High-strength HDPE (high-density polyethylene) composite material as well as preparation method and application thereof

Abstract

The invention relates to a high-strength HDPE (high-density polyethylene) composite material and a preparation method and application thereof, and belongs to the technical field of composite material preparation. Basalt fibers are subjected to modification pretreatment through a titanate coupling agent, titanium hydroxyl groups formed by alkoxy hydrolysis and hydroxyl groups on the surfaces of the basalt fibers are subjected to dehydration condensation, and stable covalent bonds are formed; the surface activity of the basalt fiber is remarkably improved, a foundation is laid for formation of a PDA coating through self-polymerization of dopamine and in-situ growth of Zn-MOF crystals, it is ensured that the fiber surface is evenly and compactly coated with the composite coating, multiple weak interactions are formed with fluorinated HDPE particles and modified granite saw mud, and the surface activity of the basalt fiber is improved. Organic long chains on the surface of the modified granite saw mud and grafted chain segments of the fluorinated HDPE particles are subjected to molecular entanglement, interface gaps are further filled, a compact and stable interface network is finally constructed, component agglomeration is effectively inhibited, interface defects are reduced, the mechanical property attenuation of the composite material is slow in the long-term service process, and the structural stability is improved.

Description

Technical Field

[0001] This invention belongs to the field of composite material preparation technology, and relates to a high-strength HDPE composite material, its preparation method and application. Background Technology

[0002] High-density polyethylene (HDPE), a thermoplastic resin with high crystallinity and excellent chemical stability, has been widely used in packaging, construction, municipal engineering, marine engineering, automobile manufacturing, and other fields due to its advantages of corrosion and wear resistance, good processability, and controllable cost. It is a core basic material in industrial production and people's livelihood applications. However, pure HDPE has inherent performance shortcomings. Its tensile strength, flexural modulus, and other mechanical properties are difficult to meet the high strength requirements of high-end structural components and harsh working conditions. It also has insufficient low-temperature toughness and limited resistance to environmental stress cracking. In scenarios such as high impact in the ocean, long-term outdoor service, and heavy industrial load-bearing, it is prone to deformation and damage. At the same time, traditional modified HDPE also faces the technical contradiction of difficulty in balancing strength and toughness, which seriously limits its application expansion in high-value-added fields.

[0003] Chinese invention patent application CN116178819A discloses a polyimide-reinforced HDPE composite material, its preparation method, and its application. The material is composed of the following raw materials in parts by weight: 100 parts high-density polyethylene, 0.25-2 parts sheet-like polyimide powder, and 0.5-5 parts maleic anhydride-grafted polyethylene; wherein the sheet-like polyimide powder is a two-dimensional sheet-like powder. Based on the high rigidity, high strength, low density, and large aspect ratio of the sheet-like polyimide powder, the rigidity and strength of the HDPE material are improved. The HDPE composite material also possesses the advantages of high impact toughness and low density.

[0004] The HDPE composite material in the above scheme relies solely on maleic anhydride-grafted polyethylene as a single compatibilizer. The interfacial bonding between polyimide and HDPE matrix is ​​achieved only through molecular entanglement of the compatibilizer. The interfacial interaction is singular and the bonding strength is limited. If used as a material for corrugated pipes, it is prone to peeling of the filler from the matrix due to the attenuation of interfacial forces under complex working conditions such as acid and alkali over a long period of time, resulting in a significant decrease in the mechanical properties of the composite material in terms of strength. Summary of the Invention

[0005] The purpose of this invention is to provide a high-strength HDPE composite material, its preparation method and application. Through multi-component synergistic modification and interface optimization design, it solves the technical problems of traditional HDPE composite materials, such as difficulty in achieving both strength and toughness, weak interfacial bonding, and insufficient environmental stability.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for preparing a high-strength HDPE composite material includes the following steps: Step 1: Basalt fiber is modified by titanate coupling agent NDZ-105 to obtain pretreated basalt fiber; polydopamine coating is formed on the surface of pretreated basalt fiber by self-polymerization, and Zn-MOF is synthesized on its surface by hydrothermal synthesis to obtain modified basalt fiber.

[0007] Step 2: Modify the granite sawdust using the rare earth coupling agent WOT-108 to obtain modified granite sawdust.

