A hyperbranched polymer modified epoxy resin, its preparation method and application

Abstract

The application provides a hyperbranched polymer modified epoxy resin and a preparation method and application thereof, and belongs to the technical field of epoxy resins.The hyperbranched polymer modified epoxy resin provided by the application is prepared from raw materials including 55-80 parts of epoxy resin, 10-30 parts of a toughening agent, 0.5-3 parts of functionalized MXene, 2-10 parts of a hyperbranched polymer and 20-35 parts of a curing agent by mass fraction.The functional groups and two-dimensional structure of the functionalized MXene are utilized to improve the oxygen compatibility and flame retardancy of the resin liquid; the hyperbranched polymer is utilized to improve the flowability of the epoxy resin, expand the free volume of the resin and improve the strength of the modified epoxy resin.It can be known from the examples that the oxygen impact sensitivity coefficient of the hyperbranched polymer modified epoxy resin obtained by the application is reduced to 0%, and the bending strength and impact strength at low temperature are respectively increased by 26.0% and 18.5%.

Description

Technical Field

[0001] The present invention relates to the technical field of epoxy resins, and in particular to a hyperbranched polymer modified epoxy resin, a preparation method thereof, and an application thereof. Background Art

[0002] Traditional spacecraft liquid oxygen tanks are typically manufactured from alloy materials. To further reduce weight and increase the payload of the vehicle, the use of carbon fiber reinforced resin-based composites (CFRP) for liquid oxygen tanks, with their high specific strength and high specific modulus, has become a research hotspot. Due to the cryogenic and highly oxidizing properties of liquid oxygen, CFRP applications in liquid oxygen environments require excellent low-temperature toughness and compatibility with liquid oxygen. Carbon fiber composites are primarily composed of carbon fibers and a resin matrix, with the resin matrix performance being a key determinant.

[0003] Epoxy resins, with their advantages of low cost, easy processability, and low molding shrinkage, have led to their widespread application in aerospace, military, automotive, and other fields. However, traditional epoxy resins suffer from flammability and brittleness. The strong oxidizing properties and low temperature properties of liquid oxygen also lead to incompatibility reactions with epoxy resins in liquid oxygen environments, limiting their application. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a hyperbranched polymer modified epoxy resin and its preparation method and application. The hyperbranched polymer modified epoxy resin provided by the present invention has good compatibility with liquid oxygen and is impact resistant and tough at low temperatures.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] The present invention provides a hyperbranched polymer modified epoxy resin, which comprises the following raw materials, calculated by weight: 55-80 parts of epoxy resin, 10-30 parts of toughening agent, 0.5-3 parts of functionalized MXene, 2-10 parts of hyperbranched polymer, and 20-35 parts of curing agent;

[0007] The functionalized MXene is obtained by surface modification of MXene with a silane coupling agent.

[0008] Preferably, the method for preparing the functionalized MXene comprises the following steps:

[0009] The MXene dispersion is mixed with a silane coupling agent and heated in an inert atmosphere to obtain functionalized MXene;

[0010] The mass ratio of the MXene to the silane coupling agent is 1:5-25.

[0011] Preferably, the silane coupling agent includes one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane.

[0012] Preferably, the hyperbranched polymer is at least one of a hyperbranched polyester, a hyperbranched polyether, a hyperbranched polysiloxane and a hyperbranched epoxy resin.

[0013] Preferably, the hyperbranched polyester includes hyperbranched polyester H30; the hyperbranched polyether includes hyperbranched polyether EHBPE; the hyperbranched polysiloxane includes hyperbranched polysiloxane HPE; and the hyperbranched epoxy resin includes hyperbranched epoxy resin HE102.

[0014] Preferably, the toughening agent is one or more of cyanate ester, polyethersulfone, imide toughening agent and polyurethane.

[0015] Preferably, the curing agent is one or more of 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenylmethane, isophoronediamine, polyetheramine and diethylenetriamine.

