Epoxy resin endogenous self-repairing material based on phase separation method as well as preparation method and application of epoxy resin endogenous self-repairing material

Abstract

The invention discloses an epoxy resin endogenous self-repairing material based on a phase separation method and a preparation method and application thereof.The preparation method comprises the steps that silicon dioxide and linseed oil are mixed to be uniform, and a first mixed solution is obtained, the silicon dioxide is at least one of hydrophilic nano silicon dioxide, hydrophilic gas-phase silicon dioxide and hydrophobic gas-phase silicon dioxide; uniformly mixing the first mixed solution with a thermosetting resin monomer to obtain a second mixed solution; uniformly mixing the second mixed solution and a cross-linking agent to obtain a third mixed solution; sequentially carrying out vacuum treatment and segmented curing on the third mixed solution, and cooling to room temperature to obtain the epoxy resin endogenous self-repairing material based on the phase separation method. Through multi-phase collaborative design, the mechanical property is not sacrificed while the self-repairing capability is maintained, and the problem that the microcapsule self-repairing system cannot give consideration to the repairing efficiency and the mechanical property is solved.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials technology, specifically relating to an epoxy resin endogenous self-healing material based on phase separation method, its preparation method, and its application. Background Technology

[0002] Polymer materials, especially thermosetting resins such as epoxy resins, are widely used in aerospace, electronic packaging, and high-end equipment fields due to their excellent mechanical properties, chemical resistance, and dimensional stability. However, these materials have high cross-linking degree and high brittleness after curing, making them prone to cracking under impact or complex loads and difficult to self-repair. Therefore, self-healing polymer materials have become a research hotspot, and existing technologies mainly include intrinsic self-healing and extrinsic self-healing. Intrinsic self-healing relies on dynamic covalent bonds or supramolecular interactions, with a short repair distance and limited ability to repair micron-sized cracks. Extrinsic self-healing is represented by microcapsule technology, which achieves repair by triggering microcapsule rupture through cracks to release repair agents. However, microcapsules are prone to agglomeration and uneven dispersion in the matrix, and a brittle shell is generally required to ensure stable storage of microcapsules in the material. However, the brittle shell is prone to sedimentation and is difficult to disperse uniformly. In addition, existing literature generally reports (Wang Han, Liang Jinhua, Gao Zhenguo, et al. Mechanical properties and repair efficiency of microcapsule-type self-healing epoxy resin materials [J]. China Plastics, 2024, 38(5):40-46.DOI:10.19491 / j.issn.1001-9278.2024.05.008.) that with the increase of microcapsule content, the tensile strength, flexural strength and other mechanical properties of epoxy resin materials decrease significantly. That is, the existing microcapsule self-healing system generally has the contradiction that the repair efficiency increases with the increase of microcapsule content, but the tensile strength, flexural strength and other mechanical properties decrease significantly. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing epoxy resin endogenous self-healing materials based on phase separation.

[0004] Another object of the present invention is to provide an epoxy resin endogenous self-healing material based on phase separation obtained by the above preparation method.

[0005] The objective of this invention is achieved through the following technical solution.

[0006] A method for preparing an epoxy resin endogenous self-healing material (a self-healing composite material based on the synergistic regulation of linseed oil phase separation and silica) based on phase separation includes the following steps:

[0007] S1, mix silica and flaxseed oil until uniform to obtain a first mixed solution, wherein the silica is at least one of hydrophilic nano silica (particles), hydrophilic fumed silica (particles) and hydrophobic fumed silica (particles);

[0008] In S1, the water contact angle of hydrophilic nano-silica is 20~30°; the water contact angle of hydrophilic vapor-phase silica is 20~30°; and the water contact angle of hydrophobic vapor-phase silica is 90~100°.

[0009] In step S1, silica and linseed oil are mixed at 15–40°C (preferably 20–30°C) and ultrasonicated until homogeneous to obtain a first mixed solution. The ultrasonic power is 200–600 W (preferably 300–400 W), and the ultrasonic time is 0.5–2 hours (preferably 0.5–1 hour).

[0010] In S1, the average particle size of the silica (particles) is 7–400 nm.

[0011] S2, the first mixed solution is mixed with the thermosetting resin monomer until homogeneous to obtain the second mixed solution;

[0012] In step S2, the first mixed solution is mixed with the thermosetting resin monomer at 40–60°C (preferably 50°C) and stirred until homogeneous to obtain the second mixed solution. The stirring speed is 200–800 rpm (preferably 300–500 rpm), and the stirring time is 0.5–4 hours (preferably 1–2 hours).

[0013] In S2, the thermosetting resin monomer is an epoxy monomer.

[0014] S3, mix the second mixed solution and the crosslinking agent until homogeneous to obtain the third mixed solution. The ratio of thermosetting resin monomer, crosslinking agent, linseed oil and silica by mass parts is (4~6):(1~2):(0.5~1.0):(0.05~0.10).

[0015] In S3, the crosslinking agent is at least one of polyamine crosslinking agents, polyanhydride crosslinking agents, and polyphenol crosslinking agents.

