A translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing

Abstract

The invention discloses a translucent bio-based toughened epoxy resin composite material that can be thermally repaired after a limit load, and relates to the technical field of epoxy resin composite materials; The translucent bio-based toughened epoxy resin composite material is made up of the following components by weight: 20 50 parts of toughening components and 50 80 parts of basic components; The toughening component includes cardanol type phthalonitrile and catalyst, and the catalyst mass is 0.1 1% of the mass of cardanol type phthalonitrile; Basic components include epoxy resin, curing agent and accelerator. The epoxy resin composite material of the present invention can be bent repeatedly without fracture within the mechanical bending limit, and then self-repair is achieved by heating. The composite material after repair still presents translucent, and has the characteristics of high toughness, high number of cycles, and the preparation process is simple, effectively solves the problems such as the brittleness of existing epoxy resin is large and the recycling rate is low, and widens the application prospects of epoxy resin.

Description

Technical Field

[0001] The present invention relates to the technical field of epoxy resin composite materials, and in particular to a translucent bio-based toughened epoxy resin composite material which can be thermally repaired after extreme bearing. Background Art

[0002] Epoxy resin, a typical thermosetting polymer, is widely used in various fields such as insulation materials, aerospace, and coatings due to its excellent wear resistance, corrosion resistance, electrical insulation properties, and low cost. However, as a thermosetting resin, it is inherently viscous and has a high cross-linking density after curing. This directly leads to the fact that epoxy resin is inherently brittle. Its crack propagation upon fracture is also a typical brittle propagation, which limits its application in high-tech fields such as composite materials and electronic appliances. Moreover, after the epoxy resin breaks, it will be treated as waste, which not only increases the overall cost but also brings serious environmental problems. If the toughness of epoxy resin can be improved and the toughened epoxy resin composite material can be thermally repaired, the recycling of materials will be realized, which will not only reduce the waste of resources but also protect the environment. To address the brittleness of epoxy resins, researchers have introduced a series of high-toughness resin compounds to improve their brittleness. For example, patent CN113603863B discloses a method for producing a high-toughness epoxy resin by mixing liquid epoxy resin, bisphenol A, 1,4-butanediol diglycidyl ether, and a catalyst, performing a polymerization reaction, and then adding a monoacid to the resulting polymerization product for end-capping. However, this method still fails to address the low recycling rate of epoxy resins and cannot be thermally repaired, making it impossible to achieve the purpose of recycling.

[0003] As a new type of high-performance resin, nitrile resin has a wide variety. Due to its unique phthalonitrile structure, it can be polymerized into a ring under high-temperature heating or catalysis, showing excellent mechanical properties, thermal stability and thermal oxidation stability. Cardanol-type phthalonitrile is usually synthesized through nucleophilic substitution reaction. Its flexible long chain and benzene ring structure have become a hot research topic in the field of materials science. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load. The epoxy resin composite material can be bent multiple times within the mechanical bending limit without breaking, and then achieve self-repair by heating. The repaired composite material remains translucent and has the characteristics of high toughness and a high number of cycles. The preparation process is simple, effectively solving the problems of existing epoxy resins such as high brittleness and low recycling rate, and broadening the application prospects of epoxy resins.

[0005] The technical solution of the present invention to solve the above technical problems is as follows: providing a translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme bearing, which is made of the following components by weight: 20-50 parts of a toughening component and 50-80 parts of a basic component; the toughening component includes cardanol-type phthalonitrile and a catalyst, and the mass of the catalyst is 0.1-1% of the mass of the cardanol-type phthalonitrile; the basic component includes an epoxy resin, a curing agent and an accelerator; the mass ratio of the epoxy resin, the curing agent and the accelerator is 10:7.6:0.04-0.05.

[0006] Furthermore, the structural formula of cardanol-type phthalonitrile is:

[0007]

[0008] Where R is

[0009] Furthermore, the catalyst is at least one of butyl stannoic acid and butanone peroxide.

[0010] Furthermore, the epoxy resin is at least one of E-51, E-54, E-44 and E-42 epoxy resins.

