Toughened polyurethane impact-resistant material based on dynamic covalent bond energy regulation
By constructing a dynamic covalent bond network and modifying multiple interfaces, the impact toughness and self-healing ability of composite polyurethane materials are enhanced. This solves the problems of weak interfacial bonding and irreversible damage in traditional composite materials under high-speed impact, and achieves a synergistic improvement in high strength and high ductility.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIANGTAN UNIV
- Filing Date
- 2026-04-22
- Publication Date
- 2026-06-05
AI Technical Summary
Traditional composite polyurethane materials exhibit weak interfacial bonding and insufficient impact toughness under high-speed, high-energy impact loads, and the damage is irreversible, making it difficult to meet stringent and extreme protection requirements.
By constructing a multi-level synergistic toughening system based on dynamic covalent bonds, including a dual covalent self-healing polyurethane matrix, modified molybdenum disulfide nanoparticles, and composite modified aramid fibers, a dynamic covalent network and multiple interface modifications are formed to achieve energy dissipation and self-healing functions.
It significantly improves the material's impact resistance, toughness, strength, and ductility, and has a highly efficient self-healing ability, solving the problem of irreversible damage to traditional composite materials under high-speed impact.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of polyurethane material technology, specifically a toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation. Background Technology
[0002] Composite polyurethane materials are polymeric materials composed of a polyurethane matrix and various reinforcing materials. Polyurethane itself has a microphase separation structure with adjustable soft and hard segments in its molecular chains, exhibiting excellent elasticity, wear resistance, and adhesion. After composite formation, its rigidity, strength, and dimensional stability are significantly improved, making it a promising candidate for applications in fields with stringent requirements for comprehensive mechanical properties, such as engineering structures, sports protection, transportation, and national defense. It is commonly used in the manufacture of safety helmets, protective armor, cushioning components, and impact-resistant structural parts.
[0003] However, traditional composite polyurethane materials have significant shortcomings when dealing with high-speed, high-energy impact loads. The reinforcing phase has poor compatibility with the matrix interface and the bonding is weak. Under impact stress, cracks are prone to initiation and propagation along the interface, leading to premature material failure. They also lack impact toughness and cannot meet the stringent and extreme protection requirements.
[0004] Chinese patent CN120365733A discloses a high-strength, impact-resistant thermoplastic polyurethane composite material and its preparation method. This innovative approach synthesizes a hydroxyl polyurethane with flavonoid derivatives as the key structure as a compatibilizer. This compatibilizer utilizes the similarity and compatibility between its molecular backbone and the polyurethane matrix, as well as the strong hydrogen bonding between the abundant phenolic hydroxyl groups in its side chains and the reinforcing phase, to construct a robust "molecular bridge" at the interface, significantly improving interfacial bonding strength and thus enhancing the tensile strength and basic toughness of the material.
[0005] However, in pursuing high strength and strong interfacial adhesion, the rigid flavonoid molecular framework selected in this technical solution to give the material better heat resistance can effectively improve the rigidity and strength of the material, but it may lead to an overly rigid interfacial region. This "rigid and brittle" interfacial layer based on static chemical bonding is limited in its plastic deformation and energy dissipation capacity when facing high-speed impact. The impact energy cannot be fully absorbed through the micro-yield and plastic flow mechanisms of the interface, and may instead promote the rapid propagation of cracks along this rigid interface. More fundamentally, its static chemical bond system is irreversible after being damaged by impact, and the damage will continue to accumulate under multiple or high-speed impact scenarios, leading to irreversible degradation of the material's protective performance, thus severely restricting the maximization of the material's impact toughness and long-term protective potential. Summary of the Invention
[0006] The purpose of this invention is to provide a toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation. By reversibly fractured and recombined dynamic covalent bonds, impact energy is effectively dissipated, and the interfacial bonding force between components is enhanced by multiple interface modifications. This gives the material excellent impact toughness, high strength, high ductility, and efficient self-healing function, solving the problems of easy interface damage, insufficient impact resistance, and irreversible damage in traditional composite materials. It has broad application prospects in fields such as safety protection and cushioning components.
