An enhanced ultra-high molecular weight polyethylene composite material and a method for preparing the same

Abstract

This invention discloses an enhanced ultra-high molecular weight polyethylene (UHMWPE) composite material and its preparation method, relating to the field of polymer composite material technology. The preparation method includes the following steps: S1, cleaning and drying an UHMWPE substrate to obtain a first substrate; S2, dispersing multi-walled carbon nanotubes (MWCNTs) in a solvent to obtain a MWCNT dispersion; S3, uniformly spraying the MWCNT dispersion onto the surface of the first substrate, and curing to obtain the enhanced UHMWPE composite material. This invention improves the comprehensive mechanical properties of UHMWPE through a simple and efficient surface modification method involving cleaning and drying the UHMWPE substrate, preparing the MWCNT dispersion, and spraying and curing. It also solves the problems of complex modification processes, high energy consumption, easy weight gain, and difficulty in large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, specifically to an enhanced ultra-high molecular weight polyethylene composite material and its preparation method. Background Technology

[0002] Ultra-high molecular weight polyethylene (UHMWPE) is a linear thermoplastic engineering plastic with a molecular weight typically exceeding 1 million. Due to its high-density entangled structure formed by its ultra-long molecular chains, UHMWPE possesses a series of outstanding comprehensive properties: extremely high impact toughness, extremely low coefficient of friction, excellent wear resistance, excellent chemical corrosion resistance, good low-temperature resistance, low density, non-toxicity, environmental friendliness, and ease of secondary processing. Leveraging these advantages, UHMWPE has become an indispensable high-performance engineering material in modern industry, widely used in numerous civilian fields such as rail transportation, sports equipment, construction machinery, building cushioning, automotive parts, food conveying, and medical accessories.

[0003] Despite the broad application prospects of ultra-high molecular weight polyethylene (UHMWPE), there are still significant technical challenges in high-end civilian applications. These challenges stem from its inherent structure and existing modification processes, and represent core needs that urgently require resolution in this field.

[0004] First, there is still room for improvement in the basic mechanical properties of pure ultra-high molecular weight polyethylene. Although its tensile strength, flexural modulus and impact resistance can meet the needs of ordinary civilian applications, the mechanical properties of pure ultra-high molecular weight polyethylene are no longer suitable for civilian structural components and lightweight load-bearing parts that have higher requirements for material strength and toughness. It is necessary to improve its comprehensive mechanical properties through modification treatment in order to expand its application range.

[0005] Secondly, existing modification technologies for ultra-high molecular weight polyethylene (UHMWPE) generally have many drawbacks, making it difficult to meet the needs of industrial production and practical applications. Traditional modification methods mainly include melt blending modification, fiber composite modification, and filler-filled modification. These processes all have significant shortcomings: melt blending modification requires high temperature and pressure conditions, making operation difficult and energy-intensive, and it easily leads to the breakage of UHMWPE molecular chains, destroying its inherent toughness; fiber composite modification is complex, has poor interfacial compatibility between fibers and substrates, and significantly increases the weight of the material, losing the core advantage of UHMWPE's lightweight nature; filler-filled modification suffers from difficulties in filler dispersion and easy agglomeration, which not only fails to effectively improve mechanical properties but may also reduce the material's processing performance and stability in use.

[0006] In addition, most existing modification processes are complicated and involve many steps, requiring high-end equipment, making it difficult to achieve large-scale, continuous industrial production. Furthermore, the modification costs are relatively high, which is not conducive to large-scale promotion and application. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides an enhanced ultra-high molecular weight polyethylene composite material and its preparation method. By cleaning and drying the ultra-high molecular weight polyethylene substrate, preparing a multi-walled carbon nanotube dispersion, and spraying and curing, the comprehensive mechanical properties of ultra-high molecular weight polyethylene are improved through a simple and efficient surface modification method. At the same time, it solves the problems of complex modification processes, high energy consumption, easy weight gain, and difficulty in large-scale industrial production.

[0008] This invention provides a method for preparing an enhanced ultra-high molecular weight polyethylene composite material, comprising the following steps: S1. The ultra-high molecular weight polyethylene substrate is cleaned and dried to obtain the first substrate. S2. Disperse multi-walled carbon nanotubes in a solvent to obtain a multi-walled carbon nanotube dispersion. S3. The multi-walled carbon nanotube dispersion is uniformly sprayed onto the surface of the first substrate, and after curing, an enhanced ultra-high molecular weight polyethylene composite material is obtained.

[0009] Specifically, in step S1, the cleaning process includes wiping the ultra-high molecular weight polyethylene substrate with anhydrous ethanol at least three times, and the drying process involves placing the cleaned ultra-high molecular weight polyethylene substrate in a ventilated environment at 20-30°C to air dry naturally.

