 The carbon nanotube dispersion had a carbon nanotube concentration of 2.0 wt%. The dispersion was first mechanically stirred for 30 min (700 rpm) and then ultrasonically treated (450 W, 45 min) to obtain the carbon nanotube dispersion. The carbon nanotube pretreatment involved adding carbon nanotubes to a mixture of concentrated nitric acid and concentrated sulfuric acid at a solid-liquid ratio of 1 g:20 mL and a volume ratio of 1:3. The mixture was magnetically stirred at 60℃ for 2 h (250 rpm). The mixture was then centrifuged and washed with deionized water at 8000 rpm for 10 min each time until the pH of the filtrate was 6–7. Finally, the mixture was vacuum dried at 60℃ and a vacuum degree of -0.08 MPa for 11 h, then ground into powder to obtain the pretreated carbon nanotubes.

[0032] The matrix solution was then prepared as follows: First, ethylene glycol, PEG400, and glycerol were mixed in a ratio of 4:3:3 by mass, and mechanically stirred for 20 minutes (stirring speed 350 rpm) to obtain a matrix solution. Then, KH550 (γ-aminopropyltriethoxysilane) and nano-montmorillonite with a particle size of 40-60 nm were added to the matrix solution. The amount of KH550 was 1.5 wt% of the matrix solution, and the amount of nano-montmorillonite was 3 wt% of the matrix solution. The mixture was stirred at 1500 rpm for 30 minutes at 35°C, and then ultrasonically treated for 20 minutes at 250 W to obtain a matrix suspension.

[0033] Subsequently, the carbon nanotube dispersion was mixed with the matrix solution at a volume ratio of 1:5, and mechanically stirred at 900 rpm for 60 min. Silica with a particle size of 12–100 nm, the reinforcing phase, and the additive were added sequentially to obtain a shear-reinforced gel. The amount of silica used was 7.5 wt% of the shear-thickening gel, and the mixture was stirred for 350 min (stirring speed 550 rpm) after adding silica. The reinforcing phase consisted of a mixture of PNIPAM (poly-N-isopropylacrylamide) microgel with a particle size of 80–120 nm and nanocellulose with a diameter of 5 nm and a length of 180–220 nm. The amount of PNIPAM microgel was 2 wt% of the shear-thickening gel, and the amount of nanocellulose was 1.5 wt%. The additive was FeCl3·6H2O, with an amount of FeCl3·6H2O of 0.2 wt% of the shear-thickening gel.

[0034] Step S3, Preparation of anti-fragmentation material: First, the negative Poisson's ratio fiber fabric woven in step S1 is screened and pre-processed. Specifically, the fabric with splices or missing yarns is first removed and cut into blocks that meet the size requirements (e.g., cut into 300mm x 300mm squares). Then, the cut fiber fabric is pre-soaked in dopamine (CAS No.: 51-61-6) and Tris (tris(hydroxymethyl)aminomethane)-HCl buffer (buffer pH is 8.5), with the dopamine dosage being 1 wt%. The mixture is left to stand at 30°C for 4 hours, then rinsed with deionized water until neutral and dried at 57°C.

[0035] The pre-processed negative Poisson's ratio fiber fabric was then immersed in shear gel for 1.2 hours; vacuum degassing treatment: the vacuum degree of the vacuum degassing treatment was -0.08 MPa, and the treatment time was 14 minutes.

[0036] Finally, the impregnated negative Poisson's ratio fiber fabric is dried and cured, specifically by drying in an oven at 50°C for 1.5 hours to obtain the anti-fragmentation material.

[0037] Example 3: A method for preparing a fragment-resistant material with a negative Poisson's ratio effect, comprising: Step S1: Preparation of negative Poisson's ratio fiber fabric: Ultra-high molecular weight polyethylene (UHMWPE) and aramid fiber (UHMWPE modulus approximately 150 GPa, aramid fiber modulus approximately 90 GPa) are selected. Aramid fiber is used as the core fiber, and UHMWPE fiber as the winding fiber. A fiber winding machine is used to spirally wind the UHMWPE fiber onto the aramid fiber to obtain a negative Poisson's ratio fiber preform (e.g., ...). Figure 1As shown), the diameter ratio of UHMWPE fiber to aramid fiber is 0.2:1, and the winding angle θ is 30°; finally, the resulting fiber preform is woven into a negative Poisson's ratio fiber fabric.

