Resin system used in ultralow-temperature liquid hydrogen environment and preparation method thereof

Abstract

The invention provides a resin system used in an ultralow-temperature liquid hydrogen environment and a preparation method of the resin system, and relates to the technical field of resin-based composite materials. The resin system used in the ultralow-temperature liquid hydrogen environment comprises 100 parts of bisphenol F epoxy resin and bisphenol A epoxy resin, 20-30 parts of an epoxy reactive diluent, 10-30 parts of a toughening aid and 20-50 parts of a curing agent. Wherein the mass ratio of the bisphenol F epoxy resin to the bisphenol A epoxy resin is (50-70): (30-50). By using the resin system in the ultralow-temperature liquid hydrogen environment, the mechanical property of the resin system can be ensured, meanwhile, the toughness of the resin system is improved, microcracks in the resin system under the combined action of high temperature difference and high pressure difference are reduced, and the liquid hydrogen permeation condition in the using process is prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of resin-based composite materials, and in particular to a resin system for use in an ultra-low temperature liquid hydrogen environment and a preparation method thereof. Background Art

[0002] In order to achieve greater lightness for advanced space launch vehicles, one of the keys is to reduce the weight of the fuel tank. The solution is to replace the currently used composite tank with a metal liner with a full composite tank without a metal liner. Since the carbon fiber composite cryogenic tank without a metal liner lacks a metal liner that acts as a seal, its carbon fiber composite winding layer not only needs to bear the high pressure load inside the tank, but also needs to prevent the leakage of liquid propellant. Once the liquid propellant leaks, it will cause serious consequences.

[0003] Epoxy resin is often used as the matrix material of composite low-temperature storage tanks because of its excellent mechanical properties, good dimensional stability, low curing shrinkage and good corrosion resistance.

[0004] The service conditions of cryogenic tanks are high temperature difference and high pressure difference. Since the thermal expansion coefficients of carbon fiber and resin matrix are very different, for example, the thermal expansion coefficient of carbon fiber is about -0.72~-0.90×10 -6 / ℃, while the thermal expansion coefficient of epoxy resin is about 39×10 -6 / ℃, so when it is in an ultra-low temperature environment, a relatively large tensile stress will appear in the resin matrix. Since the ordinary resin matrix will shrink due to the internal molecular chain segments in an ultra-low temperature environment, resulting in embrittlement, the failure strain of the resin matrix is ​​significantly reduced. Due to the internal tensile stress caused by the difference in thermal expansion coefficients of carbon fiber and resin matrix and the reduction of resin failure strain in ultra-low temperature environment, more microcracks may be formed inside the resin matrix in the fiber winding layer. It is worth noting that when the composite material low-temperature storage tank is continuously cycled with stress and temperature, the microcracks are likely to gradually expand, thereby forming cracks in the thickness direction of the single layer, and further expansion will cause cracks between the composite material layers and delamination. When cracks appear in the thickness direction of each layer of the winding layer of the metal-free liner cryogenic storage tank and cracks occur between layers, resulting in delamination, a connected leakage path will be generated in the thickness direction of the composite material cryogenic storage tank, which will eventually cause leakage of the cryogenic propellant stored inside. Therefore, the design focus of the metal-free liner cryogenic storage tank is to ensure that under the combined action of high temperature difference and high pressure difference, the composite material cryogenic storage tank will not leak and fail due to the generation and expansion of microcracks in the resin matrix. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a resin system for use in an ultra-low temperature liquid hydrogen environment. The resin system is obtained by compounding bisphenol F epoxy resin, bisphenol A epoxy resin, epoxy reactive diluent, toughening aid and curing agent, which can ensure the mechanical properties of the resin system, while improving the toughness of the resin system, reducing the generation of microcracks in the resin system under the combined action of high temperature difference and high pressure difference, and avoiding the occurrence of liquid hydrogen penetration during use below -100°C.

[0006] On the one hand, the present invention provides a resin system for use in an ultra-low temperature liquid hydrogen environment. The resin system for use in an ultra-low temperature liquid hydrogen environment comprises, by weight, 100 parts of bisphenol F epoxy resin and bisphenol A epoxy resin, 20-30 parts of epoxy reactive diluent, 10-30 parts of toughening aid, and 20-50 parts of curing agent;

[0007] Wherein, the mass ratio of bisphenol F epoxy resin to bisphenol A epoxy resin is (50-70): (30-50).