[0010] Specifically, after step S1, the process further includes: roughening the first substrate.

[0011] Specifically, the roughening treatment is atmospheric pressure low-temperature plasma treatment, the discharge mode is dielectric barrier discharge, the working gas is normal pressure air, the working power is 150-250W, the treatment time is 40-80s, the distance between the working nozzle and the first substrate is 8-12mm, and the surface roughness of the first substrate after treatment is 0.8-1.5μm.

[0012] Specifically, in step S2, the inner diameter of the multi-walled carbon nanotube is in the range of 5–10 nm, the outer diameter of the multi-walled carbon nanotube is in the range of 10–20 nm, the length of the multi-walled carbon nanotube is in the range of 5–15 μm, and the purity of the multi-walled carbon nanotube is ≥98%.

[0013] Specifically, in step S2, the solvent is anhydrous ethanol; the components of the multi-walled carbon nanotube dispersion, by mass percentage, have a multi-walled carbon nanotube content ranging from 0.4 to 0.6 wt%, with the remainder being anhydrous ethanol.

[0014] Specifically, in step S2, multi-walled carbon nanotubes are dispersed in a solvent by ultrasonic dispersion treatment, with an ultrasonic power of 200–400 W and an ultrasonic time of 20–40 min; or In step S2, multi-walled carbon nanotubes are dispersed in a solvent by high-shear homogenization treatment, with a shearing speed of 5000-15000 r / min and a shearing time of 10-30 min.

[0015] Specifically, in step S3, the multi-walled carbon nanotube dispersion is uniformly sprayed onto the surface of the first substrate using air spraying. The spraying pressure is 0.25-0.35 MPa, the spraying distance is 10-20 cm, and the spraying thickness is 5-12 μm. The spraying environment temperature is 20-30℃, and the spraying environment relative humidity is 40%-60%.

[0016] Specifically, in step S3, the curing involves placing the first substrate coated with the multi-walled carbon nanotube dispersion at 50–70°C for 30–40 minutes.

[0017] This invention also provides a reinforced ultra-high molecular weight polyethylene composite material, prepared by the aforementioned method, wherein the reinforced ultra-high molecular weight polyethylene composite material has an interfacial adhesive strength ≥40 MPa, a tensile strength of 70–85 MPa, and an impact resistance of 60–75 J / m. 2 The flexural modulus is 2.5–3.5 GPa.

[0018] Compared with the prior art, the beneficial effects of the present invention are: The preparation method of the reinforced ultra-high molecular weight polyethylene composite material of the present invention is simple and efficient. The modification can be completed through three core steps: cleaning and drying, dispersion preparation, and spray curing. The process is short and easy to operate, without the need for harsh conditions such as high temperature and high pressure, which reduces the difficulty and cost of production and makes it easy to realize large-area, continuous industrial production. Moreover, the surface spraying modification does not require the addition of a large amount of filler or composite reinforcing fiber, and does not significantly increase the weight of the material, thus retaining the core advantage of ultra-high molecular weight polyethylene's lightweight nature. At the same time, it can effectively improve the comprehensive mechanical properties of pure ultra-high molecular weight polyethylene, improve its insufficient tensile strength, flexural modulus and impact resistance, and broaden the application range of the material in mid-to-high-end civilian fields. Furthermore, it avoids the defects of easy chain breakage in melt blending, poor compatibility of fiber composite interface, and easy agglomeration of filler. The modification process has little impact on the properties of the substrate, and the material has higher stability in use. The overall modification conditions are mild and highly applicable, and it can be adapted to ultra-high molecular weight polyethylene products of different specifications and shapes. It has good industrialization and promotion value and is conducive to large-scale promotion and application. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic flowchart illustrating the preparation method of the reinforced ultra-high molecular weight polyethylene composite material in this embodiment of the invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] This invention provides a method for preparing an enhanced ultra-high molecular weight polyethylene composite material. Figure 1 A schematic flowchart of a method for preparing reinforced ultra-high molecular weight polyethylene composite material according to an embodiment of the present invention is shown. The preparation method includes the following steps: S1. The ultra-high molecular weight polyethylene substrate is cleaned and dried to obtain the first substrate. Cleaning and drying remove impurities such as oil, dust, and weak boundary layers from the substrate surface, eliminating solvent or moisture interference and providing a clean substrate for subsequent multi-walled carbon nanotube adhesion. This not only enhances the substrate surface energy and improves coating wetting and adhesion, but also prevents impurities from causing weak interfacial bonding and coating peeling, and further prevents residual solvents / moisture from affecting curing and film uniformity.