[0016] In step S3, the second mixed solution is preheated to 50–70°C (preferably 50–60°C), a crosslinking agent is added, and the mixture is stirred until homogeneous to obtain the third mixed solution.

[0017] S4, the third mixed solution was subjected to vacuum treatment and segmented curing in sequence, and then cooled to room temperature to obtain an epoxy resin endogenous self-healing material based on phase separation method.

[0018] In S4, the vacuum treatment includes: treating at 50-60°C and a vacuum degree ≤0.09 MPa for 5-10 minutes.

[0019] In S4, the segmented curing includes: curing at 70–100°C for 1–7 hours under vacuum conditions (vacuum degree ≤ 0.09 MPa), followed by curing at 90–100°C for 6 hours. Preferably, curing is performed at 70–100°C for 5–7 hours, followed by curing at 90°C for 6 hours.

[0020] The above preparation method yields an epoxy resin endogenous self-healing material based on phase separation.

[0021] In the above technical solution, the epoxy resin endogenous self-healing material based on phase separation method includes: a thermosetting resin enriched phase (epoxy resin enriched phase), a linseed oil enriched phase, and silica. The silica is dispersed in the epoxy resin endogenous self-healing material, so that the size of the linseed oil enriched phase is refined and it presents a more uniform and dense distribution inside the epoxy resin endogenous self-healing material.

[0022] In the above technical solution, the tensile strength of the epoxy resin endogenous self-healing material based on phase separation method is 35~60MPa; the flexural strength is ≥120 MPa; and the impact strength is 20~40 kJ / m. 2 .

[0023] The above-mentioned epoxy resin endogenous self-healing materials based on phase separation method are used to improve the tensile strength, impact strength, flexural strength, friction properties and / or corrosion resistance of materials.

[0024] The above-mentioned epoxy resin endogenous self-healing materials based on phase separation method are used in aerospace structural components, electronic packaging materials or marine anti-corrosion coatings.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. This invention is based on reaction-induced phase separation (RIPS) technology to construct a system with epoxy enriched phase as matrix, linseed oil (Lo) as repair agent, and silica as reinforcing phase. This process yields an epoxy resin endogenous self-healing material based on phase separation. In this epoxy resin endogenous self-healing material, the linseed oil enriched phase serves as the endogenous repair phase (liquid repair phase), while silica serves as the reinforcing phase and phase structure regulating phase. The introduction of silica not only effectively compensates for the mechanical property loss caused by linseed oil but also achieves a breakthrough in comprehensive performance through multi-phase synergy (enabling the epoxy resin endogenous self-healing material to also possess excellent frictional properties and long-term corrosion resistance).

[0027] 2. Existing microencapsulated self-healing epoxy systems typically require additional interfacial polymerization or in-situ polymerization processes to prepare microcapsules. Furthermore, the microcapsules have relatively large particle sizes and brittle, non-supporting shells, making them prone to sedimentation and agglomeration during casting and curing, hindering uniform dispersion and ultimately introducing interfacial defects into the matrix. This invention, however, utilizes reaction-induced phase separation technology to construct a linseed oil-rich phase (oil droplet structure) in situ within the epoxy resin, eliminating the need for microcapsules. Compared to traditional microencapsulated self-healing epoxy systems, this invention directly forms a micron-sized, adjustable linseed oil-rich phase through phase separation during curing. This linseed oil-rich phase (dispersed phase) is uniformly distributed within the epoxy resin-rich phase (continuous phase), without the presence of brittle shell interfaces, effectively eliminating defects caused by brittle shell interfaces. Simultaneously, the entire preparation process involves only raw material blending, vacuum defoaming, and segmented curing, simplifying the material preparation process. The preparation method of this invention is simple, highly controllable, and more suitable for engineering and large-scale applications.

[0028] 3. This invention improves the problem that microcapsule self-healing systems cannot balance repair efficiency and mechanical properties by using a multiphase synergistic design of "linseed oil (endogenous repair phase) + silica (reinforcing phase) + epoxy resin (continuous phase)".

[0029] Therefore, the preparation method proposed in this invention, while retaining the high reactivity of flaxseed oil (a dry oil repair agent), overcomes the limitations of complex preparation, poor dispersion uniformity, and fragile shell of microcapsule-type self-healing materials, providing a new technical approach for achieving controllable self-healing design of epoxy resin-based materials. Attached Figure Description

[0030] Figure 1 SEM images of the epoxy resin endogenous self-healing material prepared in Example 1 are shown, where (a) is the unetched SEM and (b) is the etched SEM.

[0031] Figure 2 This is a SEM image of the epoxy resin endogenous self-healing material prepared in Example 2 after etching.

[0032] Figure 3 This is a SEM image of the epoxy resin endogenous self-healing material prepared in Example 3 after etching.

[0033] Figure 4 SEM image of the pretreated pure thermosetting resin material prepared in Comparative Example 1;

[0034] Figure 5 SEM image of the composite material prepared in Comparative Example 2 after etching;

[0035] Figure 6The images show a comparison before and after the material repair. In the images, a is the SEM image of the pure thermosetting resin material prepared in Comparative Example 1 before repair, b is the SEM image of the pure thermosetting resin material prepared in Comparative Example 1 after repair, c is the SEM image of the composite material prepared in Comparative Example 2 after repair, and d is the SEM image of the epoxy resin endogenous self-healing material prepared in Example 3 after repair.

