Modified polyhedral oligomeric silsesquioxane, toughening agent, and preparation method and application of modified polyhedral oligomeric silsesquioxane and toughening agent

Abstract

The invention relates to the technical field of preparation of composite materials for spaceflight, and discloses modified polyhedral oligomeric silsesquioxane, a toughening agent and a preparation method and application of the modified polyhedral oligomeric silsesquioxane and the toughening agent. The modified polyhedral oligomeric silsesquioxane takes oligomeric silsesquioxane as a core and has double reaction groups; wherein the double-reactive group is a hydroxyl group and an imino group, and the double-reactive group can be subjected to nucleophilic ring-opening reaction with an epoxy group. The toughened high-temperature-resistant epoxy resin prepared from the multi-component toughening agent composition has excellent toughness, rigidity and heat resistance, and has remarkable industrial value and social significance for realizing optimal balance among the strength, toughness and high-temperature stability of epoxy resin in composite materials used in extreme environments such as spaceflight and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite material preparation for aerospace, in particular to a modified polyhedral oligomeric silsesquioxane, a toughening agent, a preparation method and an application thereof. BACKGROUND

[0002] When resin-based fiber composites are applied to aerospace structures and devices, they often face extreme environmental temperature conditions. For example, the space environment temperature of a spacecraft during on-orbit operation can range from -100 to 100°C, and the service environment of high-performance composites is becoming increasingly severe. During high-speed flight, thermal loads caused by factors such as aerodynamic heating can cause serious damage to the matrix of the composite material. Even if the composite material does not fail completely in a complex aerospace environment, its performance often decreases significantly. To meet the rapid development needs of high-tech fields such as aviation and aerospace, higher requirements are placed on the performance of matrix materials such as epoxy resins, including heat resistance, toughness, high flame resistance, excellent processing performance, etc. Among them, the structure and performance of the epoxy resin as the polymer phase directly affect the overall service behavior of the composite material. Therefore, developing high-performance epoxy resin matrix to improve the comprehensive performance and service reliability of the composite material in a complex aerospace environment has become a key issue to be addressed in the current composite material field.

[0003] Epoxy resin (EP) is one of the most commonly used thermosetting resin materials. Uncured epoxy resin has little value, and only after chemical cross-linking reaction with a curing agent to form a three-dimensional network cross-linked polymer does it have excellent use performance. Epoxy resin cured product has excellent comprehensive performance, such as good bonding performance to fibers, insulation performance, solvent resistance, chemical corrosion resistance, and small curing shrinkage, etc., and is widely used in the fields of aerospace, machinery, coatings, ships, etc. However, the presence of rigid groups in the epoxy resin molecule and the highly cross-linked network structure after curing makes it brittle and poor in fracture resistance, which limits the application of epoxy resin in some high-end fields. Therefore, the toughening modification of epoxy resin is crucial to optimize the service performance of epoxy resin and expand the application scenarios.

[0004] In the prior art, various toughening agents are often introduced for the toughening modification of epoxy resin, such as rubber elastomers, nanoparticles, and thermoplastic polymers, etc. However, the above methods have the following shortcomings: The introduction of rubber elastomers can significantly reduce the strength, modulus, and heat resistance of the resin matrix, and only when the rubber can form a second phase with a particle size of micron level in the epoxy resin matrix, can it significantly toughen; The use of thermoplastic resins requires a large amount of modification, which often leads to poor solubility and flowability, and after curing, reactive phase separation occurs, resulting in weak interfacial forces. Nanoparticles are prone to induce agglomeration due to their high surface energy and significant solubility difference with epoxy resin, resulting in increased viscosity of the whole system.

[0005] At present, with the continuous optimization and improvement of toughening methods, various composite toughening methods have been gradually developed on the basis of various single toughening methods, in order to further improve the comprehensive performance of resin matrix through the complementary effect and synergistic effect between single toughening methods. However, the simple combination of different toughening agents may not always achieve the expected synergistic toughening effect, and sometimes even damages the performance of epoxy resin, which is due to the lack of strong interfacial interaction or the competition between different toughening mechanisms.

