Ultralow-temperature-resistant fiber-reinforced resin-based composite material and preparation method thereof

Abstract

The invention provides an ultralow-temperature-resistant fiber-reinforced resin-based composite material and a preparation method thereof, and belongs to the technical field of composite materials. Firstly, alpha, beta unsaturated ketene and diamine are synthesized into a hyperbranched polymer through a one-pot method, a hyperbranched polymer solution serves as a sizing agent to conduct surface treatment on fibers, and then the fibers and ultralow-temperature-resistant thermosetting resin are compounded and cured to obtain the ultralow-temperature-resistant fiber-reinforced resin-based composite material. The hyperbranched polymer with a dendritic three-dimensional space structure is used as an interface phase, has abundant amido bonds, is terminated by primary amine, not only forms intramolecular and intermolecular multiple hydrogen-bond interaction, but also can be chemically reacted with resin to construct a covalent bond-hydrogen bond hybrid cross-linked network, so that the cross-linked network structure is improved; the interface of the fiber reinforced composite material is reinforced and toughened under ultralow temperature and room / ultralow temperature circulation, and the fiber reinforced composite material can be applied to ultralow temperature scenes such as liquid hydrogen storage tanks, conveying pipes, deep space exploration component materials, polar region scientific investigation and icebreaking equipment and the like.

Description

Technical Field

[0001] The invention relates to an ultra-low temperature resistant fiber reinforced resin-based composite material and a preparation method thereof, belonging to the technical field of composite materials. Background Art

[0002] Hydrogen energy has the characteristics of wide sources, cleanness and high efficiency, and is the main carrier for promoting the development of new energy worldwide. Compared with 70MPa high-pressure gaseous hydrogen storage cylinder technology (mass hydrogen storage density is only about 4.0wt%), low-temperature liquid hydrogen storage has attracted much attention because of its density of up to 71g / L, high hydrogen storage density per unit mass, and good safety performance. Compared with traditional metal materials, carbon fiber resin-based composites will not suffer from hydrogen embrittlement and have the advantages of light weight, high strength and high modulus, good fatigue resistance, and strong machinability, but their application in low-temperature environments is limited. At low temperatures, the molecular segments of the resin matrix freeze, the toughness decreases, the thermal expansion coefficient of the resin is quite different from that of the fiber, and thermal stress mismatch occurs at the interface between the fiber and the resin, causing debonding of the interface and inducing microcracks, which greatly reduces the performance of the composite material.

[0003] Hydrogen bonding is a reversible dynamic bond that absorbs energy when broken. At low temperatures, hydrogen bonding is enhanced due to the reduced molecular distance. Amide groups can provide strong hydrogen bonding. Introducing amide bonds into hyperbranched polymers with a dendritic three-dimensional molecular configuration can form multiple hydrogen bonds within and between molecules, building a dynamic multi-level hydrogen bond network at the carbon fiber-resin interface, achieving ultra-low temperature interface toughening, increasing interface damage tolerance, and improving fatigue resistance. By optimizing the polymerization monomer, the ends of the hyperbranched polymer molecular chains are primary amine groups, which can react with epoxy groups in the resin to form chemical bonds, effectively improving the interfacial bonding between the fiber and the resin, increasing load transfer efficiency, enhancing interfacial strength, inhibiting the generation of microcracks, and resisting interfacial debonding. Patent CN112358634A provides a method for modifying the ultra-low temperature interface properties of composite materials with nanofillers. This carbon fiber surface modification method is cumbersome and has certain operational risks, and the nanofillers have problems such as difficulty in dispersion and stress concentration. Existing industrial fiber surface treatment technology mainly relies on sizing, but there is little work on improving the ultra-low temperature performance of composite materials. Therefore, the development of a simple, efficient, green and environmentally friendly fiber interface modification method with significant ultra-low temperature interface improvement effect is of great significance to the development of high-performance fiber-reinforced resin-based composite materials for application in ultra-low temperature environments such as liquid hydrogen storage and transportation, deep space exploration, and polar regions. Summary of the Invention

[0004] The purpose of the present invention is to address the problem of poor ultra-low temperature performance of fiber-reinforced resin-based composite materials, provide an ultra-low temperature resistant fiber-reinforced resin-based composite material and a preparation method thereof, use a hyperbranched polymer aqueous solution as a sizing agent, construct a dynamic multi-level hydrogen bond network and covalent bond combination at the fiber-resin interface, and achieve ultra-low temperature interface enhancement and toughening of the fiber-reinforced resin-based composite material.