[0023] In some specific embodiments, the cleaning process includes wiping the ultra-high molecular weight polyethylene (UHMWPE) substrate at least three times with anhydrous ethanol. Anhydrous ethanol has moderate polarity and can efficiently remove oil, dust, organic residues, mold release agents, and other weak interfacial substances from the UHMWPE surface without corroding or swelling the UHMWPE substrate. Wiping ≥3 times ensures that there are no dead corners or residual contaminants on the surface, guarantees the consistency of interfacial bonding, maximizes the cleanliness of the substrate surface, and provides a high surface energy substrate for subsequent multi-walled carbon nanotube coating.

[0024] In some specific embodiments, the drying process involves placing the cleaned ultra-high molecular weight polyethylene substrate in a ventilated environment at 20-30°C for natural air drying. This is a gentle drying method that does not generate thermal stress, does not cause warping or deformation of the substrate, and does not lead to loosening of internal chain segments. The drying conditions are relaxed, the energy consumption is extremely low, and it is suitable for continuous industrial operation. Moreover, there is no solvent residue or moisture interference after drying, which helps to avoid subsequent coating blistering, pinholes, and peeling.

[0025] Preferably, the substrate is air-dried naturally in a ventilated environment at 25°C. 25°C is a standard room temperature condition, highly compatible with the thermal stability of the ultra-high molecular weight polyethylene (UHMWPE) substrate, and far below its heat distortion and softening temperatures. This ensures that the drying process does not cause thermal damage, molecular chain relaxation, warping, or dimensional deviations to the substrate, thus fully preserving its mechanical properties and structural stability. Simultaneously, anhydrous ethanol evaporates uniformly and fully at 25°C, avoiding both surface blemishes caused by rapid solvent boiling at excessively high temperatures and slow drying rates and solvent residues caused by excessively low temperatures. Combined with a ventilated environment, this accelerates solvent diffusion and gas convection on the substrate surface, achieving uniform drying across the entire surface. This ensures no solvent residue, no moisture retention, and no secondary contamination, providing a clean, stable, and high-surface-energy substrate for subsequent plasma roughening treatment and multi-walled carbon nanotube dispersion spraying. This significantly improves the interfacial bonding strength and the consistency and repeatability of the composite material's performance.

[0026] In some specific embodiments, step S1 is followed by: roughening the first substrate. The roughening treatment can physically etch to increase the surface roughness of the substrate, while introducing polar active sites to achieve mechanical interlocking and chemical bonding. This can not only significantly improve the interfacial bonding strength between the subsequent multi-walled carbon nanotube coating and the substrate, but also enhance stress transfer efficiency, allowing the high strength of the multi-walled carbon nanotubes to be truly transferred to the substrate, and preventing the coating from delaminating under stress, friction, and bending.

[0027] Specifically, the roughening treatment is atmospheric pressure low-temperature plasma treatment, the discharge mode is dielectric barrier discharge, the working gas is normal pressure air, the working power is 150-250W, the treatment time is 40-80s, the distance between the working nozzle and the first substrate is 8-12mm, and the surface roughness of the first substrate after treatment is 0.8-1.5μm.

[0028] By clearly defining the key processes and parameters of the roughening treatment, uniform and controllable micro-etching and efficient activation of the first substrate surface can be achieved under mild conditions of room temperature, non-vacuum, and no chemical reagents throughout the process. This avoids high-temperature deformation, molecular chain breakage, or degradation of the substrate's bulk properties, fully preserving its original core advantages such as high toughness, low friction, and wear resistance. Furthermore, the surface roughness can be precisely controlled within an excellent range of 0.8–1.5 μm, preventing problems such as low interfacial bonding due to insufficient roughness or stress concentration and coating cracking caused by excessive roughness. Simultaneously, this plasma treatment can introduce a large amount of oxygen- and nitrogen-containing polar active agents onto the first substrate surface. The presence of reactive groups significantly enhances surface energy and wettability. Combined with the mechanical interlocking effect formed by appropriate roughness, it can greatly enhance the interfacial bonding strength between the multi-walled carbon nanotube coating and the first substrate, ensuring that the subsequent sprayed modified layer adheres firmly and is not easily peeled off. This improves the efficiency of mechanical property transfer, resulting in a stable increase in the tensile strength, flexural modulus, and impact toughness of the composite material. In addition, this process uses atmospheric pressure air as the working gas, eliminating the need for vacuum equipment, producing no waste liquid or waste gas emissions, making it green and environmentally friendly. Furthermore, the parameters are stable and controllable, the processing time is short, and the uniformity is good. It can be adapted to large-area, continuous industrial production, effectively improving product consistency and production efficiency.

[0029] S2. Disperse multi-walled carbon nanotubes in a solvent to obtain a multi-walled carbon nanotube dispersion. The reinforcing phase (multi-walled carbon nanotubes) is uniformly dispersed in a solvent to form a stable, sprayable system. Preparing a multi-walled carbon nanotube dispersion effectively retains the high mechanical properties of the multi-walled carbon nanotubes, enhancing the strength, modulus, and toughness of the substrate. It also forms a uniformly dispersed system, avoiding localized stress concentration and ensuring consistent material properties. The solvent is used to assist in spray coating and film formation, achieving thin-layer modification.

