Hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material and preparation and degradation recycling method thereof

Abstract

The present invention belongs to the technical field of polymer composite materials, and specifically relates to a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material and its preparation and degradation cycle recovery method. The present invention uses terminal thiol hyperbranched polyester and terminal isocyanate monomer dynamically cross-linked carbon fiber to prepare a high-performance carbon fiber composite material with controllable cycle degradation. The prepared carbon fiber composite material can be degraded and recycled under different conditions to obtain raw material monomers or prepolymers, thereby realizing controllable closed-loop recovery of the carbon fiber composite material. The preparation process of the present invention is simple, and the carbon fiber composite material has high performance and controllable closed-loop recycling function, and is expected to be used in aerospace, wind power generation, automobile manufacturing and other fields.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer composite materials, and specifically relates to a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material and a preparation method and a degradation cycle recovery method thereof. Background Art

[0002] As an inorganic fiber material, carbon fiber is widely used in military and civilian fields such as aerospace, wind power generation, and transportation. However, with the increase in carbon fiber production capacity and the continuous expansion of its application fields, a large amount of waste will be generated during the production of prepregs and composites, the expiration of the service life of carbon fiber products, and the replacement of components. Taking the wind power field as an example, the service life of wind turbine blades is generally 20 to 25 years. By 2034, the global carbon fiber waste from wind turbine blades will exceed 225,000 tons. The growing total amount of carbon fiber waste over the years has forced the recycling and reuse of carbon fiber waste to become an industry technical problem that needs to be overcome urgently.

[0003] Traditional recycling methods of thermosetting resins and their carbon fiber composites, such as mechanical recycling, oxidation and pyrolysis, will inevitably damage the surface and performance of carbon fibers, and cause serious waste of resources and environmental pollution, making it difficult to achieve high-value recycling of thermosetting resins and carbon fibers. In recent years, more and more studies have shown that the introduction of dynamic covalent structures, including Diels-Alder reactions, disulfide bonds, ester bonds, borate bonds, acetal bonds, Schiff base bonds, and imine bonds, into thermosetting cross-linked networks can enable carbon fiber composites with them as matrix resins to be disassembled under specific conditions, thereby ensuring the surface morphology, mechanical properties, chemical properties and weaving structure of the recycled carbon fibers, which is conducive to the high-value recycling of carbon fibers and matrix resins in carbon fiber composites.

[0004] However, the self-healing and recycling properties and mechanical strength of thermosetting polymers containing dynamic covalent bonds are mutually constrained. Dynamic covalent bonds sacrifice the rigidity and cross-linking density of the material, resulting in the material being unable to bear large loads, and reducing dimensional stability and chemical resistance, which limits the application of dynamic covalent bonds in thermosetting resins and their carbon fiber composites. Therefore, achieving efficient closed-loop recycling of carbon fiber composites without reducing performance has become a major challenge. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material and a preparation and degradation cycle recycling method thereof. The present invention utilizes terminal thiol hyperbranched polyester and terminal isocyanate monomer to dynamically cross-link carbon fibers to prepare a high-performance carbon fiber composite material with controllable cyclic degradation. The prepared carbon fiber composite material can be degraded and recycled under different conditions to obtain raw monomers or prepolymers, thereby realizing controllable closed-loop recycling of the carbon fiber composite material. The preparation process of the present invention is simple, and the carbon fiber composite material has high performance and controllable closed-loop recycling functions, and is expected to be used in aerospace, wind power generation, automobile manufacturing and other fields.