[0006] Polyhedral oligomeric silsesquioxane (POSS) is a kind of nanoscale organic-inorganic hybrid particles. Due to its special physicochemical properties, it has incomparable advantages over other ordinary inorganic nanomaterials in polymer modification. In order to be applied in epoxy resin curing, a special active functional group must be introduced on the vertex of the POSS molecule. The inorganic phase and the organic polymer are uniformly distributed in the whole epoxy resin composite through covalent or chemical bonding, which improves the interfacial bonding force between the two phases, and has the high temperature stability of inorganic materials and the excellent compatibility and reactivity of organic components, so as to achieve the purpose of performance complementation and improving the comprehensive performance of materials. The cage structure of POSS inorganic core can act as a stress concentration point to terminate the development of epoxy resin cracks, induce silver streaks and shear bands, and form the effect of reinforcement and toughening. At the same time, its rigid skeleton and highly ordered molecular structure endow the material with excellent strength and thermal stability. These characteristics make POSS one of the most potential candidate materials for epoxy resin toughening modification. However, POSS is prone to agglomeration due to its high surface energy, which limits its toughening effect on epoxy resin matrix. Moreover, the strength and toughness of epoxy resin using POSS as a single toughening agent are often difficult to meet the practical application requirements.

[0007] CN discloses a preparation process of nano core-shell particle toughening modified epoxy resin, which uses nano core-shell particles with rubber particles as core and polymethyl methacrylate as shell as the toughening agent of epoxy resin, but the toughness of the prepared core-shell particle modified epoxy resin is still low, and the rigidity is not obviously improved.

[0008] CN uses a polyether with epoxy end group as the toughening agent of epoxy resin. However, due to the presence of long chain polyether, the glass transition temperature of epoxy resin is sharply reduced, which may have certain influence on its application.

[0009] CN discloses a preparation method of silicone-modified epoxy resin, which effectively improves the toughness and water resistance of the epoxy resin. However, due to the low glass transition temperature of the silicone, the introduction of the silicone may greatly affect the glass transition temperature of the epoxy resin, thereby affecting the application range of the epoxy resin.

[0010] CN discloses an epoxy resin and polyhedral cage silsesquioxane nanohybrid material. The hybrid material is obtained by adding γ-(2,3-epoxypropoxy) propyl trimethoxy octa cage silsesquioxane as nanoparticles to the epoxy resin. Under the action of a curing agent, the octa-epoxy POSS and the epoxy resin undergo crosslinking reaction, thereby introducing the octa-epoxy POSS monomer into the structure of the epoxy resin to form a network crosslinking structure. The prepared hybrid material exhibits extremely low dielectric constant and dielectric loss value. However, due to the rigid structure of the octa-epoxy POSS, the toughness of the hybrid material may be reduced while improving the heat resistance and mechanical properties of the hybrid material.

[0011] In summary, it is of great industrial value and social significance to develop a toughening agent with good compatibility and reactivity in an epoxy resin matrix for achieving an optimized balance between strength, toughness and high-temperature stability of the epoxy resin in composite materials used in extreme environments such as aerospace. SUMMARY

[0012] The purpose of the present application is to provide a toughening agent suitable for extreme environments such as aerospace and having good compatibility and reactivity in an epoxy resin matrix.

[0013] To achieve the above-mentioned purpose, the first aspect of the present application provides a modified polyhedral oligomeric silsesquioxane, which has a double reactive group and takes oligomeric silsesquioxane as a core; wherein the double reactive group is hydroxyl and imino, and the double reactive group can undergo nucleophilic ring-opening reaction with an epoxy group.

[0014] The second aspect of the present application provides a method for preparing the modified polyhedral oligomeric silsesquioxane of the first aspect, which comprises the following steps: (1) in the presence of a solvent, a first contact reaction of γ-glycidyl ether propyl trimethoxysilane and a catalyst is carried out, and after washing, purification and drying, EP-POSS is obtained; the catalyst is selected from any one of concentrated hydrochloric acid, acetic acid and benzyl trimethyl ammonium hydroxide; (2) in the presence of a solvent, a second contact reaction of the EP-POSS and a primary amine compound is carried out, and after washing and drying, the modified polyhedral oligomeric silsesquioxane is obtained.

