Semitransparent bio-based toughened epoxy resin composite material capable of being thermally repaired after ultimate bearing

Abstract

The invention discloses a semitransparent bio-based toughened epoxy resin composite material capable of being thermally repaired after ultimate bearing, and relates to the technical field of epoxy resin composite materials. The semitransparent bio-based toughened epoxy resin composite material is prepared from the following components in parts by weight: 20-50 parts of a toughening component and 50-80 parts of a basic component, the toughening component comprises anacardol type phthalonitrile and a catalyst, and the mass of the catalyst is 0.1-1% of that of the anacardol type phthalonitrile; the basic components comprise epoxy resin, a curing agent and an accelerant. The epoxy resin composite material disclosed by the invention can be bent for multiple times within a mechanical bending limit without fracture, then self-repairing is realized through heating, the repaired composite material is still semitransparent and has the characteristics of high toughness, high cycle index and the like, the preparation process is simple, the problems of high brittleness, low cycle utilization rate and the like of the existing epoxy resin are effectively solved, and the application prospect is wide. The application prospect of the epoxy resin is widened.

Description

Technical Field

[0001] The 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] As a typical thermosetting polymer, epoxy resin is widely used in various fields such as insulation materials, aerospace, and coatings due to its excellent wear resistance, corrosion resistance, electrical insulation performance, and low cost. However, as a thermosetting resin, it has high viscosity and a high cross-linking density after curing, which directly leads to the fact that epoxy resin is brittle in nature. Its crack extension when broken is also a typical brittle extension, which limits its application in high-tech fields such as composite materials and electronic appliances. After the epoxy resin breaks, it will be treated as waste, which will not only increase the overall cost but also bring 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 can not only reduce the waste of resources but also protect the environment. In order to solve the problem of epoxy resin brittleness, researchers have introduced a series of high-toughness resin compounds to improve its brittleness; for example, patent CN113603863B discloses a method of mixing liquid epoxy resin, bisphenol A, 1,4-butanediol diglycidyl ether and a catalyst, performing a polymerization reaction, adding a monoacid to the obtained polymerization product, performing a capping reaction, and obtaining a high-toughness epoxy resin. However, this method still cannot solve the problem of low recycling of epoxy resin, and cannot perform thermal repair, and cannot achieve the purpose of recycling.

[0003] As a new type of high-performance resin, nitrile resin has many types. Due to its unique phthalonitrile structure, it can be polymerized into a ring under high-temperature heating or catalysis, and exhibits excellent mechanical properties, thermal stability and thermal oxidation stability. Cardanol-type phthalonitrile is usually synthesized through nucleophilic substitution reaction. The flexible long chain and benzene ring structure it contains have become a hot topic of research 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 is still translucent and has the characteristics of high toughness and high number of cycles. The preparation process is simple, which effectively solves the problems of high brittleness and low recycling rate of existing epoxy resins, and broadens the application prospects of epoxy resins.

[0005] The technical solution of the present invention to solve the above technical problems is as follows: a translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing is provided, which is made of the following components in parts 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] Further, the structural formula of cardanol-type phthalonitrile is:

[0007]

[0008] Among them, R is

[0009] Furthermore, the catalyst is at least one of butyl stannoic acid and methyl ethyl ketone 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 bearing, comprising the following steps:

[0015] (1) mixing cardanol-type phthalonitrile and a catalyst, reacting at 80-120° C. for 1-10 hours to obtain a toughening component; mixing an epoxy resin, a curing agent and an accelerator, reacting at 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, and demolded after cooling 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-based resin with an epoxy resin, and prepares a highly tough, heat-repairable translucent epoxy resin composite material under the action of a promoter and a curing agent, and greatly improves the toughness of the epoxy resin composite material by introducing a flexible long chain on the cardanol-type phthalonitrile. The epoxy resin composite material can be bent multiple times within the mechanical bending limit without breaking, and then self-repair is achieved by heating. The repaired composite material is still translucent, and has the characteristics of high toughness and high number of cycles. The preparation process is simple, and the existing epoxy resin has effectively solved the problems of large brittleness and low recycling rate, and has broadened the application prospects of epoxy resin.

[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, bends and deforms but does not break after the initial extreme load, and has a bending strength greater than 23Mpa; the translucent epoxy resin composite material that is 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 is still translucent, has a second extreme load capacity retention rate of greater than 95%, can bend and deform but still does not break after the second extreme load, and can be subjected to extreme load and thermal repair at least once.

[0022] 3. The present invention can improve the brittleness of epoxy resin, significantly improve the toughness of epoxy resin composite materials, and expand its application in high-tech fields. While improving the toughness, the composite material can reach the bending limit without breaking, and can be thermally repaired under heating, thereby realizing the recycling of the composite material and improving the utilization rate of the epoxy resin composite material. In addition, the preparation process of the present invention is simple, the equipment cost is low, and it has broad prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a physical picture 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 does not break after reaching the bending limit and the physical picture after thermal repair;

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

[0026] Figure 4 This is a physical picture of the translucent bio-based toughened epoxy resin composite material obtained in Example 1, which begins to show cracks 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, and the examples are only used to explain the present invention and are not used to limit the scope of the present invention. If no specific conditions are specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0031] Example 1

[0032] A translucent bio-based toughened epoxy resin composite material which can be thermally repaired after extreme load bearing is made of the following components in parts 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) are stirred and mixed at 150 rpm, and then prepolymerized at 80°C for 0.5 h. The mixture is then transferred into a mold and cured according to a temperature program of 140°C / 2h and 160°C / 2h. The mold is then demolded after cooling to obtain a translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing.