[0006] The technical solution provided by the present invention is as follows:

[0007] A terminal mercapto group hyperbranched polyester, the structural formula of which is as follows:

[0008]

[0009] Wherein, R', R'', and R''' are the same or different and are independently represented by the structure of general formula (2), general formula (3) or general formula (4):

[0010]

[0011]

[0012] R1 is represented by the general formula (5), wherein * represents the position of connection with R2:

[0013]

[0014] R2 is represented by one of the general formula (6), general formula (7), general formula (8), and general formula (9), wherein ** represents the position connected to R1:

[0015]

[0016] R3 is represented by the general formula (10), (11) wherein *** indicates the position of connection with R2:

[0017]

[0018] The present invention also provides a method for preparing the above-mentioned thiol-terminated hyperbranched polyester, comprising the following steps:

[0019] 1) Mix hydroxyethyl hexahydro-s-triazine, dibasic acid or dibasic acid anhydride, organic solvent and catalyst at 80℃-120℃ and stir for reaction for 4-6h. After the reaction, remove the organic solvent under reduced pressure to obtain a terminal hydroxyl hyperbranched polymer. The dibasic acid or dibasic acid anhydride is one of malonic acid, succinic acid, glutaric anhydride and maleic anhydride, the organic solvent is one of N'N-dimethylformamide and 1,4-dioxane, and the catalyst is p-toluenesulfonic acid. The mass ratio of hydroxyethyl hexahydro-s-triazine, dibasic acid or dibasic acid anhydride, organic solvent and catalyst is (1.6-2.5):(1-2):(1-2):(0.008-0.14).

[0020] 2) The terminal hydroxyl hyperbranched polymer, thioglycolic acid or thiopropionic acid, organic solvent and catalyst are uniformly mixed and stirred at 80°C-120°C for 6h-10h, and after the reaction is completed, the mixture is washed with a 5% sodium bicarbonate aqueous solution until the pH value is 7, and the organic layer is decompressed to remove the organic solvent to obtain the terminal thiol hyperbranched polyester. The organic solvent is one of toluene and xylene, the catalyst is one of p-toluenesulfonic acid, sulfuric acid and boric acid, and the mass ratio of the terminal hydroxyl hyperbranched polymer, thioglycolic acid or thiopropionic acid, organic solvent and catalyst is (1.6-2.6):(1:2-5):(0.008-0.01).

[0021] The preparation method prepares a terminal mercapto hyperbranched polyester containing a degradable s-triazine structural unit, and the prepared terminal mercapto hyperbranched polyester has the functions of interface reinforcement and degradation and recycling for carbon fiber composite materials.

[0022] The present invention provides a method for preparing a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material, and the preparation process is as follows:

[0023] 1) soaking the carbon fiber cloth in an organic solvent containing a terminal thiol hyperbranched polyester and a photoinitiator, performing a thiol-olefin click reaction under a UV curing apparatus with a power of 300W to 800W, the reaction time being 1-2 minutes, and then drying at 80-100°C for 0.5-2 hours to obtain a thiol-functionalized carbon fiber cloth; the photoinitiator is one of benzoin dimethyl ether, photoinitiator 651, 4-dimethylaminopyridine, and benzophenone; the organic solvent is one of tetrahydrofuran, ethyl acetate, dioxane, and dichloromethane; the carbon fiber cloth is one of T300, T600, T700, or T800; and the mass ratio of the terminal thiol hyperbranched polyester, the photoinitiator, the organic solvent, and the carbon fiber cloth is 2:0.01:(2-5):1.

[0024] 2) The terminal mercapto hyperbranched polyester and isocyanate monomer are mixed and coated on the surface of the mercapto functionalized carbon fiber cloth to obtain a carbon fiber cloth prepreg.

[0025] 3) 8-12 layers of carbon fiber cloth prepreg are neatly stacked and placed in a flat vulcanizer, and hot-pressed and cured at 80-100° C. and 5-20 MPa for 1-2 hours to obtain a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material; the isocyanate monomer is one of toluene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate, and the mass ratio of the terminal thiol hyperbranched polyester, the isocyanate monomer, and the thiol-functionalized carbon fiber cloth is (4-4.5):(1-1.5):11.