[0015] The third aspect of the present application provides a multi-component toughening agent composition, which contains the modified polyhedral oligomeric silsesquioxane of the first aspect, and contains the following components which are stored independently or mixed: The content of the modified polyhedral oligomeric silsesquioxane is 1.23-83.87 wt%, and the content of the polythioprene is 16.13-98.77 wt% based on the total weight of the composition.

[0016] The fourth aspect of the present application provides the use of the multi-component toughening agent composition of the third aspect in the preparation of a composite material for aerospace.

[0017] Compared with the prior art, the present application has at least the following beneficial effects: (1) The modified polyhedral oligomeric silsesquioxane provided by the present application is prepared by forming a chemical bond connection through efficient amine-epoxy click reaction of nano cage type POSS and amine compounds, and is an organic-inorganic nanohybrid material with rigid skeleton and double reactive groups. The method is simple and easy to operate, the reaction is efficient and fast, and the reaction conditions are relatively mild; (2) The multi-component toughening agent provided by the present application participates in the curing reaction of the epoxy resin through chemical bonding, can be well dispersed in the epoxy resin matrix, and realizes the optimal balance between the strength, toughness and high temperature stability of the epoxy resin; (3) The use of the multi-component toughening agent provided by the present application to prepare an epoxy resin-based fiber composite material can improve the toughness of the epoxy resin by at least 44% through a synergistic toughening mechanism; at the same time, the internal POSS skeleton can effectively improve the heat resistance and mechanical properties of the epoxy resin / rubber system. Finally, the maximum decomposition temperature and glass transition temperature of the epoxy resin can be increased by at least and compared with the single toughening agent, respectively, and the tensile strength and bending strength of the epoxy resin can be increased by at least 16% and 18% compared with the single toughening agent, respectively. The prepared epoxy resin-based fiber composite material can be mass-produced, the product is stable and easy to store, has a wide application prospect, and can improve the working performance and service reliability of the resin-based fiber composite material in complex aerospace environments. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the infrared spectrum of the octa-epoxy POSS cage molecule EP-POSS and the modified polyhedral oligomeric silsesquioxane FPOSS prepared in Example 1 of the present application; Figure 2 is the SEM image of the composite material epoxy resin DP1 prepared in Comparative Example 1 of the present application; Figure 3 is the SEM image of the composite material epoxy resin DP2 prepared in Comparative Example 2 of the present application; Figure 4SEM image of the toughened high-temperature resistant epoxy resin P2 prepared in Application Example 2 of the present application. DETAILED DESCRIPTION

[0019] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the present application. Any numerical range recited herein is intended to include all sub-ranges of the same numbers (i.e., every subset of numbers within the indicated range). For ranges containing endpoints, any numerical range explicitly indicated should be interpreted as being inclusive of the endpoints. For a numerical range having a lower limit of zero, this is intended to mean that the numerical range includes zero, unless the context clearly indicates otherwise.

[0020] The principles of the present application include: POSS itself is a rigid cage-like structure of organic-inorganic nanohybrid material, which can realize excellent reactivity and compatibility with epoxy resin matrix after modification. When used as a toughener for epoxy resin together with polysulfide rubber, the polysulfide rubber can improve the overall plastic deformation ability of the epoxy resin system by inducing phase separation, and the POSS can act as a stress concentration point to generate a silver shearing band and terminate the crack. The combination of the two can effectively dissipate multi-scale energy, thereby greatly improving the toughness of the epoxy resin system.

[0021] Through the molecular design of inorganic nano-POSS core and double reactive groups, the modified polyhedral oligomeric silsesquioxane can participate in the curing reaction of the epoxy resin through chemical bonding, promote good compatibility with the resin system, limit the movement of polymer chains, and enhance the interfacial bonding force, thereby better improving the rigidity and heat resistance of the epoxy resin / rubber material system.

[0022] As described above, the first aspect of the present application provides a modified polyhedral oligomeric silsesquioxane, which has a double reactive group and takes oligomeric silsesquioxane as a core; wherein the double reactive group is hydroxyl and imino, and the double reactive group can undergo nucleophilic ring-opening reaction with epoxy group.

[0023] According to a preferred embodiment, the structural formula of the modified polyhedral oligomeric silsesquioxane is: ; wherein the R group is selected from the following groups: alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclyl, halogenated hydrocarbon group, silane group, epoxy group, cyano group, boronic acid group.