[0038] Step S2, Preparation of Shear-Thickening Gel: First, prepare a carbon nanotube dispersion. Specifically, 1-Butyl-3-methylimidazolium tetrafluoroborate (CAS No.: 174501-65-6) and 1-Butyl-4-methylpyridine tetrafluoroborate (CAS No.: 343952-33-0) are stirred in a 50°C water bath for 28 min (stirring speed 400 rpm) to achieve uniform mixing and obtain a mixed ionic liquid. The mass ratio of 1-Butyl-3-methylimidazolium tetrafluoroborate to 1-Butyl-4-methylpyridine tetrafluoroborate is 7:3. Then, hydroxypropyl-β-cyclodextrin (CAS No.: 128446-5-5) is added, and the mixture is kept in a 50°C water bath and stirred continuously for 1 h (stirring speed 500 rpm) until the hydroxypropyl-β-cyclodextrin is completely dissolved. The mass ratio of hydroxypropyl-β-cyclodextrin to carbon nanotubes is 3:1. Then, pretreated carbon nanotubes with a diameter of 5–10 nm and an aspect ratio of 10 are added. 4 ~10 5 The carbon nanotube dispersion had a carbon nanotube concentration of 3.0 wt%. The dispersion was first mechanically stirred for 28 min (800 rpm) and then ultrasonically treated (500 W, 40 min) to obtain the carbon nanotube dispersion. The carbon nanotube pretreatment involved adding carbon nanotubes to a mixture of concentrated nitric acid and concentrated sulfuric acid at a solid-liquid ratio of 1.2 g:22 mL and a volume ratio of 1:3. The mixture was magnetically stirred at 65℃ for 1.8 h (300 rpm). The mixture was then centrifuged and washed with deionized water at 8500 rpm for 8 min each time until the pH of the filtrate was 6–7. Finally, the mixture was vacuum dried at 65℃ and a vacuum degree of -0.09 MPa for 10 h, then ground into powder to obtain the pretreated carbon nanotubes.

[0039] The matrix solution was then prepared as follows: First, ethylene glycol, PEG400, and glycerol were mixed in a ratio of 4.2:3.2:3.2 by mass. The mixture was mechanically stirred for 18 minutes (stirring speed 400 rpm) to obtain a matrix solution. Then, KH550 (γ-aminopropyltriethoxysilane) and nano-montmorillonite with a particle size of 40-60 nm were added to the matrix solution. The amount of KH550 was 1.7 wt% of the matrix solution, and the amount of nano-montmorillonite was 3.2 wt%. The mixture was stirred at 1600 rpm for 28 minutes at 40°C, and then ultrasonically treated for 18 minutes at 300 W to obtain a matrix suspension.

[0040] Subsequently, the carbon nanotube dispersion was mixed with the matrix solution at a volume ratio of 1.2:5.2, and mechanically stirred at 1000 rpm for 50 min. Silica with a particle size of 12–100 nm, the reinforcing phase, and the additive were added sequentially to obtain a shear-reinforced gel. The amount of silica used was 10 wt% of the shear-thickening gel, and the mixture was stirred for 30 min (stirring speed 600 rpm) after adding silica. The reinforcing phase consisted of a mixture of PNIPAM (poly-N-isopropylacrylamide) microgel with a particle size of 80–120 nm and nanocellulose with a diameter of 5 nm and a length of 180–220 nm. The amount of PNIPAM microgel was 2.5 wt% of the shear-thickening gel, and the amount of nanocellulose was 1.8 wt%. The additive was FeCl3·6H2O, with an amount of FeCl3·6H2O of 0.25 wt% of the shear-thickening gel.

[0041] Step S3, Preparation of anti-fragmentation material: First, the negative Poisson's ratio fiber fabric woven in step S1 is screened and pre-processed. Specifically, the fabric with splices or missing yarns is first removed and cut into blocks that meet the size requirements (e.g., cut into 300mm x 300mm squares). Then, the cut fiber fabric is pre-soaked in dopamine (CAS No.: 51-61-6) and Tris (tris(hydroxymethyl)aminomethane)-HCl buffer (buffer pH is 8.5), with the dopamine dosage being 1.2wt%. The mixture is left to stand at 33℃ for 3.5h, then rinsed with deionized water until neutral and dried at 60℃.

