Ultraviolet grafting modified UHMWPE (Ultra High Molecular Weight Polyethylene) fiber, fiber reinforced composite material as well as preparation method and application of fiber reinforced composite material

Abstract

The invention provides an ultraviolet light grafting modified UHMWPE fiber, a fiber reinforced composite material and a preparation method and application of the UHMWPE fiber and the fiber reinforced composite material. The preparation method of the ultraviolet light grafting modified UHMWPE fiber comprises the following steps: (1) grafting Diazirine on the UHMWPE fiber: preparing absolute ethyl alcohol and 4-[3-(trifluoromethyl)-3H-bis (aziridin-3-yl) benzyl bromide (Diazirine) into a Diazirine ethanol solution; the UHMWPE fiber is immersed in a Diazirne ethanol solution, the surface of the fiber is fully wetted, the fiber is naturally aired, the two faces of the fiber are irradiated through an ultraviolet light source, and a UHMWPE-Dia fiber is obtained; (2) grafting the UHMWPE-Dia fiber with PEI: dissolving polyethyleneimine (PEI) in a solvent absolute ethyl alcohol to prepare a PEI solution, putting the UHMWPE-Dia fiber obtained in the step (1) and the PEI solution into a sealed container, and carrying out horizontal mechanical shaking for reaction; after the reaction is finished, the fiber is flatly laid and dried to remove the solvent absolute ethyl alcohol, and the UHMWPE-Dia-PEI fiber is obtained. The fiber reinforced composite material comprises epoxy resin, an amine curing agent and ultraviolet grafting modified UHMWPE (Ultra High Molecular Weight Polyethylene) fibers.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and particularly relates to a UV-grafted modified UHMWPE fiber, fiber-reinforced composite material, its preparation method and application. Background Technology

[0002] Ultra-high molecular weight polyethylene (UHMWPE) fiber, as a representative of high-performance fiber materials, has found important applications in defense, aerospace, marine engineering, and personal protective equipment due to its excellent specific strength, impact toughness, and chemical stability. However, the highly crystalline and non-polar nature of UHMWPE fiber results in extremely low surface energy and significant chemical inertness, with interfacial bonding with polymer matrices such as epoxy resins mainly relying on weak van der Waals physical adsorption. This interfacial incompatibility severely restricts the effective transfer of the fiber's high-strength properties to composite materials, becoming a key bottleneck limiting its structural applications.

[0003] To improve interface performance, existing technologies mainly adopt the following two types of solutions: The first category is physical surface treatment technology. For example, plasma treatment introduces oxygen-containing polar groups onto the fiber surface through high-energy particle bombardment, generating oxygen-containing functional groups such as hydroxyl and carboxyl groups. However, this method has significant drawbacks: the introduced active sites are prone to molecular chain rearrangement and decay under humid and hot environments, resulting in poor interface stability; the treatment effect typically decreases by more than 50% within 30 days; and the treatment depth is difficult to control, easily leading to uneven etching and other problems.

[0004] The second category is chemical modification technology. Strong chemical oxidation methods, such as acid etching, can introduce functional groups such as carboxyl and hydroxyl groups onto the fiber surface. However, the strong oxidation process will randomly attack the CC backbone, leading to a loss of fiber strength.

[0005] The common problems of the aforementioned existing technologies are: the inability to achieve targeted introduction of high-density, high-stability functional groups onto the inert surface of UHMWPE under mild conditions, the difficulty in balancing interfacial reactivity and fiber bulk properties, resulting in low chemical bonding efficiency between the fiber and matrix, poor continuity of the interfacial phase structure, and limited improvement in the interlaminar shear strength of the composite material. These technical problems are precisely the core technical problems that this invention aims to solve. Summary of the Invention

[0006] The purpose of this invention is to provide a UV-grafted modified UHMWPE fiber, fiber-reinforced composite material, its preparation method and application, which solves the technical problems of insufficient surface functionalization reaction sites, harsh reaction conditions requiring acid etching or plasma, and loss of fiber bulk strength in the prior art. The method of this invention achieves PEI grafting on the fiber surface under room temperature conditions, realizing the introduction of surface amine groups and the synergistic preservation of the fiber bulk mechanical properties, thereby constructing a continuous and stable covalent interface with the epoxy resin matrix, and improving the interlaminar shear strength of the composite material.