[0024] More preferably, the structural formula of the modified polyhedral oligomeric silsesquioxane is: .

[0025] As previously described, the second aspect of the present application provides a method for preparing the modified polyhedral oligomeric silsesquioxane of the first aspect, the method comprising the following steps: (1) in the presence of a solvent, a first contact reaction of γ-glycidoxypropyltrimethoxysilane with a catalyst, after washing, purifying and drying, to obtain EP-POSS; the catalyst is selected from any one of concentrated hydrochloric acid, acetic acid and benzyltrimethylammonium hydroxide; (2) in the presence of a solvent, a second contact reaction of the EP-POSS with a primary amine compound, after washing and drying, to obtain the modified polyhedral oligomeric silsesquioxane.

[0026] According to a preferred embodiment, the method for preparing the modified polyhedral oligomeric silsesquioxane of the first aspect comprises the following steps: Preferably, in step (1), the concentration of the concentrated hydrochloric acid is 36-38 wt%.

[0027] Preferably, in step (2), the molar ratio of the primary amine compound to the EP-POSS is 8-9.6:1.

[0028] Preferably, in step (2), the primary amine compound is 2-furfurylamine.

[0029] Preferably, in step (1) and / or step (2), the washing is sequentially performed using an organic solvent and deionized water.

[0030] More preferably, in step (1) and step (2), the organic solvent is independently selected from at least one of methanol, dichloromethane and chloroform.

[0031] Preferably, the method of the present application further comprises, in step (1), before the drying, purifying by column chromatography.

[0032] Preferably, in the present application, in step (1) and step (2), the solvent is independently selected from at least one of methanol, ethanol, isopropanol, acetone, tetrahydrofuran, chloroform, dichloromethane, toluene, mesitylene and N,N-dimethylformamide.

[0033] Preferably, in the present application, in step (1) and step (2), the drying is performed by vacuum drying, and each independently satisfies: temperature is 40, time is 8-24h.

[0034] Preferably, in step (1), the first contact reaction is performed by heating reflux under a nitrogen atmosphere, and at least satisfies: temperature is 50, time is 2-36h.

[0035] Preferably, in step (2), the conditions of the second contact reaction at least meet: temperature is 25, time is 12-36h.

[0036] According to a preferred embodiment, the method of the present application comprises the following steps: (1) adding solvent and catalyst into a reactor and stirring to disperse uniformly, then adding γ-glycidoxypropyltrimethoxysilane, and carrying out a first contact reaction of the obtained solution under nitrogen protection at 50 for 2-36h; after removing the solvent, the obtained crude product is washed with organic solvent and deionized water respectively, and then vacuum dried after column chromatography purification to obtain EP-POSS; (2) dissolving and dispersing the EP-POSS and solvent, then adding primary amine compound; carrying out a second contact reaction of the obtained solution at 25 for 12-36h; after removing the solvent, the obtained product is washed with organic solvent and deionized water respectively, and finally vacuum dried to obtain modified polyhedral oligomeric silsesquioxane.

[0037] As described above, the third aspect of the present application provides a multi-component toughening agent composition, which contains the modified polyhedral oligomeric silsesquioxane of the first aspect, and contains the following components which are independently stored or mixedly stored: The content of the modified polyhedral oligomeric silsesquioxane is 1.23-83.87wt% and the content of the polysulfide rubber is 16.13-98.77wt% based on the total weight of the composition.

[0038] Preferably, the polysulfide rubber has the following structural formula: , and the number average molecular weight is 1000-7500.

[0039] More preferably, the number average molecular weight of the polysulfide rubber is 1000-1500.

[0040] As described above, the fourth aspect of the present application provides the use of the multi-component toughening agent composition of the third aspect in preparing aerospace composite materials.

[0041] Preferably, the use of the present application comprises the following steps: S1, heating and stirring the epoxy resin and the polysulfide rubber in the multi-component toughening agent, then adding solvent and the modified polyhedral oligomeric silsesquioxane in the multi-component toughening agent for pre-curing, removing the solvent after reaction; S2, cooling to 25, adding curing agent, removing bubbles after mixing uniformly, and then curing to obtain toughened high-temperature-resistant epoxy resin.