[0026] In the above technical scheme: the thiol group of the thiol-terminated hyperbranched polyester and the -C=C- of the carbon fiber are grafted onto the surface of the carbon fiber through a thiol-olefin click reaction, which is beneficial to improving the interface strength of the composite material; the thiol group in the thiol-terminated hyperbranched polyester undergoes a cross-linking reaction with the isocyanate group of the isocyanate monomer, thereby introducing a dynamic urea bond; the thiol group on the surface of the thiol-functionalized carbon fiber cloth can also react with the isocyanate group of the isocyanate monomer to form a dynamic urea bond; based on the above process, cross-linking and curing of the carbon fiber composite material is also achieved.

[0027] The present invention also provides a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material prepared according to the above preparation method.

[0028] The present invention provides a degradation and recycling method for the above-mentioned hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material, and the specific steps are as follows:

[0029] Recycling method 1:

[0030] 1) The hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material is placed in a 0.1-1.0 mol / L acidic organic solvent, and the carbon fiber and the degradation liquid are separated after degradation for 1-2 hours at normal pressure and 25-90°C. The acid is one of formic acid, phosphoric acid, and acetic acid, and the organic solvent is one of dichloromethane, ethyl acetate, dioxane, and N,N-dimethylformamide. The mass ratio of the carbon fiber composite material to the acidic solution is 1:(2-5).

[0031] 2) The separated carbon fiber cloth is dried at 60°C-80°C for 1h-3h to obtain the recycled carbon fiber cloth.

[0032] 3) A degradation liquid and a 35%-40% formaldehyde aqueous solution are mixed and coated on the surface of the regenerated carbon fiber cloth to obtain a regenerated carbon fiber cloth prepreg; 8-12 layers of the regenerated carbon fiber cloth prepreg are neatly stacked and placed in a flat vulcanizer for hot pressing and curing at 80-100° C. and 5-20 MPa for 1-2 hours to obtain a regenerated carbon fiber composite material; the mass ratio of the degradation liquid, the 35%-40% formaldehyde aqueous solution and the regenerated carbon fiber cloth is (3-5:(1.6-1.8):1.

[0033] In the above technical solution: the isotriazine structure in the carbon fiber composite material is degraded into amino oligomers and carbon fibers under acidic conditions, and formaldehyde is added to the degradation solution for reaction to re-prepare the carbon fiber composite material.

[0034] Recycling method 2:

[0035] 1) placing the hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material in an organic solvent of terminal thiol hyperbranched polyester, degrading at room temperature and pressure for 1-12 hours, and separating the carbon fiber and the degradation liquid. The organic solvent is one of acetone, N'N-dimethylformamide, 1,4-dioxane, tetrahydrofuran, chloroform and ethyl acetate, and the mass ratio of the carbon fiber composite material, the terminal thiol hyperbranched polyester and the organic solvent is 1:18:(30-45).

[0036] 2) The separated carbon fiber cloth is dried at 80-100° C. for 2-3 hours to obtain a regenerated carbon fiber cloth. The degradation liquid is decompressed to remove the organic solvent, extracted with ethanol, and then decompressed to remove the solvent to obtain the recovered terminal mercapto hyperbranched polyester.

[0037] 3) Mix the recovered terminal mercapto hyperbranched polyester and isocyanate monomer and apply them on the surface of the above-mentioned recycled carbon fiber cloth to obtain a recycled carbon fiber cloth prepreg; stack 8-12 layers of recycled carbon fiber cloth prepreg neatly and put them into a flat vulcanizer for hot pressing and curing at 80-100°C and 5-20MPa for 1-2h to obtain a recycled carbon fiber composite material; the isocyanate monomer is one of toluene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. The mass ratio of the recovered terminal mercapto hyperbranched polyester, isocyanate monomer and recycled carbon fiber cloth is (1.5-1.7):(0.8-1):5.

[0038] In the above technical scheme: the dynamic urea bond dissociates under the action of excess terminal mercapto hyperbranched polyester to obtain recoverable terminal mercapto oligomers and carbon fiber cloth, and the recovered terminal mercapto oligomers and carbon fiber cloth are used as raw materials to re-prepare carbon fiber composite materials.