[0007] To achieve the above objectives, the present invention provides a method for preparing UHMWPE fiber modified by ultraviolet light grafting, which includes the following steps: (1) grafting Diazirne onto UHMWPE fiber: anhydrous ethanol and 4-[3-(trifluoromethyl)-3H-bisacrididin-3-yl]benzyl bromide (Diazirine) are prepared into a Diazirine ethanol solution, UHMWPE fiber is immersed in the Diazirne ethanol solution to fully wet the fiber surface, air-dry naturally, and irradiate both sides of the fiber with an ultraviolet light source to obtain UHMWPE-Dia fiber; (2) grafting PEI onto UHMWPE-Dia fiber: polyethyleneimine (PEI) is dissolved in anhydrous ethanol to prepare a PEI solution, and the UHMWPE-Dia fiber obtained in step (1) and the PEI solution are placed in a sealed container and the reaction is carried out by horizontal mechanical shaking; after the reaction is completed, the fiber is laid flat, dried and the anhydrous ethanol solvent is removed to obtain UHMWPE-Dia-PEI fiber.

[0008] Optionally, before grafting Diazirne onto UHMWPE fibers in step (1), the UHMWPE fibers are pretreated, including the following steps: immersing the UHMWPE fibers in hydrochloric acid solution with pH=6~7 and sodium hydroxide solution with pH=7~8 for 1 hour, then immersing them in anhydrous ethanol and deionized water for 12 hours each, and drying them in an oven at 80°C for 12 hours.

[0009] Optionally, the UHMWPE-Dia-PEI fiber obtained in step (2) can be placed in anhydrous ethanol solution and ultrasonically treated to remove residual PEI.

[0010] The present invention also provides a UV-grafted modified UHMWPE fiber prepared according to the preparation method described above.

[0011] The present invention also provides a fiber-reinforced composite material comprising an epoxy resin, an amine curing agent, and UHMWPE fibers modified by ultraviolet light grafting as described above.

[0012] Optionally, the mass ratio of the epoxy resin to the amine curing agent is 100:30, and the UV-grafted modified UHMWPE fiber accounts for 47% to 50% of the total volume of the composite material.

[0013] Optionally, the UV-grafted modified UHMWPE fibers account for 47% of the total volume of the composite material.

[0014] Optionally, the epoxy resin is E-51 epoxy resin.

[0015] Optionally, the amine curing agent is D-230.

[0016] The present invention also provides a method for preparing fiber-reinforced composite material according to the above description, which includes the following steps: (1) mixing epoxy resin and amine curing agent with a strong magnetic stirrer, and then degassing using a three-dimensional blender; (2) cutting UHMWPE fiber modified by ultraviolet light grafting according to the above description into thin sheets, brushing the mixed epoxy resin and amine curing agent onto the UHMWPE fiber in proportion, stacking the fiber sheets neatly, and hot-pressing to cure and form a composite material board.

[0017] Optionally, the hot pressing temperature is 100~127℃, the pressure is 36~40Mpa, and the curing time is 5-6h.

[0018] The present invention also provides an application of UHMWPE fiber modified by ultraviolet light grafting as described above, which is used in the fields of defense, aerospace, marine engineering and personal protective equipment.