[0030] Specifically, the multi-walled carbon nanotubes have an inner diameter ranging from 5 to 10 nm, an outer diameter ranging from 10 to 20 nm, a length ranging from 5 to 15 μm, and a purity ≥ 98%. These multi-walled carbon nanotubes possess a suitable aspect ratio and high purity, allowing for the formation of a continuous flexible network through subsequent spraying. This network provides both reinforcement and toughening, ensuring excellent dispersibility and preventing agglomeration in the dispersion while fully leveraging the reinforcing effects of high mechanical strength and high modulus. It also avoids the introduction of impurities that could cause internal defects, stress concentration, or performance instability, ensuring a stable and controllable reinforcing effect.

[0031] Furthermore, the solvent is anhydrous ethanol, which has moderate volatility, suitable surface tension for spraying, and is compatible with UHMWPE without causing corrosion. The components of the multi-walled carbon nanotube dispersion are, by mass percentage, that the content of multi-walled carbon nanotubes ranges from 0.4 to 0.6 wt%, with the balance being anhydrous ethanol. Multi-walled carbon nanotubes with a concentration of 0.4 to 0.6 wt% can be stably dispersed in anhydrous ethanol, forming a long-term stable, non-stratified, and non-precipitated dispersion. During subsequent spraying, this ensures the formation of a continuous and uniform reinforcing network while avoiding multi-walled carbon nanotube agglomeration, coating cracking, or significant material weight gain, thus balancing reinforcement efficiency, lightweight advantages, and production costs.

[0032] In some specific embodiments, multi-walled carbon nanotubes are dispersed in a solvent by ultrasonic dispersion treatment. The ultrasonic power is 200-400W and the ultrasonic time is 20-40min. The ultrasonic dispersion process uses 200-400W ultrasonic power in combination with 20-40min ultrasonic time. Relying on the ultrasonic cavitation effect, instantaneous microjets and local impact forces are generated inside the solvent. This can gently and efficiently break the van der Waals forces that aggregate the multi-walled carbon nanotubes. Single-tube-level dispersion is achieved without destroying the aspect ratio of the carbon nanotubes or damaging the tube wall structure. This allows the multi-walled carbon nanotubes to remain stably suspended in the anhydrous ethanol system for a long time without settling or agglomerating. As a result, the reinforcement layer after spraying is uniform and continuous, and the mechanical properties are stable and consistent.

[0033] In some specific embodiments, multi-walled carbon nanotubes are dispersed in a solvent through high-shear homogenization treatment. The shearing speed is 5000–15000 r / min, and the shearing time is 10–30 min. The high-shear homogenization process uses a shearing speed of 5000–15000 r / min and a treatment time of 10–30 min. Relying on the strong shear force, turbulent force, and hydraulic shear effect generated by high-speed rotation, it quickly and powerfully breaks up the aggregated clusters of multi-walled carbon nanotubes, significantly shortening the dispersion time and improving the dispersion efficiency. It is particularly suitable for the preparation of large-scale, industrial-scale dispersions, and can obtain highly uniform and consistent multi-walled carbon nanotube dispersions in a short time. At the same time, it avoids excessive shearing that could cause carbon nanotube breakage or length loss, ensuring that its mechanical reinforcing effect is fully utilized.

[0034] S3. The multi-walled carbon nanotube dispersion is uniformly sprayed onto the surface of the first substrate, and after curing, an enhanced ultra-high molecular weight polyethylene composite material is obtained. By spraying, a thin, uniform layer of multi-walled carbon nanotubes is uniformly applied to the substrate surface. Curing allows the solvent to evaporate, and the multi-walled carbon nanotubes bond tightly to the substrate, forming a surface reinforcement layer. This allows for surface modification with no or minimal weight gain, preserving the lightweight advantages of UHMWPE. Furthermore, the process is simple, requiring no high temperature or pressure, and does not damage the UHMWPE molecular chains or toughness. It also allows for large-area continuous application, making it suitable for industrial production. Overall mechanical properties are significantly improved, expanding into high-end applications.

[0035] Specifically, the multi-walled carbon nanotube dispersion is uniformly sprayed onto the surface of the first substrate using air spraying. The spraying pressure is 0.25–0.35 MPa, the spraying distance is 10–20 cm, and the coating thickness is 5–12 μm. The spraying ambient temperature is 20–30 °C, and the relative humidity is 40%–60%. By controlling the air spraying pressure, spraying distance, coating thickness, and ambient temperature and humidity, the multi-walled carbon nanotube dispersion is deposited on the surface of the first substrate in the form of uniform droplets, forming a dense, reinforced thin layer with precise thickness, no sagging, no missed spraying, and no pinholes. This allows for large-area application on flat and irregularly shaped parts, improving film quality and product performance consistency.