[0016] The present invention also provides a method for preparing the hyperbranched polymer modified epoxy resin described in the above technical solution, comprising the following steps:

[0017] The epoxy resin and the hyperbranched polymer are mixed at a mixing temperature of 100 to 120° C.; the functionalized MXene, the toughening agent, and the curing agent are added to the obtained mixed solution, and the mixture is stirred to obtain a mixed liquid;

[0018] Curing the mixed liquid by increasing the temperature in stages to obtain the hyperbranched polymer modified epoxy resin;

[0019] The staged temperature rise curing includes: an initial curing temperature of 80-100° C., a temperature rise rate of 15-25° C. / h, and keeping the temperature for 0.5-2h after every 1h of temperature rise, until the temperature reaches 190-220° C. and the temperature is kept for 0.5-2h.

[0020] Preferably, the adding of functionalized MXene, toughening agent and curing agent to the obtained mixed liquid and stirring to obtain a mixed liquid comprises: adding functionalized MXene and toughening agent to the obtained mixed liquid and stirring, and adding curing agent to the obtained stirred product and stirring to obtain a mixed liquid.

[0021] The present invention also provides the use of the hyperbranched polymer modified epoxy resin prepared by the preparation method described in the above technical solution in the liquid oxygen propellant tank of a large space vehicle.

[0022] The present invention provides a hyperbranched polymer modified epoxy resin, which comprises the following raw materials, calculated by weight: 55-80 parts of epoxy resin, 10-30 parts of toughening agent, 0.5-3 parts of functionalized MXene, 2-10 parts of hyperbranched polymer, and 20-35 parts of curing agent; the functionalized MXene is prepared by coupling MXene (Ti3C2T4) with a silane coupling agent. X ) is surface modified. The present invention utilizes hyperbranched polymers to improve the fluidity of epoxy resin, expand the free volume of the resin, and enhance the strength of the modified epoxy resin. In addition, since hyperbranched polymers have good thermal stability and flame retardancy, they also provide a guarantee for achieving good liquid oxygen compatibility of the modified epoxy resin. The surface of the modified MXene contains functional groups such as siloxane groups, amino groups, epoxy groups, and carbon-carbon double bonds, which increases the interlamellar spacing of the MXene structure and facilitates the formation of a strong interfacial bonding force with the resin matrix. At the same time, the special two-dimensional structure and properties of MXene itself are more conducive to the modification of the resin, thereby improving the liquid oxygen compatibility of the resin. The Ti element in MXene forms TiO2 during the combustion process, which plays a role in catalyzing carbonization. The decomposition of the silicon-containing chemical structure on the surface of the resin matrix further enhances the density of the carbon layer, thereby reducing the gas exchange between the inside and outside of the matrix and the release of toxic gases. The synergistic effect of the two plays a key role in preventing further incompatible reactions between the inside of the resin and liquid oxygen. The data from the examples show that the liquid oxygen impact sensitivity coefficient of the hyperbranched polymer-modified epoxy resin obtained in the present invention can be reduced to 0%, and it has good compatibility with liquid oxygen. At the same time, compared with existing epoxy resins, the flexural strength and impact strength of the hyperbranched polymer-modified epoxy resin at low temperature (77K) are increased by 26.0% and 18.5%, respectively, showing excellent low-temperature mechanical properties.

[0023] The present invention also provides a method for preparing the hyperbranched polymer modified epoxy resin described in the above technical solution. By controlling the amount of each component, the preparation process and the conditions of staged temperature increase and curing, the reaction between the epoxy resin, toughening agent, flame retardant and curing agent is ensured to be complete, the finished product has few defects, a high yield and good comprehensive performance. DETAILED DESCRIPTION

[0024] The present invention provides a hyperbranched polymer modified epoxy resin, which comprises the following raw materials, calculated by weight: 55-80 parts of epoxy resin, 10-30 parts of toughening agent, 0.5-3 parts of functionalized MXene, 2-10 parts of hyperbranched polymer, and 20-35 parts of curing agent;

[0025] The functionalized MXene is obtained by surface modification of MXene with a silane coupling agent.

[0026] In the present invention, unless otherwise specified, the raw materials used are commercially available products in the art.