[0007] The objective of this invention can be achieved through the following technical solutions: The toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation includes the following steps: Step 1: A polyurethane prepolymer was prepared using PTMG-2000 and IPDI as raw materials. Then, furfurylamine and diethyl cysteine were added sequentially, and finally bismaleimide was added to obtain a double covalent self-healing polyurethane.
[0008] Step 2: Modify the nano-molybdenum disulfide with silane coupling agent KH550 to obtain modified nano-molybdenum disulfide powder.
[0009] Step 3: The aramid fibers are impregnated sequentially with tannic acid solution and Fe3+ solution, and then reacted in polyethyleneimine aqueous solution to obtain composite modified aramid fibers.
[0010] Step 4: Mix double covalent self-healing polyurethane, modified nano-molybdenum disulfide and modified aramid fiber, and hot-press to cure, to obtain a toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation.
[0011] Furthermore, the mass ratio of the dual covalent self-healing polyurethane, modified nano-molybdenum disulfide, and modified aramid fiber is 100-120:1.5-2.5:10-15.
[0012] Furthermore, the hot-press curing conditions are: hot-press curing at 80-90℃ for 6-8 hours under a pressure of 5-10MPa.
[0013] Furthermore, the specific preparation steps for the composite modified aramid fiber are as follows: Tannic acid powder and Tris buffer solution were added to a reaction vessel and stirred at 200-300 rpm for 10-15 min at room temperature. Then, ferric chloride hexahydrate was added and stirred for 10-15 min. Finally, polyethyleneimine was added and stirred at 300-400 rpm for 20-30 min to obtain an immersion solution. The dried aramid fibers were immersed in the immersion solution for 12-16 h. The fibers were then removed and washed with deionized water until the final washing solution was neutral. Finally, the fibers were dried at 60 °C for 2-3 h to obtain composite modified aramid fibers.
[0014] Furthermore, the ratio of tannic acid powder, Tris buffer solution, ferric chloride hexahydrate, polyethyleneimine, and aramid fiber is 0.8-1.2g: 8-12L: 8-12g: 8-12g: 80-120g.
[0015] Furthermore, the specific preparation steps of the modified nano-molybdenum disulfide powder are as follows: Nano-molybdenum disulfide powder and KH-550-toluene solution were added to a reaction vessel, first ultrasonically dispersed for 25-35 min, then reacted at 115-125℃ under nitrogen protection for 22-26 h, then washed and centrifuged with anhydrous toluene, and vacuum dried at 120℃ for 7-9 h to obtain modified nano-molybdenum disulfide powder.
[0016] Furthermore, the ratio of nano-molybdenum disulfide powder to KH-550-toluene solution is 4-6g:15-20mL.
[0017] Furthermore, the concentration of the KH-550-toluene solution is 5 wt%.
[0018] Furthermore, the specific preparation steps of the dual covalent self-healing polyurethane are as follows: PTMG-2000, IPDI, and N,N-dimethylformamide were added to a reactor and mixed. Dibutyltin dilaurate was added at 70-80℃, and the mixture was reacted at 500-800 r / min for 1-2 h. After the reaction was completed, the mixture was cooled to room temperature, and furfurylamine was added to the reactor. The mixture was reacted at 800-1000 r / min for 30-60 min. The temperature was then raised to 55-65℃, and diethyl cystine was added to the reactor. The reaction was continued for 1-2 h. Finally, bismaleimide was added at 60℃ and the reaction was carried out for 24 h to obtain a double covalent self-healing polyurethane.
[0019] Furthermore, the ratio of PTMG-2000, IPDI, N,N-dimethylformamide, dibutyltin dilaurate, furfurylamine, diethyl cysteine, and bismaleimide is 114-126g: 26.1-27.3g: 165-195mL: 0.3-0.6mL: 5.7-6g: 7.8-8.4g: 6.6-6.9g.