[0042] The pre-processed negative Poisson's ratio fiber fabric was then immersed in shear gel for 1.5 hours; vacuum degassing treatment: the vacuum degree of the vacuum degassing treatment was -0.09 MPa, and the treatment time was 12 minutes.

[0043] Finally, the impregnated negative Poisson's ratio fiber fabric is dried and cured, specifically by drying in an oven at 55°C for 1 hour to obtain the anti-fragmentation material.

[0044] Example 4: As a preferred embodiment of the present invention, based on any one of Examples 1 to 3, the PNIPAM (poly-N-isopropylacrylamide) microgel is prepared by reverse emulsion polymerization, specifically as follows: First, the N-isopropylacrylamide monomer was recrystallized from n-hexane, i.e., dissolved at 55–65°C, crystallized at -18–-22°C, and vacuum dried at 38–42°C and -0.09 MPa for 10–12 hours. Then, liquid paraffin was taken, and a compound emulsifier consisting of sorbitan monooleate (Span-80, CAS No.: 1338-43-8) and polyoxyethylene sorbitan monooleate (Tween-80, CAS No.: 9005-65-6) was added. The mass ratio of Span-80 to Tween-80 was 3:1. The mass ratio of the chemical agent to liquid paraffin is 3:100. The mixture is stirred at 250-350 rpm for 10-12 minutes at room temperature to form a homogeneous oil phase. Then, vacuum-dried N-isopropylacrylamide is added to deionized water at a concentration of 10-20 wt%. Next, crosslinking agent MBA (N,N'-methylenebisacrylamide) is added in sequence at a dosage of 0.05-0.4 wt% (relative to the aqueous phase), and initiator APS (ammonium persulfate) is added in a dosage of 0.05-0.2 wt% (relative to the aqueous phase). The mixture is stirred in the dark until completely dissolved to obtain an aqueous phase.

[0045] Then, under nitrogen protection, the aqueous phase was added dropwise to the oil phase at a rate of 0.9–1.1 mL / min, and stirred at 600–800 rpm. After the addition was complete, stirring was continued for 20–30 min to obtain a homogeneous emulsion. Nitrogen was continuously introduced and the temperature was raised to 50–70 °C. The mixture was stirred at 600–800 rpm for 3–6 h.

[0046] Finally, the mixture was subjected to the following steps: demulsification (after cooling to room temperature, saturated NaCl solution was added, with the volume of the solution being 1 / 5 of the emulsion; stirring was performed at 300–400 rpm for 30 min, resulting in the precipitation of microgels), washing (first centrifugation was performed at 3000–5000 rpm for 10–12 min, and the lower precipitate was collected; then the mixture was washed twice with ethanol and once with acetone, with centrifugation performed after each washing), and drying (vacuum drying was performed at 40–60℃ and a vacuum degree of -0.08 to -0.09 MPa for 12–24 h) to obtain a white powder of PNIPAM microgels.

[0047] Comparative Example 1: A method for preparing a fragmentation-resistant material, comprising: Step S1, Preparation of negative Poisson's ratio fiber fabric: The preparation method is the same as in Example 2.

[0048] Step S2, Preparation of Shear-Thickening Gel: First, prepare a carbon nanotube dispersion. Specifically, 1-Butyl-3-methylimidazolium tetrafluoroborate (CAS No.: 174501-65-6) and 1-hexyl-3-methylpyridine hexafluorophosphate (CAS No.: 942196-38-5) are stirred in a 45°C water bath for 30 min (stirring speed 350 rpm) to achieve uniform mixing, obtaining a mixed ionic liquid. The mass ratio of 1-Butyl-3-methylimidazolium tetrafluoroborate to 1-hexyl-3-methylpyridine hexafluorophosphate is 6.5:3.5. Then, hydroxypropyl-β-cyclodextrin (CAS No.: 128446-5-5) is added, and the mixture is kept in a 45°C water bath and stirred continuously for 1.5 h (stirring speed 450 rpm) until the hydroxypropyl-β-cyclodextrin is completely dissolved. The mass ratio of hydroxypropyl-β-cyclodextrin to carbon nanotubes is 2:1. Then, pretreated carbon nanotubes with a diameter of 5–10 nm and an aspect ratio of 10 are added. 4 ~10 5 The carbon nanotube dispersion had a carbon nanotube concentration of 2.0 wt%. The dispersion was first mechanically stirred for 30 min (700 rpm) and then ultrasonically treated (450 W, 45 min) to obtain the carbon nanotube dispersion. The carbon nanotube pretreatment involved adding carbon nanotubes to a mixture of concentrated nitric acid and concentrated sulfuric acid at a solid-liquid ratio of 1 g:20 mL and a volume ratio of 1:3. The mixture was magnetically stirred at 60℃ for 2 h (250 rpm). The mixture was then centrifuged and washed with deionized water at 8000 rpm for 10 min each time until the pH of the filtrate was 6–7. Finally, the mixture was vacuum dried at 60℃ and a vacuum degree of -0.08 MPa for 11 h, then ground into powder to obtain the pretreated carbon nanotubes.