[0019] The beneficial effects of this invention are as follows: 1. This invention first inserts benzyl bromide groups into the surface of UHMWPE fibers using 4-[3-(trifluoromethyl)-3H-bisacrididin-3-yl]benzyl bromide (diazirine), and then performs a grafting reaction between polyethyleneimine (PEI) and the UHMWPE fibers with the inserted benzyl bromide groups to improve the interfacial properties of the UHMWPE fibers. The raw materials used in the above method are basically non-toxic and harmless, the equipment used is easy to operate, the preparation method is relatively simple, and it has almost no impact on the original mechanical properties of the UHMWPE fibers. The modified fiber surface has increased wettability. In addition, the PEI grafted on the surface contains a large number of primary amine groups, which increases the polarity of the fiber surface. Furthermore, the amino groups can also participate in the curing of epoxy resin to form covalent bonds, thereby greatly enhancing the interfacial shear strength between the fiber and the resin, which is beneficial to improving the interfacial strength between UHMWPE fibers and composite materials.

[0020] 2. Diazirine generates carbene radicals upon UV irradiation, which can easily insert into the CH bonds on the UHMWPE surface, achieving covalent grafting. Furthermore, diazirine grafting does not damage the fiber's bulk structure, allowing for group insertion while preserving the fiber's original mechanical, appearance, and morphological properties. Based on this, benzyl bromide diazirine was selected, as it facilitates the insertion of benzyl bromide groups into the UHMWPE surface, aiding in the subsequent covalent grafting. Polyethyleneimine (PEI) contains numerous primary amine groups, which can undergo nucleophilic substitution with benzyl bromide on the UHMWPE surface at room temperature without other additives, achieving covalent grafting. Furthermore, primary amines can participate in the curing of epoxy resins. Primary amines open the epoxy groups, which acts as a link between epoxy resins and UHMWPE fibers at the interface, forming a strong adhesive interface between epoxy resins and UHMWPE. The grafted PEI is very thin, which helps to maintain the lightweight nature of the fiber composite material and does not cause adhesion between fibers. The introduction of amine groups also greatly enhances the surface energy of the fibers, enhances the wettability of epoxy resins, and helps to enhance the overall performance of the composite material.

[0021] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0022] The above and other objects, features, and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings. It will be obvious to those skilled in the art that other drawings can be obtained from these drawings without any inventive effort.

[0023] Figure 1 The graph shows the XPS test results of the UHMWPE-Dia-PEI fiber of Example 1, the UHMWPE fiber of Comparative Example 1 that underwent only pretreatment, and the UHMWPE-Dia fiber of Comparative Example 2.

[0024] Figure 2 The results of SEM tests on the UHMWPE-Dia-PEI fiber of Example 1, the UHMWPE fiber of Comparative Example 1 that underwent only pretreatment, and the UHMWPE-Dia fiber of Comparative Example 2 are shown.

[0025] Figure 3 The results of static water contact angle tests are shown for the UHMWPE-Dia-PEI fiber of Example 1, the UHMWPE fiber of Comparative Example 1 that underwent only pretreatment, and the UHMWPE-Dia fiber of Comparative Example 2.

[0026] Figure 4The graph shows the results of AFM testing on the UHMWPE-Dia-PEI fiber of Example 1, the UHMWPE fiber of Comparative Example 1 that underwent only pretreatment, and the UHMWPE-Dia fiber of Comparative Example 2.

[0027] Figure 5 The figure shows the results of tensile strength tests on the UHMWPE-Dia-PEI fiber of Example 1, the UHMWPE fiber of Comparative Example 1 that underwent only pretreatment, and the UHMWPE-Dia fiber of Comparative Example 2.

[0028] Figure 6 The graph shows the results of short beam shear strength tests on the UHMWPE-Dia-PEI fiber-reinforced composite material prepared in Example 1 and the UHMWPE fiber-reinforced composite material prepared in Comparative Example 1. Detailed Implementation