[0020] The beneficial effects of this invention are: 1. This invention constructs a multi-level synergistic toughening system consisting of a "dual dynamic covalent bond network - interface-modified nano-reinforcing phase - composite modified fiber-reinforcing phase", which achieves a synergistic improvement in impact toughness, high strength, high ductility and efficient self-healing function. It fundamentally solves the technical problems of insufficient impact resistance and irreversible damage caused by weak interfacial bonding and static chemical bonding in traditional composite polyurethane materials.
[0021] 2. The dual covalent self-healing polyurethane matrix constructed in step S1 of this invention is based on a polyurethane prepolymer, with furan groups and disulfide bonds introduced sequentially. Finally, a Diels-Alder reaction occurs through bismaleimide, forming a dual dynamic covalent network with both DA bonds and disulfide bonds. The DA bonds can undergo reversible breakage and recombination under thermal stimulation, while the disulfide bonds also possess dynamic exchange characteristics. The two work synergistically to effectively dissipate energy and inhibit crack propagation under impact stress through the continuous breakage and recombination of dynamic bonds. At the same time, after damage, the material can achieve self-healing function and restore its mechanical properties through the recombination of dynamic bonds triggered by thermal stimulation. The soft and hard segment microphase separation structure of the polyurethane matrix itself contributes to elasticity and rigidity, making the matrix possess high toughness, high strength, and intelligent repair characteristics.
[0022] 3. The KH-550 modified molybdenum disulfide nanoparticles prepared in this invention have aminopropyl functional groups grafted onto their surface, which significantly improves the interfacial compatibility between the nanoparticles and the polyurethane matrix. The modified molybdenum disulfide nanoparticles are uniformly dispersed in the matrix, avoiding the problem of stress concentration points caused by the agglomeration of unmodified particles. At the same time, the surface-grafted organic functional groups form strong chemical bonds with the matrix molecular chains, improving the interfacial stress transfer efficiency and enabling the nanoparticles to effectively bear and disperse impact loads, thereby improving the strength, rigidity, and impact toughness of the material. The molybdenum disulfide nanoparticles themselves have excellent mechanical properties and slip characteristics, which help dissipate energy, and the bridging effect of KH-550 ensures a strong bond between the nanoparticles and the matrix, thus achieving synergistic toughening of the nano-reinforcing phase and the matrix.
[0023] 4. The composite modified aramid fiber prepared by this invention uses tannic acid-Fe3+ complex and polyethyleneimine to construct a metal-polyphenol network and polymer composite interface layer on the fiber surface. First, TA and Fe3+ form a stable coating through coordination, chemically anchored to the fiber surface. Subsequently, PEI interweaves with the MPN layer through hydrogen bonding, electrostatic interaction, etc., to form a composite interface rich in active groups. This interface layer not only significantly improves the interfacial bonding strength between the aramid fiber and the polyurethane matrix, but also introduces multiple energy dissipation mechanisms. During impact, energy is absorbed through the plastic deformation and bond recombination of the interface layer, preventing interface debonding. At the same time, the highly active surface of the composite interface layer helps to form a strong interaction with the matrix, further optimizing stress transmission. TA provides abundant phenolic hydroxyl groups for complexation and adhesion, Fe3+ serves as a crosslinking center to enhance network stability, and PEI increases interfacial toughness and reactivity. The three work together to construct a strong and functional transition layer on the fiber surface, realizing the mechanical synergy between the fiber reinforcement phase and the matrix. Detailed Implementation
[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0025] Example 1: Toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation, prepared through the following steps: S1: 120g of dehydrated PTMG-2000, 26.7g of isophorone diisocyanate (IPDI), and 180mL of N,N-dimethylformamide (DMF) were added to a reaction vessel and mixed. The temperature was raised to 75℃ and 0.4mL of dibutyltin dilaurate (DBTDL) was added. The mixture was stirred at 650r / min for 1.5h. After the reaction was completed, the mixture was cooled to room temperature. 5.82g of furfurylamine was added to the vessel and the reaction was continued at 900r / min for 45min. The temperature was raised to 60℃ and 8.04g of diethyl cysteine was added to the vessel and the reaction was continued for 1.5h. Then, at 60℃, 6.84g of bismaleimide (BMI) was added to the system and the reaction was carried out for 24h to obtain a double covalent self-healing polyurethane.