[0011] Furthermore, the curing agent is at least one of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride and methyltetrahydrophthalic anhydride.

[0012] Furthermore, the accelerator is 2,4,6-3 (dimethylaminomethyl)phenol.

[0013] Furthermore, the mass ratio of epoxy resin, curing agent and accelerator is 10:7.6:0.044.

[0014] The present invention also provides a method for preparing the above-mentioned translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load, comprising the following steps:

[0015] (1) mixing cardanol-type phthalonitrile and a catalyst, reacting them at a temperature of 80-120° C. for 1-10 hours to obtain a toughening component; mixing an epoxy resin, a curing agent, and an accelerator, reacting them at a temperature of 25-120° C. for 0.5-6 hours to obtain a basic component;

[0016] (2) The toughening component obtained in step (1) and the basic component are mixed, and then prepolymerized at a temperature of 25-80°C for 0.5-4h, and then transferred into a mold, and cured and molded according to a temperature program of 140°C / 2h and 160°C / 2h. After cooling, the mold is demolded to obtain a translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load.

[0017] Furthermore, in step (2), the mixture is stirred at 140-160 rpm to mix.

[0018] The present invention also provides the use of the above-mentioned translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load in the resin matrix of the composite material, the smart material or the pressure sensing material.

[0019] The present invention has the following beneficial effects:

[0020] 1. The present invention compounds a cardanol-type nitrile resin with an epoxy resin, and under the action of a accelerator and a curing agent, prepares a highly tough, heat-repairable translucent epoxy resin composite material. By introducing a flexible long chain on the cardanol-type phthalonitrile, the toughness of the epoxy resin composite material is greatly improved. The epoxy resin composite material can be bent multiple times within the mechanical bending limit without breaking, and then self-repairs by heating. The repaired composite material remains translucent and has the characteristics of high toughness and a high number of cycles. The preparation process is simple, effectively solving the problems of large brittleness and low recycling rate of existing epoxy resins, and broadening the application prospects of epoxy resins.

[0021] 2. The translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load of the present invention is translucent in appearance, undergoes bending deformation but does not break after the initial extreme load, and has a bending strength greater than 23 MPa; the translucent epoxy resin composite material that has been deformed after the extreme load is placed at 10-20°C above or below its glass transition temperature for heat treatment until its appearance is restored to its original state; the repaired composite material remains translucent, has a second extreme load capacity retention rate greater than 95%, can undergo bending deformation but still does not break after the second extreme load, and can undergo extreme load and thermal repair at least once.

[0022] 3. The present invention can alleviate the brittleness of epoxy resins, significantly improving the toughness of epoxy resin composites and expanding their application in high-tech fields. While achieving this improvement in toughness, the composite material can withstand bending limits without breaking and can be thermally repaired under heating, thereby enabling the recycling of the composite material and increasing the utilization rate of the epoxy resin composite material. Furthermore, the present invention has a simple preparation process and low equipment costs, and has broad prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a photo of the bending test of the translucent bio-based toughened epoxy resin composite material obtained in Example 1;

[0024] Figure 2 The translucent bio-based toughened epoxy resin composite material obtained in Example 1 is shown as a physical image of the composite material without breaking after reaching the bending limit and after thermal repair;

[0025] Figure 3This is the stress-strain diagram of the translucent bio-based toughened epoxy resin composite material obtained in Example 1 after multiple bending;

[0026] Figure 4 This is a photo of the translucent bio-based toughened epoxy resin composite material obtained in Example 1, showing cracks starting to appear after the 16th bending test;

[0027] Figure 5 This is a photo of the translucent bio-based toughened epoxy resin composite material obtained in Example 1 after it broke in the 25th bending test;

[0028] Figure 6 The physical image and bending stress-strain diagram of the product obtained in Comparative Example 4;

[0029] Figure 7 The actual image and bending stress-strain diagram of the product obtained in Comparative Example 5. DETAILED DESCRIPTION

[0030] The principles and features of the present invention are described below. The examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. In the examples, where specific conditions are not specified, conventional conditions or manufacturer-recommended conditions were used. Reagents or instruments used where the manufacturer is not specified are conventional products that can be purchased commercially.