[0027] The preparation raw material of the hyperbranched polymer modified epoxy resin provided by the present application comprises 55-80 parts, preferably 60-75 parts, and more preferably 65-70 parts of epoxy resin in terms of mass fraction. In the present application, the epoxy resin is preferably a bisphenol A type epoxy resin or a bisphenol F type epoxy resin, and more preferably a bisphenol A type epoxy resin; wherein the bisphenol A type epoxy resin is preferably one or more of E54, E51, E44 and E42, and more preferably E44.

[0028] The preparation raw material of the hyperbranched polymer modified epoxy resin provided by the present application comprises 10-30 parts, preferably 15-25 parts, and more preferably 18-22 parts of toughening agent in terms of mass fraction of the epoxy resin. The toughening agent is preferably one or more of cyanate ester, polyether sulfone, imide-based toughening agent and polyurethane, and more preferably imide-based toughening agent, and the imide-based toughening agent is preferably one or more of polyimide, bis-citraconimide and bismaleimide, and more preferably bis-citraconimide. The addition of the toughening agent can make the epoxy resin have more excellent low-temperature mechanical properties.

[0029] The preparation raw material of the hyperbranched polymer modified epoxy resin provided by the present application comprises 0.5-3 parts, preferably 1-2.5 parts, and more preferably 1.5-2.0 parts of functionalized MXene in terms of mass fraction of the epoxy resin. After modification, the surface of MXene contains functional groups such as siloxane groups, amino groups, epoxy groups and carbon-carbon double bonds, which increases the interlayer spacing of the MXene structure, easily forms a firm interfacial bonding force with the resin matrix, and at the same time, due to the special two-dimensional structure and properties of MXene, it is more conducive to the modification of the resin, improves the liquid oxygen compatibility of the resin, and the Ti element in MXene forms TiO2 in the combustion process to catalyze carbonization, and the decomposition of the silicon-containing chemical structure on the surface of the resin matrix further improves the density of the carbon layer, thereby reducing the gas exchange and the release of toxic gas decomposition inside and outside the matrix, enhancing the flame retardant properties of the epoxy resin, and the synergistic effect of the two can hinder the contact between the resin and liquid oxygen, thereby improving the liquid oxygen compatibility of the resin.

[0030] In the present application, the preparation method of the functionalized MXene preferably comprises the following steps:

[0031] The dispersion liquid of MXene is mixed with a silane coupling agent, heated in an inert atmosphere to obtain functionalized MXene.

[0032] In the present application, the dispersion liquid of MXene is preferably obtained by dispersing MXene into an organic solvent and ultrasonicating in an ice bath environment.

[0033] In the present invention, the MXene is preferably made of titanium carbide (Ti3C2T X , MXene) 99%.

[0034] In the present invention, the organic solvent is preferably one or more of methanol, ethanol, acetone, isopropanol, toluene or N,N-dimethylformamide, more preferably ethanol. The ultrasonication time is preferably 0.5 to 4 hours.

[0035] In the present invention, the silane coupling agent preferably includes one or more of γ-aminopropyltriethoxysilane (KH550), γ-glycidyloxypropyltrimethoxysilane (KH560) and γ-methacryloxypropyltrimethoxysilane (KH570), more preferably γ-aminopropyltriethoxysilane. The silane coupling agent provided by the present invention contains active groups such as siloxane groups, amino groups, epoxy groups and carbon-carbon double bonds in its structure, which can react chemically with components such as resin monomers, curing agents, toughening agents, diluents in the epoxy resin curing system to form chemical bonds, thereby promoting the dispersibility and compatibility of the functionalized MXene flame retardant in the epoxy resin, and improving its flame retardant properties and liquid oxygen compatibility.

[0036] In the present invention, the mass ratio of the MXene to the silane coupling agent is preferably 1:5 to 25, more preferably 1:7 to 20, and even more preferably 1:10 to 17. The present invention improves the yield and functionalization effect of the functionalized MXene by controlling the dosage.

[0037] In the present invention, mixing the MXene dispersion with a silane coupling agent preferably includes: adding a silane coupling agent to the MXene dispersion.

[0038] In the present invention, the inert atmosphere is preferably nitrogen. The present invention performs heating in an inert atmosphere to prevent MXene from being oxidized and losing activity in an oxygen environment.