[0049] The matrix solution was then prepared using the same method as in Example 2.

[0050] Subsequently, the carbon nanotube dispersion was mixed with the matrix solution at a volume ratio of 1:5, and mechanically stirred at 900 rpm for 60 min. Silica with a particle size of 12–100 nm, the reinforcing phase, and the additive were added sequentially to obtain a shear-reinforced gel. The amount of silica used was 7.5 wt% of the shear-thickening gel, and the mixture was stirred for 350 min (stirring speed 550 rpm) after adding silica. The reinforcing phase consisted of a mixture of PNIPAM (poly-N-isopropylacrylamide) microgel with a particle size of 80–120 nm and nanocellulose with a diameter of 5 nm and a length of 180–220 nm. The amount of PNIPAM microgel was 2 wt% of the shear-thickening gel, and the amount of nanocellulose was 1.5 wt%. The additive was FeCl3·6H2O, with an amount of FeCl3·6H2O of 0.2 wt% of the shear-thickening gel.

[0051] Step S3, Preparation of anti-fragmentation material: The preparation method is the same as in Example 2.

[0052] Comparative Example 2: A method for preparing a fragmentation-resistant material, comprising: Step S1, Preparation of negative Poisson's ratio fiber fabric: The preparation method is the same as in Example 2.

[0053] Step S2, Preparation of Shear-Thickening Gel: First, prepare a carbon nanotube dispersion. Specifically, 1-Butyl-3-methylimidazolium tetrafluoroborate (CAS No.: 174501-65-6) and 1-Butyl-4-methylpyridine tetrafluoroborate (CAS No.: 343952-33-0) are stirred in a 45°C water bath for 30 min (stirring speed 350 rpm) to achieve uniform mixing and obtain a mixed ionic liquid. The mass ratio of 1-Butyl-3-methylimidazolium tetrafluoroborate to 1-Butyl-4-methylpyridine tetrafluoroborate is 6.5:3.5. Then, methyl-β-cyclodextrin (CAS No.: 128446-36-6) is added, and the mixture is kept in a 45°C water bath and stirred continuously for 1.5 h (stirring speed 450 rpm) until the methyl-β-cyclodextrin is completely dissolved. The mass ratio of methyl-β-cyclodextrin to carbon nanotubes is 2:1. Then, pretreated carbon nanotubes with a diameter of 5–10 nm and an aspect ratio of 10 are added. 4 ~10 5The carbon nanotube dispersion had a carbon nanotube concentration of 2.0 wt%. The dispersion was first mechanically stirred for 30 min (700 rpm) and then ultrasonically treated (450 W, 45 min) to obtain the carbon nanotube dispersion. The carbon nanotube pretreatment involved adding carbon nanotubes to a mixture of concentrated nitric acid and concentrated sulfuric acid at a solid-liquid ratio of 1 g:20 mL and a volume ratio of 1:3. The mixture was magnetically stirred at 60℃ for 2 h (250 rpm). The mixture was then centrifuged and washed with deionized water at 8000 rpm for 10 min each time until the pH of the filtrate was 6–7. Finally, the mixture was vacuum dried at 60℃ and a vacuum degree of -0.08 MPa for 11 h, then ground into powder to obtain the pretreated carbon nanotubes.

[0054] The matrix solution was then prepared using the same method as in Example 2.