[0039] Recycling method three:

[0040] 1) placing a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material in a mixed solution of 16wt%-27wt% alcohol and an organic solvent, degrading at room temperature and pressure for 1-12h, and separating the carbon fiber and the degradation solution. The alcohol is methanol, the organic solvent is one of dichloromethane and N,N-dimethylformamide, and the mass ratio of the carbon fiber composite material to the mixed solvent of the alcohol is 1:(93-156).

[0041] 2) The separated carbon fiber cloth is dried at 70° C.-80° C. for 2-4 hours to obtain a regenerated carbon fiber cloth. The degradation liquid is decompressed to remove the organic solvent to obtain the recovered terminal mercapto hyperbranched polyester.

[0042] 3) The recycled terminal mercapto hyperbranched polyester and isocyanate monomer are mixed and coated on the surface of the above-mentioned regenerated carbon fiber cloth to obtain a recycled carbon fiber cloth prepreg; 8-12 layers of the recycled carbon fiber cloth prepreg are neatly stacked and placed in a flat vulcanizer for hot pressing and curing at 80-100° C. and 5-20 MPa for 1-2 hours to obtain a recycled carbon fiber composite material; the isocyanate monomer is one of toluene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate, and the mass ratio of the recycled terminal mercapto hyperbranched polyester, the isocyanate monomer and the recycled carbon fiber cloth is (2-3):(1.4-2):5.

[0043] In the above technical scheme: the dynamic urea bond dissociates under the action of alcohol to obtain the recovered terminal thiol hyperbranched polyester and carbon fiber cloth, and the recovered terminal thiol hyperbranched polyester and carbon fiber cloth are used as raw materials to re-prepare the carbon fiber composite material.

[0044] The beneficial effects of the present invention are:

[0045] 1) The terminal mercapto hyperbranched polyester of the present invention, by introducing degradable s-triazine structural units and dynamic urea bonds, enables the hyperbranched polymer to have the functions of strengthening and toughening the carbon fiber composite material, reinforcing the interface, and degrading and recycling.

[0046] 2) The hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material of the present invention can be degraded and recycled by a variety of methods under mild conditions to obtain initial monomers and carbon fibers for preparing the composite material. The regenerated carbon fiber composite material prepared using the recycled monomers and recycled carbon fibers has a high performance retention rate, thereby realizing high-value closed-loop recycling of carbon fiber composite materials.

[0047] 3) The hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material of the present invention has the advantages of fast curing speed, low curing temperature, good resin and reinforcing fiber wettability, high physical and mechanical strength of the product, etc., and can be widely used in automotive carbon fiber composite materials, wind turbine blades and high-pressure hydrogen storage tank systems.

[0048] 4) The carbon fiber composite material of the present invention has excellent comprehensive performance, simple process, low cost, high added value, and is suitable for industrial production. DETAILED DESCRIPTION

[0049] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0050] The raw material carbon fiber cloth used in Examples 1-7 is T600.

[0051] Embodiment 1:

[0052] A method for preparing a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material and recycling the same, the steps of which are as follows:

[0053] (1) 145 g of hydroxyethyl hexahydro-s-triazine, 54 g of malonic acid, 60 g of N'N-dimethylformamide and 0.7 g of p-toluenesulfonic acid were mixed and stirred at 120° C. for 5 h. After the reaction, the organic solvent was removed under reduced pressure to obtain 180 g of a hydroxyl-terminated hyperbranched polymer with a yield of 90.4%. The molecular weight was 1080 g / mol as determined by GPC.

[0054] (2) 180 g of a terminal hydroxyl hyperbranched polymer, 106 g of mercaptopropionic acid, 300 g of toluene and 0.8 g of p-toluenesulfonic acid were mixed uniformly and stirred at 120° C. for 10 h. After the reaction, the mixture was washed with a 5% sodium bicarbonate aqueous solution until the pH value was 7. The organic layer was decompressed to remove the organic solvent to obtain 254 g of a terminal mercapto hyperbranched polyester with a yield of 88.8%. The molecular weight was 1608 g / mol as determined by GPC.