[0039] In the present invention, the heating is preferably performed while reflux is condensed; the heating temperature is preferably 60 to 120°C, and the heating time is preferably 10 to 15 hours. By controlling the heating temperature and time, the present invention reduces process costs and synthesis cycle, simplifies post-processing, and increases yield.

[0040] After heating, the heated system is sequentially filtered, washed, and dried to obtain a functionalized MXene. The present invention has no specific requirements for the filtering and washing methods; commonly used filtering methods can be employed. The present invention also has no specific requirements for the drying method; commonly used drying methods can be employed. In specific embodiments of the present invention, vacuum freeze drying is used, and the drying time is preferably 12 to 36 hours.

[0041] Based on the mass fraction of the epoxy resin, the raw materials for preparing the hyperbranched polymer-modified epoxy resin provided by the present invention include 2 to 10 parts of hyperbranched polymer, preferably 4 to 8 parts, and more preferably 6 to 7 parts. The hyperbranched polymer is preferably at least one of a hyperbranched polyester, a hyperbranched polyether, a hyperbranched polysiloxane, and a hyperbranched epoxy resin. The hyperbranched polyester preferably includes hyperbranched polyester H30, the hyperbranched polyether preferably includes hyperbranched polyether EHBPE, the hyperbranched polysiloxane preferably includes hyperbranched polysiloxane HPE, the hyperbranched epoxy resin preferably includes hyperbranched epoxy resin HE102, and the hyperbranched polymer is more preferably hyperbranched epoxy resin HE102. The structural formula of the hyperbranched epoxy resin HE102 is:

[0042]

[0043] The hyperbranched epoxy resin is a macromolecule with a three-dimensional structure obtained by synthetic polymerization of monomer small molecules. It has a large number of terminal groups, which are conducive to chemical reactions and the formation of a homogeneous structure. It has significant strengthening and toughening functions, can reduce the viscosity of the epoxy resin, increase the bonding strength, and has the advantages of low viscosity, multi-functionality, solubility, good thermal stability, high molecular weight, and high activity. The hyperbranched resin containing a benzene ring structure has good heat resistance and low viscosity, can simultaneously strengthen and toughen the epoxy resin, and also has a certain flame retardant effect. The hyperbranched resin contains a large number of hydroxyl groups and can be grafted to the surface of the two-dimensional material MXene through a surface functionalization method, forming chemical bonds with the surface groups of the MXene, improving the dispersibility of the MXene in the resin, and enhancing the interfacial interaction between the MXene and the epoxy resin. The hyperbranched resin containing a large number of hydroxyl groups forms hydrogen bonds in the curing system, making the intermolecular force stronger, and the large number of flexible chain segments helps to reduce the residual internal stress of the resin, absorbs a large amount of energy through its own distortion, thereby improving the strength and toughness of the resin system. The present invention first mixes the epoxy resin with the hyperbranched resin so that the reactants can be evenly mixed without excessive viscosity causing subsequent uneven dispersion.

[0044] The raw materials for preparing the hyperbranched polymer-modified epoxy resin provided herein include 20 to 35 parts, preferably 22 to 32 parts, and more preferably 24 to 27 parts, of a curing agent, based on the weight of the epoxy resin. The curing agent is preferably one or more of 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenylmethane, isophoronediamine, polyetheramine, and diethylenetriamine, with 4,4'-diaminodiphenylmethane being more preferred. In the present invention, the curing agent promotes a curing reaction of the epoxy resin monomer to form a cured product.

[0045] The hyperbranched polymer modified epoxy resin obtained by the present invention utilizes the two-dimensional structure and active functional groups of functionalized MXene to improve the liquid oxygen compatibility of the epoxy resin. At the same time, the two elements Ti and Si in the functionalized MXene work synergistically to improve the surface density of the resin and increase its flame retardant properties. The macromolecular structure and terminal groups of the hyperbranched polymer are utilized to reduce the viscosity of the epoxy resin and increase the bonding strength, so that the epoxy resin has the advantages of low viscosity, multifunctionality, good thermal stability, high activity, etc. At the same time, the benzene ring structure in the hyperbranched polymer can strengthen and toughen the epoxy resin and further improve the flame retardant properties. In addition, the large number of flexible segments in the hyperbranched polymer help to reduce the residual internal stress of the resin, and the hydroxyl groups form hydrogen bonds in the resin system to enhance the intermolecular force. The two work together to improve the strength and toughness of the resin system.