[0008] Step 3: Graft a fluorinated silane coupling agent onto the surface of HDPE particles to obtain fluorinated HDPE particles.

[0009] Step 4: Mix fluorinated HDPE particles, modified basalt fibers and modified granite sawdust, melt blend, and mold to obtain a high-strength HDPE composite material.

[0010] Furthermore, the specific preparation process of the pretreated basalt fiber is as follows: Deionized water and titanate coupling agent NDZ-105 were added to the reactor, followed by acid solution. The pH value was adjusted to 4-5, and the mixture was stirred for 2-3 hours to obtain a modified solution. After ultrasonic cleaning, the basalt fiber was placed in the modified solution and stirred for 2-3 hours to obtain pretreated basalt fiber.

[0011] Furthermore, the ratio of deionized water, titanate coupling agent NDZ-105, and basalt fiber is 400-500mL: 2.0-2.3g: 150-170g.

[0012] Furthermore, the acid solution is either citric acid or acetic acid.

[0013] Furthermore, the specific preparation process of modified basalt fiber is as follows: Pretreated basalt fiber, deionized water, anhydrous ethanol, and dopamine were added to a reaction vessel. The pH was adjusted to 9 with ammonia. The mixture was stirred for 30-34 hours at 25-30℃ and 500-600 rpm. After filtration, washing, and drying, the mixture was added to the reaction vessel with zinc nitrate hexahydrate, terephthalic acid, 5 wt% nitric acid, and N,N-dimethylformamide. The mixture was stirred for 3-5 hours and then transferred to a high-pressure reaction vessel. The mixture was reacted at 100-110℃ for 24-26 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to obtain modified basalt fiber.

[0014] Furthermore, the ratio of the amounts of pretreated basalt fiber, deionized water, anhydrous ethanol, dopamine, zinc nitrate hexahydrate, terephthalic acid, nitric acid, and N,N-dimethylformamide is 150-170g: 300-400mL: 200-300mL: 0.3-0.5g: 8.9-10.9g: 5-7g: 2.1-2.5mL: 300-360mL.

[0015] Furthermore, the specific preparation process of modified granite sawdust is as follows: Add the dried granite sawdust and rare earth coupling agent WOT-108 to a high-speed mixer, stir for 3-5 minutes, and dry at 100-110℃ for 2-3 hours to obtain modified granite sawdust.

[0016] Furthermore, the ratio of granite sawdust to rare earth coupling agent WOT-108 is 400-500g: 4.5-5.0mL.

[0017] Furthermore, the specific preparation process of fluorinated HDPE particles is as follows: Deionized water, anhydrous ethanol, and a fluorinated silane coupling agent were added to a reactor and stirred at 20-25°C for 1-2 hours. HDPE particles were then added, followed by the addition of triethylamine. The mixture was stirred at 1000-1200 rpm and 60-65°C for 6-8 hours. The mixture was then filtered, washed, and dried to obtain fluorinated HDPE particles.

[0018] Furthermore, the ratio of deionized water, anhydrous ethanol, fluorinated silane coupling agent, HDPE particles, and triethylamine is 300-400mL: 200-300mL: 0.5-0.9mL: 400-500g: 2-4mL.

[0019] Furthermore, the fluorine-containing silane coupling agent is any one of tridecafluorooctyltriethoxysilane, 1H,1H,2H,2H-perfluorohexyltriethoxysilane, and tridecafluorooctyltrimethoxysilane.

[0020] Furthermore, the mass ratio of fluorinated HDPE particles, modified basalt fiber, and modified granite sawdust is 40-45:8-9:12-13.

[0021] Furthermore, the melt blending temperature is 165-175℃, and the rotation speed is 15-25 r / min.

[0022] Furthermore, the molding temperature is 170-180℃, the board pressure is 15-17MPa, the venting interval is 5-7s, and the holding time is 200-220s.

[0023] This invention also provides a high-strength HDPE composite material, which is obtained by mixing fluorinated HDPE particles, modified basalt fibers and modified granite sawdust, melting and blending them in an open rubber mixing mill for 4-6 minutes, and then molding the open-milled raw materials into shape using a flat vulcanizing mill.

[0024] The present invention also provides an application of high-strength HDPE composite material in octagonal HDPE corrugated pipe.