[0036] Figure 7 The tensile strength trend graphs are shown for the epoxy resin endogenous self-healing materials prepared in Examples 1-3, the pure thermosetting resin material prepared in Comparative Example 1, and the composite material prepared in Comparative Example 2.

[0037] Figure 8 The bending strength trend graphs are for the epoxy resin endogenous self-healing materials prepared in Examples 1-3, the pure thermosetting resin material prepared in Comparative Example 1, and the composite material prepared in Comparative Example 2.

[0038] Figure 9 The impact strength trend graphs are for the epoxy resin endogenous self-healing materials prepared in Examples 1-3, the pure thermosetting resin material prepared in Comparative Example 1, and the composite material prepared in Comparative Example 2.

[0039] Figure 10 The test results of the friction properties of the epoxy resin endogenous self-healing material prepared in Examples 1-3, the pure thermosetting resin material prepared in Comparative Example 1, and the composite material prepared in Comparative Example 2 are shown. Among them, (a) is the curve of friction coefficient changing with test time, and (b) is the average value of friction coefficient and the trend of friction loss.

[0040] Figure 11 The Nyquist plot of the working electrode prepared for the mixed system of Comparative Example 1;

[0041] Figure 12 Bode impedance modulus diagram of the working electrode prepared for the mixed system of Comparative Example 1;

[0042] Figure 13 The phase angle diagram corresponding to the working electrode prepared from the mixed system of Comparative Example 1;

[0043] Figure 14 The Nyquist plot corresponding to the working electrode prepared from mixed solution B of Comparative Example 2;

[0044] Figure 15 Bode impedance modulus diagram of the working electrode prepared from mixed solution B of Comparative Example 2;

[0045] Figure 16 The phase angle diagram corresponding to the working electrode prepared from mixed solution B in Comparative Example 2;

[0046] Figure 17 The Nyquist plot corresponding to the working electrode prepared from the third mixed solution in Example 3;

[0047] Figure 18 The Bode impedance modulus diagram corresponding to the working electrode prepared from the third mixed solution in Example 3;

[0048] Figure 19 The phase angle diagram is shown for the working electrode prepared from the third mixed solution in Example 3. Detailed Implementation

[0049] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0050] The following examples and comparative examples involve the following raw material information:

[0051]

[0052] In this invention, the triglyceride (C3H5(OOCR1)(OOCR2)(OOCR3)) content in flaxseed oil is approximately 99 wt%.

[0053] The hydrophilic nano-silica (particles) have a water contact angle of 30°, an average particle size of 100 nm, and a BET specific surface area of ​​approximately 200 m². 2 / g.

[0054] The water contact angle of hydrophilic fumed silica (particles) is 30°. Hydrophilic fumed silica is obtained by forming aggregates (approximately 7–40 nm) from primary particles, and has a specific surface area of ​​approximately 100 m². 2 / g.

[0055] The hydrophobic fumed silica (particles) has a water contact angle of 100°, an average particle size of approximately 7–40 nm, and a specific surface area of ​​approximately 100 m². 2 / g. Methods for obtaining hydrophobic fumed silica include: using the silane coupling agent methyltrimethoxysilane (MTMS) to polymerize hydrophilic fumed silica (the water contact angle of the hydrophilic fumed silica is 30°, and the hydrophilic fumed silica is obtained by forming aggregates (approximately 7~40 nm) from primary particle size, with a specific surface area of ​​approximately 100 m². 2Hydrophobicity was achieved by grafting hydroxyl groups onto the surface of the silica (g) to remove hydroxyl groups. Specifically, hydrophilic fumed silica was first dried at 100°C for 2 h. Then, 1 g of hydrophilic fumed silica was dispersed in 20 mL of anhydrous ethanol, and methyltrimethoxysilane (MTMS) was added at 10 wt% of the hydrophilic fumed silica. The mixture was then refluxed at 80°C for 6 h. After the reaction, the product was filtered, washed with anhydrous ethanol, and finally dried at 80°C to constant weight to obtain hydrophobic fumed silica with a significantly reduced -OH content. It should be noted that hydrophobic fumed silica can also be obtained by plasma treatment or acid-base treatment.