[0026] Based on the polyurethane prepolymerization and dual dynamic covalent bond construction reaction, firstly, under heating and catalysis, the hydroxyl groups of the soft segment PTMG-2000 and the isocyanate groups of the hard segment IPDI undergo a polymerization reaction to generate a -NCO-terminated liquid polyurethane prepolymer. Subsequently, the amino group of furfurylamine undergoes a rapid addition reaction with the -NCO of the prepolymer at room temperature, introducing a furan component with a diene addition (DA) bond into the molecular chain. Next, the system is heated to 60°C, and the hydroxyl group of diethyl cysteine undergoes an addition reaction with the remaining -NCO, introducing a disulfide bond dynamic component. Finally, the maleimide group of bismaleimide undergoes a diene addition reaction with the furan group at 60°C to form a DA dynamic covalent bond, ultimately constructing a dual dynamic covalent network of "DA bond and disulfide bond". The high-viscosity liquid prepolymer obtained in this step is a flowable gel after cooling, which provides a reactive matrix with intrinsic self-healing ability for subsequent composite and hot-press curing.
[0027] S2: 5g of nano molybdenum disulfide powder and 18mL of toluene solution containing 5wt% γ-aminopropyltriethoxysilane (KH-550) were added to the reaction vessel. The mixture was first ultrasonically dispersed for 30min, and then reacted at 120℃ under nitrogen protection for 24h. After washing and centrifugation with anhydrous toluene, the mixture was vacuum dried at 120℃ for 8h to obtain modified nano molybdenum disulfide powder.
[0028] Based on the hydrolysis and condensation reaction of the silane coupling agent KH-550, the ethoxy group at one end of the KH-550 molecule can be hydrolyzed in toluene solution to generate highly reactive silanol groups. These silanol groups can undergo dehydration condensation with a small number of hydroxyl groups or defect sites on the surface or edge of the molybdenum disulfide nanosheets to form strong Si-O-Mo or Si-OS covalent bonds. Through this process, the aminopropyl group at the other end of the KH-550 molecule is introduced and grafted onto the surface of the molybdenum disulfide nanosheets, thereby significantly improving its compatibility and interfacial bonding with the organic polymer matrix.
[0029] S3: Add 1g of tannic acid (TA) powder and 10L of Tris buffer solution with a pH of 8.5 to the reactor and stir at 250r / min for 13min at room temperature until dissolved. Then add 10g of ferric chloride hexahydrate and stir for 13min under the same conditions. Finally, add 10g of polyethyleneimine (PEI, molecular weight 600) and stir thoroughly at 350r / min for 25min to obtain a homogeneous impregnation solution. Place 100g of dried aramid fiber in the impregnation solution and immerse for 14h. Remove the fiber and wash it with deionized water until the last washing solution is neutral. Finally, dry at 60℃ for 2.5h to obtain composite modified aramid fiber.