[0025] The beneficial effects of this invention are: This invention first pretreats basalt fibers with a titanate coupling agent. The titanium hydroxyl groups formed by the hydrolysis of alkoxy groups undergo dehydration condensation with the hydroxyl groups on the surface of the basalt fibers, forming stable covalent bonds. This significantly enhances the surface activity of the basalt fibers, laying a solid foundation for the subsequent dopamine self-polymerization to form a PDA coating and the in-situ growth of Zn-MOF crystals. This ensures that the PDA-MOF composite coating is uniformly and densely coated on the fiber surface. At the same time, it can form multiple weak interactions such as hydrogen bonds and van der Waals forces with fluorinated HDPE particles and modified granite sawdust. This causes the organic long chains on the surface of the modified granite sawdust to become molecularly entangled with the grafted segments of the fluorinated HDPE particles, further filling the interfacial gaps. Finally, a dense and stable interfacial network is constructed, effectively inhibiting component aggregation and delamination, reducing interfacial defects, and enabling the composite material to slowly degrade its mechanical properties and improve its structural stability during long-term service. This provides a strong guarantee for long-term service under special working conditions.

[0026] The modified basalt fiber in this invention retains its inherent high strength and toughness. Through the active groups of the surface PDA-MOF composite coating, it interacts with other components to provide skeletal support, effectively absorbing external impact energy and significantly improving the impact toughness of the composite material. After modification with rare earth coupling agents, the organic long chains grafted onto the surface of the modified granite sawdust greatly improve its dispersion uniformity. Its inorganic rigidity can specifically enhance the tensile strength and flexural modulus of the composite material, providing stable rigid support. Fluorinated HDPE particles, as the matrix, not only possess a good toughness foundation, but the organic segments grafted onto their surface can also form molecular entanglements with the organic long chains of the modified granite sawdust and the PDA-MOF coating on the surface of the modified basalt fiber, further strengthening the interfacial bonding and achieving a balanced improvement in strength and toughness.

[0027] 3. In this invention, after the fluorinated HDPE particles are modified with a fluorinated silane coupling agent, the fluorinated groups introduced on the surface effectively reduce the surface energy of the material, thereby reducing the water absorption rate of the composite material. At the same time, the dense interfacial network and the hydrophobic protection of the fluorinated groups form a synergistic effect, which can effectively block the penetration of corrosive media, resulting in excellent corrosion resistance. The improved corrosion resistance and hydrophobicity can avoid damage to the material interface structure under complex working conditions (humid, acidic and alkaline environments), thereby protecting the synergistic mechanical effect between the components from being weakened, extending the service life of the material, and allowing the synergistic mechanical effect to play a full role under complex working conditions.

[0028] 4. The high-strength HDPE composite material prepared by this invention possesses excellent synergistic mechanical properties, corrosion resistance, and structural stability. It is particularly suitable for the application requirements of octagonal HDPE corrugated pipes. Its high ring stiffness, achieved through synergistic mechanical effects, can effectively resist buried soil pressure. Its high impact toughness can withstand construction collisions and fluid impacts. Its excellent corrosion resistance can withstand sewage and soil acid and alkali erosion. At the same time, it can also be extended to other fields such as packaging, construction, and municipal engineering, where there are high requirements for material strength and corrosion resistance. This allows the synergistic mechanical effects to play a role in different scenarios, significantly improving the application value of the material. Detailed Implementation

[0029] To further illustrate the technical means and effects of the present invention in achieving the intended purpose, the following detailed description of the specific implementation methods, features and effects of the present invention, in conjunction with preferred embodiments, is provided below.

[0030] Example 1: This example provides a high-strength HDPE composite material, prepared through the following steps: S1: Add 400 mL of deionized water and 2.0 g of titanate coupling agent NDZ-105 to the reactor, then add 20 mL of acetic acid to adjust the pH to 4. Stir at 65 °C for 2 h until the solution is hydrolyzed to a colorless and precipitate-free state to obtain the modified solution. Place 150 g of basalt fiber in 300 mL of acetone solution and sonicate it multiple times. Then place it in the modified solution and stir and mix at 75 r / min for 2 h to obtain the pretreated basalt fiber.