[0056] The implementation principle of this invention is as follows:

[0057] Based on the principle of reaction-induced phase separation (RIPS), this invention proposes a preparation method using linseed oil (Lo) as the liquid-phase self-healing component. Phase separation is initiated during the segmented curing process. The basic principle is as follows: In the initial stage of the curing reaction (curing at 70–100°C for 5–7 hours), the epoxy resin and linseed oil are thermodynamically partially compatible. As the crosslinking reaction progresses, the degree of crosslinking and viscosity of the system continuously increase, accompanied by changes in the free energy surface, causing the initially partially compatible system (the third mixed solution) to gradually enter the phase separation region. At this point, the linseed oil gradually separates from the mixed system, undergoing phase separation and forming a dispersed enriched phase structure. Simultaneously, the epoxy resin phase rapidly crosslinks and evolves into a continuous epoxy resin phase, while the linseed oil-enriched phase is "frozen" at a specific scale and distribution, thus obtaining a linseed oil-enriched phase (liquid repair phase) with controllable particle size and uniform spatial distribution within the system. At the same time, silica with surface wettability is introduced as a solid reinforcing phase to influence the phase separation kinetics and provide reinforcement to the cured system. This allows the solid reinforcing phase, liquid repair phase, and continuous epoxy phase to form an integrated synergistic structure within the epoxy resin endogenous self-healing material based on phase separation, enabling self-repair upon damage and effectively compensating for any potential strength reduction caused by the introduction of the linseed oil-enriched phase. This invention achieves the fixation of the linseed oil-enriched phase based on a reaction-induced phase separation mechanism, allowing it to be stably stored within the epoxy resin endogenous self-healing material without the need for an additional outer shell, avoiding the adverse effects of introducing a brittle shell in microcapsule systems.

[0058] The linseed oil-rich phase is distributed in the form of fine, uniform oil droplets. When the epoxy resin endogenous self-healing material based on the phase separation method is subjected to external force and microcracks are generated, the cracks will extend and penetrate the pore structure of the linseed oil-rich phase inside the epoxy resin endogenous self-healing material, causing the linseed oil stored therein to be released into the crack area. The released linseed oil spreads along the crack gap under capillary action and fully fills the damaged area. Subsequently, under the action of oxygen, the unsaturated fatty acid chains contained in the linseed oil undergo oxidative cross-linking reaction, gradually forming a continuous and dense protective self-healing film (oxidative cross-linking repair film). This protective self-healing film effectively covers the crack surface, preventing further crack propagation and thus achieving self-repair. Simultaneously, silica synergistically regulates the phase separation process, stabilizing and refining the structure of the linseed oil-enriched phase. As a solid reinforcing phase, it constructs an effective load transfer network, effectively enhancing the rigidity of the epoxy resin intrinsic self-healing material and compensating for the mechanical property loss caused by the introduction of linseed oil. It cleverly avoids the complex preparation and uneven dispersion problems of traditional microencapsulation technology, enabling the epoxy resin intrinsic self-healing material based on phase separation to maintain good tensile strength, flexural strength, and impact strength while achieving self-healing functionality. This provides a more promising technological path for developing composite materials with both high self-healing capabilities and excellent comprehensive mechanical properties, suitable for aerospace, marine vessels, and anti-corrosion coatings.

[0059] Examples 1-3

[0060] A method for preparing an epoxy resin endogenous self-healing material based on phase separation includes the following steps:

[0061] S1, at 25°C, silica and flaxseed oil are mixed and ultrasonicated until homogeneous (ultrasonic power is 300W, ultrasonic time is 0.5 hours) to obtain the first mixed solution, where silica is Y;

[0062] S2, preheat the first mixed solution to 50°C, add the thermosetting resin monomer, and stir at 50°C until homogeneous (stirring speed is 500 rpm, stirring time is 1 hour) to obtain the second mixed solution, wherein the thermosetting resin monomer is an epoxy monomer and the epoxy monomer is bisphenol A diglycidyl ether.

[0063] S3, preheat the second mixed solution to 50°C, add the crosslinking agent, and stir at 50°C for 5 minutes until uniform to obtain the third mixed solution (homogeneous transparent system). The ratio of thermosetting resin monomer, crosslinking agent, linseed oil and silica by mass is X, and the crosslinking agent is 4,4'-diaminodicyclohexylmethane (DDCM, polyamine crosslinking agent).

[0064] S4. The third mixed solution was subjected to vacuum treatment and segmented curing in sequence, cooled to room temperature, and demolded to obtain an epoxy resin endogenous self-healing material based on phase separation method. The vacuum treatment included: placing the third mixed solution in a vacuum drying oven and pouring it into a mold, and treating it at 60°C for 5 minutes in a vacuum environment (vacuum degree of 0.09 MPa) to eliminate air bubbles; the segmented curing included: curing at 100°C for 6 hours in a vacuum environment (vacuum degree of 0.09 MPa), and then curing at 90°C for 6 hours.

[0065] X and Y are shown in Table 1.

[0066] Table 1

[0067]

[0068] Comparative Example 1

[0069] A method for preparing a pure thermosetting resin material includes the following steps:

[0070] S1, preheat the thermosetting resin monomer to 50°C, add the crosslinking agent, and stir at 50°C for 5 min until a homogeneous and transparent system is formed to obtain a mixed system. The ratio of thermosetting resin monomer to crosslinking agent by mass is 5:1.5. The thermosetting resin monomer is the same as in Example 1, and the crosslinking agent is the same as in Example 1.

[0071] S2, The 50°C mixing system is placed in a vacuum drying oven for vacuum treatment to obtain a pure thermosetting resin material precursor. The vacuum treatment includes: pouring the mixing system into a mold and treating it at 60°C for 5 minutes in a vacuum environment (vacuum degree of 0.09 MPa) to eliminate air bubbles.