[0029] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention are described in detail, clearly, and completely below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention; however, the present invention may also be implemented in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0030] The method for preparing UHMWPE fiber modified by ultraviolet light grafting according to the present invention includes the following steps: (1) grafting Diazirne onto UHMWPE fiber: anhydrous ethanol and 4-[3-(trifluoromethyl)-3H-bisacrididin-3-yl]benzyl bromide (Diazirine) are prepared into Diazirine ethanol solution, UHMWPE fiber is immersed in Diazirne ethanol solution to fully wet the fiber surface, air-dry naturally, and irradiate both sides of the fiber with ultraviolet light source to obtain UHMWPE-Dia fiber; (2) grafting PEI onto UHMWPE-Dia fiber: polyethyleneimine (PEI) is dissolved in anhydrous ethanol to prepare PEI solution, and the UHMWPE-Dia fiber obtained in step (1) and PEI solution are placed in a sealed container and the reaction is carried out by horizontal mechanical shaking; after the reaction is completed, the fiber is laid flat, dried and the anhydrous ethanol solvent is removed to obtain UHMWPE-Dia-PEI fiber. The obtained UHMWPE-Dia-PEI fibers can be placed in anhydrous ethanol solution and ultrasonically treated to remove residual PEI.

[0031] The UHMWPE fibers are pretreated before grafting Diazirne onto them. The pretreatment method includes the following steps: immersing the UHMWPE fibers in a hydrochloric acid solution with pH=6~7 and a sodium hydroxide solution with pH=7~8 for 1 hour, then immersing them in anhydrous ethanol and deionized water for 12 hours each, and finally drying them in an oven at 80°C for 12 hours.

[0032] The fiber-reinforced composite material according to the present invention comprises an epoxy resin, an amine curing agent, and UHMWPE fibers modified by ultraviolet light grafting as described above. The epoxy resin and amine curing agent are present in a mass ratio of 100:30, and the ultraviolet-grafted UHMWPE fibers account for 47% to 50% of the total volume of the composite material, preferably 47%. In one embodiment, the epoxy resin may be E-51 epoxy resin. In one embodiment, the amine curing agent may be D-230.

[0033] The method for preparing fiber-reinforced composite materials according to the present invention includes the following steps: (1) mixing epoxy resin and amine curing agent with a strong magnetic stirrer, and then degassing using a three-dimensional blender; (2) cutting UHMWPE fibers modified by ultraviolet light grafting as described above into thin sheets, brushing the mixed epoxy resin and amine curing agent onto the UHMWPE fibers in proportion, neatly stacking the fiber sheets, and hot-pressing and curing to obtain a composite material board. The hot-pressing temperature can be 100~127℃, the pressure can be 36~40 MPa, and the curing time can be 5-6 h.

[0034] The UHMWPE fiber modified by ultraviolet light grafting according to the present invention can be used in the fields of national defense, aerospace, marine engineering and personal protection.

[0035] The following detailed description, in conjunction with specific embodiments, illustrates the present invention of a UV-grafted modified UHMWPE fiber, a fiber-reinforced composite material, its preparation method, and its application.

[0036] Main raw materials and equipment used: Unless otherwise specified, the raw materials and equipment used in each embodiment and comparative example are the same; materials without specific models or types are sourced from common, same models purchased from the market, and no specific restrictions are imposed.

[0037] Example 1 (1) UHMWPE fiber pretreatment UHMWPE fibers were first immersed in hydrochloric acid solution (pH=6) and then in sodium hydroxide solution (pH=8) for 1 hour, followed by immersion in anhydrous ethanol and deionized water for 12 hours each, and then dried in an oven at 80°C for 12 hours.

[0038] (2) UHMWPE fiber grafted with Diazirne Anhydrous ethanol and Diazirine were mixed to prepare a 0.1 wt% Diazirine ethanol solution. UHMWPE fibers were immersed in the 0.1 wt% Diazirine ethanol solution at a mass ratio of 1:2 to fully wet the fiber surface. The fibers were then air-dried for 30 minutes. Both sides of the fibers were then irradiated for 5 minutes each using an 80W 365nm ultraviolet light source to obtain UHMWPE-Dia fibers.