[0031] The alkoxy group of titanate coupling agent NDZ-105 is hydrolyzed into titanium hydroxyl group, which undergoes dehydration condensation with the hydroxyl group on the surface of basalt fiber to form stable covalent bonds such as Ti-O-Si and Ti-O-Al.

[0032] S2: 150g of pretreated basalt fiber, 300mL of deionized water, 200mL of anhydrous ethanol and 0.3g of dopamine were added to a reaction vessel. The pH was adjusted to 9 with ammonia. The mixture was stirred at 25℃ and 500r / min for 30h. After filtration, washing and drying, the mixture was added to a reaction vessel with 8.9g of zinc nitrate hexahydrate, 5g of terephthalic acid, 2.1mL of nitric acid (5wt%) and 300mL of N,N-dimethylformamide. The mixture was stirred at 500r / min for 3h. The mixture was then transferred to a high-pressure reaction vessel and reacted at 100℃ for 24h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed three times with anhydrous ethanol and deionized water, and vacuum dried at 70℃ for 8h to obtain modified basalt fiber.

[0033] The polydopamine (PDA) coating, which is formed by the self-polymerization of dopamine in a weakly alkaline environment, has a surface rich in amino and catechol groups, which can serve as anchoring points for MOF crystal growth. Nitric acid provides an acidic environment, promoting the coordination polymerization of zinc nitrate hexahydrate and terephthalic acid to form Zn-MOF crystals. Zn-MOF grows in situ on the surface of basalt fibers through the coordination of the amino and hydroxyl groups of the PDA coating with zinc ions, forming a dense PDA-MOF composite coating. At the same time, the PDA coating can enhance the bonding stability between MOF and basalt fibers.

[0034] S3: Dry 400g of granite sawdust at 130℃, add the granite sawdust and 4.5mL of rare earth coupling agent WOT-108 into a high-speed mixer, stir for 3min, and dry at 100℃ for 2h to obtain modified granite sawdust.

[0035] The active groups of rare earth coupling agent WOT-108 undergo coordination reactions with the hydroxyl groups on the surface of granite sawdust (mainly composed of SiO2 and Al2O3), grafting long organic chains onto the surface of the granite sawdust.

[0036] S4: Add 300 mL of deionized water, 200 mL of anhydrous ethanol, and 0.5 mL of 1H,1H,2H,2H-perfluorohexyltriethoxysilane to a reaction vessel and stir for 1 h at 20 °C and 500 r / min. Add 400 g of HDPE granules and dropwise add 2 mL of triethylamine. Stir for 6 h at 1000 r / min and 60 °C. Filter, wash three times with deionized water, and dry to obtain fluorinated HDPE granules.

[0037] Perfluorohexyltriethoxysilane hydrolyzes to generate silanol groups, which undergo a polycondensation reaction with hydrogen atoms on the surface of HDPE particles (activated by triethylamine catalysis), thereby grafting onto the material surface and reducing the surface energy of the material. A mixed solvent of deionized water and anhydrous ethanol can ensure uniform mixing.

[0038] S5: Mix 40g of fluorinated HDPE granules, 8g of modified basalt fiber, and 12g of modified granite sawdust evenly to obtain a mixture. Place the mixture in a vacuum drying oven and evacuate it to -0.1MPa to ensure that the air is completely removed. Dry it at 50℃ for 12 hours. Melt-blend it in an open mixing mill for 4 minutes. The temperature of the front and rear rollers of the open mill is 165℃, and the rotation speed is 15r / min. Then, use a flat vulcanizing machine to mold the open-milled raw material. The temperature of the upper and lower plates of the vulcanizing machine is 170℃, the plate pressure is 15MPa, the venting interval is 5s, and the pressure is held for 200s to obtain a high-strength HDPE composite material.

[0039] Fluorinated HDPE particles, through surface-grafted organic segments, become entangled with the organic long chains on the surface of modified granite sawdust, the PDA coating on the surface of pretreated basalt fibers, and the MOF layer, forming a continuous three-dimensional network structure. Meanwhile, the amino and hydroxyl groups on the surface of the PDA-MOF composite coating interact with the active groups on the surface of modified granite sawdust and the functional groups of the HDPE matrix through weak interactions such as hydrogen bonds and van der Waals forces, further enhancing the interfacial bonding between the components and synergistically improving the mechanical properties of the composite material.