[0005] The technical solution adopted in the present invention is as follows:

[0006] The present invention provides a method for preparing a fiber-reinforced resin-based composite material resistant to ultra-low temperature, which comprises the following steps:

[0007] S1: Dissolve the α,β-unsaturated ketene monomer and the diamine monomer in deionized water respectively, stir and react at 30-60°C, concentrate the reaction solution by rotary evaporation, pour into a precipitant to precipitate to obtain a crude product, wash it more than 3 times, and vacuum dry to obtain a hyperbranched polymer;

[0008] S2: dissolving the hyperbranched polymer in deionized water to obtain a sizing agent solution;

[0009] S3: performing surface activation treatment on the fiber to obtain surface-activated fiber;

[0010] S4: Immersing the fiber obtained in S3 in the sizing agent solution obtained in S2 to allow the hyperbranched polymer macromolecules to diffuse and adsorb onto the fiber surface, and vacuum drying to obtain a fiber with a surface modified with the hyperbranched polymer;

[0011] S5: Compounding and curing the fiber with the surface modified by the hyperbranched polymer obtained in S4 with an ultra-low temperature resistant resin to obtain an ultra-low temperature resistant fiber reinforced resin-based composite material.

[0012] Preferably, the α,β-unsaturated ketene monomer in step S1 is one or more of N,N'-bisacrylamide, diacrylate, and acrylate-terminated polyethylene glycol.

[0013] Preferably, the diamine monomer in step S1 is one or more of linear diamines and derivatives thereof containing hydroxyl side chains, piperazine and derivatives thereof containing aminoalkane side chains.

[0014] Preferably, in step S1, the molar ratio of the diamine monomer to the α,β-unsaturated ketene monomer is (1-1.5):1, and the precipitant is one of acetone, dichloromethane, dimethyl sulfoxide, N,N-dimethylformamide or acetonitrile.

[0015] Preferably, the mass fraction of the hyperbranched polymer in the sizing agent solution obtained in step S2 is 1 to 5%.

[0016] Preferably, the fiber surface activation treatment in step S3 is one of plasma treatment, anodizing treatment, acidification treatment and high-energy ray treatment.

[0017] Preferably, the fiber used in step S3 is one of high-strength carbon fiber, high-modulus carbon fiber, aramid fiber, polyimide fiber, polyester fiber, and ultra-high molecular weight polyethylene fiber.

[0018] Preferably, the mass fraction of the sizing agent in the hyperbranched polymer surface-modified fiber obtained in step S4 is 0.8% to 2.1%.

[0019] Preferably, the ultra-low temperature resistant resin used in step S5 is one or more of toughened epoxy resin, toughened bismaleimide resin, toughened cyanate resin, polyimide, and polyetherimide resin, wherein the ultra-low temperature resistant resin accounts for 35%-45% of the total volume of the composite material.

[0020] The present invention also provides a cryogenically resistant fiber-reinforced resin-based composite material prepared using the method. Furthermore, after 50 room-temperature to cryogenic cycles, the composite material exhibits an interfacial shear strength of no less than 26 MPa and a transverse fiber bundle tensile strength of no less than 27 MPa. The room-temperature to cryogenic cycling range is 25°C to -196°C.

[0021] The present invention has no special requirements for the composite implementation method in the composite curing, and a composite method well known to those skilled in the art can be used, and specifically, stage curing can be used.