[0055] (3) 100 g of carbon fiber cloth was immersed in 300 g of acetone containing 200 g of terminal thiol hyperbranched polyester and 1 g of benzoin dimethyl ether, and a thiol-olefin click reaction was carried out under a UV curing apparatus with a power of 500 W for 2 minutes, and then dried at 90° C. for 1 hour to obtain 160 g of thiol-functionalized carbon fiber cloth.

[0056] (4) 60 g of terminal thiol hyperbranched polyester and 15 g of isocyanate monomer are mixed and coated on the surface of the above-mentioned thiol-functionalized carbon fiber cloth to obtain a carbon fiber cloth prepreg; 12 layers of carbon fiber cloth prepreg are neatly stacked and placed in a flat vulcanizer and hot-pressed and cured at 100°C and 10 MPa for 2 h to obtain 220 g of a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material.

[0057] (5) 5 g of a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material was placed in 15 ml of a 1 mol / L phosphoric acid DMF solution. After degradation for 1 hour at normal pressure and 25° C., the carbon fiber and the degradation solution were separated.

[0058] (6) The separated carbon fiber cloth was dried at 60°C for 1 h to obtain 4.5 g of regenerated carbon fiber cloth.

[0059] (7) 14 ml of degradation liquid and 7 ml of 35% formaldehyde aqueous solution were mixed and coated on the surface of the above-mentioned regenerated carbon fiber cloth to obtain a regenerated carbon fiber cloth prepreg; 10 layers of regenerated carbon fiber cloth prepreg were neatly stacked and placed in a flat vulcanizer and hot-pressed and cured at 80°C and 10 MPa for 2 h to obtain a regenerated carbon fiber composite material; the tensile strength, interlaminar shear strength, and single fiber tensile strength are shown in Table 1.

[0060] Example 2

[0061] A method for preparing a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material and recycling the same, the steps of which are as follows:

[0062] (1) 150 g of hydroxyethyl hexahydro-s-triazine, 60 g of glutaric anhydride, 60 g of N'N-dimethylformamide and 0.6 g of p-toluenesulfonic acid were mixed and stirred at 120° C. for 5 h. After the reaction, the organic solvent was removed under reduced pressure to obtain 180 g of a terminal hydroxyl hyperbranched polymer with a yield of 85.7%. The molecular weight of the polymer was 1131 g / mol as determined by GPC.

[0063] (2) 180 g of terminal hydroxyl hyperbranched polymer, 100 g of mercaptopropionic acid, 300 g of toluene and 0.8 g of p-toluenesulfonic acid were mixed uniformly and stirred at 120° C. for 10 h. After the reaction, the mixture was washed with a 5% sodium bicarbonate aqueous solution until the pH value was 7. The organic layer was decompressed to remove the organic solvent to obtain 220 g of terminal mercapto hyperbranched polyester with a yield of 78.5%. The molecular weight was 1659 as determined by GPC.

[0064] (3) 100 g of carbon fiber cloth was immersed in 300 g of acetone containing 200 g of terminal thiol hyperbranched polyester and 1 g of benzoin dimethyl ether, and a thiol-olefin click reaction was performed under a UV curing apparatus with a power of 500 W for 2 minutes, and then dried at 90° C. for 1 hour to obtain 150 g of thiol-functionalized carbon fiber cloth.

[0065] (4) 62 g of terminal thiol hyperbranched polyester and 20 g of isocyanate monomer are mixed and coated on the surface of the above-mentioned thiol-functionalized carbon fiber cloth to obtain a carbon fiber cloth prepreg; 12 layers of carbon fiber cloth prepreg are neatly stacked and placed in a flat-plate vulcanizer and hot-pressed and cured at 90°C and 10 MPa for 2 h to obtain 200 g of a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material.