[0072] S3, the pure thermosetting resin material precursor is cured in stages, cooled to room temperature, and demolded to obtain the pure thermosetting resin material. The staged curing includes: curing at 100°C for 6 hours in a vacuum environment (vacuum degree of 0.09MPa), and then curing at 90°C for 6 hours.

[0073] Comparative Example 2 (without silicon dioxide)

[0074] A method for preparing a composite material includes the following steps:

[0075] S1, at 50°C, flaxseed oil and thermosetting resin monomer are mixed and stirred until homogeneous (stirring speed is 500 rpm, stirring time is 1 hour) to obtain mixed solution A, wherein, by mass parts, the ratio of thermosetting resin monomer to flaxseed oil is 5:0.75, and the thermosetting resin monomer is the same as in Example 1.

[0076] S2, add crosslinking agent to mixed solution A at 50°C, stir at 500 rpm for 5 min until a homogeneous transparent system is formed, to obtain mixed solution B, wherein, by mass parts, the ratio of thermosetting resin monomer to crosslinking agent is 5:1.5, and the crosslinking agent is the same as in Example 1;

[0077] S3, the mixed solution B at 50℃ is placed in a vacuum drying oven and subjected to vacuum treatment to obtain the composite material precursor. The vacuum treatment includes: pouring the mixed solution B into a mold and treating it at 60℃ for 5 minutes in a vacuum environment (vacuum degree of 0.09 MPa) to eliminate air bubbles.

[0078] S4. The composite material precursor is cured in stages, cooled to room temperature, and demolded to obtain the composite material. The staged curing includes curing at 100°C for 6 hours in a vacuum environment (vacuum degree of 0.09MPa) and then curing at 90°C for 6 hours.

[0079] The morphology of the epoxy resin endogenous self-healing material prepared in Example 1 was observed using a scanning electron microscope (Hitachi Regulus 8220, accelerating voltage 10kV). The obtained SEM images are shown below. Figure 1 As shown in (a), in Figure 1 In (a), uniformly distributed bright spots can be seen, which are silicon dioxide.

[0080] To clearly characterize the microstructure of the material, the material is pretreated:

[0081] Pretreatment was performed on one of the epoxy resin endogenous self-healing materials prepared by phase separation method in Examples 1-3 and the composite material prepared in Comparative Example 2: the material was etched with anhydrous ethanol (EtOH): the material was subjected to Soxhlet extraction in anhydrous ethanol at 100°C for 24 hours to dissolve and remove the linseed oil-enriched phase (silica was also removed simultaneously, but since this etching was only for understanding the distribution of the linseed oil-enriched phase, the removal of silica did not affect subsequent analysis). The material was one of the epoxy resin endogenous self-healing materials prepared by phase separation method in Examples 1-3 and the composite material prepared in Comparative Example 2.

[0082] The pure thermosetting resin material prepared in Comparative Example 1 was pretreated: the pure thermosetting resin material prepared in Comparative Example 1 was ultrasonically dispersed for 10 min under 300W and then cleaned (since linseed oil was not introduced in the preparation method of Comparative Example 1, etching was not required).

[0083] The morphology of the pretreated epoxy resin endogenous self-healing materials prepared by phase separation method in Examples 1-3, the pure thermosetting resin material prepared in Comparative Example 1, and the composite material prepared in Comparative Example 2 were observed using a scanning electron microscope (Hitachi Regulus 8220, accelerating voltage 10kV). Specifically, the epoxy resin endogenous self-healing materials prepared by phase separation method in Examples 1-3 were obtained... Figure 1 of (b) Figure 2 and Figure 3 The SEM image shown; obtained from the pure thermosetting resin material of Comparative Example 1. Figure 4 The SEM image shown; obtained from the composite material of Comparative Example 2 Figure 5 The SEM shown is shown.

[0084] Depend on Figure 1 of (b) Figure 2 and Figure 3 It can be seen that in Examples 1-3, the flaxseed oil enriched phase mainly exhibits a discrete oil droplet distribution, uniformly dispersed within the thermosetting resin enriched phase. Figure 4 It can be seen that the pure thermosetting resin material in Comparative Example 1 did not undergo phase separation. Figure 5 It can be seen that in Comparative Example 2, the density of the flaxseed oil enriched phase distribution in the composite material without added silica is much lower than that in Examples 1-3, indicating that silica has the effect of regulating the phase separation structure, making the structure of the flaxseed oil enriched phase more refined and the distribution more uniform.

[0085] Self-healing performance test: Standardized cracks were prepared by scratching the material surface with a blade under a constant load. The sample was fixed on a stage, and a sharp blade was used to scratch the surface under a constant load of 2N, forming surface cracks with a width of approximately 20-50 μm. The sample was one of the following: the pure thermosetting resin material prepared in Comparative Example 1, the composite material prepared in Comparative Example 2, and the epoxy resin endogenous self-healing material based on phase separation prepared in Example 3. The surface crack of the pure thermosetting resin material prepared in Comparative Example 1 is shown in the figure. Figure 6 As shown in Figure a. The surface cracks of the composite material prepared in Comparative Example 2 and the epoxy resin intrinsic self-healing material prepared in Example 3 based on phase separation method are... Figure 6 The values ​​of a are basically the same. Samples with surface cracks were left to stand for 24 hours at room temperature and in air to repair them. The SEM images of Comparative Example 1, Comparative Example 2, and Example 3 after repair are shown below. Figure 6 b, Figure 6 c and Figure 6As shown in Figure d, the composite material prepared in Comparative Example 2 and the epoxy resin endogenous self-healing material prepared in Example 3, based on the phase separation method, completed self-healing after standing at room temperature for 24 hours. The pure thermosetting resin material prepared in Comparative Example 1 did not repair, indicating that linseed oil has self-healing capabilities.