[0055] Subsequently, the carbon nanotube dispersion was mixed with the matrix solution at a volume ratio of 1:5, and mechanically stirred at 900 rpm for 60 min. Silica with a particle size of 12–100 nm, the reinforcing phase, and the additive were added sequentially to obtain a shear-reinforced gel. The amount of silica used was 7.5 wt% of the shear-thickening gel, and the mixture was stirred for 350 min (stirring speed 550 rpm) after adding silica. The reinforcing phase consisted of a mixture of PNIPAM (poly-N-isopropylacrylamide) microgel with a particle size of 80–120 nm and nanocellulose with a diameter of 5 nm and a length of 180–220 nm. The amount of PNIPAM microgel was 2 wt% of the shear-thickening gel, and the amount of nanocellulose was 1.5 wt%. The additive was FeCl3·6H2O, with an amount of FeCl3·6H2O of 0.2 wt% of the shear-thickening gel.

[0056] Step S3, Preparation of anti-fragmentation material: The preparation method is the same as in Example 2.

[0057] Comparative Example 3: A method for preparing a fragmentation-resistant material, comprising: Step S1, Preparation of negative Poisson's ratio fiber fabric: The preparation method is the same as in Example 2.

[0058] Step S2, preparation of shear-thickening gel: First, prepare a carbon nanotube dispersion, using the same method as in Example 2.

[0059] The matrix solution was then prepared as follows: First, ethylene glycol, PEG400, and glycerol were mixed in a ratio of 4:3:3 by mass, and mechanically stirred for 20 minutes (stirring speed 350 rpm) to obtain a matrix solution. Then, KH550 (γ-aminopropyltriethoxysilane) was added to the matrix solution, with the amount of KH550 accounting for 1.5 wt% of the matrix solution. At 35°C, the solution was first stirred at 1500 rpm for 30 minutes, and then ultrasonically treated at 250 W for 20 minutes to obtain a matrix suspension.

[0060] Subsequently, the carbon nanotube dispersion was mixed with the matrix solution at a volume ratio of 1:5, and mechanically stirred at 900 rpm for 60 min. Silica with a particle size of 12–100 nm, the reinforcing phase, and the additive were added sequentially to obtain a shear-reinforced gel. The amount of silica used was 7.5 wt% of the shear-thickening gel, and the mixture was stirred for 350 min (stirring speed 550 rpm) after adding silica. The reinforcing phase consisted of a mixture of PNIPAM (poly-N-isopropylacrylamide) microgel with a particle size of 80–120 nm and nanocellulose with a diameter of 5 nm and a length of 180–220 nm. The amount of PNIPAM microgel was 2 wt% of the shear-thickening gel, and the amount of nanocellulose was 1.5 wt%. The additive was FeCl3·6H2O, with an amount of FeCl3·6H2O of 0.2 wt% of the shear-thickening gel.

[0061] Step S3, Preparation of anti-fragmentation material: The preparation method is the same as in Example 2.

[0062] Comparative Example 4: A method for preparing a fragmentation-resistant material, comprising: Step S1, Preparation of negative Poisson's ratio fiber fabric: The preparation method is the same as in Example 2.

[0063] Step S2, preparation of shear-thickening gel: First, prepare a carbon nanotube dispersion, using the same method as in Example 2.

[0064] The matrix solution was then prepared using the same method as in Example 2.

[0065] Subsequently, the carbon nanotube dispersion was mixed with the matrix solution at a volume ratio of 1:5, and mechanically stirred at 900 rpm for 60 min. Silica with a particle size of 12–100 nm, a reinforcing phase, and an additive were added sequentially to obtain a shear-enhanced gel. The amount of silica used was 7.5 wt% of the shear-thickening gel, and the mixture was stirred for 350 min (stirring speed 550 rpm) after adding silica. The reinforcing phase was a mixture of nanocellulose with a diameter of 5 nm and a length of 180–220 nm, and the amount of nanocellulose used was 1.5 wt% of the shear-thickening gel. The additive was FeCl3·6H2O, and the amount of FeCl3·6H2O used was 0.2 wt% of the shear-thickening gel.

[0066] Step S3, Preparation of anti-fragmentation material: The preparation method is the same as in Example 2.

[0067] Comparative Example 5: A method for preparing a fragmentation-resistant material, comprising: Step S1, Preparation of negative Poisson's ratio fiber fabric: The preparation method is the same as in Example 2.