[0040] Example 2: This example provides a high-strength HDPE composite material, prepared through the following steps: S1: Add 450 mL of deionized water and 2.15 g of titanate coupling agent NDZ-105 to the reactor, then add 25 mL of acetic acid to adjust the pH to 4. Stir at 67 °C for 2.5 h until the solution is hydrolyzed to a colorless and precipitate-free state to obtain the modified solution. Place 160 g of basalt fiber in 300 mL of acetone solution and sonicate it multiple times. Then place it in the modified solution and stir and mix at 77 r / min for 2.5 h to obtain the pretreated basalt fiber.

[0041] S2: 160g of pretreated basalt fiber, 350mL of deionized water, 250mL of anhydrous ethanol and 0.4g of dopamine were added to a reaction vessel. The pH was adjusted to 9 with ammonia. The mixture was stirred at 27℃ and 550r / min for 32h. After filtration, washing and drying, the mixture was added to a reaction vessel with 9.9g of zinc nitrate hexahydrate, 6g of terephthalic acid, 2.3mL of nitric acid (5wt%) and 330mL of N,N-dimethylformamide. The mixture was stirred at 550r / min for 4h. The mixture was then transferred to a high-pressure reaction vessel and reacted at 105℃ for 25h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed four times with anhydrous ethanol and deionized water, and vacuum dried at 72℃ for 9h to obtain modified basalt fiber.

[0042] S3: Dry 450g of granite sawdust at 135℃, add the granite sawdust and 4.75mL of rare earth coupling agent WOT-108 into a high-speed mixer, stir for 4min, and dry at 105℃ for 2.5h to obtain modified granite sawdust.

[0043] S4: Add 350 mL of deionized water, 250 mL of anhydrous ethanol, and 0.7 mL of 1H,1H,2H,2H-perfluorohexyltriethoxysilane to a reaction vessel and stir for 1.5 h at 22 °C and 550 r / min. Add 450 g of HDPE granules and dropwise add 3 mL of triethylamine. Stir for 7 h at 1100 r / min and 62 °C. Filter, wash 4 times with deionized water, and dry to obtain fluorinated HDPE granules.

[0044] S5: Mix 42g of fluorinated HDPE granules, 8.5g of modified basalt fiber, and 12.5g of modified granite sawdust evenly to obtain a mixture. Place the mixture in a vacuum drying oven and evacuate it to -0.1MPa to ensure that the air is completely removed. Dry it at 55℃ for 13h. Melt-blend it in an open mixing mill for 5min. The temperature of the front and rear rollers of the open mill is 170℃, and the rotation speed is 20r / min. Then, use a flat vulcanizing machine to mold the open-milled raw material. The temperature of the upper and lower plates of the vulcanizing machine is 175℃, the plate pressure is 16MPa, the venting interval is 6s, and the pressure holding time is 210s to obtain a high-strength HDPE composite material.

[0045] Example 3: This example provides a high-strength HDPE composite material, prepared through the following steps: S1: Add 500 mL of deionized water and 2.3 g of titanate coupling agent NDZ-105 to the reactor, then add 30 mL of acetic acid to adjust the pH to 5. Stir at 70 °C for 3 h until the solution is hydrolyzed to a colorless and precipitate-free state to obtain the modified solution. Place 170 g of basalt fiber in 300 mL of acetone solution and sonicate it multiple times. Then place it in the modified solution and stir and mix at 80 r / min for 3 h to obtain the pretreated basalt fiber.

[0046] S2: 170g of pretreated basalt fiber, 400mL of deionized water, 300mL of anhydrous ethanol and 0.5g of dopamine were added to a reaction vessel. The pH was adjusted to 9 with ammonia. The mixture was stirred at 30℃ and 600r / min for 34h. After filtration, washing and drying, the mixture was added to a reaction vessel with 10.9g of zinc nitrate hexahydrate, 7g of terephthalic acid, 2.5mL of nitric acid (5wt%) and 360mL of N,N-dimethylformamide. The mixture was stirred at 600r / min for 5h. The mixture was then transferred to a high-pressure reaction vessel and reacted at 110℃ for 26h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed 5 times with anhydrous ethanol and deionized water, and vacuum dried at 75℃ for 10h to obtain modified basalt fiber.