[0086] Tensile tests were conducted on the epoxy resin endogenous self-healing materials prepared in Examples 1-3 based on the phase separation method, the pure thermosetting resin material prepared in Comparative Example 1, and the composite material prepared in Comparative Example 2 according to GB / T1040.2-2022 standard (using a WDW-5C electronic universal testing machine). The test results are as follows: Figure 7 As shown, it can be seen that after introducing linseed oil in Comparative Example 2, the tensile strength of the composite material decreased significantly compared with the pure thermosetting resin material in Comparative Example 1. Examples 1-3 not only introduced linseed oil but also added silica. The tensile strength of Examples 1-3 increased by 5.45% to 22.2% compared with Comparative Example 2. It can be seen that silica played a significant compensatory role in the loss of mechanical properties caused by linseed oil and effectively improved the overall mechanical properties of the material.

[0087] According to GB / T9341-2008 standard, the flexural strength of the epoxy resin endogenous self-healing material prepared by phase separation method in Examples 1-3, the pure thermosetting resin material prepared in Comparative Example 1, and the composite material prepared in Comparative Example 2 were tested (using a TYE-300D bending tester; the test results are as follows). Figure 8 As shown, the introduction of linseed oil in Comparative Example 2 significantly reduced the flexural strength of the composite material compared to the pure thermosetting resin material in Comparative Example 1. Examples 1-3 not only introduced linseed oil but also added silica. The flexural strength of Examples 1-3 increased by 11.2%–33.3% compared to Comparative Example 2. This demonstrates that silica significantly compensated for the mechanical property loss caused by linseed oil, effectively improving the overall mechanical properties of the material. In particular, Example 3 exhibited a flexural strength even higher than that of the pure thermosetting resin material in Comparative Example 1.

[0088] The impact strength of the epoxy resin endogenous self-healing materials prepared in Examples 1-3 based on the phase separation method, the pure thermosetting resin material prepared in Comparative Example 1, and the composite material prepared in Comparative Example 2 were tested according to GB / T1843-2008 standard (using a WZY-240 cantilever beam impact testing machine). The test results are as follows: Figure 9 As shown, the epoxy resin endogenous self-healing material prepared in Example 3 based on phase separation method has an impact strength comparable to that of pure thermosetting resin materials.

[0089] According to GB / T 3960-2016 standard, the tribological properties of the epoxy resin endogenous self-healing materials prepared by phase separation method in Examples 1-3, the pure thermosetting resin material prepared in Comparative Example 1, and the composite material prepared in Comparative Example 2 were tested (using a UMT-3 tribometer). The test results are as follows: Figure 10 As shown in (a), in the initial stage of testing (0~720s), the epoxy resin endogenous self-healing material prepared by phase separation method in Examples 1-3, the pure thermosetting resin material prepared by Comparative Example 1, and the composite material prepared by Comparative Example 2 all experienced a significant running-in stage, and then entered the steady-state stage (720~1800s). In contrast, Example 3 showed the lowest coefficient of friction and the smallest fluctuation range in the steady-state stage, indicating that its friction interface has better stability. The average coefficients of friction of Comparative Example 1, Comparative Example 2, Example 1, Example 2, and Example 3 in the range of 720s~1800s were 0.189, 0.088, 0.071, 0.066, and 0.042, respectively; taking Figure 10 The average friction coefficient from 720s to 1800s in (a) is used as... Figure 10 The left ordinate of (b) is taken as the mass loss of the material from 0s to 1800s in the above friction performance test. Figure 10 The right-hand ordinate of (b) shows the mass loss (g / 0.5H), which is obtained by subtracting the mass of the material in the 1800s from the mass of the material in the 0s. The material is one of the epoxy resin endogenous self-healing material prepared by phase separation method in Examples 1-3, the pure thermosetting resin material prepared in Comparative Example 1, and the composite material prepared in Comparative Example 2.

[0090] according to Figures 6-10 As can be seen from (b), although flaxseed oil has a self-healing function, adding flaxseed oil alone will significantly reduce the mechanical and frictional properties of the material. However, introducing flaxseed oil and silica at the same time can solve this problem well.