[0031] Example 1

[0032] A translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing is made of the following components by weight: 30 parts of a toughening component and 70 parts of a basic component; the toughening component includes cardanol-type phthalonitrile and a catalyst, and the basic component includes an epoxy resin, a curing agent, and an accelerator.

[0033] The method for preparing the above-mentioned translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing comprises the following steps:

[0034] (1) 7.6 g of cardanol-type phthalonitrile and 0.015 g of catalyst (methyl ethyl peroxide) were mixed and reacted at 80 ° C for 1 h to obtain a toughening component; 10 g of epoxy resin E-51, 7.6 g of curing agent (methyltetrahydrophthalic anhydride) and 0.044 g of accelerator (2,4,6-3 (dimethylaminomethyl) phenol) were mixed and reacted at 80 ° C for 1 h to obtain a basic component;

[0035] (2) The toughening component and the basic component obtained in step (1) were stirred and mixed at 150 rpm, and then prepolymerized at 80°C for 0.5 h, and then transferred into a mold and cured according to a temperature program of 140°C / 2 h and 160°C / 2 h. After cooling, the mold was demoulded to obtain a translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load.

[0036] After the above-obtained product was subjected to extreme load-bearing and treated at 100°C for 10 minutes, the translucent epoxy resin composite material that had undergone bending deformation was restored.

[0037] The repaired specimen was further subjected to the ultimate bending load test. Example 1 was able to repeat 24 times and broke during the 25th ultimate bending load test.

[0038] Example 2

[0039] A translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing is made of the following components by weight: 20 parts of a toughening component and 80 parts of a basic component; the toughening component includes cardanol-type phthalonitrile and a catalyst, and the basic component includes an epoxy resin, a curing agent, and an accelerator.

[0040] The method for preparing the above-mentioned translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing comprises the following steps:

[0041] (1) 4.4 g of cardanol-type phthalonitrile and 0.009 g of catalyst (methyl ethyl peroxide) were mixed and reacted at 80 ° C for 1 h to obtain a toughening component; 10 g of epoxy resin E-51, 7.6 g of curing agent (methyltetrahydrophthalic anhydride) and 0.044 g of accelerator (2,4,6-3 (dimethylaminomethyl) phenol) were mixed and reacted at 80 ° C for 1 h to obtain a basic component;

[0042] (2) The toughening component and the basic component obtained in step (1) were stirred and mixed at 150 rpm, and then prepolymerized at 80°C for 0.5 h, and then transferred into a mold and cured according to a temperature program of 140°C / 2 h and 160°C / 2 h. After cooling, the mold was demoulded to obtain a translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load.

[0043] After the above-obtained product was subjected to extreme load-bearing and treated at 110°C for 5 minutes, the translucent epoxy resin composite material that had undergone bending deformation was restored.

[0044] The repaired specimen was further subjected to the ultimate bending load test. Example 2 was able to be repeated 4 times, and fracture occurred during the fifth ultimate bending load test.

[0045] Example 3

[0046] A translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing is made of the following components by weight: 40 parts of a toughening component and 60 parts of a basic component; the toughening component includes cardanol-type phthalonitrile and a catalyst, and the basic component includes an epoxy resin, a curing agent, and an accelerator.

[0047] The method for preparing the above-mentioned translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing comprises the following steps:

[0048] (1) 11.8 g of cardanol-type phthalonitrile and 0.024 g of catalyst (methyl ethyl peroxide) were mixed and reacted at 80 ° C for 1 h to obtain a toughening component; 10 g of epoxy resin E-51, 7.6 g of curing agent (methyltetrahydrophthalic anhydride) and 0.044 g of accelerator (2,4,6-3 (dimethylaminomethyl) phenol) were mixed and reacted at 80 ° C for 1 h to obtain a basic component;

[0049] (2) The toughening component and the basic component obtained in step (1) were stirred and mixed at 150 rpm, and then prepolymerized at 80°C for 0.5 h, and then transferred into a mold and cured according to a temperature program of 140°C / 2 h and 160°C / 2 h. After cooling, the mold was demoulded to obtain a translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load.