[0022] The beneficial effects of the present invention are:

[0023] 1) The present invention adopts a method of sizing the fiber surface with a hyperbranched polymer to improve the chemical activity, wettability and processability of the fiber surface, wherein the hyperbranched polymer is synthesized in a one-pot process and the sizing agent uses water as a solvent. The preparation method is simple, rapid and environmentally friendly.

[0024] 2) Hyperbranched polymers, with abundant amide bonds, serve as the composite material's interfacial structure, enabling the formation of multiple hydrogen bonds within and between molecules. Furthermore, the amino groups at the ends of the hyperbranched polymer chains can crosslink with the resin to form chemical bonds. This creates a hydrogen-covalent hybrid crosslinked network interface that acts as a molecular bridge between the fiber and the resin, absorbing more energy during destruction and achieving enhanced interface toughening and reinforcement at ultra-low temperatures for the resin-based composite material.

[0025] 3) Hydrogen bonding is a reversible dynamic bond that absorbs a large amount of energy when broken. More importantly, at low temperatures, hydrogen bonding is enhanced due to the reduced molecular distance. The hyperbranched polyamide of the present invention can construct a dynamic multi-level hydrogen bond network at the carbon fiber-resin interface, achieving ultra-low temperature interface toughening, increasing interface damage tolerance, and effectively improving fatigue resistance under room-to-ultra-low temperature cyclic impact. This has important value for the application of resin-based composites in ultra-low temperature environments such as liquid hydrogen storage and transportation, deep space exploration, and polar regions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the surface morphology SEM image of the commercial T700 carbon fiber of the comparative example;

[0027] Figure 2 is a SEM image of the surface morphology of the T700 carbon fiber after sizing with a hyperbranched polymer in Example 3;

[0028] Figure 3 This is the SEM morphology of the comparative transverse fiber bundle after tensile damage;

[0029] Figure 4 This is the SEM morphology of the transverse fiber bundle after tensile failure in Example 3. DETAILED DESCRIPTION

[0030] The following examples provide those of ordinary skill in the art with an understanding of how to make and evaluate the present invention, and the examples are intended to be illustrative of the present disclosure and are not intended to limit the scope thereof. Although every effort has been made to ensure the accuracy of the values ​​(e.g., amounts, temperatures, etc.), some errors and deviations should be considered. Unless otherwise indicated, temperatures are in ° C. or at ambient temperature, and pressures are at or near atmospheric pressure.

[0031] The following methods are merely exemplary, and the temperature, concentration, raw material composition, and other process conditions may be varied as needed without departing from the scope of the present invention. The reagents and raw materials used in the examples of the present invention are all commercially available.

[0032] The main purpose of the present invention is to address the problem of poor ultra-low temperature interface performance of carbon fiber resin-based composites. The technical route is: α, β unsaturated ketene monomers are reacted with diamine monomers to synthesize hyperbranched polymers, the hyperbranched polymer aqueous solution is used as a sizing agent, the fibers are sized and dried, and then composited with ultra-low temperature resistant resin to obtain ultra-low temperature resistant fiber-reinforced resin-based composites. Among them, the fibers are preferably high-strength carbon fibers, high-modulus carbon fibers, or high-strength and high-modulus carbon fibers. High-strength carbon fibers generally refer to carbon fibers with a tensile strength of ≥4.9GPa, such as T700, T800, and T1000 grades. High-modulus carbon fibers generally refer to carbon fibers with an elastic modulus of ≥350GPa, such as M40J and M60J grades. High-strength and high-modulus carbon fibers generally refer to carbon fibers with a tensile strength of ≥5.5GPa and an elastic modulus of ≥300GPa, such as T1100G and M55J grades.

[0033] In the present invention, the hyperbranched polymer has a dendritic three-dimensional molecular configuration, with abundant amide bonds in its molecular chain and primary amine groups at the ends. It not only forms multiple hydrogen bonds within and between molecules, but also can react chemically with the resin to construct a covalent bond-hydrogen bond hybrid cross-linking network, thereby achieving interface reinforcement and toughening of carbon fiber composite materials at ultra-low temperatures, and effectively improving the interface bonding strength and interlaminar shear strength of carbon fiber composite materials after ultra-low temperature treatment.