[0030] Based on a composite modification mechanism that combines chemical complexation and physical adsorption, firstly, in a weakly alkaline Tris buffer solution, the abundant catechol groups in tannic acid molecules undergo rapid coordination complexation with Fe3+ released from ferric chloride hexahydrate, forming a stable metal-polyphenol network (MPN) coating in situ on the surface of aramid fibers, achieving deep chemical anchoring. Subsequently, the added polyethyleneimine (PEI) is physically adsorbed and intertwined on the MPN coating through multiple hydrogen bonds, electrostatic interactions, and possible Michael addition / Schiff base reactions between its numerous amino groups and the MPN coating, constructing a composite interface layer rich in active groups. Finally, the chemically anchored MPN and the physically adsorbed PEI layer synergistically introduce high-density phenolic hydroxyl and amino groups onto the fiber surface, significantly enhancing its surface energy and reactivity, thereby endowing the composite modified aramid fibers with stronger interfacial adhesion and mechanical synergistic effects.
[0031] S4: 110g of double covalent self-healing polyurethane was added to the reactor and stirred for 13min at 75℃ and 500r / min. Then, 2g of modified nano-molybdenum disulfide powder was added to the reactor, and the temperature was kept constant. The mixture was stirred for 1.5h at 900r / min to obtain a nano-composite polyurethane slurry. 12.5g of composite modified aramid fiber was impregnated in the nano-composite polyurethane slurry and degassed for 25min under a vacuum of 0.6MPa to fully impregnate the fiber. Finally, the composite material was poured into a polytetrafluoroethylene mold preheated to 80℃ and hot-pressed at 85℃ for 7h under a pressure of 5MPa. After demolding, a toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation was obtained.
[0032] Example 2: Toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation, prepared through the following steps: S1: 114g of dehydrated PTMG-2000, 26.1g of isophorone diisocyanate (IPDI), and 165mL of N,N-dimethylformamide (DMF) were added to a reaction vessel and mixed. The temperature was raised to 70℃ and 0.3mL of dibutyltin dilaurate (DBTDL) was added. The mixture was stirred at 500r / min for 1h. After the reaction was completed, the mixture was cooled to room temperature. 5.7g of furfurylamine was added to the vessel and the reaction was continued at 800r / min for 30min. The temperature was raised to 55℃ and 7.8g of diethyl cysteine was added to the vessel and the reaction was continued for 1h. Then, 6.6g of bismaleimide (BMI) was added to the system at 60℃ and the reaction was carried out for 24h to obtain a double covalent self-healing polyurethane.
[0033] S2: 4g of nano-molybdenum disulfide powder and 15mL of toluene solution containing 5wt% γ-aminopropyltriethoxysilane (KH-550) were added to the reaction vessel. The mixture was first ultrasonically dispersed for 25min, and then reacted at 115℃ under nitrogen protection for 22h. After washing and centrifugation with anhydrous toluene, the mixture was vacuum dried at 120℃ for 7h to obtain modified nano-molybdenum disulfide powder.
[0034] S3: Add 0.8g of tannic acid (TA) powder and 8L of Tris buffer solution with a pH of 8.5 to the reactor. Stir at 200r / min for 10min at room temperature until dissolved. Then add 8g of ferric chloride hexahydrate and stir for 10min under the same conditions. Finally, add 8g of polyethyleneimine (PEI, molecular weight 600) and stir thoroughly at 300r / min for 20min to obtain a homogeneous impregnation solution. Place 80g of dried aramid fiber in the impregnation solution and immerse for 12h. Remove the fiber and wash it with deionized water until the last washing solution is neutral. Finally, dry at 60℃ for 2h to obtain composite modified aramid fiber.
[0035] S4: Add 100g of dual covalent self-healing polyurethane to the reactor and stir for 10min at 70℃ and 400r / min. Then add 1.5g of modified nano molybdenum disulfide powder to the reactor, keep the temperature constant, and stir for 1h at 800r / min to obtain nanocomposite polyurethane slurry. Impregnate 10g of composite modified aramid fiber in the nanocomposite polyurethane slurry and degas for 20min under a vacuum of 0.5MPa to fully impregnate the fiber. Finally, pour the composite material into a polytetrafluoroethylene mold preheated to 75℃ and hot-press it at 80℃ for 6h under a pressure of 5MPa. After demolding, a toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation is obtained.