[0039] (3) UHMWPE-Dia fiber grafted with PEI PEI was dissolved in anhydrous ethanol to prepare a 10wt% PEI solution. UHMWPE-Dia fibers and the PEI solution were added to a sealed tray at a mass ratio of 1:80 and placed on a horizontal shaker for 12 hours. After the reaction, the fibers were spread evenly on an uncovered tray and placed in a 70℃ oven for 1 hour to remove the anhydrous ethanol, yielding UHMWPE-Dia-PEI fibers. The UHMWPE-Dia-PEI fibers were then immersed in anhydrous ethanol solution and sonicated for 1 hour to remove residual PEI. Finally, the UHMWPE-Dia-PEI fibers were spread evenly on an uncovered tray and dried in a 70℃ oven for 1 hour.

[0040] (4) Preparation of UHMWPE epoxy resin composite material Epoxy resin E-51 and amine curing agent D-230 were mixed using a strong magnetic stirrer, and then degassed using a three-dimensional blender for later use. Fibers were cut into 15cm × 7.5cm sheets, and the mixed resin was brushed onto the fibers at 47% of their total volume. Twenty-four sheets of the fibers were neatly stacked, placed in a pressure bag for vacuum degassed, and then placed in an autoclave for curing. The autoclave temperature was set to a single gradient of 127℃, the pressure to 36 MPa, and the curing time to 5 hours, resulting in a UHMWPE-Dia-PEI fiber-reinforced composite material board.

[0041] Comparative Example 1 The difference from Example 1 is that steps (2) and (3) are omitted, and UHMWPE fiber and UHMWPE fiber reinforced composite material plate with only pretreatment are obtained in sequence.

[0042] Comparative Example 2 The difference from Example 1 is that step (3) is omitted, and UHMWPE-Dia fiber and UHMWPE-Dia fiber reinforced composite material plate are obtained sequentially.

[0043] Performance testing and test results The UHMWPE-Dia-PEI fibers from Example 1, Comparative Example 1, and Comparative Example 2, as well as the UHMWPE fibers and UHMWPE-Dia fibers that underwent only pretreatment, were cut into thin sheets for the following performance tests.

[0044] 1. X-ray energy dispersive spectroscopy (XPS) characterization X-ray energy dispersive spectroscopy (XPS) was performed on the UHMWPE-Dia-PEI fiber of Example 1, the UHMWPE fiber of Comparative Example 1 that underwent only pretreatment, and the UHMWPE-Dia fiber of Comparative Example 2 to study the surface grafting elements of the fibers.

[0045] The XPS test results are shown in the figure below. Figure 1 As shown, the three curves illustrate the surface elements of UHMWPE fibers before and after modification. Compared to unmodified UHMWPE, fibers pretreated with Diazirine exhibit an F1s signal from the trifluoromethyl group of Diazirine at 700 eV, indicating successful bonding of surface bisacrylidine to the fiber surface. An N1s signal on the amino group of PEI appears at 400 eV, indicating successful PEI grafting.

[0046] 2. SEM testing SEM tests were performed on the UHMWPE-Dia-PEI fiber of Example 1, the UHMWPE fiber of Comparative Example 1 (pretreated only), and the UHMWPE-Dia fiber of Comparative Example 2. Due to the poor conductivity of the fibers, the fiber surface was sputter-coated with gold (5mA, 90s). Secondary electron microscopy (SEmode) under high vacuum conditions was used for observation, with an activation voltage of 10kV and a physical distance of 12.5mm.

[0047] The SEM results are shown in the image below. Figure 2 As shown. Figure 2 (a) in the image is UHMWPE fiber with a smooth surface. Figure 2 (b) shows UHMWPE-Dia fibers pretreated with Diazirine. The fiber surface remains smooth, indicating that the insertion of carbene radicals does not significantly affect the surface structure of UHMWPE. Figure 2 (c) is UHMWPE-Dia-PEI fiber. After grafting PEI, the fiber surface remains smooth as before, proving the uniformity of the grafting.