[0050] After the above-obtained product was subjected to extreme load-bearing and treated at 90°C for 12 minutes, the translucent epoxy resin composite material that had undergone bending deformation was restored.

[0051] The repaired specimens were further subjected to the ultimate bending load test, and Example 2 was able to be repeated at least 40 times.

[0052] Comparative Example 1

[0053] Patent CN112778703A discloses a high-toughness composite material composed of two-dimensional lamellar boron nitride, one-dimensional tubular carbon nanotubes, and epoxy resin. This preparation method uses a pre-curing temperature of 80°C / 1 hour, a high-temperature curing temperature of 110-130°C, and a high-temperature curing time of 5-6 hours. The toughness is increased to 1.112-1.225 MPa m0.5. However, this method only achieves an improvement in toughness. After initially reaching the ultimate load, the spline will break, and the composite material cannot be recycled.

[0054] Comparative Example 2

[0055] Literature Peng, Hongke, et al. "Hierarchical curing mechanism in epoxy / bismaleimide composites: Enhancing mechanical properties without compromising thermal stabilities." European Polymer Journal (2024): 113604. reported a bismaleimide resin modified epoxy resin, selected 4,4'-diaminodiphenyl sulfone (DDS) as the curing agent, and the curing procedure was: 160℃ / 1h, 180℃ / 1h, 200℃ / 2h. The toughness of the composite material with the optimal mass ratio was only increased by 45%, the toughening effect was not significant, and the composite material would fracture after the initial limit load.

[0056] Comparative Example 3

[0057] Patent CN109206891A discloses a self-healing epoxy resin-based composite material using bisphenol A epoxy resin as a matrix resin. Molecular segments containing Upy groups are grafted onto the bisphenol A epoxy resin molecular chain by a chemical grafting method. Polyetheramine D1000 is used as a curing agent and 330Nsp is added. This preparation method takes more than 24 hours, which is time-consuming and does not discuss its toughening effect. It only explores the self-healing of the width and depth of scratches, and does not achieve the material's ultimate load-bearing capacity and complete macroscopic recovery. In addition, the performance of the material after repair is not discussed.

[0058] Comparative Example 4

[0059] An epoxy matrix resin material, which differs from Example 1 in that it does not contain a toughening component; a preparation method thereof comprises the following steps:

[0060] 10g of epoxy resin E-51, 7.6g of methyltetrahydrophthalic anhydride, and 0.044g of 2,4,6-3(dimethylaminomethyl)phenol (DMP-30) were stirred continuously in a beaker and reacted at 80°C for 90 minutes at a rotation speed of 150 rpm. The prepolymerized mixture was poured into a preheated mold and cured using a temperature program of 140°C / 2h and 160°C / 2h. After cooling and demolding, the sample was obtained. This sample fractured after the initial ultimate load.

[0061] Comparative Example 5

[0062] An epoxy matrix resin material, which differs from Example 1 in that the toughening component contains 10 parts and the basic component contains 90 parts. The sample breaks after the initial ultimate load.

[0063] The actual picture of the translucent bio-based toughened epoxy resin composite material that can be thermally repaired after the ultimate load obtained in Example 1 undergoing a bending test on a mechanical testing machine, the actual picture of the material that does not break after reaching the bending limit on the mechanical testing machine, and the actual picture of the material after thermal repair are shown in Figures 1 and 2. Figure 1-2 As shown; at the same time, the stress-strain diagram of multiple bending is shown as Figure 3 As shown in the figure; among them, the actual picture of the cracks starting to appear in the 16th bending test is shown in the figure Figure 4 As shown; the actual picture after the fracture occurred in the 25th bending test is as follows Figure 5 As shown. The physical diagram and bending stress-strain diagram of comparative examples 4-5 are shown as follows. Figure 6-7 shown.