[0068] Step S2, preparation of shear-thickening gel: First, prepare a carbon nanotube dispersion, using the same method as in Example 2.

[0069] The matrix solution was then prepared using the same method as in Example 2.

[0070] Subsequently, the carbon nanotube dispersion was mixed with the matrix solution at a volume ratio of 1:5, and mechanically stirred at 900 rpm for 60 min. Silica with a particle size of 12–100 nm and a reinforcing phase were added sequentially to obtain a shear-reinforced gel. The amount of silica used was 7.5 wt% of the shear-thickening gel, and the mixture was stirred for 350 min (stirring speed 550 rpm) after adding silica. The reinforcing phase consisted of a mixture of PNIPAM (poly-N-isopropylacrylamide) microgel with a particle size of 80–120 nm and nanocellulose with a diameter of 5 nm and a length of 180–220 nm. The amount of PNIPAM microgel was 2 wt% of the shear-thickening gel, and the amount of nanocellulose was 1.5 wt% of the shear-thickening gel.

[0071] Step S3, Preparation of anti-fragmentation material: The preparation method is the same as in Example 2.

[0072] Comparative Example 6: A method for preparing a fragmentation-resistant material, comprising: Step S1, Preparation of negative Poisson's ratio fiber fabric: The preparation method is the same as in Example 2.

[0073] Step S2, preparation of shear-thickened gel: consistent with the preparation method in Example 2.

[0074] Step S3, Preparation of anti-fragmentation material: First, the negative Poisson's ratio fiber fabric woven in step S1 is screened and pre-processed. Specifically, the fabric with splices or missing yarns is removed and cut into blocks that meet the size requirements (e.g., cut into 300mm x 300mm squares).

[0075] The pre-processed negative Poisson's ratio fiber fabric was then immersed in shear gel for 1.2 hours; vacuum degassing treatment: the vacuum degree of the vacuum degassing treatment was -0.08 MPa, and the treatment time was 14 minutes.

[0076] Finally, the impregnated negative Poisson's ratio fiber fabric is dried and cured, specifically by drying in an oven at 50°C for 1.5 hours to obtain the anti-fragmentation material.

[0077] The anti-fragmentation performance of the anti-fragmentation materials in Examples 1 to 3 and Comparative Examples 1 to 6 was tested, and the test results are shown in the table below:

[0078] Note: Fragmentation resistance is measured in areal density (1kg / m³). 2 The V50 value.

[0079] As shown in the table above, this invention effectively enhances the anti-fragmentation performance of fiber fabrics through the uniform dispersion of carbon nanotubes, the preparation of matrix solutions, the addition of specific reinforcing phases and additives, and the pretreatment of fiber fabrics, thereby achieving the goal of "lightweight, high-efficiency, and high-stability" anti-fragmentation materials.

Claims

1. A method for preparing an anti-fragmentation material with a negative Poisson's ratio effect, characterized in that: include: Step S1: Preparation of negative Poisson's ratio fiber fabric: Select any two of ultra-high molecular weight polyethylene, aramid, and carbon fiber, use low modulus fiber as core fiber and high modulus fiber as winding fiber, spirally wind high modulus fiber onto low modulus fiber to obtain negative Poisson's ratio fiber preform, and finally weave the resulting fiber preform into negative Poisson's ratio fiber fabric. Step S2, preparation of shear-thickening gel: First, prepare a carbon nanotube dispersion, then prepare a matrix solution; then, mix the carbon nanotube dispersion and the matrix solution, and add silica, reinforcing phase and additives in sequence to obtain a shear-enhanced gel; Step S3, Preparation of anti-fragmentation material: First, the negative Poisson's ratio fiber fabric woven in step S1 is screened and pre-processed. Then, the pre-processed negative Poisson's ratio fiber fabric is impregnated in shear gel and vacuum degassed. Finally, the impregnated negative Poisson's ratio fiber fabric is dried and cured to obtain the anti-fragmentation material.

2. The method for preparing an anti-fragmentation material with a negative Poisson's ratio effect according to claim 1, characterized in that: The diameter ratio of the high-modulus fiber to the low-modulus fiber is 0.1 to 2:1, and the winding angle θ is 10° to 80°.