[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 be repeated 24 times and fractured during the 25th ultimate bending load test.

[0038] Example 2

[0039] A translucent bio-based toughened epoxy resin composite material which can be thermally repaired after extreme load bearing is made of the following components in parts 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) are stirred and mixed at 150 rpm, and then prepolymerized at 80°C for 0.5 h. The mixture is then transferred into a mold and cured according to a temperature program of 140°C / 2h and 160°C / 2h. The mold is then demolded after cooling to obtain a translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing.

[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 which can be thermally repaired after extreme load bearing is made of the following components in parts 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) are stirred and mixed at 150 rpm, and then prepolymerized at 80°C for 0.5 h. The mixture is then transferred into a mold and cured according to a temperature program of 140°C / 2h and 160°C / 2h. The mold is then demolded after cooling to obtain a translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing.

[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. The preparation method has a pre-curing temperature of 80°C / 1h, a high-temperature curing temperature of 110-130°C, and a high-temperature curing time of 5-6h. The toughness is increased to 1.112-1.225MPa m0.5, but it only achieves an improvement in toughness. After reaching the ultimate load for the first time, 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, the curing procedure: 160℃ / 1h, 180℃ / 1h, 200℃ / 2h, the toughness of the composite material with the best quality ratio was only increased by 45%, the toughening effect was not significant, and the composite material would break after the initial limit load.

[0056] Comparative Example 3

[0057] Patent CN109206891A discloses a self-repairable epoxy resin-based composite material using bisphenol A epoxy resin as a base resin, grafting molecular segments containing Upy groups onto the bisphenol A epoxy resin molecular chain by a chemical grafting method, using polyetheramine D1000 as a curing agent and adding 330Nsp. The preparation method requires more than 24 hours, is time-consuming, and does not discuss its toughening effect. It only discusses the self-repair of the width and depth of scratches, and does not achieve the material's ultimate load-bearing capacity and complete macroscopic recovery, and 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 epoxy resin E-51, 7.6g methyltetrahydrophthalic anhydride, 0.044g 2,4,6-3 (dimethylaminomethyl) phenol (DMP-30) were continuously stirred and mixed in a beaker, and reacted at 80℃ for 90min, with the rotation speed maintained at 150rpm. The prepolymerized mixed sample was poured into a preheated mold, and cured according to the program of 140℃ / 2h and 160℃ / 2h. The sample was obtained after cooling and demolding. The sample broke after the initial limit load.

[0061] Comparative Example 5

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

[0063] The actual picture of the semi-transparent 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, and the actual picture of the actual object that does not break after reaching the bending limit on the mechanical testing machine and the actual picture after thermal repair are shown respectively as follows Figure 1-2 As shown; at the same time, the stress-strain diagram of multiple bending is shown 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 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 epoxy resin composite materials. 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 it 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 having less toughening components fractured after the first load-bearing.

[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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing, characterized in that: The invention is prepared from the following components in parts by weight: 20-50 parts of a toughening component and 50-80 parts of a basic component; the toughening component comprises 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 comprises 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.

2. The translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing according to claim 1, characterized in that: The cardanol type phthalonitrile structural formula is: Among them, R is 3. The translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing according to claim 1, characterized in that: The catalyst is at least one of butyl stannoic acid and butanone peroxide.

4. The translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing according to claim 1, characterized in that: The epoxy resin is at least one of E-51, E-54, E-44 and E-42 epoxy resins.

5. The translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing according to claim 1, characterized in that: The curing agent is at least one of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride and methyltetrahydrophthalic anhydride.

6. The translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing according to claim 1, characterized in that: The accelerator is 2,4,6-3 (dimethylaminomethyl) phenol.

7. The translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing according to claim 1, characterized in that: The mass ratio of the epoxy resin, the curing agent and the accelerator is 10:7.6:0.

044.

8. The method for preparing the semi-transparent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) mixing cardanol-type phthalonitrile and a catalyst, reacting at 80-120° C. for 1-10 hours to obtain a toughening component; mixing an epoxy resin, a curing agent and an accelerator, reacting at 25-120° C. for 0.5-6 hours 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 0.5-4h, and then transferred into a mold, and cured and molded according to a temperature program of 140°C / 2h and 160°C / 2h, and demolded after cooling to obtain a translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load.

9. The method for preparing the 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), the mixture is stirred at 140-160 rpm.

10. Use of the translucent bio-based toughened epoxy resin composite material that can be thermally repaired after extreme load bearing as claimed in any one of claims 1 to 7 in the resin matrix of a composite material, a smart material or a pressure sensing material.

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