[0042] Preferably, the epoxy resin, the curing agent, the modified polyhedral oligomeric silsesquioxane and the polysulfide rubber are used in a weight ratio of 100:30-50:0.5-26:5-40.

[0043] Preferably, in step S1, the temperature of the heating stirring is 60, and the time is 1-3h.

[0044] More preferably, in step S1, the temperature of the heating stirring is 120.

[0045] Preferably, in step S1, the temperature of the heating pre-curing is 40, and the time is 1-3h.

[0046] More preferably, in step S1, the temperature of the heating pre-curing is 40.

[0047] It should be noted that, in the present application, the removal of the solvent is performed by using conventional technical means in the art, and exemplarily, rotary evaporation or distillation can be used.

[0048] Preferably, in step S1, the epoxy resin is selected from at least one of glycidyl amine type epoxy resin, bisphenol A type epoxy resin, aliphatic glycidyl ether epoxy resin, phenolic epoxy resin, glycidyl ester type epoxy resin.

[0049] More preferably, the epoxy resin is glycidyl amine type epoxy resin.

[0050] Further preferably, the epoxy resin is AFG-90.

[0051] Preferably, in step S1, the solvent is selected from at least one of methanol, ethanol, isopropanol, acetone, tetrahydrofuran, chloroform, dichloromethane, toluene, mesitylene and N,N-dimethylformamide.

[0052] Preferably, in step S2, the curing agent is selected from at least one of 4,4'-diaminodiphenyl sulfone, 4,4'-diphenyl methane, 4,4'-diaminodiphenyl ether, m-phenylenediamine and other aromatic amine curing agents.

[0053] Preferably, in step S2, the removal of the bubbles is performed by using vacuum extraction.

[0054] Preferably, in step S2, the curing includes: first pre-curing at 60 for 1-3h, then middle-curing at 100 for 1-5h, and finally post-curing at 150 for 1-3h.

[0055] The present application is described in detail below by way of examples, and the raw materials used are all commercially available unless otherwise specified.

[0056] It should be noted that in the present application, each "part" represents a weight of.

[0057] Primary amine compound: 2-furfurylamine (FA); Concentrated hydrochloric acid: concentration of 37wt%; Organic solvent: methanol at 0°C; Polythiourethane: structural formula is, and the number average molecular weight is 1000; Curing agent: 4,4'-diaminodiphenyl sulfone; Epoxy resin: AFG-90.

[0058] Example 1 This example is used to illustrate that the method for preparing modified polyhedral oligomeric silsesquioxane provided by the present application is carried out in the following steps: (1) 360 mL of solvent (methanol) and 30 mL of catalyst were added to a reactor equipped with a magnetic stirrer and stirred and dispersed uniformly, then 15 mL of γ-glycidoxypropyltrimethoxysilane was slowly added dropwise under nitrogen protection for 1 h; then the obtained solution was subjected to a first contact reaction under nitrogen protection for 24 h; after the solvent (methanol) was removed by rotary evaporation, the obtained crude product was washed with organic solvent and deionized water in sequence, and the washing with organic solvent and deionized water was repeated three times, and then the product was purified by column chromatography, vacuum dried at 60°C for 24 h, and EP-POSS was obtained; (2) After the EP-POSS and 15 mL of solvent (methanol) were dissolved and dispersed, a primary amine compound was added through a constant pressure dropping funnel; then the obtained solution was subjected to a second contact reaction under the condition for 24 h; after the solvent (methanol) was removed by rotary evaporation, the obtained product was washed with organic solvent and deionized water in sequence, and the washing with organic solvent and deionized water was repeated three times, and finally vacuum dried at 60°C for 24 h, and a modified polyhedral oligomeric silsesquioxane was obtained, which was named as FPOSS.