[0047] S3: Dry 500g of granite sawdust at 140℃, add granite sawdust and 5.0mL of rare earth coupling agent WOT-108 into a high-speed mixer, stir for 5min, and dry at 110℃ for 3h to obtain modified granite sawdust.

[0048] S4: Add 400 mL of deionized water, 300 mL of anhydrous ethanol, and 0.9 mL of 1H,1H,2H,2H-perfluorohexyltriethoxysilane to a reaction vessel and stir for 2 h at 25 °C and 600 r / min. Add 500 g of HDPE granules and dropwise add 4 mL of triethylamine. Stir for 8 h at 1200 r / min and 65 °C. Filter, wash 5 times with deionized water, and dry to obtain fluorinated HDPE granules.

[0049] S5: Mix 45g of fluorinated HDPE granules, 9g of modified basalt fiber, and 13g of modified granite sawdust evenly to obtain a mixture. Place the mixture in a vacuum drying oven and evacuate it to -0.1MPa to ensure that the air is completely removed. Dry it at 60℃ for 14h. Melt-blend it in an open mixing mill for 6min. The temperature of the front and rear rollers of the open mill is 175℃, and the rotation speed is 25r / min. Then, use a flat vulcanizing machine to mold the open-milled raw material. The temperature of the upper and lower plates of the vulcanizing machine is 180℃, the plate pressure is 17MPa, the venting interval is 7s, and the pressure is held for 220s to obtain a high-strength HDPE composite material.

[0050] Example 4: This example provides a high-strength HDPE composite material. The difference from Example 1 is that in step S4, tridecafluorooctyltriethoxysilane is used instead of 1H,1H,2H,2H-perfluorohexyltriethoxysilane.

[0051] Example 5: This example provides a high-strength HDPE composite material. The difference from Example 1 is that in step S4, tridecafluorooctyltrimethoxysilane is used instead of 1H,1H,2H,2H-perfluorohexyltriethoxysilane.

[0052] Example 6: This example provides a high-strength HDPE composite material. The difference from Example 1 is that citric acid is used instead of acetic acid in step S1.

[0053] The raw materials used in the above embodiments are sourced as follows: Titanate coupling agent NDZ-105: limited component content 99%, purchased from Hubei Bohuer New Materials Co., Ltd.; Basalt fiber: 25mm, purchased from Taian Anfeng New Material Technology Co., Ltd.; Granite sawdust: with an average particle size of 20.11 μm, purchased from Shandong Dida Ecological Technology Co., Ltd., and crushed and ground by Shandong Fengli Heavy Industry Co., Ltd. 1H,1H,2H,2H-Perfluorohexyltriethoxysilane: 99% active ingredient content, purchased from Wuhan Smike Biotechnology Co., Ltd. Rare earth coupling agent WOT-108: active ingredient content 99.9%, purchased from Guangdong Weilinna New Material Technology Co., Ltd.; Dopamine: CAS No. 51-61-6, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; HDPE granules: density 0.958 g / cm³ 3 Purchased from Shanghai Muhuocan Polymer Materials Co., Ltd. Zinc nitrate hexahydrate: analytical grade, purchased from Nanjing Chemical Reagent Co., Ltd.; Terephthalic acid: 99% purity, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0054] Comparative Example 1: This comparative example provides a high-strength HDPE composite material, which differs from Example 1 in that the modified basalt fiber is removed in step S5.

[0055] Comparative Example 2: This comparative example provides a high-strength HDPE composite material, which differs from Example 1 in that the modified granite sawdust is removed in step S5.

[0056] Comparative Example 3: This comparative example provides a high-strength HDPE composite material, which differs from Example 1 in that the pretreated basalt fiber prepared in step S1 is used instead of the modified basalt fiber in step S5.

[0057] The high-strength HDPE composite materials prepared in Examples 1-6 and Comparative Examples 1-3 were subjected to performance testing: Tensile property test: The tensile properties of the samples were tested according to GB / T 1040.1-2018 standard using a CTM2500 universal testing machine.

[0058] Bending performance test: The bending performance of the samples was tested according to GB / T 9341-2008 standard using a CTM2500 universal testing machine.