[0046] The present invention also provides a method for preparing the hyperbranched polymer modified epoxy resin described in the above technical solution, comprising the following steps:

[0047] The epoxy resin and the hyperbranched polymer are mixed at a mixing temperature of 100 to 120° C.; the functionalized MXene, the toughening agent, and the curing agent are added to the obtained mixed solution, and the mixture is stirred to obtain a mixed liquid;

[0048] Curing the mixed liquid by increasing the temperature in stages to obtain the hyperbranched polymer modified epoxy resin;

[0049] The staged temperature rise curing includes: an initial curing temperature of 80-100° C., a temperature rise rate of 15-25° C. / h, and keeping the temperature for 0.5-2h after every 1h of temperature rise, until the temperature reaches 190-220° C. and the temperature is kept for 0.5-2h.

[0050] The present invention mixes epoxy resin and hyperbranched polymer, adds functionalized MXene, toughening agent and curing agent to the obtained mixed liquid, and stirs to obtain a mixed liquid.

[0051] In the present invention, the mixing temperature is 100-120°C, preferably 105-115°C, and the mixing time is preferably 20-40 minutes, more preferably 25-35 minutes. In the present invention, the mixing is preferably carried out under stirring conditions, at which the mixture is liquid and no additional organic solvent is required. By controlling the mixing temperature, the present invention ensures that all components of the system are evenly mixed at a low viscosity, while preventing the premature curing reaction due to excessively high temperatures.

[0052] After obtaining the mixed liquid, the present invention preferably waits for the mixed liquid to be cooled to 70-90°C, and then adds the functionalized MXene, toughening agent and curing agent to the mixed liquid. In the present invention, adding the functionalized MXene, toughening agent and curing agent to the obtained mixed liquid preferably includes: adding the functionalized MXene and toughening agent to the obtained mixed liquid and stirring, adding the curing agent to the obtained stirred material and stirring, to obtain a mixed liquid. The present invention has no special requirements for the order of adding the functionalized MXene and toughening agent. Specifically, the functionalized MXene can be added first, the toughening agent can be added first, or the functionalized MXene and toughening agent can be added at the same time. After the functionalized MXene is added to the mixed liquid of the epoxy resin and the hyperbranched polymer, the functional groups on the surface of the functionalized MXene form a covalent bond with the epoxy resin, so that the functionalized MXene is fused with the resin matrix without obvious interface stratification, thereby preventing agglomeration. The present invention adds materials in sequence so that all components of the system are mixed evenly before a curing reaction occurs. Adjusting the order of adding materials will result in the system having too high viscosity when the curing agent is added, thereby failing to fully mix with the curing agent and subsequently cure.

[0053] The present invention preferably stirs after each reagent is added. In the present invention, the stirring time after adding the functionalized MXene is preferably 20 to 40 minutes, more preferably 25 to 35 minutes, and the temperature for stirring when adding the functionalized MXene is preferably 70 to 90°C, more preferably 75 to 85°C; the stirring time after adding the toughening agent is preferably 3 to 12 minutes, more preferably 5 to 8 minutes, and the temperature for stirring when adding the toughening agent is preferably 70 to 90°C, more preferably 75 to 85°C; the stirring time after adding the curing agent is preferably 20 to 40 minutes, more preferably 25 to 35 minutes, and the temperature for stirring when adding the curing agent is preferably 70 to 90°C, more preferably 75 to 85°C. The present invention stirs after adding the curing agent to promote the curing reaction of the epoxy resin monomer to form a cured product. A prepolymerization reaction occurs after adding the curing agent. The degree of the prepolymerization reaction can be controlled by controlling the temperature and time of stirring after adding the curing agent.

[0054] After obtaining the mixed liquid, the present invention performs stage-by-stage temperature raising and curing on the mixed liquid to obtain a hyperbranched polymer modified epoxy resin.