[0034] The fibers and ultra-low temperature resistant resins involved in the embodiments of the present invention are all commercially available, among which the toughened cyanate ester resin was purchased from Yangzhou Tianqi New Materials Co., Ltd. with the brand name TA1000S; the polyimide fiber precursor was purchased from Jiangsu Xiannuo New Materials Technology Co., Ltd. with the brand name S35; the toughened bismaleimide resin was purchased from Shandong Guangxuan New Materials Co., Ltd. with the brand name B501; the aramid fiber was purchased from Taihe New Materials Group Co., Ltd. with the brand name aramid filament; the ultra-low temperature resistant polyurethane modified epoxy resin was purchased from Shandong Guangxuan New Materials Co., Ltd. with the brand name E203; and the T700 carbon fiber precursor was purchased from Jiangsu Hengshen Co., Ltd. with the brand name HF30T.

[0035] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments.

[0036] Example 1

[0037] 1) Weigh 6.94g of 1,4-butanediol diacrylate and 2.35g of 1,4-butanediamine into two beakers, add 20ml of deionized water to each beaker, and stir at 30°C until the solid is completely dissolved. Combine the two solutions and stir at 30°C for 24 hours. Concentrate the reaction solution by rotary evaporation and pour into acetonitrile to precipitate the crude product. Wash it five times with acetonitrile and dry it in a vacuum to obtain a hyperbranched polymer. Dissolve 0.3g of the hyperbranched polymer in 30ml of deionized water to obtain a sizing solution. Treat the polyimide fiber precursor with high-energy gamma rays. The treated polyimide fiber is then immersed in the sizing solution at room temperature for 1 hour and dried in a vacuum to obtain a polyimide fiber with a surface modified by the hyperbranched polymer.

[0038] 2) The toughened cyanate ester resin is heated to 120°C and air bubbles are removed to obtain a resin adhesive. The resin adhesive and hyperbranched polymer-modified polyimide fiber are cured at 150°C for 2 hours, 180°C for 2 hours, and 2000°C for 2 hours to obtain an ultra-low temperature-resistant polyimide fiber-reinforced cyanate ester resin-based composite material, wherein the toughened cyanate ester resin accounts for 38% of the total volume of the composite material.

[0039] Example 2

[0040] 1) Weigh 6.94g of N,N'-bis(acryloyl)cystamine and 3.44g of 1-(2-aminoethyl)piperidine into two beakers, add 20ml of deionized water to each beaker, and stir at 30°C until the solids are completely dissolved. The two solutions are mixed and stirred at 30°C for 24 hours. The reaction solution is concentrated by rotary evaporation and poured into N,N-dimethylformamide to precipitate a crude product. The product is washed five times with N,N-dimethylformamide and vacuum dried to obtain a hyperbranched polymer. 0.3g of the hyperbranched polymer is dissolved in 30ml of deionized water to obtain a sizing solution. Aramid fiber precursor is plasma treated at 150W for 5 minutes. The treated aramid fiber is then immersed in the sizing solution and soaked at room temperature for 1 hour. After vacuum drying, the aramid fiber surface is modified with the hyperbranched polymer.

[0041] 2) A toughened bismaleimide resin was stirred at 130°C until homogeneous, and air bubbles were removed to obtain a resin adhesive. The resin adhesive was then cured with hyperbranched polymer-modified aramid fiber at 150°C for 2 hours, 180°C for 2 hours, and 200°C for 2 hours to obtain an ultra-low temperature-resistant aramid fiber-reinforced bismaleimide resin-based composite, in which the toughened bismaleimide resin accounted for 41% of the total volume of the composite.