[0036] Example 3: Toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation, prepared through the following steps: S1: 126g of dehydrated PTMG-2000, 27.3g of isophorone diisocyanate (IPDI), and 195mL of N,N-dimethylformamide (DMF) were added to a reaction vessel and mixed. The temperature was raised to 80℃ and 0.6mL of dibutyltin dilaurate (DBTDL) was added. The mixture was stirred at 800r / min for 1-2h. After the reaction was completed, the mixture was cooled to room temperature. 6g of furfurylamine (FAm) was added to the vessel and the reaction was continued at 800-1000r / min for 60min. The temperature was raised to 65℃ and 8.4g of diethyl cysteine was added to the vessel and the reaction was continued for 2h. Then, at 60℃, 6.9g of bismaleimide (BMI) was added to the system and the reaction was continued for 24h to obtain a double covalent self-healing polyurethane.
[0037] S2: 6g of nano-molybdenum disulfide powder and 20mL of toluene solution containing 5wt% γ-aminopropyltriethoxysilane (KH-550) were added to a reaction vessel. The mixture was first ultrasonically dispersed for 35min, and then reacted for 26h under nitrogen protection at 115-125℃. After washing and centrifugation with anhydrous toluene, the mixture was vacuum dried at 120℃ for 9h to obtain modified nano-molybdenum disulfide powder.
[0038] S3: Add 1.2g of tannic acid (TA) powder and 12L of Tris buffer solution with a pH of 8.5 to the reactor. Stir at 300r / min for 15min at room temperature until dissolved. Then add 12g of ferric chloride hexahydrate and stir for 15min under the same conditions. Finally, add 12g of polyethyleneimine (PEI, molecular weight 600) and stir thoroughly at 400r / min for 30min to obtain a homogeneous impregnation solution. Place 120g of dried aramid fiber in the impregnation solution and immerse for 16h. Remove the fiber and wash it with deionized water until the last washing solution is neutral. Finally, dry at 60℃ for 3h to obtain composite modified aramid fiber.
[0039] S4: Add 120g of dual covalent self-healing polyurethane to the reactor and stir for 15min at 80℃ and 600r / min. Then add 2.5g of modified nano molybdenum disulfide powder to the reactor, keep the temperature constant, and stir for 2h at 1000r / min to obtain nanocomposite polyurethane slurry. Impregnate 15g of composite modified aramid fiber in the nanocomposite polyurethane slurry and degas for 30min under a vacuum of 0.7MPa to fully impregnate the fiber. Finally, pour the composite material into a polytetrafluoroethylene mold preheated to 85℃ and hot-press it at 90℃ for 8h under a pressure of 10MPa. After demolding, a toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation is obtained.
[0040] All materials used in Examples 1-3 of this application are commercially available. PTMG-2000, N,N-dimethylformamide, γ-aminopropyltriethoxysilane, ferric chloride hexahydrate (≥99%), bismaleimide, and tannic acid were purchased from Shanghai Aladdin Biochemical Co., Ltd.; dibutyltin dilaurate, molybdenum disulfide nanoparticles (purity ≥99.5%, 100nm), and polyethyleneimine (molecular weight 600) were purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; and aramid fiber (purity 99%) was purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd. Cystine diethyl ester was prepared by referring to the paper (Liu Haocheng. Preparation and performance study of copper sulfide modified double covalent thermally reversible self-healing polyurethane elastomer [D]. Lanzhou Jiaotong University, 2024. DOI:10.27205 / d.cnki.gltec.2024.000890.).
[0041] Comparative Example 1: Based on Example 1, step S2 was modified: the reaction of adding diethyl cysteine and subsequent bismaleimide (BMI) was omitted. After the reaction of adding furfurylamine, an equimolar amount (relative to diethyl cysteine) of the small molecule triol crosslinking agent trimethylolpropane was added to the system to react with the remaining -NCO groups to form a static chemical crosslinking network. All other steps and parameters remained the same as in Example 1, resulting in a composite polyurethane impact-resistant material.