[0055] In the present application, the stage-wise temperature curing comprises: an initial curing temperature of 80-100 DEG C, preferably 85-95 DEG C, a temperature rising rate of 15-25 DEG C / h, preferably 20 DEG C / h, 0.5-2 h of holding after each 1 h of temperature rising, preferably 1 h of holding, until the temperature is raised to 190-220 DEG C (preferably 195-205 DEG C) and held for 0.5-2 h, preferably 1 h. The present application uses the above-mentioned stage-wise temperature curing to ensure that the epoxy resin, toughening agent and flame retardant are uniformly mixed before being fully reacted with the curing agent, so that the finished product has few defects, high yield and good comprehensive performance.

[0056] The present application also provides the application of the hyperbranched polymer modified epoxy resin prepared by the preparation method to a large space vehicle liquid oxygen propellant storage tank.

[0057] The present application does not have special limitations on the specific mode of the application, and the mode well known to those skilled in the art can be used.

[0058] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the present application will be described clearly and completely below in combination with specific examples, and the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Any modification, equivalent replacement, improvement, etc. made to the embodiments of the present application according to the technical essence and general principles of the present application without creative labor shall be within the protection scope of the present application.

[0059] Example 1

[0060] Preparation of KH550 functionalized MXene:

[0061] The MXene was dispersed into a 500 mL flask containing 300 mL of ethanol, and was ultrasonically treated in an ice bath environment for 2 h using an ultrasonic cleaner. Then, silane coupling agent KH-550 was added to obtain a mixed solution, and the mass ratio of MXene to KH-550 was 1:10. The mixed solution was condensed and refluxed at 80 DEG C under a nitrogen atmosphere for 12 h to obtain a modified MXene solution. The modified MXene solution was filtered to obtain a filter cake, which was washed with a large amount of ethanol and deionized water, and was dried in a vacuum freeze dryer for 24 h to obtain KH550 functionalized MXene, and the yield was 92.37%.

[0062] Preparation of hyperbranched polymer modified epoxy resin:

[0063] Calculated by mass, 4 parts of hyperbranched polymer toughener HE102 were mixed with 74.4 parts of epoxy resin E44, and mechanically stirred at 120°C for 30 minutes. The solution temperature was lowered to 80°C, and 1.6 parts of KH550 functionalized MXene flame retardant were added in sequence and stirred for 30 minutes. 20 parts of toughening agent biscitraconimide were stirred for 8 minutes, and 24.7 parts of curing agent 4,4'-diaminodiphenylmethane were stirred for 10 minutes. The temperature was raised and cured. After heating to 100°C, the temperature was raised by 20°C per hour and kept warm for 1 hour. The temperature was raised to 200°C and kept warm for another 1 hour. The mixture was naturally cooled to room temperature to obtain a hyperbranched polymer modified epoxy resin.

[0064] Example 2

[0065] Preparation of KH560 functionalized MXene:

[0066] The MXene was dispersed in a 500mL flask containing 300mL of toluene and ultrasonically treated for 1 hour in an ice bath. The silane coupling agent KH-560 was then added to obtain a mixed solution with a mass ratio of MXene to KH-560 of 1:20. The mixed solution was refluxed at 120°C under a nitrogen atmosphere for 8 hours to obtain a modified MXene solution. The modified MXene solution was filtered to obtain a filter cake, which was washed with copious amounts of ethanol and deionized water and dried in a vacuum freeze dryer for 24 hours to obtain KH560-functionalized MXene with a yield of 90.26%.

[0067] Preparation of hyperbranched polymer modified epoxy resin:

[0068] Calculated by mass fraction, 6 parts of hyperbranched polymer toughening agent HPE and 70 parts of epoxy resin E51 were mixed and mechanically stirred at 100°C for 30 minutes. The solution temperature was lowered to 90°C, and 2 parts of KH560 functionalized MXene flame retardant were added in sequence and stirred for 20 minutes. 20 parts of toughening agent biscitraconimide were stirred for 8 minutes, and 20 parts of curing agent 4,4'-diaminodiphenyl sulfone were stirred for 15 minutes. The temperature was raised and cured. After heating to 100°C, the temperature was raised by 20°C per hour and kept warm for 1 hour. The temperature was raised to 200°C and kept warm for another 1 hour. The mixture was naturally cooled to room temperature to obtain a hyperbranched polymer modified epoxy resin.