[0042] Example 3

[0043] 1) Weigh 4.11g N,N'-methylenebisacrylamide and 3.65g 1,3-diaminopropanol into two beakers, add 20ml deionized water to each beaker, stir at 30°C until the solid is completely dissolved, mix the two solutions and stir at 30°C for 24h. The reaction solution is concentrated by rotary evaporation, poured into acetone to precipitate the crude product, washed with acetone 5 times, and vacuum dried to obtain a hyperbranched polymer. Take 0.3g of hyperbranched polymer and dissolve it in 30ml deionized water to obtain a sizing agent solution. The T700 carbon fiber precursor is placed in concentrated nitric acid (68%) for acidification. The treated T700 carbon fiber is immersed in the sizing agent solution, soaked at room temperature for 1h, and vacuum dried to obtain T700 carbon fiber with a surface modified by a hyperbranched polymer.

[0044] 2) Stirring an ultra-low temperature resistant polyurethane-modified epoxy resin at 60°C until uniform, and removing air bubbles to obtain a resin adhesive. The resin adhesive and hyperbranched polymer-modified T700 carbon fiber are then cured at 90°C for 1 hour, 120°C for 2 hours, and 150°C for 3 hours to obtain an ultra-low temperature resistant T700 carbon fiber reinforced epoxy resin-based composite material, wherein the ultra-low temperature resistant polyurethane-modified epoxy resin accounts for 39% of the total volume of the composite material.

[0045] Comparative Example

[0046] Using exactly the same epoxy resin system as in Example 3, the epoxy resin system and commercially sized T700 carbon fiber were cured at 90°C / 1h+120°C / 2h+180°C / 3h to obtain a commercially sized T700 carbon fiber reinforced epoxy resin-based composite material, in which the epoxy resin accounted for 39% of the total volume of the composite material.

[0047] Figure 1 、 Figure 2 The surface morphology SEM images of commercial sized T700 carbon fiber of the comparative example and the T700 carbon fiber modified by hyperbranched polymer in Example 3 of the present invention are shown in the figure. Figure 1 It is commercially sized T700 carbon fiber with a smooth and uniform surface and a coating of commercial sizing agent; Figure 2 The surface of T700 carbon fiber modified with hyperbranched polymer is also relatively smooth, with fine particles attached, and a hyperbranched polymer coating layer exists on the carbon fiber surface, indicating that the hyperbranched polymer has successfully modified the carbon fiber surface. Figure 3 、 Figure 4 They are respectively the SEM morphology of the transverse fiber bundle after tensile failure of the comparative example commercial sizing T700 carbon fiber and the embodiment 3 of the present invention based on hyperbranched polymer modified T700 carbon fiber reinforced epoxy resin based composite material. Figure 3It can be seen that after the commercial sizing T700 carbon fiber composite material is damaged by transverse tension, the fiber surface is completely exposed and no resin remains, indicating that the failure mode is interface damage and the interface phase formed by the commercial sizing agent is weakly bonded to the resin. Figure 4 After the transverse tensile failure of the hyperbranched polymer modified carbon fiber composite material, a large amount of resin remained on the fiber surface and ductile fracture occurred, indicating that the failure mode was cohesive failure. The interface phase formed by the hyperbranched polymer was firmly bonded to the resin, which improved the interface bonding performance of the composite material.

[0048] Table 1 is a summary of the elemental composition of carbon fiber surfaces in Examples 1 to 3 and the comparative example

[0049]

[0050] The elemental composition of the fiber surfaces of Examples 1-3 and the comparative example was characterized by X-ray photoelectron spectroscopy, and the results are shown in Table 1. Compared to the comparative example, the nitrogen content on the fiber surfaces of Examples 1-3 increased, with Example 3 exhibiting a higher oxygen content. This indicates that the hyperbranched polymer successfully sizing the carbon fiber surface introduced more polar groups, increasing the chemical activity of the fiber surface.

[0051] Table 2 shows the interface mechanical properties of Examples 1 to 3 and the comparative example before and after room temperature-ultra-low temperature (25°C to -196°C) cycle treatment.