[0008] Optionally, the mass ratio of bisphenol F epoxy resin to bisphenol A epoxy resin is (55-65):(30-45).

[0009] The ultra-low temperature of the present invention is below -100°C. Further, the ultra-low temperature is between -250°C and 100°C.

[0010] Optionally, a hydrogen permeation barrier is also included, and the hydrogen permeation barrier is sodium molybdate. Specifically, the hydrogen permeation barrier is 6-10 parts.

[0011] Optionally, the bisphenol F epoxy resin and the bisphenol A epoxy resin are modified separately; the modification method is: adding ferrosoferric oxide-modified graphene oxide to the bisphenol F epoxy resin and the bisphenol A epoxy resin respectively;

[0012] Among them, the method of modifying graphene oxide with ferroferric oxide is to mix an aqueous solution of graphene oxide with Fe under alkaline conditions. 3+ and Fe 2+ After mixing with an aqueous solution, heating reaction is carried out to obtain a ferroferric oxide / graphene oxide composite material; then the ferroferric oxide / graphene oxide composite material is mixed with an alkylamine to react to obtain ferroferric oxide modified graphene oxide.

[0013] The amount of the ferroferric oxide modified graphene oxide added is 2-5wt%. The graphene oxide modified by magnetic Fe3O4 is used to modify bisphenol F epoxy resin and bisphenol A epoxy resin respectively, and the graphene oxide can be orderly dispersed in the resin under the action of a magnetic field without agglomeration. The mechanical strength and toughness of the bisphenol F epoxy resin and the bisphenol A epoxy resin can be further improved.

[0014] Optionally, 23-27 parts of epoxy active diluent are used. The present invention can reduce the viscosity of the material during the reaction process by adding a certain proportion of epoxy active diluent, while ensuring the cross-linking density of the resin and improving the reaction degree and dispersion degree of each substance.

[0015] Optionally, the epoxy reactive diluent is one or more of alkyl glycidyl ether, acrylate, acetate, caprolactone. Specifically, the alkyl group in the alkyl glycidyl ether is butyl, octyl, ethyl or phenyl;

[0016] Optionally, the acrylate is methyl methacrylate, cyclohexane acrylate, glycerol triacrylate, allyl acrylate, 1.6-hexanediol diacrylate or vinyl acrylate;

[0017] Optionally, the acetate is vinyl acetate;

[0018] Optionally, the caprolactone is γ-caprolactone, δ-caprolactone or ε-caprolactone.

[0019] Optionally, the toughening aid is 15-25 parts. Preferably, the toughening aid is 20-22 parts.

[0020] Optionally, the toughening aid is a core-shell particle; the shell material in the core-shell particle is polyvinyl butyral or polymethyl methacrylate; the core material is nano-alumina or nano-silicon dioxide. Specifically, the mass ratio of the shell material to the core material is (5-8): (2-4). The shell material is a polymer with good compatibility with the epoxy resin. The addition of the shell material will not significantly reduce the crosslinking density of the resin, and it helps to evenly disperse the core-shell particles in the resin, solving the problem of the toughening effect being affected by the aggregation of bisphenol F epoxy resin and bisphenol A epoxy resin.

[0021] Optionally, 2-5 parts of a coupling agent are also included, and the coupling agent is a silane coupling agent.

[0022] The silane coupling agent is one or more of γ-aminopropyltriethoxysilane (abbreviated as KH550), γ-(2,3-epoxypropyloxy)propyltrimethoxysilane (abbreviated as KH560) or γ-methacryloxypropyltrimethoxysilane (abbreviated as KH570). Adding a coupling agent can further improve the compatibility between materials.

[0023] Optionally, the curing agent is 30-45 parts. Preferably, the curing agent is 34-36 parts.

[0024] Optionally, the curing agent is a compound of aliphatic amine aromatic curing agent and polyether amine curing agent;

[0025] Among them, the aliphatic amine aromatic curing agent is diethyltoluenediamine or meta-xylylenediamine. The curing agent can introduce flexible chain segments into the cross-linked network, improve the flexibility of the network chain molecules, and further improve the toughness of the epoxy resin.

[0026] Optional, ultra-low temperature liquid hydrogen environment using resin system with helium permeability less than 10 -9 of magnitude.