[0064] Depend on Figure 1 It can be seen that the translucent bio-based toughened epoxy resin composite material obtained in Example 1 does not break after reaching the bending limit, which shows that its toughness has been greatly improved; Figure 2 It can be seen that the sample can be completely restored after repair and still presents a translucent color.

[0065] Depend on Figure 3-5 It can be seen that the translucent bio-based toughened epoxy resin composite material obtained in Example 1 does not break for many times within the bending limit, which shows that its toughness has been greatly improved. The epoxy groups in the epoxy resin can form new network nodes with the nitrile groups in the cardanol-type nitrile resin, which can improve the absorption and dissipation of energy when the material is subjected to external stress, and the flexible long chains, benzene rings and nitrile structures in the cardanol-type nitrile resin can improve the flexibility of the polymer chain segments. The synergistic effect of the two improves the toughness of the epoxy resin composite material. And it can be recycled many times, achieving the purpose of toughening and thermal repair of the epoxy resin composite material. The sample is still translucent after each repair, and cracks begin to appear when it is repeated for the 16th time. And combined with Figure 4-5 It can be seen that after cracks appear, they can generally recover to their original state, but cracks still exist at the location where the cracks appear. During this process, the composite sample still appears translucent, and breaks during the 25th bending test.

[0066] Depend on Figure 6-7 It can be seen that the composite material of Comparative Example 4 lacking a toughening component and the composite material of Comparative Example 5 with less toughening component fractured after the first load.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Application of a translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load in a resin matrix of a composite material, a smart material, or a pressure sensing material, characterized in that: The translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing is made of the following components by weight: 20-50 parts of a toughening component and 50-80 parts of a basic component; the toughening component includes cardanol-type phthalonitrile and a catalyst, the mass of the catalyst being 0.1-1% of the mass of the cardanol-type phthalonitrile; the basic component includes an epoxy resin, a curing agent, and an accelerator; the mass ratio of the epoxy resin, the curing agent, and the accelerator is 10:7.6:0.04-0.05; The cardanol-type phthalonitrile structural formula is: ； Where R is ; The translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing undergoes bending deformation but does not break after the initial extreme load bearing, and has a bending strength greater than 23 MPa; the translucent epoxy resin composite material that has deformed after extreme load bearing is placed at 20°C above or below its glass transition temperature for heat treatment until its appearance is restored to its original state; the repaired composite material remains translucent, has a second extreme load bearing capacity retention rate greater than 95%, can undergo bending deformation but still does not break after the second extreme load bearing, and can undergo extreme load bearing and thermal repair at least once.

2. The use according to claim 1, characterized in that The translucent epoxy resin composite material that was deformed after extreme load bearing was placed at 10°C above or below its glass transition temperature for heat treatment.

3. The use according to claim 1, characterized in that The catalyst is at least one of butyl stannoic acid and butanone peroxide.

4. The use according to claim 1, wherein The epoxy resin is at least one of E-51, E-54, E-44 and E-42 epoxy resins.

5. The use according to claim 1, wherein The curing agent is at least one of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride and methyltetrahydrophthalic anhydride.

6. The use according to claim 1, wherein The accelerator is 2,4,6-tris(dimethylaminomethyl)phenol.

7. The use according to claim 1, wherein The mass ratio of the epoxy resin, curing agent and accelerator is 10:7.6:0.

044.

8. The method for preparing the translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing as claimed in claim 1, characterized in that: The following steps are involved: (1) Mixing cardanol-type phthalonitrile and a catalyst, reacting at 80-120 °C for 1-10 h to obtain a toughening component; mixing epoxy resin, a curing agent and an accelerator, reacting at 25-120 °C for 0.5-6 h to obtain a basic component; (2) The toughening component obtained in step (1) and the basic component are mixed, and then prepolymerized at a temperature of 25-80 °C for 0.5-4 h, and then transferred into a mold and cured according to a temperature program of 140 °C / 2 h and 160 °C / 2 h. After cooling, the mold is demolded to obtain a translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load.

9. The method for preparing a translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing according to claim 8, characterized in that: In step (2), stir and mix at 140-160 rpm.

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