[0059] Impact performance test: The impact strength of the test samples was tested according to GB / T 1843-2008 standard using a JHY 5D simply supported beam impact testing machine.

[0060] Water absorption rate: Tested according to GB / T 1034-2024 standard (immersed for 15 days at 23±2℃), the calculation formula is as follows: W=(W a -W o ) / W o The initial weight is W o The quality W after soaking a (Wipe away any moisture adhering to the sample surface before weighing).

[0061] Corrosion resistance: The electrochemical impedance of different composite materials was tested using an electrochemical workstation to characterize their corrosion resistance. The working electrode was the test sample, with a working area of ​​1 cm². 2 A saturated calomel electrode (SCE) was used as the reference electrode, and a platinum sheet (Pt) was used as the counter electrode. The test samples were immersed in a 3.5% NaCl electrolyte and removed for electrochemical analysis after 15 days. In the EIS test, the test amplitude was ±0.5V, the scan rate was 1mV / s, and the test range was 10... -2 -10 5 Hz.

[0062] The test results are shown in the table below: Table 1 Performance Test Overview

[0063] As shown in Table 1, the tensile strength, flexural strength, and impact strength of Examples 1-6 are all greater than those of Comparative Examples 1-3. This may be because the targeted modification of each component creates a synergistic reinforcing effect. The basalt fiber, after pretreatment with titanate coupling agent and PDA-MOF composite coating modification, forms stable covalent bonds and enhances surface activity. It retains its high strength and toughness while also playing a supporting role by interacting with other components through surface-active groups. The granite sawdust, after modification with rare earth coupling agent, is grafted with organic long chains, which greatly improves the dispersion uniformity. Its inorganic rigidity can enhance the tensile strength and flexural modulus of the material. The fluorinated HDPE particles, after graft modification with fluorinated silane coupling agent, provide good toughness as a matrix. The grafted chain segments on the surface form molecular entanglement with the modified granite sawdust and modified basalt fiber, strengthening the interfacial bonding. At the same time, the modification steps are coordinated and connected, laying the foundation for melt blending and molding, so that the three form a continuous and stable three-dimensional network structure to achieve efficient stress transfer.

[0064] The water absorption rates of Examples 1-6 are lower than those of Comparative Examples 1-3, possibly because after the HDPE particles in these examples were grafted with a fluorinated silane coupling agent, hydrophobic fluorinated groups were introduced onto the surface, effectively reducing the surface energy of the material and decreasing the adsorption and penetration of water. At the same time, after targeted modification, the components entangle with each other and form a dense interfacial network with multiple weak interactions, filling the gaps between the components, reducing the channels for water penetration, and further hindering water intrusion.

[0065] The 15-day electrochemical impedance of Examples 1-6 is higher than that of Comparative Example 3, indicating that Examples 1-6 have better anti-corrosion performance. This may be because the examples adopted a multi-dimensional anti-corrosion synergistic design. The fluorinated groups on the surface of the fluorinated HDPE particles form a hydrophobic protective layer, which can effectively prevent water, corrosive ions and other media from contacting the interior of the material. The PDA-MOF composite coating on the surface of the modified basalt fiber is dense and stable, which can not only enhance the interfacial bonding force, but also play a physical barrier role, further preventing the penetration of corrosive media. The dense interfacial network formed by the synergistic effect of the components fills the micropores inside the material, preventing corrosive media from penetrating into the matrix through the pores and causing corrosion. At the same time, the surface of each component is free of obvious defects after targeted modification, which reduces the adsorption sites of corrosive media and effectively delays the corrosion process.

[0066] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0067] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing a high-strength HDPE composite material, characterized in that, Includes the following steps: Step 1: Basalt fiber is modified by titanate coupling agent NDZ-105 to obtain pretreated basalt fiber; polydopamine coating is formed on the surface of pretreated basalt fiber by self-polymerization, and Zn-MOF is synthesized on its surface by hydrothermal synthesis to obtain modified basalt fiber. Step 2: Modify the granite sawdust using the rare earth coupling agent WOT-108 to obtain modified granite sawdust. Step 3: Graft a fluorinated silane coupling agent onto the surface of HDPE particles to obtain fluorinated HDPE particles. Step 4: Mix fluorinated HDPE particles, modified basalt fibers and modified granite sawdust, melt blend, and mold to obtain a high-strength HDPE composite material.