[0036] Furthermore, the curing process involves placing the first substrate coated with the multi-walled carbon nanotube dispersion at 50–70°C for 30–40 minutes. Under gentle heating conditions, the solvent evaporates rapidly, promoting tight anchoring of the multi-walled carbon nanotubes to the first substrate and achieving complete coating curing. This avoids thermal deformation or performance degradation of the substrate caused by high temperatures, maximizes interfacial bonding strength, and ensures the overall performance of the composite material remains stable and meets standards.

[0037] This invention also provides a reinforced ultra-high molecular weight polyethylene composite material, prepared by the aforementioned method, wherein the reinforced ultra-high molecular weight polyethylene composite material has an interfacial adhesive strength ≥40 MPa, a tensile strength of 70–85 MPa, and an impact resistance of 60–75 J / m. 2 The flexural modulus is 2.5–3.5 GPa. The reinforced ultra-high molecular weight polyethylene composite material prepared through the above optimized process possesses an interfacial adhesive strength of not less than 40 MPa, a tensile strength of 70–85 MPa, and an impact resistance of 60–75 J / m. 2 With excellent comprehensive performance and a flexural modulus of 2.5 to 3.5 GPa, it retains the inherent advantages of ultra-high molecular weight polyethylene such as lightweight, chemical corrosion resistance, low temperature resistance, and low friction, while achieving a comprehensive improvement in mechanical properties. It can be widely used in high-end civil structural components, lightweight load-bearing components, and other scenarios, and has outstanding industrialization value.

[0038] Example 1 (1) Substrate cleaning and drying: Take ultra-high molecular weight polyethylene substrate and wipe it back and forth 4 times with anhydrous ethanol to remove surface oil, dust and weak boundary layer; place the wiped substrate in a ventilated environment at 25℃ and air dry for 25 minutes to obtain the first substrate.

[0039] (2) Preparation of dispersion: Multi-walled carbon nanotubes with an inner diameter of 6-8 nm, an outer diameter of 13-17 nm, a length of 8-12 μm and a purity of 99% were selected and a dispersion was prepared by adding 0.5 wt% multi-walled carbon nanotubes and 99.5 wt% anhydrous ethanol. Ultrasonic dispersion was used with an ultrasonic power of 300 W and an ultrasonic time of 30 min to obtain a uniform and stable multi-walled carbon nanotube dispersion.

[0040] (3) Spraying construction: Air spraying is used with a spraying pressure of 0.3MPa and a spraying distance of 15cm. The dispersion is evenly sprayed onto the roughened substrate surface, and the spraying thickness is controlled at 7-10μm. The spraying environment is controlled at a temperature of 25℃ and a relative humidity of 50%.

[0041] (4) Curing and molding: The sprayed substrate is placed in a 60℃ oven for 35 minutes to complete the curing and obtain the reinforced ultra-high molecular weight polyethylene composite material.

[0042] The material properties obtained in this embodiment were tested and found to be as follows: Interfacial bond strength: 40 MPa; tensile strength: 70 MPa; impact resistance: 60 J / m. 2 Flexural modulus 2.5 GPa.

[0043] Example 2 (1) Substrate cleaning and drying: Take ultra-high molecular weight polyethylene substrate and wipe it back and forth 4 times with anhydrous ethanol to remove surface oil, dust and weak boundary layer; place the wiped substrate in a ventilated environment at 25℃ and air dry for 25 minutes to obtain the first substrate.

[0044] (2) Plasma roughening treatment: The first substrate is subjected to atmospheric pressure low temperature plasma treatment. The discharge mode is dielectric barrier discharge, the working gas is normal pressure air, the working power is 200W, the treatment time is 60s, the distance between the nozzle and the substrate is 10mm, and the surface roughness of the substrate after treatment is 1.0~1.2μm.

[0045] (3) Preparation of dispersion: Multi-walled carbon nanotubes with an inner diameter of 6-8 nm, an outer diameter of 13-17 nm, a length of 8-12 μm and a purity of 99% were selected and a dispersion was prepared by adding 0.5 wt% multi-walled carbon nanotubes and 99.5 wt% anhydrous ethanol. Ultrasonic dispersion was used with an ultrasonic power of 300 W and an ultrasonic time of 30 min to obtain a uniform and stable multi-walled carbon nanotube dispersion.

[0046] (4) Spraying construction: Air spraying is used, with a spraying pressure of 0.3MPa and a spraying distance of 15cm. The dispersion is evenly sprayed onto the roughened substrate surface, and the spraying thickness is controlled at 7-10μm. The spraying environment is controlled at a temperature of 25℃ and a relative humidity of 50%.