[0066] (5) 5 g of the hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material was placed in 25 g of 1.0 mol / L acidic DMF solvent, and the carbon fiber and the degradation liquid were separated after degradation for 1 hour under normal pressure and 25 °C.

[0067] (6) The separated carbon fiber cloth was dried at 60°C for 1 h to obtain 4.5 g of regenerated carbon fiber cloth.

[0068] (7) 22.5 ml of degradation liquid and 8 ml of 40% formaldehyde aqueous solution were mixed and coated on the surface of the above-mentioned regenerated carbon fiber cloth to obtain a regenerated carbon fiber cloth prepreg; 10 layers of regenerated carbon fiber cloth prepreg were neatly stacked and placed in a flat vulcanizer and hot-pressed and cured at 80°C and 10 MPa for 2 h to obtain a regenerated carbon fiber composite material; the tensile strength, interlaminar shear strength, and single fiber tensile strength are shown in Table 1.

[0069] Example 3

[0070] A method for preparing a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material and recycling the same, the steps of which are as follows:

[0071] (1) 180 g of hydroxyethyl hexahydro-s-triazine, 72 g of malonic acid, 60 g of N'N-dimethylformamide and 4.8 g of p-toluenesulfonic acid were mixed and stirred at 110° C. for 5 h. After the reaction, the organic solvent was removed under reduced pressure to obtain 160 g of a hydroxyl-terminated hyperbranched polymer with a yield of 63.3%. The molecular weight was 1080 g / mol as determined by GPC.

[0072] (2) 160 g of terminal hydroxyl hyperbranched polymer, 80 g of mercaptopropionic acid, 300 g of toluene and 0.64 g of catalyst were mixed uniformly and stirred at 100° C. for 8 h. After the reaction, the mixture was washed with a 5% sodium bicarbonate aqueous solution until the pH value was 7. The organic layer was decompressed to remove the organic solvent to obtain 215 g of terminal mercapto hyperbranched polyester with a yield of 89.5%. The molecular weight was 1608 g / mol as determined by GPC.

[0073] (3) 100 g of carbon fiber cloth was immersed in 300 g of acetone containing 200 g of terminal thiol hyperbranched polyester and 1 g of benzoin dimethyl ether, and a thiol-olefin click reaction was performed under a UV curing apparatus with a power of 500 W for 2 minutes, and then dried at 90° C. for 1 hour to obtain 150 g of thiol-functionalized carbon fiber cloth.

[0074] (4) 59 g of terminal mercapto hyperbranched polyester and 16 g of isocyanate monomer are mixed and coated on the surface of the above-mentioned mercapto functionalized carbon fiber cloth to obtain a carbon fiber cloth prepreg; 12 layers of carbon fiber cloth prepreg are neatly stacked and placed in a flat vulcanizer and hot-pressed and cured at 100°C and 10 MPa for 1 h to obtain 220 g of a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material.

[0075] (5) 5 g of the hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material was placed in 150 ml of acetone containing 90 g of terminal thiol hyperbranched polyester, and degraded at room temperature and pressure for 8 h, and then the carbon fiber and the degradation liquid were separated.

[0076] (6) The separated carbon fiber cloth was dried at 80°C for 3 hours to obtain 2.4 g of regenerated carbon fiber cloth. The degradation liquid was decompressed to remove the organic solvent, and then extracted with ethanol to obtain a mixture of ethanol and terminal mercapto group hyperbranched polyester. The mixture was decompressed to remove the solvent to obtain 1.7 g of terminal mercapto group hyperbranched polyester.

[0077] (7) The recycled terminal mercapto hyperbranched polyester and 0.9 g of isocyanate monomer were mixed and coated on the surface of the above-mentioned regenerated carbon fiber cloth to obtain a recycled carbon fiber cloth prepreg; 12 layers of regenerated carbon fiber cloth prepreg were neatly stacked and placed in a flat vulcanizer and hot-pressed and cured at 95°C and 15 MPa for 1 h to obtain a recycled carbon fiber composite material; the tensile strength, interlaminar shear strength, and single fiber tensile strength are shown in Table 1.