[0042] Comparative Example 2: Based on Example 1, step S2, which involves the preparation of modified molybdenum disulfide nanopowder, was omitted. In step S4, an equal mass of unmodified molybdenum disulfide nanopowder without any surface treatment was directly mixed with a double covalent self-healing polyurethane matrix. All other steps and parameters remained the same as in Example 1, resulting in a composite polyurethane impact-resistant material.
[0043] Comparative Example 3: Based on Example 1, step S3, the preparation of the composite modified aramid fiber, was omitted. In step S4, an equal mass of aramid fiber surface-treated with a traditional silane coupling agent KH-550 (1-2 wt%) ethanol solution was used to replace the composite modified aramid fiber. All other steps and parameters remained the same as in Example 1, resulting in a composite polyurethane impact-resistant material.
[0044] The composite polyurethane impact-resistant material samples prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests. The impact strength test was conducted according to the method specified in GB / T 1043.1-2008. A simply supported beam impact testing machine was used. The samples were machined to 80mm × 10mm × 4mm and prepared with a standard Type A notch. A pendulum was released to impact the back of the notch at a standard temperature of 23±2℃. The results are expressed as notched impact strength (kJ / m²), which directly reflects the material's ability to absorb energy and resist fracture under high-speed impact. A higher value indicates better impact toughness. Tensile properties were tested according to GB / T... The test was conducted according to the method specified in standard 1040.2-2022. A standard type 1A dumbbell-shaped specimen was subjected to tensile testing at a constant speed of 50 mm / min using a universal testing machine. The test was conducted at 23±2℃, and the maximum stress and elongation changes before fracture were recorded. The results included tensile strength (MPa) and elongation at break (%), which were used to evaluate the material's ultimate bearing capacity against tensile failure and its plastic deformation capacity before fracture, respectively. The bending performance test was conducted according to the method specified in GB / T 9341-2008. An 80 mm × 10 mm × 4 mm specimen was subjected to a three-point bending test using a universal testing machine with a span of 64 mm. The load was applied at a rate of 2 mm / min until the specimen fractured or reached the specified deflection. The test environment temperature was 23±2℃. The results included bending strength (MPa) and bending modulus (MPa), which were used to evaluate the material's maximum stress under bending load and its stiffness against deformation during the elastic deformation stage, respectively. The hardness test was conducted according to GB / T The test was conducted according to the method specified in standard 531.1-2008, using a Shore D hardness tester. A vertical indentation test was performed on a flat surface with a sample thickness of not less than 6 mm. The test was completed under constant temperature conditions of 23±2℃. The result is expressed as Shore D hardness (°). This value characterizes the material surface's ability to resist the indentation of a rigid indenter. The larger the value, the harder the material, and the stronger its wear resistance and compressive strength. The self-healing performance was determined according to the laboratory standard scratch-heat repair test: a scratch with a length of 10 mm and a width of about 80 μm was made on the surface of the composite material sample with a blade at a uniform speed. The sample was then placed horizontally in a 70℃ constant temperature forced-air drying oven for 2 hours and then removed. After naturally cooling to 23℃, the remaining width of the scratch was measured using a super depth-of-field three-dimensional microscope. The recovery rate was calculated based on the initial width. A recovery rate of ≥90% after 120 minutes was considered as the scratch basically disappearing. The higher the recovery rate and the shorter the healing time, the stronger the dynamic covalent bond exchange capacity of the coating and the better the self-healing performance.
[0045] All test results are the average of three parallel experiments, and the test results are shown in Table 1 below.