3. A method for preparing an anti-fragmentation material with a negative Poisson's ratio effect according to claim 1 or 2, characterized in that: The specific preparation steps of the carbon nanotube dispersion are as follows: First, 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-4-methylpyridine tetrafluoroborate are stirred in a constant temperature water bath at 40-50℃ for 28-32 minutes to achieve uniform mixing and obtain a mixed ionic liquid; then, hydroxypropyl-β-cyclodextrin is added, and the mixture is kept in a constant temperature water bath at 40-50℃ and stirred continuously for 1-2 hours until the hydroxypropyl-β-cyclodextrin is completely dissolved; after that, pretreated carbon nanotubes with a diameter of 5-10 nm and an aspect ratio of 10 are added. 4 ~10 5 First, mechanically stir for 28–32 minutes, then sonicate to obtain a carbon nanotube dispersion.

4. A method for preparing an anti-fragmentation material with a negative Poisson's ratio effect according to claim 1 or 3, characterized in that: The mass ratio of 1-butyl-3-methylimidazolium tetrafluoroborate to 1-butyl-4-methylpyridine tetrafluoroborate is 6-7:3-4; the mass ratio of hydroxypropyl-β-cyclodextrin to carbon nanotubes is 1-3:1; and the concentration of carbon nanotubes in the carbon nanotube dispersion is 0.5-3.0 wt%.

5. A method for preparing an anti-fragmentation material with a negative Poisson's ratio effect according to claim 1 or 3, characterized in that: The carbon nanotube pretreatment process is as follows: First, carbon nanotubes are added to a mixture of concentrated nitric acid and concentrated sulfuric acid, with a solid-liquid ratio of 0.8–1.2 g: 18–22 mL and a volume ratio of concentrated nitric acid to concentrated sulfuric acid of 1:

3. The mixture is then magnetically stirred at 55–65 °C for 1.8–2.2 h. Next, the mixture is centrifuged and washed with deionized water at 7500–8500 rpm for 8–12 min each time, until the pH of the filtrate is 6–7. Finally, the mixture is vacuum dried at 55–65 °C and a vacuum degree of -0.08 MPa to -0.09 MPa for 10–12 h, and then ground into powder to obtain the pretreated carbon nanotubes.

6. The method for preparing an anti-fragmentation material with a negative Poisson's ratio effect according to claim 1, characterized in that: The specific preparation steps of the matrix solution are as follows: First, ethylene glycol, PEG400 and glycerol are mixed in proportion and mechanically stirred for 18-22 min to obtain a base solution; then, KH550 (γ-aminopropyltriethoxysilane) and nano-montmorillonite with a particle size of 40-60 nm are added to the base solution, and the mixture is stirred at high speed at 1400-1600 rpm for 28-32 min at a temperature of 30-40°C, and then ultrasonically treated at a power of 200-300 W for 18-22 min to obtain a matrix suspension.

7. The method for preparing an anti-fragmentation material with a negative Poisson's ratio effect according to claim 1, characterized in that: The carbon nanotube dispersion and the matrix solution are mixed at a volume ratio of 0.8-1.2:4.8-5.2 and mechanically stirred at 800-1000 rpm for 50-70 min. The silica particles have a diameter of 12-100 nm and the amount of silica used is 5-10 wt% of the shear-thickening gel.

8. The method for preparing an anti-fragmentation material with a negative Poisson's ratio effect according to claim 1, characterized in that: The pre-processing of the negative Poisson's ratio fiber fabric in step S3 is as follows: First, fabrics with splices or missing yarns are removed and cut into blocks that meet the size requirements; then, the cut fiber fabric is pre-soaked in a dopamine and Tris-HCl buffer solution, with the dopamine dosage being 0.8-1.2 wt%, and left to stand at a temperature of 27-33°C for 3.5-4.5 hours. After removal, it is rinsed with deionized water until neutral and dried at 55-60°C.

9. The method for preparing an anti-fragmentation material with a negative Poisson's ratio effect according to claim 1, characterized in that: In step S3, the pre-processed negative Poisson's ratio fiber fabric is impregnated in the shear gel for 1 to 1.5 hours; the vacuum degree of the vacuum degassing treatment is -0.08 MPa to -0.09 MPa, and the treatment time is 12 to 16 minutes.

10. The method for preparing an anti-fragmentation material with a negative Poisson's ratio effect according to claim 1, characterized in that: The drying and curing process in step S3 specifically involves drying in an oven at 45–55°C for 1–2 hours.

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