[0027] Another aspect of the present invention provides a method for preparing the above-mentioned resin system for use in an ultra-low temperature liquid hydrogen environment, the preparation method comprising the following steps:

[0028] The bisphenol F epoxy resin and the bisphenol A epoxy resin are melted and mixed, and then an epoxy active diluent, a toughening agent and a curing agent are added in sequence, and curing is performed in stages at 40-140° C. The resin system for use in an ultra-low temperature liquid hydrogen environment is obtained by natural cooling.

[0029] Optionally, the staged curing includes:

[0030] Stage I: curing temperature 40-60℃, curing time 1-2h; Stage II: curing temperature 100-120℃, curing time 2-3h; Stage III: curing temperature 120-140℃, curing time 2-4h. The curing temperature of stage I is relatively low, and the bisphenol F epoxy resin and bisphenol A epoxy resin undergo a preliminary reaction. During the curing process of this stage, many components do not react completely, and there is a large porosity, which helps the toughening additive to be evenly dispersed in the resin network to form an interpenetrating and semi-interpenetrating network structure for toughening. At the same time, it also helps the curing agent to introduce flexible chain segments into the cross-linked network, improve the flexibility of the network chain molecules, further improve the toughness of the epoxy resin, and avoid microcracks caused by brittleness during later use, which leads to hydrogen leakage. As the curing of the later stages II and III continues, it can further promote the reaction of each component, solidify the compatibility between the components, and further improve the mechanical properties of the resin system.

[0031] Compared with the prior art, the present invention achieves at least one of the following beneficial effects:

[0032] (1) The use of the resin system in the ultra-low temperature liquid hydrogen environment of the present invention can ensure the mechanical properties of the resin system, while improving the toughness of the resin system, reducing the generation of microcracks in the resin system under the combined action of high temperature difference and high pressure difference, and preventing the occurrence of liquid hydrogen penetration during use.

[0033] (2) In the present invention, a hydrogen permeation barrier is added to the resin system used in the ultra-low temperature liquid hydrogen environment. The hydrogen permeation barrier is compounded with bisphenol F epoxy resin, bisphenol A epoxy resin, epoxy reactive diluent, toughening aid and curing agent, which can further reduce the liquid hydrogen permeation under high pressure and reduce the generation of microcracks in the resin system under the combined effect of high temperature difference and high pressure difference.

[0034] (3) The bisphenol F epoxy resin and bisphenol A epoxy resin of the present invention are modified with ferroferric oxide, and the bisphenol F epoxy resin and bisphenol A epoxy resin are modified with the graphene oxide modified with magnetic Fe3O4, respectively, so that the graphene oxide can be orderly dispersed in the resin under the action of a magnetic field without agglomeration. The mechanical strength and toughness of the bisphenol F epoxy resin and the bisphenol A epoxy resin can be further improved.

[0035] (4) The toughening aid of the present invention is a core-shell particle; the shell material in the core-shell particle is polyvinyl butyral or polymethyl methacrylate; the core material is nano-alumina or nano-silicon dioxide. The shell material has good compatibility with bisphenol F epoxy resin and bisphenol A epoxy resin, can ensure the crosslinking degree of the epoxy resin, and at the same time helps to evenly disperse the core-shell particles in the resin to improve the toughness of the resin system.

[0036] (5) The addition of a coupling agent in the present invention can further improve the compatibility of the components, thereby further improving the mechanical properties and reducing the hydrogen permeability. DETAILED DESCRIPTION

[0037] In order to more clearly illustrate the overall concept of the present invention, a detailed description is given below by way of examples.

[0038] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from those described herein, and therefore, the scope of protection of the present invention is not limited by the specific embodiments disclosed below. In the description of this specification, the description of reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily have to be directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0039] Example 1

[0040] The method for preparing a resin system for use in an ultra-low temperature liquid hydrogen environment comprises the following steps:

[0041] 50 parts of bisphenol F epoxy resin, 50 parts of bisphenol A epoxy resin, 20 parts of epoxy active diluent, wherein the epoxy active diluent is ethyl glycidyl ether: methyl methacrylate: γ-caprolactone added in a mass ratio of 10:5:5; 10 parts of toughening auxiliary core-shell particles, wherein the shell material in the core-shell particles is polyvinyl butyral, and the core material is nano-alumina; the curing agent is a composite of diethyltoluenediamine and polyetheramine curing agent, totaling 20 parts; 6 parts of sodium molybdate, melt mixing, and curing in stages, stage I: curing temperature is 60°C, curing time is 1h; stage II: curing temperature is 80°C, curing time is 2h; stage III: curing temperature is 100°C, curing time is 2h. Natural cooling is performed to obtain a resin system for use in an ultra-low temperature liquid hydrogen environment.