[0052]

[0053] As shown in Table 2, the interface mechanical properties of the fiber resin-based composite material modified by the method of the present invention at room temperature are better than those of the commercial sizing T700 carbon fiber resin-based composite material. After 50 room temperature-ultra-low temperature cycles, the interface mechanical properties of each group have decreased, while the interface mechanical properties of the fiber composite material modified by the method of the present invention are still better than those of the commercial sizing system. Among them, the transverse fiber bundle tensile strength of the composite material of Example 3 is still higher than before treatment, which is 33.42MPa, which is 88% higher than that of the comparative example. It shows that the hyperbranched polymer modified T700 carbon fiber epoxy resin-based composite material prepared by the present invention has better interface performance and ultra-low temperature resistance.

[0054] The above-described embodiments merely represent several implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a fiber-reinforced resin-based composite material resistant to ultra-low temperature, characterized in that: The steps include: S1: Dissolve the α,β-unsaturated ketene monomer and the diamine monomer in deionized water respectively, stir and react at 30-60°C, concentrate the reaction solution by rotary evaporation, pour into a precipitant to precipitate to obtain a crude product, wash it more than 3 times, and vacuum dry to obtain a hyperbranched polymer; S2: dissolving the hyperbranched polymer in deionized water to obtain a sizing agent solution; S3: performing surface activation treatment on the fiber to obtain surface-activated fiber; S4: Immersing the fiber obtained in S3 in the sizing agent solution obtained in S2 to allow the hyperbranched polymer macromolecules to diffuse and adsorb onto the fiber surface, and vacuum drying to obtain a fiber with a surface modified with the hyperbranched polymer; S5: Compounding and curing the fiber with the surface modified by the hyperbranched polymer obtained in S4 with an ultra-low temperature resistant resin to obtain an ultra-low temperature resistant fiber reinforced resin-based composite material.

2. The preparation method according to claim 1, wherein The α,β-unsaturated ketene monomer in step S1 is one or more of N,N'-bisacrylamide, diacrylate, and acrylate-terminated polyethylene glycol.

3. The preparation method according to claim 1, wherein The diamine monomers described in step S1 are one or more of linear diamines and derivatives thereof containing hydroxyl side chains, piperazine and derivatives thereof containing aminoalkane side chains.

4. The preparation method according to claim 1, wherein In step S1, the molar ratio of the diamine monomer to the α,β-unsaturated ketene monomer is (1-1.5):1, and the precipitant is one of acetone, dichloromethane, dimethyl sulfoxide, N,N-dimethylformamide or acetonitrile.

5. The preparation method according to claim 1, wherein The mass fraction of the hyperbranched polymer in the sizing agent solution obtained in step S2 is 1 to 5%.

6. The preparation method according to claim 1, wherein The fiber surface activation treatment in step S3 is one of plasma treatment, anodizing treatment, acidification treatment and high-energy ray treatment.

7. The preparation method according to claim 1, wherein The fiber used in step S3 is one of high-strength carbon fiber, high-modulus carbon fiber, aramid fiber, polyimide fiber, polyester fiber, and ultra-high molecular weight polyethylene fiber.

8. The preparation method according to claim 1, wherein The mass fraction of the sizing agent in the fiber surface-modified with the hyperbranched polymer obtained in step S4 is 0.8% to 2.1%.

9. The preparation method according to claim 1, wherein The ultralow temperature resistant resin used in step S5 is one or more of toughened epoxy resin, toughened bismaleimide resin, toughened cyanate resin, polyimide, and polyetherimide resin, wherein the ultralow temperature resistant resin accounts for 35%-45% of the total volume of the composite material.

10. An ultra-low temperature resistant fiber-reinforced resin-based composite material prepared by the method according to any one of claims 1 to 9, characterized in that: After 50 cycles of room temperature to ultra-low temperature, the composite material has an interface shear strength of not less than 26 MPa and a transverse fiber bundle tensile strength of not less than 27 MPa, wherein the temperature range of the room temperature to ultra-low temperature cycles is 25°C to -196°C.

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