[0091] Electrochemical impedance spectroscopy (EIS) was performed using a three-electrode system. The three electrodes were the working electrode, the counter electrode, and the reference electrode. The counter electrode was a platinum electrode, and the reference electrode was a saturated calomel electrode. The method for preparing the working electrode included: sequentially polishing the metal substrate (a steel plate with dimensions of 200×200×2mm) with 600-grit and 800-grit sandpaper for 3 minutes each to remove rust and stains from the steel plate surface; then ultrasonically cleaning the steel plate in anhydrous ethanol at 200 W for 1 minute; and finally ultrasonically cleaning it in acetone at 200 W for 1 minute. To further remove residual contaminants from the surface, the steel plate was dried in an oven after cleaning. The slurry was then applied to one side of the dried steel plate surface using a scraping method. Under vacuum (0.09 MPa), the coating was first cured at 100°C for 6 hours, then at 90°C for 6 hours, resulting in a 100 μm thick coating on the steel plate. The coating was then scratched with a blade under a constant load of 2 N to create scratches on the surface. The steel plate and the scratched coating together served as the working electrode. The slurry was one of the third mixed solution prepared in Example 3, the mixed system prepared in Comparative Example 1, or mixed solution B prepared in Comparative Example 2. The working electrode, counter electrode, and reference electrode were immersed in a sodium chloride aqueous solution (NaCl concentration 3.5 wt%) for 1–10 days. The working electrode, on the 1st, 5th, and 10th day of immersion, was tested under a 20 mV sinusoidal perturbation within a scanning frequency range of 100 kHz to 0.01 Hz (i.e., scanning frequency from high to low frequency). The coating area was 4 cm². 2 The Nyquist plot, Bode impedance modulus plot, and phase angle plot of the working electrode prepared from the mixed system of Comparative Example 1 are shown below. Figures 11-13 As shown, the Nyquist plot, Bode impedance modulus plot, and phase angle plot corresponding to the working electrode prepared from the mixed solution B of Comparative Example 2 are respectively as follows: Figures 14-16 As shown, the Nyquist plot, Bode impedance modulus plot, and phase angle plot corresponding to the working electrode obtained from the preparation of the third mixed solution in Example 3 are respectively as follows: Figures 17-19 As shown. The Nyquist plot has the real part of the impedance on the horizontal axis and the imaginary part of the impedance on the vertical axis. The Bode impedance magnitude plot has the Log value of the scanning frequency on the horizontal axis and the Log value of the impedance magnitude on the vertical axis. The phase angle plot has the Log value of the scanning frequency on the horizontal axis and the phase difference between the current and the voltage on the vertical axis.

[0092] Depend on Figure 11 It can be seen that the maximum impedance modulus of the working electrode prepared by Comparative Example 1, after being immersed in sodium chloride aqueous solution for 10 days, decreased from 4.5 × 10⁻⁶ on the first day of immersion. 4 Ω· cm 2It dropped sharply to 0.5 × 10⁻⁶ on the 10th day of soaking. 4 Ω·cm 2 The decrease was nearly an order of magnitude, indicating a rapid decline in its protective performance. In contrast, [the following text appears to be incomplete and requires further context: "by..."] Figure 14 It can be seen that the maximum impedance modulus of Comparative Example 2 on the first day of immersion reaches 3.2 × 10⁻⁶. 8 Ω·cm 2 The maximum impedance modulus remained at 6.5 × 10⁻⁶ on the 10th day of soaking. 7 Ω·cm 2 It exhibits excellent barrier performance. Compared with Comparative Examples 1-2, Example 3 shows the most outstanding performance, due to... Figure 17 It can be seen that the maximum impedance modulus on the first day of soaking is 4 × 10⁻⁶. 8 Ω·cm 2 After 10 days of immersion, the maximum impedance modulus remained at 0.9 × 10⁻⁶. 8 Ω·cm 2 Its high impedance value proves that it has the best long-term protection capability.

[0093] Bode impedance modulus plots can provide in-depth analysis of coating degradation kinetics. Figure 12 It can be seen that in Comparative Example 1, the impedance modulus decreased sharply in the initial immersion period (days 1-5) and then stabilized, indicating that the corrosive medium (NaCl) had penetrated the coating and reached the metal substrate in a short period of time. Figure 15 It can be seen that the impedance modulus of Comparative Example 2 showed a continuous decreasing trend throughout the immersion period, indicating that although the coating formed in Comparative Example 2 had a good barrier effect, a slow medium penetration process still existed. Figure 18 It can be seen that the impedance modulus of Example 3 changed very little during the immersion period. The impedance modulus curves on the 1st, 5th and 10th days of immersion almost overlapped, and the impedance modulus remained at a high level, proving that it has relatively stable protective performance.