2. The method for preparing a high-strength HDPE composite material according to claim 1, characterized in that, The specific preparation process of the pretreated basalt fiber is as follows: Deionized water and titanate coupling agent NDZ-105 were added to the reaction vessel, followed by acid solution. The pH value was adjusted to 4-5, and the mixture was stirred for 2-3 hours to obtain a modified solution. After ultrasonic cleaning, the basalt fiber was placed in the modified solution and stirred for 2-3 hours to obtain pretreated basalt fiber. The ratio of deionized water, titanate coupling agent NDZ-105, and basalt fiber is 400-500 mL : 2.0-2.3 g : 150-170 g; The acid solution is either citric acid or acetic acid.

3. The method for preparing a high-strength HDPE composite material according to claim 1, characterized in that, The specific preparation process of the modified basalt fiber is as follows: Pretreated basalt fiber, deionized water, anhydrous ethanol, and dopamine were added to a reaction vessel. The pH was adjusted to 9 with ammonia. The mixture was stirred for 30-34 hours at 25-30℃ and 500-600 rpm. After filtration, washing, and drying, the mixture was added to the reaction vessel with zinc nitrate hexahydrate, terephthalic acid, 5 wt% nitric acid, and N,N-dimethylformamide. The mixture was stirred for 3-5 hours and then transferred to a high-pressure reaction vessel. The mixture was reacted at 100-110℃ for 24-26 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to obtain modified basalt fiber.

4. The method for preparing a high-strength HDPE composite material according to claim 3, characterized in that, The ratio of the pretreated basalt fiber, deionized water, anhydrous ethanol, dopamine, zinc nitrate hexahydrate, terephthalic acid, nitric acid, and N,N-dimethylformamide is 150-170g: 300-400mL: 200-300mL: 0.3-0.5g: 8.9-10.9g: 5-7g: 2.1-2.5mL: 300-360mL.

5. The method for preparing a high-strength HDPE composite material according to claim 1, characterized in that, The specific preparation process of the modified granite sawdust is as follows: Add the dried granite sawdust and rare earth coupling agent WOT-108 into a high-speed mixer, stir for 3-5 minutes, and dry at 100-110℃ for 2-3 hours to obtain modified granite sawdust. The ratio of granite sawdust to rare earth coupling agent WOT-108 is 400-500g: 4.5-5.0mL.

6. The method for preparing a high-strength HDPE composite material according to claim 1, characterized in that, The specific preparation process of the fluorinated HDPE particles is as follows: Deionized water, anhydrous ethanol, and a fluorinated silane coupling agent were added to a reactor and stirred at 20-25°C for 1-2 hours. HDPE particles were then added, followed by the addition of triethylamine. The mixture was stirred at 1000-1200 rpm and 60-65°C for 6-8 hours. The mixture was then filtered, washed, and dried to obtain fluorinated HDPE particles.

7. The method for preparing a high-strength HDPE composite material according to claim 6, characterized in that, The ratio of deionized water, anhydrous ethanol, fluorinated silane coupling agent, HDPE particles, and triethylamine is 300-400mL: 200-300mL: 0.5-0.9mL: 400-500g: 2-4mL. The fluorine-containing silane coupling agent is any one of tridecafluorooctyltriethoxysilane, 1H,1H,2H,2H-perfluorohexyltriethoxysilane, and tridecafluorooctyltrimethoxysilane.

8. The method for preparing a high-strength HDPE composite material according to claim 1, characterized in that, The mass ratio of the fluorinated HDPE particles, modified basalt fiber, and modified granite sawdust is 40-45:8-9:12-13; The melt blending temperature is 165-175℃, and the rotation speed is 15-25 r / min; The molding temperature is 170-180℃, the board pressure is 15-17MPa, the venting interval is 5-7s, and the holding time is 200-220s.

9. A high-strength HDPE composite material, characterized in that, It is prepared by the preparation method of a high-strength HDPE composite material according to any one of claims 1-8.

10. The application of the high-strength HDPE composite material according to claim 9 in octagonal HDPE corrugated pipes.

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