[0069] Example 3

[0070] Preparation of KH570 functionalized MXene:

[0071] The MXene was dispersed in a 500mL flask containing 300mL of toluene and ultrasonically treated for 1 hour in an ice bath. The silane coupling agent KH-570 was then added to obtain a mixed solution with a mass ratio of MXene to KH-560 of 1:15. The mixed solution was refluxed at 60°C under a nitrogen atmosphere for 10 hours to obtain a modified MXene solution. The modified MXene solution was filtered to obtain a filter cake, which was washed with copious amounts of ethanol and deionized water and dried in a vacuum freeze dryer for 24 hours to obtain KH570-functionalized MXene with a yield of 89.14%.

[0072] The preparation method of liquid oxygen compatible epoxy resin is the same as that in Example 1.

[0073] Example 4

[0074] Calculated by weight, 8 parts of hyperbranched polymer HE102, 70.4 parts of epoxy resin E44, and 24.3 parts of curing agent 4,4'-diaminodiphenylmethane. Other conditions are the same as in Example 1.

[0075] Comparative Example 1

[0076] Calculated by weight, the following ingredients were used: 4 parts KH550 functionalized MXene, 12 parts hyperbranched polymer HE102, 66.4 parts epoxy resin E44, and 20 parts curing agent 4,4'-diaminodiphenylmethane. Other conditions were the same as in Example 1.

[0077] Comparative Example 2

[0078] Calculated by weight, 0.2 parts of KH550 functionalized MXene, 1 part of hyperbranched polymer HE102, 60.2 parts of epoxy resin E44, and 7 parts of curing agent 4,4'-diaminodiphenylmethane. Other conditions are the same as in Example 1.

[0079] Comparative Example 3

[0080] When the hyperbranched polymer was added, the stirring temperature was 60° C. and the stirring time was 10 min. Other conditions were the same as those in Example 1.

[0081] Comparative Example 4

[0082] Unmodified MXene was used. Other conditions were the same as in Example 1.

[0083] Comparative Example 5

[0084] No hyperbranched polymer was added. Other conditions were the same as in Example 1.

[0085] Comparative Example 6

[0086] No KH550 functionalized MXene flame retardant was added. Other conditions were the same as in Example 1.

[0087] Comparative Example 7

[0088] No hyperbranched polymer and KH550 functionalized MXene flame retardant were added. Other conditions were the same as in Example 1.

[0089] The epoxy resins prepared in Examples 1 to 4 and Comparative Examples 1 to 7 were subjected to liquid oxygen impact sensitivity coefficient test and low-temperature mechanical property test, respectively. The test methods are as follows:

[0090] Liquid oxygen shock sensitivity test: Refer to ASTM D2512-17 standard, use XCM-120 liquid oxygen shock tester, disc sample diameter 20mm, thickness 3-5mm). Reaction phenomena are mainly divided into combustion, explosion, sparks, and scorch marks. Impact test 20 consecutive samples of a material. If no reaction occurs, the batch of samples is compatible with liquid oxygen; otherwise, when one reaction occurs, continue to test 40 times. If there is no reaction at this time, the batch of samples is compatible with liquid oxygen, otherwise the liquid oxygen is incompatible; and when there are 2 or more reactions during the test of 20 samples, the batch of samples is incompatible with liquid oxygen. The lower the liquid oxygen shock sensitivity coefficient (IRS), the better the liquid oxygen compatibility of the sample. IRS is calculated according to the following formula:

[0091]

[0092] Among them, w i Represents the weighting coefficients of different experimental phenomena, n i Represents the number of different reaction phenomena, and N represents the total number of tests, where w1 = 1.0 (combustion), w2 = 0.9 (explosion), w3 = 0.6 (spark), and w4 = 0.4 (scorch mark).

[0093] Low temperature bending performance test: The bending performance of the sample at low temperature (77K) was tested using an INSTRON 5967 electronic universal testing machine in accordance with the GB / T 2567-2008 test standard.