[0059] Application Example 1 This application example is used to illustrate the application of the multi-component toughening agent composition provided by the present application in the preparation of a composite material for aerospace in the following steps: S1, under the condition, the epoxy resin (100 parts) and the polythiourethane (20 parts) in the multi-component toughening agent were heated and stirred for 1 h, then the solvent (acetone) and the modified polyhedral oligomeric silsesquioxane (1 part) in the multi-component toughening agent were added for heating and pre-curing for 1 h (60°C), and after the reaction, the solvent was removed by rotary evaporation; S2, cooling to, adding a curing agent (50 parts), after mixing evenly, using vacuum to remove bubbles, then first in the pre-curing 2h, then in the middle of the curing 2h, finally in the post-curing 2h to complete the curing, to get the aerospace composite - toughened high temperature resistant epoxy resin, named P1.

[0060] Application Example 2 The application example adopts the similar method with application example 1, the difference is that in step S1, the amount of modified polyhedral oligomeric silsesquioxane is 3 parts by weight; Finally, the aerospace composite - toughened high temperature resistant epoxy resin is obtained, named P2.

[0061] Comparative Example 1 The comparative example adopts the similar method with application example 1, the difference is that in step S1, the amount of modified polyhedral oligomeric silsesquioxane and polythioprene is 0 parts by weight; Finally, the composite epoxy resin is obtained, named DP1.

[0062] Comparative Example 2 The comparative example adopts the similar method with application example 1, the difference is that in step S1, the amount of modified polyhedral oligomeric silsesquioxane is 0 parts by weight; Finally, the composite epoxy resin is obtained, named DP2.

[0063] Test Example 1 The Fourier transform infrared (FTIR) spectrum analysis of the above-mentioned eight epoxy POSS cage molecules (EP-POSS) and modified polyhedral oligomeric silsesquioxane (FPOSS) prepared in example 1 is carried out, the specific method is as follows: The Nicolet iN10 spectrometer of American Thermo Fisher Scientific Company is used for testing, the test wave number range is 400 -1 , and the scanning number is 32 times.

[0064] Figure 1 The FTIR spectrum of EP-POSS, FA and FPOSS is shown, wherein the characteristic absorption peak of epoxy group in EP-POSS -1 , and the doublet of primary amino group (-NH2) in FA -1 and -1 all disappear, and the characteristic peak of secondary amino group (-NH-) generated in the reaction and the O-H stretching vibration peak are superimposed, forming a new wide peak at -1 . These spectral changes confirm that the ring opening reaction of amine group and epoxy group occurs, and there is no free primary amino group left in the system after the reaction.

[0065] Test Example 2 The toughened high-temperature-resistant epoxy resin and the composite epoxy resin prepared in the above application examples and comparative examples were subjected to fracture micro-morphology test, and the specific method was as follows: The fracture surface of the epoxy resin sample after tensile test was observed under a scanning electron microscope (SEM, Czech Republic TESCAN Company) at an acceleration voltage of 15 kV.

[0066] Among them, Figure 2 The SEM image of the composite epoxy resin DP1 is shown, and it can be seen that DP1 presents a smooth fracture surface, the cracks are sparse, straight and have no obvious deflection, showing typical brittle fracture characteristics; Figure 3 The SEM image of the composite epoxy resin DP2 is shown, Figure 3 It can be seen from (a) that the DP2 matrix shows more extensive plastic shear deformation, Figure 3 The cavity structure on the fracture surface is clearly visible in (b), and these cavities are derived from the peeling of rubber particles from the resin matrix; Figure 4 The SEM image of the toughened high-temperature-resistant epoxy resin P2 is shown, wherein, Figure 4 It can be seen from (a) that in addition to the plastic deformation of the matrix, some white particles can also be seen on the cross-sectional morphology of the fracture of the sample, which are formed by the plastic deformation zone of the resin matrix after the debonding of POSS, showing the characteristics of ductile fracture, and Figure 4 No obvious large-scale agglomeration phenomenon was observed in (b), indicating that the compatibility of POSS with the epoxy resin matrix was good.

[0067] Test Example 3 The toughened high-temperature-resistant epoxy resin and the composite epoxy resin prepared in the application examples and comparative examples were subjected to performance test, and the specific method was as follows: Tensile strength and elongation at break: evaluated according to ISO527-2:2012 standard, the size was (170±2) mm×(20.0±0.2) mm×(4.0±0.2) mm, the test speed was set to 5 mm / min, and 5 samples were averaged for each group; Bending strength: evaluated according to ISO178:2001 standard, the size was (80±2) mm×(10.0±0.2) mm×(4.0±0.2) mm, the span length was 60 mm, the test speed was set to 5 mm / min, and 5 samples were averaged for each group; Glass transition temperature (Tg): evaluated according to GB / T 19466.2-2004 standard, using a TA differential scanning calorimeter, the heating rate was 10 ℃ / min; Maximum degradation temperature (Tmax), coke yield (Wt) under: using TA thermal gravimetric analyzer, air atmosphere, heating rate is 10 / min, temperature range is 30-800℃; The performance test results are shown in Table 1.