[0048] 3. Static water contact angle test Static water contact angle tests were conducted on the UHMWPE-Dia-PEI fibers of Example 1, the UHMWPE fibers of Comparative Example 1 (pretreated only), and the UHMWPE-Dia fibers of Comparative Example 2 to observe the changes in contact angle before and after modification. The specific method was as follows: three types of UHMWPE fibers were cut into 3×3 pieces and fully flattened using a polytetrafluoroethylene (PTFE) plate. 0.02 ml of ultrapure water was precisely dripped using a flat-tipped syringe, and the water contact angle at five points was measured and averaged.

[0049] Static water contact angle results are as follows Figure 3 As shown. Figure 3 (a) in the image is a UHMWPE fiber with a contact angle of 120°±2°, exhibiting hydrophobicity. Figure 3 (b) in the figure is a Diazirine-treated UHMWPE-Dia fiber, whose contact angle remains almost unchanged at 120°±2°. Figure 3 (c) is UHMWPE-Dia-PEI fiber, and the contact angle of 0° after grafting PEI proves its good wettability.

[0050] 4. AFM Test AFM tests were performed on the UHMWPE-Dia-PEI fibers of Example 1, the UHMWPE fibers of Comparative Example 1 (pretreated only), and the UHMWPE-Dia fibers of Comparative Example 2. Atomic force microscopy (AFM) images of the fiber surfaces were collected using the AFM tapping mode, and the roughness was calculated using NanoScope Analysis software. Roughness was defined as arithmetic mean roughness (Ra) and root mean square roughness (Rq). R represents the overall smoothness of the surface, while Rq indicates the presence of significant deviations and irregularities on the surface.

[0051] AFM test results are as follows Figure 4 As shown. Figure 4 (a) in the figure is UHMWPE fiber, with Ra of only 42.7±7nm and Rq of only 55.9±6nm. Figure 4 (b) shows UHMWPE-Dia fibers pretreated with Diazirine. The Ra and Rq of the fibers were almost unchanged compared with the untreated fibers, at 45.4±6 nm and 58.4±6 nm, respectively. Figure 4 (c) is UHMWPE-Dia-PEI fiber, which is grafted with PEI after pretreatment with bisacrylidine. The roughness of the fiber is not significantly different from that of the untreated fiber, Ra=49.8±4nm, Rq=54.2±8nm.

[0052] 5. Tensile strength test Tensile strength tests were conducted on the UHMWPE-Dia-PEI fiber of Example 1, the UHMWPE fiber of Comparative Example 1 (pretreated only), and the UHMWPE-Dia fiber of Comparative Example 2. The mechanical properties of the fibers were tested using a universal tensile tester (AI-7000S1) from Dongguan High-Speed ​​Rail Testing Instruments Co., Ltd. The tensile strength of the fibers was tested according to GB / T19975-2005, with a tensile speed of 250 mm / min, a fiber length of 80 mm in the test area, a twist count of 80, and a clamping distance of 500 mm. Each sample was tested at least 10 times, and the average value was taken.

[0053] Fiber tensile strength test results are as follows Figure 5 As shown, the tensile strength of UHMWPE-Dia-PEI fiber is 473.9±6N, that of UHMWPE fiber is 463.9±9N, and that of pretreated UHMWPE-Dia fiber is 465.4±10N. The tensile strength of UHMWPE-Dia-PEI fiber is 2.1% higher than that of UHMWPE fiber, demonstrating that the carbene CH insertion grafting onto UHMWPE destroys fiber strength, and that the tensile strength of the fiber is slightly improved after grafting PEI.

[0054] The thickness of the UHMWPE-Dia-PEI fiber-reinforced composite board prepared in Example 1 and the UHMWPE fiber-reinforced composite board prepared in Comparative Example 1 were measured, and the boards were machined according to the thickness dimensions in accordance with standards ASTM D3846 and ASTM D2344 to obtain fiber-reinforced epoxy resin composite material specimens. Short beam shear strength tests were then performed on the obtained composite material specimens.

[0055] 6. Short beam shear strength test The shear strength of the short beams was tested using a universal tensile tester (AI-7000S1) from Dongguan High-Speed ​​Rail Testing Instruments Co., Ltd. The shear strength of the composite short beams was tested according to standard ASTM D2344-2016, where the specimen length = thickness × 6, the specimen width = thickness × 2, the test speed was a beam movement speed of 1.00 mm / min, and the span-to-thickness ratio was 4.0. Each sample was tested at least 5 times, and the average value was taken.