[0046] Table 1 Performance test results of composite polyurethane impact-resistant materials
Claims
1. A toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation, characterized in that, Prepared by the following steps: Step 1: A polyurethane prepolymer was prepared using PTMG-2000 and IPDI as raw materials. Then, furfurylamine and diethyl cysteine were added sequentially, and finally bismaleimide was added to obtain a double covalent self-healing polyurethane. Step 2: Modify the nano-molybdenum disulfide with silane coupling agent KH550 to obtain modified nano-molybdenum disulfide powder; Step 3: The aramid fibers are impregnated sequentially with tannic acid solution and Fe3+ solution, and then reacted in polyethyleneimine aqueous solution to obtain composite modified aramid fibers; Step 4: Mix double covalent self-healing polyurethane, modified nano-molybdenum disulfide and modified aramid fiber, and hot-press to cure, to obtain a toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation.
2. The toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation according to claim 1, characterized in that, The mass ratio of the dual covalent self-healing polyurethane, modified nano-molybdenum disulfide, and modified aramid fiber is 100-120:1.5-2.5:10-15.
3. The toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation according to claim 1, characterized in that, The hot-press curing conditions are as follows: hot-press curing at 80-90℃ for 6-8 hours under a pressure of 5-10MPa.
4. The toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation according to claim 1, characterized in that, The specific preparation steps of the composite modified aramid fiber are as follows: Tannic acid powder and Tris buffer solution were added to a reaction vessel and stirred at 200-300 rpm for 10-15 min at room temperature. Then, ferric chloride hexahydrate was added and stirred for 10-15 min. Finally, polyethyleneimine was added and stirred at 300-400 rpm for 20-30 min to obtain an immersion solution. The dried aramid fibers were immersed in the immersion solution for 12-16 h. The fibers were then removed and washed with deionized water until the final washing solution was neutral. Finally, the fibers were dried at 60 °C for 2-3 h to obtain composite modified aramid fibers.
5. The toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation according to claim 4, characterized in that, The ratio of tannic acid powder, Tris buffer solution, ferric chloride hexahydrate, polyethyleneimine and aramid fiber is 0.8-1.2g: 8-12L: 8-12g: 8-12g: 80-120g.
6. The toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation according to claim 1, characterized in that, The specific preparation steps of the modified nano-molybdenum disulfide powder are as follows: Nano-molybdenum disulfide powder and KH-550-toluene solution were added to a reaction vessel, first ultrasonically dispersed for 25-35 min, then reacted at 115-125℃ under nitrogen protection for 22-26 h, then washed and centrifuged with anhydrous toluene, and vacuum dried at 120℃ for 7-9 h to obtain modified nano-molybdenum disulfide powder.
7. The toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation according to claim 6, characterized in that, The ratio of the amount of nano-molybdenum disulfide powder to KH-550-toluene solution is 4-6g:15-20mL.
8. The toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation according to claim 6, characterized in that, The concentration of the KH-550-toluene solution is 5 wt%.
9. The toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation according to claim 1, characterized in that, The specific preparation steps of the dual covalent self-healing polyurethane are as follows: PTMG-2000, IPDI, and N,N-dimethylformamide were added to a reactor and mixed. Dibutyltin dilaurate was added at 70-80℃, and the mixture was reacted at 500-800 r / min for 1-2 h. After the reaction was completed, the mixture was cooled to room temperature, and furfurylamine was added to the reactor. The mixture was reacted at 800-1000 r / min for 30-60 min. The temperature was then raised to 55-65℃, and diethyl cysteine was added to the reactor. The reaction was continued for 1-2 h. Finally, bismaleimide was added at 60℃ and the mixture was reacted for 24 h to obtain a double covalent self-healing polyurethane.
10. The toughened composite polyurethane impact-resistant material based on dynamic covalent bond energy regulation according to claim 8, characterized in that, The ratio of PTMG-2000, IPDI, N,N-dimethylformamide, dibutyltin dilaurate, furfurylamine, diethyl cysteine, and bismaleimide is 114-126g. 26.1-27.3g: 165-195mL: 0.3-0.6mL: 5.7-6g: 7.8-8.4g: 6.6-6.9g.