[0047] (5) Curing and molding: The sprayed substrate is placed in a 60℃ oven for 35 minutes to complete the curing and obtain the reinforced ultra-high molecular weight polyethylene composite material.

[0048] The material properties obtained in this embodiment were tested and found to be as follows: Interfacial bond strength: 45 MPa; tensile strength: 78 MPa; impact resistance: 70 J / m. 2 Flexural modulus 3.0 GPa.

[0049] Example 3 (1) Substrate cleaning and drying: Take ultra-high molecular weight polyethylene substrate and wipe it back and forth 5 times with anhydrous ethanol to remove surface oil, dust and weak boundary layer; place the wiped substrate in a ventilated environment at 25℃ and air dry for 30 minutes to obtain the first substrate.

[0050] (2) Plasma roughening treatment: The first substrate is subjected to atmospheric pressure low temperature plasma treatment. The discharge mode is dielectric barrier discharge, the working gas is normal pressure air, the working power is 200W, the treatment time is 60s, the distance between the nozzle and the substrate is 10mm, and the surface roughness of the substrate after treatment is 1.0~1.2μm.

[0051] (3) Preparation of dispersion: Multi-walled carbon nanotubes with an inner diameter of 6-8 nm, an outer diameter of 13-17 nm, a length of 8-12 μm and a purity of 99% were selected and a dispersion was prepared by adding 0.5 wt% multi-walled carbon nanotubes and 99.5 wt% anhydrous ethanol. High shear homogenization dispersion was adopted with a shearing speed of 10000 r / min and a shearing time of 20 min to prepare a multi-walled carbon nanotube dispersion.

[0052] (4) Spraying construction: Air spraying is used, with a spraying pressure of 0.3MPa and a spraying distance of 15cm. The dispersion is evenly sprayed onto the roughened substrate surface, and the spraying thickness is controlled at 7-10μm. The spraying environment is controlled at a temperature of 25℃ and a relative humidity of 50%.

[0053] (5) Curing and molding: The sprayed substrate is placed in a 60℃ oven for 35 minutes to complete the curing and obtain the reinforced ultra-high molecular weight polyethylene composite material.

[0054] The material properties obtained in this embodiment were tested and found to be as follows: Interfacial bond strength: 45 MPa; tensile strength: 77 MPa; impact resistance: 68 J / m. 2 Flexural modulus 3.0 GPa.

[0055] Example 4 (1) Substrate cleaning and drying: Take ultra-high molecular weight polyethylene substrate and wipe it three times with anhydrous ethanol to remove surface oil, dust and weak boundary layer; place the wiped substrate in a ventilated environment at 20℃ and air dry for 30 minutes to obtain the first substrate.

[0056] (2) Plasma roughening treatment: The first substrate is subjected to atmospheric pressure low temperature plasma treatment. The discharge mode is dielectric barrier discharge, the working gas is normal pressure air, the working power is 150W, the treatment time is 40s, the distance between the nozzle and the substrate is 8mm, and the surface roughness of the substrate after treatment is 0.8~1.1μm.

[0057] (3) Preparation of dispersion: Multi-walled carbon nanotubes with an inner diameter of 5-7 nm, an outer diameter of 10-15 nm, a length of 5-9 μm and a purity of 98% were selected and a dispersion was prepared by adding 0.4 wt% multi-walled carbon nanotubes and 99.6 wt% anhydrous ethanol. Ultrasonic dispersion was used with an ultrasonic power of 200 W and an ultrasonic time of 20 min to obtain a uniform and stable multi-walled carbon nanotube dispersion.

[0058] (4) Spraying construction: Air spraying is used with a spraying pressure of 0.25MPa and a spraying distance of 10cm. The dispersion is evenly sprayed onto the roughened substrate surface, and the spraying thickness is controlled to be 5-9μm. The spraying environment is controlled at a temperature of 20℃ and a relative humidity of 40%.

[0059] (5) Curing and molding: The sprayed substrate is placed in a 50℃ oven for 40 minutes to complete the curing and obtain the reinforced ultra-high molecular weight polyethylene composite material.

[0060] The material properties obtained in this embodiment were tested and found to be as follows: Interfacial bond strength: 42 MPa; tensile strength: 72 MPa; impact resistance: 64 J / m. 2 Flexural modulus 2.7 GPa.

[0061] Example 5 (1) Substrate cleaning and drying: Take ultra-high molecular weight polyethylene substrate and wipe it back and forth 5 times with anhydrous ethanol to remove surface oil, dust and weak boundary layer; place the wiped substrate in a 30℃ ventilated environment to air dry naturally for 20 minutes to obtain the first substrate.