[0068] The above results show that the toughened high-temperature-resistant epoxy resin prepared by using the multi-component toughening agent composition of the present application has excellent toughness, rigidity and heat resistance. The toughness (elongation at break) is about 2.25 times that of DP1, and the rigidity (tensile strength, bending strength) is also better, and the coke yield is 4.41 times that of DP1, and the maximum degradation temperature is increased by 50℃. The toughness, bending strength and heat resistance are also significantly improved compared with DP2, among which the glass transition temperature is increased by 17℃, and in DP2, only the addition of polysulfide rubber toughens the epoxy resin, which leads to a significant decrease in the glass transition temperature of the material.

[0069] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application, and all belong to the protection scope of the present application.

Claims

1. A modified polyhedral oligomeric silsesquioxane, characterized in that, The modified polyhedral oligomeric silsesquioxane has an oligomeric silsesquioxane core and a dual reactive group; wherein the dual reactive group is a hydroxyl group and an imino group, and the dual reactive group can undergo a nucleophilic ring-opening reaction with an epoxy group.

2. The modified polyhedral oligomeric silsesquioxane according to claim 1, characterized in that, The structural formula of the modified polyhedral oligomeric silsesquioxane is: ； The R group is selected from the following groups: alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, halogenated hydrocarbon, silyl, epoxy, cyano, and borate.

3. The modified polyhedral oligomeric silsesquioxane according to claim 1 or 2, characterized in that, The structural formula of the modified polyhedral oligomeric silsesquioxane is: 。 4. A method for preparing the modified polyhedral oligomeric silsesquioxane according to any one of claims 1-3, characterized in that, The method includes the following steps: (1) In the presence of a solvent, γ-glycidoxypropyltrimethoxysilane is reacted with a catalyst in a first contact reaction, and EP-POSS is obtained after washing, purification and drying; the catalyst is selected from any one of concentrated hydrochloric acid, acetic acid and benzyltrimethylammonium hydroxide; (2) In the presence of a solvent, the EP-POSS is reacted with a primary amine compound in a second contact reaction, and after washing and drying, a modified polyhedral oligomeric silsesquioxane is obtained.

5. The method according to claim 4, characterized in that, In step (1), the first contact reaction is carried out under a nitrogen atmosphere by heating and reflux, and at least the following conditions must be met: the temperature is 50°C and the time is 2-36 hours. In step (2), the conditions for the second contact reaction must at least be: temperature of 25°C and time of 12-36 hours.

6. A multi-component toughening agent composition, characterized in that, The composition contains the modified polyhedral oligomeric silsesquioxane as described in any one of claims 1-3, and contains the following components, which may be stored independently or in combination: Based on the total weight of the composition, the content of the modified polyhedral oligomeric silsesquioxane is 1.23-83.87 wt%, and the content of polysulfide rubber is 16.13-98.77 wt%.

7. The multi-component toughening agent composition according to claim 6, characterized in that, The structural formula of the polysulfide rubber is: And the number average molecular weight is 1000-7500.

8. The use of the multi-component toughening agent composition according to claim 6 or 7 in the preparation of aerospace composite materials.

9. The application according to claim 8, characterized in that, The aerospace composite material is a resin-based fiber composite material.

10. The application according to claim 8 or 9, characterized in that, The application includes the following steps: S1. The epoxy resin and the polysulfide rubber in the multi-component toughening agent are heated and stirred, and then the solvent and the modified polyhedral oligomeric silsesquioxane in the multi-component toughening agent are added and heated for pre-curing. The solvent is removed after the reaction. S2. Cool to 25°C, add curing agent, mix evenly, remove air bubbles, and then cure to obtain toughened high-temperature resistant epoxy resin.

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