[0056] The shear strength test results of UHMWPE fiber composite short beams are as follows: Figure 6 As shown, the shear strength of the short beam of UHMWPE-Dia-PEI composite material is 21.2 ± 0.6 MPa, while that of the short beam of UHMWPE fiber composite material is 17.6 ± 0.7 MPa. The strength of the composite material prepared by UHMWPE-Dia-PEI fiber is increased by 20% compared with that prepared by UHMWPE fiber, which proves that surface grafting improves the interfacial shear strength of fiber and resin.

[0057] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A method for preparing ultraviolet light grafted modified UHMWPE fibers, characterized in that, Includes the following steps: (1) Grafting Diazirne onto UHMWPE fibers: Anhydrous ethanol and 4-[3-(trifluoromethyl)-3H-bisacrylidine-3-yl]benzyl bromide (Diazirine) were prepared into a Diazirine ethanol solution. UHMWPE fibers were immersed in the Diazirne ethanol solution to fully wet the fiber surface. The fibers were then air-dried naturally. Both sides of the fibers were irradiated with an ultraviolet light source to obtain UHMWPE-Dia fibers. (2) Grafting PEI onto UHMWPE-Dia fiber: Dissolve polyethyleneimine (PEI) in anhydrous ethanol to prepare a PEI solution. Place the UHMWPE-Dia fiber obtained in step (1) and the PEI solution into a sealed container and shake it horizontally to carry out the reaction. After the reaction is completed, spread the fiber flat, dry it to remove the anhydrous ethanol solvent, and obtain UHMWPE-Dia-PEI fiber.

2. The preparation method according to claim 1, characterized in that, Step (1) Before grafting Diazirne onto UHMWPE fibers, the UHMWPE fibers are pretreated, including the following steps: the UHMWPE fibers are immersed in hydrochloric acid solution with pH=6~7 and sodium hydroxide solution with pH=7~8 for 1 hour, then immersed in anhydrous ethanol and deionized water for 12 hours each, and dried in an oven at 80°C for 12 hours.

3. The preparation method according to claim 1, characterized in that, The UHMWPE-Dia-PEI fiber obtained in step (2) was placed in anhydrous ethanol solution and ultrasonically treated to remove residual PEI.

4. A UV-grafted modified UHMWPE fiber prepared by the preparation method according to any one of claims 1-3.

5. A fiber-reinforced composite material, characterized in that, It includes epoxy resin, amine curing agent and UHMWPE fiber grafted and modified according to claim 4.

6. The fiber-reinforced composite material according to claim 5, characterized in that, The mass ratio of epoxy resin to amine curing agent is 100:30, and the UV-grafted modified UHMWPE fiber accounts for 47% to 50% of the total volume of the composite material.

7. The fiber-reinforced composite material according to claim 5 or 6, characterized in that, The epoxy resin is E-51 epoxy resin; the amine curing agent is D-230.

8. A method for preparing a fiber-reinforced composite material according to any one of claims 5-7, characterized in that, Includes the following steps: (1) Mix epoxy resin and amine curing agent with a strong magnetic stirrer, and then degas the mixture using a three-dimensional blender; (2) Cut the UV-grafted modified UHMWPE fiber according to claim 4 into thin sheets, brush the mixed epoxy resin and amine curing agent onto the UV-grafted modified UHMWPE fiber in proportion, stack the fiber sheets neatly, and heat-press to cure and form a composite material board.

9. The preparation method according to claim 8, characterized in that, The hot pressing temperature is 100~127℃, the pressure is 36~40Mpa, and the curing time is 5-6h.

10. An application of the UV-grafted modified UHMWPE fiber according to claim 4, characterized in that, Used in national defense, aerospace, marine engineering, and personal protective equipment.

Images