[0062] (2) Plasma roughening treatment: The first substrate is subjected to atmospheric pressure low temperature plasma treatment. The discharge mode is dielectric barrier discharge, the working gas is normal pressure air, the working power is 250W, the treatment time is 80s, the distance between the nozzle and the substrate is 12mm, and the surface roughness of the substrate after treatment is 1.3~1.5μm.

[0063] (3) Preparation of dispersion: Multi-walled carbon nanotubes with an inner diameter of 8-10 nm, an outer diameter of 16-20 nm, a length of 12-15 μm and a purity of 99% were selected and a dispersion was prepared by adding 0.6 wt% multi-walled carbon nanotubes and 99.4 wt% anhydrous ethanol. High shear homogenization dispersion was adopted with a shearing speed of 15000 r / min and a shearing time of 30 min to prepare a multi-walled carbon nanotube dispersion.

[0064] (4) Spraying construction: Air spraying is used, with a spraying pressure of 0.35MPa and a spraying distance of 20cm. The dispersion is evenly sprayed onto the roughened substrate surface, and the spraying thickness is controlled at 9-12μm. The spraying environment is controlled at a temperature of 30℃ and a relative humidity of 60%.

[0065] (5) Curing and molding: The sprayed substrate is placed in a 70℃ oven for 30 minutes to complete the curing and obtain the reinforced ultra-high molecular weight polyethylene composite material.

[0066] The material properties obtained in this embodiment were tested and found to be as follows: Interfacial bond strength: 48 MPa; tensile strength: 85 MPa; impact resistance: 75 J / m. 2 Flexural modulus 3.5 GPa.

[0067] Comparative Example 1 Unmodified ultra-high molecular weight polyethylene substrate was used as a blank control.

[0068] Test results: Tensile strength 55 MPa, impact resistance 42 J / m 2 Flexural modulus 1.5 GPa.

[0069] Comparative Example 2 Multi-walled carbon nanotubes were added by high-temperature and high-pressure melt blending, with a processing temperature of 180℃ and a pressure of 10MPa.

[0070] Test results: Obvious molecular chain breakage was observed; tensile strength was 62 MPa; impact resistance was 36 J / m. 2 Flexural modulus 1.7 GPa.

[0071] Comparative Example 3 The only difference was that the concentration of multi-walled carbon nanotubes in the dispersion was changed to 0.2 wt%, and the rest was the same as in Example 1.

[0072] Test results: interfacial adhesion strength 32MPa, tensile strength 63MPa, impact resistance 50J / m 2 Flexural modulus 1.8 GPa.

[0073] Comparative Example 4 The only difference was that the concentration of multi-walled carbon nanotubes in the dispersion was changed to 1.0 wt%, and the rest was the same as in Example 1.

[0074] Test results: Multi-walled carbon nanotubes showed severe agglomeration, coating cracking and numerous pinholes, interfacial strength of 28 MPa, tensile strength of 61 MPa, and impact resistance reduced to 50 J / m. 2 Flexural modulus 1.8 GPa.

[0075] Comparative Example 5 After spraying, no heating is required for curing; the product is allowed to air dry at room temperature for 2 hours. The rest of the process is the same as in Example 1.

[0076] Test results: Solvent residue, poor coating adhesion, interfacial strength 31 MPa, tensile strength 65 MPa, impact resistance 55 J / m. 2 Flexural modulus 2.2 GPa.

[0077] Summarize Through system performance testing and comparative analysis of five sets of examples and five sets of comparative examples, the feasibility, superiority, and technical uniqueness of the method for preparing reinforced ultra-high molecular weight polyethylene composite materials by surface spraying modification of multi-walled carbon nanotubes proposed in this invention were fully verified. Test results show that the composite material prepared using the optimized process of this invention has an interfacial adhesion strength ≥40 MPa, a tensile strength of 70–85 MPa, and an impact resistance of 60–75 J / m. 2 With a flexural modulus of 2.5–3.5 GPa, compared to unmodified ultra-high molecular weight polyethylene pure material, the tensile strength is increased by 27%–55%, the impact resistance is increased by 43%–79%, and the flexural modulus is increased by 67%–133%. The comprehensive mechanical properties are comprehensively and stably improved, which can meet the performance requirements of high-end civil structural components and lightweight load-bearing components.

[0078] Compared with traditional high-temperature and high-pressure melt blending modification processes, this invention completes the modification under ambient temperature and pressure conditions, avoiding defects such as molecular chain breakage and material toughness deterioration in ultra-high molecular weight polyethylene. It also solves the technical problems of high energy consumption, complex operation, and easy damage to the substrate's intrinsic properties associated with traditional processes. Comparative results confirm that the concentration of multi-walled carbon nanotubes is a key factor affecting the modification effect. When the concentration is controlled at 0.4–0.6 wt%, stable dispersion can be achieved in anhydrous ethanol, forming a uniform, continuous, and defect-free reinforced thin layer after spraying. Too low a concentration leads to insufficient reinforcement, while too high a concentration causes problems such as multi-walled carbon nanotube agglomeration, coating cracking, and a significant decrease in interfacial strength.