[0094] Phase angle diagrams can further illustrate changes in the internal structure of the coating, from Figure 13 It can be seen that the phase angle curves measured on days 1, 5, and 10 of immersion in Comparative Example 1 are similar in shape, all showing two clearly overlapping capacitive peaks, and the differences between the three phase angle curves are small. This characteristic indicates that the corrosive medium (NaCl) has rapidly penetrated to the coating-metal substrate interface in the early stage of immersion, forming a stable electric double layer at the interface, causing the original barrier protection of the coating to be essentially lost in a short period of time. Figure 16It can be seen that Comparative Example 2 exhibits different characteristics. While its phase angle curves on days 1, 5, and 10 of immersion all show a trend of slow growth followed by a plateau, the separation between the three phase angle curves is significant. This indicates that the damage repair function brought about by the introduction of linseed oil slows down the penetration rate of the corrosive medium, thus improving the protective performance of the coating. However, the phase angle curves still change significantly with immersion time, indicating that the protective effect of the coating continuously decays during the test, and its protective durability still has room for improvement. Figure 19 It is evident that Example 3 exhibits the best performance. Under different immersion times, the three phase angle curves corresponding to Example 3 not only all show the ideal shape of a slow increase followed by a plateau, but also have the smallest difference between them, almost overlapping. This characteristic proves that the coating has an extremely dense and stable microstructure, effectively resisting electrolyte penetration. During a 10-day immersion process, it maintains its complete physical barrier function and stable interface properties, demonstrating excellent long-term protective durability.

[0095] The density of the linseed oil (Lo) enriched phase in the composite material of Comparative Example 2 was much lower than that in Examples 1-3, resulting in poor performance in all aspects of Comparative Example 2. This demonstrates that the size, morphology, and spatial distribution of the linseed oil enriched phase directly determine the material's performance: a refined and uniformly distributed liquid phase region can provide a stable transport path for the repair agent after material damage occurs, ensuring timely repair reactions; simultaneously, this structure maintains the load transfer network formed by the epoxy resin continuous phase and the silica reinforcing phase, thus maintaining the material's mechanical properties while providing repair functionality. Therefore, the size and structural characteristics of the linseed oil enriched phase can serve as important structural parameters for regulating macroscopic properties. By controlling phase separation conditions, comprehensive optimization of self-healing ability, mechanical properties, tribological properties, and corrosion resistance can be achieved.

[0096] Based on the comprehensive analysis of tensile strength, impact strength, flexural strength, friction properties, self-healing effect and corrosion resistance, the introduction of silica in Examples 1 to 3 compensated for the loss of mechanical properties caused by linseed oil. Furthermore, Example 3, by using hydrophobic fumed silica, achieved the optimal balance in terms of comprehensive performance.

[0097] In summary, this invention utilizes reaction-induced phase separation technology to construct an epoxy resin composite material system with endogenous self-healing function. By introducing silica particles, the self-healing function is successfully achieved while simultaneously improving mechanical properties. Compared with traditional microencapsulated self-healing systems, the method proposed in this invention not only has significant advantages in terms of process cost and scalability, but also fundamentally solves the bottleneck problems of uneven capsule dispersion and limited repair efficiency by forming a uniform repair phase structure through reaction induction.

[0098] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing an epoxy resin endogenous self-healing material based on phase separation, characterized in that, Includes the following steps: S1, mix silica and flaxseed oil until uniform to obtain a first mixed solution, wherein the silica is at least one of hydrophilic nano silica, hydrophilic fumed silica and hydrophobic fumed silica; S2, the first mixed solution is mixed with the thermosetting resin monomer until homogeneous to obtain the second mixed solution; S3, mix the second mixed solution and the crosslinking agent until homogeneous to obtain the third mixed solution. The ratio of thermosetting resin monomer, crosslinking agent, linseed oil and silica by mass parts is (4~6):(1~2):(0.5~1.0):(0.05~0.10). S4, the third mixed solution was subjected to vacuum treatment and segmented curing in sequence, and then cooled to room temperature to obtain an epoxy resin endogenous self-healing material based on phase separation method.

2. The preparation method according to claim 1, characterized in that, In S1, the water contact angle of hydrophilic nano-silica is 20~30°; the water contact angle of hydrophilic vapor-phase silica is 20~30°; and the water contact angle of hydrophobic vapor-phase silica is 90~100°.

3. The preparation method according to claim 1, characterized in that, In S2, the thermosetting resin monomer is an epoxy monomer.

4. The preparation method according to claim 1, characterized in that, In S3, the crosslinking agent is at least one of polyamine crosslinking agents, polyanhydride crosslinking agents, and polyphenol crosslinking agents.

5. The preparation method according to claim 1, characterized in that, In S4, the vacuum treatment includes: treating at 50-60°C and a vacuum degree ≤0.09 MPa for 5-10 minutes.

6. The preparation method according to claim 1, characterized in that, In S4, the segmented curing includes: curing at 70-100°C for 1-7 hours in a vacuum environment, followed by curing at 90-100°C for 6 hours.

7. The preparation method according to claim 1, characterized in that, In S1, the average particle size of the silica is 7–400 nm.

8. The epoxy resin endogenous self-healing material based on phase separation method obtained by the preparation method according to any one of claims 1 to 7.

9. The epoxy resin endogenous self-healing material based on phase separation method according to claim 8, characterized in that, include: Thermosetting resin enriched phase, linseed oil enriched phase, and silica are dispersed in the epoxy resin endogenous self-healing material, thereby refining the size of the linseed oil enriched phase and making it more uniform and densely distributed within the epoxy resin endogenous self-healing material.

10. The application of the epoxy resin endogenous self-healing material based on phase separation method as described in claim 8 in improving the tensile strength, impact strength, flexural strength, friction properties and / or corrosion resistance of materials.

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