[0094] Low-temperature impact performance test: The RJJ-30 impact testing machine was used to test the impact performance of the samples at low temperature (77K) according to the GB / T 2567-2021 test standard. The test results are shown in Table 1.

[0095] Table 1 Test results of Examples 1 to 4 and Comparative Examples 1 to 7

[0096]

[0097]

[0098] As can be seen from Table 1, compared with the comparative example, the liquid oxygen impact sensitivity coefficient of the epoxy resin system prepared in Examples 1 to 4 is reduced to 0%, achieving liquid oxygen compatibility, and at the same time, it has excellent mechanical properties at 77K. Compared with the comparative example, the flexural strength and impact strength are significantly improved; in Comparative Example 1, when the addition amount of the functionalized MXene flame retardant and the hyperbranched polymer is higher than the range specified in the present invention, the prepared epoxy resin system is compatible with liquid oxygen, but due to the high viscosity of the system and the uneven dispersion of the filler, the low-temperature mechanical properties are poor; in Comparative Example 2, when the addition amount of the functionalized MXene flame retardant and the hyperbranched polymer is lower than the range specified in the present invention, the prepared epoxy resin is not only incompatible with liquid oxygen, but also has poor low-temperature mechanical properties; in Comparative Example 3, when the system preparation process set by the present invention is not adopted, it will lead to the hyperbranched polymer It cannot be fully mixed in the resin, resulting in poor liquid oxygen compatibility and low-temperature mechanical properties of the system; in Comparative Example 4, the functionalized MXene flame retardant prepared in the above embodiment is replaced by unmodified MXene, and although the low-temperature mechanical properties of the obtained epoxy resin are improved, liquid oxygen compatibility cannot be achieved; in Comparative Example 5, if the hyperbranched polymer is not added, the prepared epoxy resin has liquid oxygen compatibility, but poor low-temperature mechanical properties; in Comparative Example 6, if the functionalized MXene flame retardant prepared in the embodiment of the present invention is not added, the obtained epoxy resin system has improved low-temperature mechanical properties, but poor liquid oxygen compatibility; in Comparative Example 7, when only the epoxy resin is reacted with the curing agent and the toughening agent, and the functionalized MXene flame retardant and the hyperbranched polymer are not added, the epoxy resin is incompatible with liquid oxygen and has poor low-temperature mechanical properties.

[0099] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A hyperbranched polymer modified epoxy resin, characterized in that, The raw materials are as follows, calculated by weight: 70.4 parts of epoxy resin, 20 parts of toughening agent, 1.6 parts of functionalized MXene, 8 parts of hyperbranched polymer, and 24.3 parts of curing agent; The functionalized MXene is obtained by surface-modifying the MXene with a silane coupling agent; The curing agent is 4,4'-diaminodiphenylmethane; The toughening agent is biscitraconimide; The epoxy resin is E44; the hyperbranched polymer is hyperbranched epoxy resin HE102, having the following structure: The preparation method of the hyperbranched polymer modified epoxy resin is: The hyperbranched polymer and epoxy resin were mixed according to the mass fraction, mechanically stirred at 120°C for 30 minutes, the solution temperature was lowered to 80°C, and the functionalized MXene, toughening agent and curing agent were added in sequence and stirred for 30 minutes, 8 minutes and 10 minutes, respectively. The mixture was heated and cured. After the temperature was raised to 100°C, the temperature was raised by 20°C per hour and kept warm for 1 hour. The temperature was raised to 200°C and kept warm for another 1 hour, and the mixture was naturally cooled to room temperature to obtain a hyperbranched polymer modified epoxy resin.

2. The hyperbranched polymer modified epoxy resin according to claim 1, wherein The preparation method of the functionalized MXene comprises the following steps: The MXene dispersion is mixed with a silane coupling agent and heated in an inert atmosphere to obtain functionalized MXene; The mass ratio of the MXene to the silane coupling agent is 1:5-25.

3. The hyperbranched polymer modified epoxy resin according to claim 1 or 2, wherein The silane coupling agent includes one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane.

4. Use of the hyperbranched polymer modified epoxy resin according to any one of claims 1 to 3 in combination with carbon fiber in a liquid oxygen propellant tank for a large space vehicle.

Images