[0042] Example 2

[0043] The method for preparing a resin system for use in an ultra-low temperature liquid hydrogen environment comprises the following steps:

[0044] 70 parts of bisphenol F epoxy resin, 30 parts of bisphenol A epoxy resin, 30 parts of epoxy active diluent, wherein the epoxy active diluent is phenyl glycidyl ether: methyl methacrylate: γ-caprolactone added in a mass ratio of 10:5:5; 30 parts of toughening auxiliary core-shell particles, wherein the shell material in the core-shell particles is polyvinyl butyral, and the core material is nano-alumina; the curing agent is 50 parts of diethyltoluenediamine and polyetheramine curing agent composite; 10 parts of sodium molybdate, melt mixing, and curing in stages, stage I: curing temperature is 40°C, curing time is 1h; stage II: curing temperature is 100°C, curing time is 2h; stage III: curing temperature is 120°C, curing time is 2h. Natural cooling is performed to obtain a resin system for use in an ultra-low temperature liquid hydrogen environment.

[0045] Example 3

[0046] The method for preparing a resin system for use in an ultra-low temperature liquid hydrogen environment comprises the following steps:

[0047] 60 parts of bisphenol F epoxy resin, 40 parts of bisphenol A epoxy resin, 25 parts of epoxy active diluent, wherein the epoxy active diluent is ethyl glycidyl ether: glycerol triacrylate: vinyl acetate added in a mass ratio of 10:5:5; 20 parts of toughening agent core-shell particles, wherein the shell material in the core-shell particles is polyvinyl butyral, and the core material is nano-alumina; the curing agent is 50 parts of diethyltoluenediamine and polyetheramine curing agent composite; 10 parts of sodium molybdate, melt mixing, and curing in stages, stage I: curing temperature is 50°C, curing time is 1h; stage II: curing temperature is 70°C, curing time is 2h; stage III: curing temperature is 90°C, curing time is 2h. Natural cooling is performed to obtain a resin system for use in an ultra-low temperature liquid hydrogen environment.

[0048] The bisphenol F epoxy resin and bisphenol A epoxy resin are modified epoxy resins respectively; the modification method is: adding 2wt% of ferrosoferric oxide-modified graphene oxide to the bisphenol F epoxy resin; adding 5wt% of ferrosoferric oxide-modified graphene oxide to the bisphenol A epoxy resin.

[0049] Example 4

[0050] Based on Example 3, the main difference is that 5 wt% of ferrosoferric oxide-modified graphene oxide is added to bisphenol F epoxy resin; 5 wt% of ferrosoferric oxide-modified graphene oxide is added to bisphenol A epoxy resin.

[0051] Example 5

[0052] The main difference from Example 1 is that no hydrogen permeation barrier is added.

[0053] Example 6

[0054] Based on Example 1, the main difference is that the epoxy reactive diluent is methyl methacrylate.

[0055] Example 7

[0056] Based on Example 1, the main difference is that the epoxy reactive diluent is vinyl acetate.

[0057] Example 8

[0058] Based on Example 1, the main difference is that the shell material of the core-shell particles is polymethyl methacrylate, and the core material is nano-silicon dioxide.

[0059] Example 9

[0060] Based on Example 3, the main difference is that 10% of ferrosoferric oxide-modified graphene oxide is added to bisphenol F epoxy resin; 10% of ferrosoferric oxide-modified graphene oxide is added to bisphenol A epoxy resin.

[0061] Example 10

[0062] Based on Example 3, the main difference is that 3 parts of silane coupling agent KH560 are further included.

[0063] Comparative Example 1

[0064] The main difference from Example 1 is that no toughening agent is added.

[0065] Comparative Example 2

[0066] Based on Example 1, the main difference is that 30 parts of bisphenol F epoxy resin and 70 parts of bisphenol A epoxy resin are used.

[0067] The mechanical properties of the resin systems prepared in Examples 1-10 and Comparative Examples 1-2 were tested at room temperature (25° C.), as shown in Table 1.

[0068] Table 1 Mechanical properties test table at room temperature

[0069]

[0070] Referring to Table 1, it can be seen that the ultra-low temperature liquid hydrogen environment resin system prepared by the present invention has a tensile strength of 60-70MPa, a tensile modulus of 15-30GPa, an elongation at break of not less than 10%, and a fracture toughness of not less than 5MPa·m at room temperature. 1 / 2 .