[0079] Meanwhile, heating and curing at 50–70°C for 30–40 minutes is a necessary step to ensure a strong bond in the coating. Omitting heating and curing and relying solely on room temperature air drying will result in solvent residue, poor coating adhesion, and a significant reduction in mechanical properties. Furthermore, after cleaning and drying, adding atmospheric pressure low-temperature plasma roughening treatment can achieve uniform micro-etching and polar activation of the substrate surface, controlling the surface roughness to 0.8–1.5 μm, further improving interfacial bonding strength and stress transfer efficiency, thus enabling the composite material to achieve excellent mechanical properties.

[0080] In summary, the three-step modification process of this invention, which focuses on cleaning and drying, dispersion preparation, and spray curing, has advantages such as simple process, mild conditions, low energy consumption, and no significant increase in material weight. It successfully solves the pain points of existing ultra-high molecular weight polyethylene modification processes, such as complexity, easy weight gain, difficulty in filler dispersion, poor interfacial compatibility, and difficulty in large-scale industrial production. While significantly improving the comprehensive mechanical properties of the material, it fully retains its inherent advantages such as lightweight, wear resistance, and chemical corrosion resistance, and has excellent industrialization promotion value and broad high-end application prospects.

[0081] The above provides a detailed description of an enhanced ultra-high molecular weight polyethylene composite material and its preparation method provided by the embodiments of the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing an enhanced ultra-high molecular weight polyethylene composite material, characterized in that, Includes the following steps: S1. The ultra-high molecular weight polyethylene substrate is cleaned and dried to obtain the first substrate. S2. Disperse multi-walled carbon nanotubes in a solvent to obtain a multi-walled carbon nanotube dispersion. S3. The multi-walled carbon nanotube dispersion is uniformly sprayed onto the surface of the first substrate, and after curing, an enhanced ultra-high molecular weight polyethylene composite material is obtained.

2. The preparation method according to claim 1, characterized in that, In step S1, the cleaning process includes wiping the ultra-high molecular weight polyethylene substrate with anhydrous ethanol at least three times, and the drying process involves placing the cleaned ultra-high molecular weight polyethylene substrate in a ventilated environment at 20-30°C to air dry naturally.

3. The preparation method according to claim 1, characterized in that, Step S1 is followed by: roughening the first substrate.

4. The preparation method according to claim 3, characterized in that, The roughening treatment is atmospheric pressure low-temperature plasma treatment, the discharge mode is dielectric barrier discharge, the working gas is normal pressure air, the working power is 150-250W, the treatment time is 40-80s, the distance between the working nozzle and the first substrate is 8-12mm, and the surface roughness of the first substrate after treatment is 0.8-1.5μm.

5. The preparation method according to claim 1, characterized in that, In step S2, the inner diameter of the multi-walled carbon nanotube is in the range of 5–10 nm, the outer diameter is in the range of 10–20 nm, the length is in the range of 5–15 μm, and the purity is ≥98%.

6. The preparation method according to claim 1, characterized in that, In step S2, the solvent is anhydrous ethanol; the components of the multi-walled carbon nanotube dispersion, by mass percentage, have a multi-walled carbon nanotube content ranging from 0.4 to 0.6 wt%, with the remainder being anhydrous ethanol.

7. The preparation method according to claim 1, characterized in that, In step S2, multi-walled carbon nanotubes are dispersed in a solvent by ultrasonic dispersion treatment, with an ultrasonic power of 200–400 W and an ultrasonic time of 20–40 min; or In step S2, multi-walled carbon nanotubes are dispersed in a solvent by high-shear homogenization treatment, with a shearing speed of 5000-15000 r / min and a shearing time of 10-30 min.

8. The preparation method according to claim 1, characterized in that, In step S3, the multi-walled carbon nanotube dispersion is uniformly sprayed onto the surface of the first substrate using air spraying. The spraying pressure is 0.25-0.35 MPa, the spraying distance is 10-20 cm, and the spraying thickness is 5-12 μm. The spraying environment temperature is 20-30℃, and the spraying environment relative humidity is 40%-60%.

9. The preparation method according to claim 1, characterized in that, In step S3, the curing process involves placing the first substrate coated with the multi-walled carbon nanotube dispersion at 50–70°C for 30–40 minutes.

10. A reinforced ultra-high molecular weight polyethylene composite material, characterized in that, The reinforced ultra-high molecular weight polyethylene composite material prepared by the preparation method according to any one of claims 1 to 9 has an interfacial adhesive strength ≥40 MPa, a tensile strength of 70–85 MPa, and an impact resistance of 60–75 J / m. 2 The flexural modulus is 2.5–3.5 GPa.

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