[0071] The resin system prepared in Examples 1-10 is tested for mechanical properties at -180°C, for example, in a liquid oxygen environment.

[0072] Table 2 -180℃ Mechanical Properties Test Table

[0073]

[0074]

[0075] Referring to Table 2, it can be seen that at -180°C, the tensile strength of the resin system used in the ultra-low temperature liquid hydrogen environment is 70-90MPa, the tensile modulus is 34-40GPa, the elongation at break is not less than 5%, and the fracture toughness is not less than 3MPa·m 1 / 2 .

[0076] The ultra-low temperature liquid hydrogen environment prepared in Examples 1-5 and 10 was tested for helium permeability using a resin system at room temperature and -196°C liquid helium environment, as shown in Table 3.

[0077] Table 3

[0078]

[0079] As shown in Table 3, the helium permeability of the resin system used in the ultra-low temperature liquid hydrogen environment of the present invention is less than 10 -9 The helium leak rate of composite tanks is less than 1×10 -5 Pa.m 3 .s -1 requirements.

[0080] In summary, the resin system used in the ultra-low temperature liquid hydrogen environment of the present invention has good mechanical properties and toughness, can avoid the generation of microcracks in the resin system under the combined action of high temperature difference and high pressure difference, and prevent the occurrence of liquid hydrogen penetration during use.

[0081] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A resin system for use in ultra-low temperature liquid hydrogen environment, characterized in that: The resin system used in the ultra-low temperature liquid hydrogen environment includes 100 parts by mass of bisphenol F epoxy resin and bisphenol A epoxy resin, 20-30 parts of epoxy reactive diluent, 10-30 parts of toughening agent and 20-50 parts of curing agent; Wherein, the mass ratio of bisphenol F epoxy resin to bisphenol A epoxy resin is (50-70): (30-50).

2. The resin system for use in ultra-low temperature liquid hydrogen environment according to claim 1, characterized in that: It also includes a hydrogen permeation barrier, which is sodium molybdate.

3. The resin system for use in ultra-low temperature liquid hydrogen environment according to claim 1, characterized in that: The bisphenol F epoxy resin and the bisphenol A epoxy resin are modified respectively; the modification method is: adding ferrosoferric oxide to the bisphenol F epoxy resin and the bisphenol A epoxy resin to modify graphene oxide; Wherein, the addition amount of ferroferric oxide modified graphene oxide is 2-5%.

4. The resin system for use in ultra-low temperature liquid hydrogen environment according to claim 1, characterized in that: The epoxy reactive diluent is one or more of alkyl glycidyl ether, acrylate, acetate, and caprolactone.

5. The resin system for use in ultra-low temperature liquid hydrogen environment according to claim 4, characterized in that: The alkyl group in the alkyl glycidyl ether is butyl, octyl, ethyl or phenyl; and / or the acrylate is methyl methacrylate, cyclohexane acrylate, glycerol triacrylate, allyl acrylate, 1,6-hexanediol diacrylate or vinyl acrylate; and / or the acetate is vinyl acetate; And / or the caprolactone is γ-caprolactone, δ-caprolactone or ε-caprolactone.

6. The resin system for use in ultra-low temperature liquid hydrogen environment according to claim 1, characterized in that: The toughening auxiliary agent is a core-shell particle; the shell material of the core-shell particle is polyvinyl butyral or polymethyl methacrylate; and the core material is nano-alumina or nano-silicon dioxide.

7. The resin system for use in ultra-low temperature liquid hydrogen environment according to claim 1, characterized in that: The invention also comprises 2-5 parts of a coupling agent, which is a silane coupling agent.

8. The resin system for use in ultra-low temperature liquid hydrogen environment according to claim 7, characterized in that: The silane coupling agent is one or more of KH550, KH560 or KH570.

9. A method for preparing a resin system for use in an ultra-low temperature liquid hydrogen environment as claimed in any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: The above raw materials are melted and mixed, and solidified in stages at 40-140° C., and naturally cooled to obtain a resin system for use in an ultra-low temperature liquid hydrogen environment.

10. The preparation method according to claim 9, characterized in that: The staged curing includes: Stage I: curing temperature 40-60℃, curing time 1-2h; Stage II: curing temperature 100-120℃, curing time 2-3h; Stage III: curing temperature 120-140℃, curing time 2-4h.

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