[0078] Example 4

[0079] A method for preparing a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material and recycling the same, the steps of which are as follows:

[0080] (1) 200 g of hydroxyethyl hexahydro-s-triazine, 80 g of malonic acid, 80 g of N'N-dimethylformamide and 4.8 g of p-toluenesulfonic acid were mixed at 110° C. and stirred for reaction for 5 h. After the reaction, the organic solvent was removed under reduced pressure to obtain 180 g of a terminal hydroxyl hyperbranched polymer with a yield of 64.3%. The molecular weight was 1080 g / mol as determined by GPC.

[0081] (2) 180 g of terminal hydroxyl hyperbranched polymer, 80 g of mercaptopropionic acid, 300 g of toluene and 0.64 g of catalyst were mixed evenly and stirred at 100° C. for 8 h. After the reaction, the mixture was washed with a 5% sodium bicarbonate aqueous solution until the pH value was 7. The organic layer was decompressed to remove the organic solvent to obtain 240 g of terminal mercapto hyperbranched polyester with a yield of 92.3%. The molecular weight was 1608 g / mol as determined by GPC.

[0082] (3) 100 g of carbon fiber cloth was immersed in 300 g of acetone containing 200 g of terminal thiol hyperbranched polyester and 1 g of benzoin dimethyl ether, and a thiol-olefin click reaction was performed under a UV curing apparatus with a power of 500 W for 2 minutes, and then dried at 90° C. for 1 hour to obtain 150 g of thiol-functionalized carbon fiber cloth.

[0083] (4) 59 g of terminal mercapto hyperbranched polyester and 16 g of isocyanate monomer are mixed and coated on the surface of the above-mentioned mercapto functionalized carbon fiber cloth to obtain a carbon fiber cloth prepreg; 12 layers of carbon fiber cloth prepreg are neatly stacked and placed in a flat vulcanizer and hot-pressed and cured at 100°C and 10 MPa for 1 h to obtain 220 g of a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material.

[0084] (5) 5 g of the hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material was placed in 220 g of acetone containing 90 g of terminal thiol hyperbranched polyester, and degraded at room temperature and pressure for 8 h, and then the carbon fiber and the degradation liquid were separated.

[0085] (6) The separated carbon fiber cloth was dried at 80°C for 3 hours to obtain 2.5 g of regenerated carbon fiber cloth. The degradation liquid was decompressed to remove the organic solvent, and then extracted with ethanol to obtain a mixture of ethanol and terminal mercapto hyperbranched polyester. The mixture was decompressed to remove the solvent to obtain 1.5 g of terminal mercapto hyperbranched polyester.

[0086] (7) The recycled terminal mercapto hyperbranched polyester and 0.9 g of isocyanate monomer were mixed and coated on the surface of the above-mentioned regenerated carbon fiber cloth to obtain a recycled carbon fiber cloth prepreg; 8-12 layers of the regenerated carbon fiber cloth prepreg were neatly stacked and placed in a flat vulcanizer and hot-pressed and cured at 95°C and 15 MPa for 1 h to obtain a recycled carbon fiber composite material; the tensile strength, interlaminar shear strength, and single-filament tensile strength are shown in Table 1.

[0087] Example 5

[0088] A method for preparing a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material and recycling the same, the steps of which are as follows:

[0089] (1) 117 g of hydroxyethyl hexahydro-s-triazine, 60 g of succinic acid, 60 g of N'N-dimethylformamide and 0.39 g of p-toluenesulfonic acid were mixed at 100° C. and stirred for reaction for 5 h. After the reaction, the organic solvent was removed under reduced pressure to obtain 158 g of a terminal hydroxyl hyperbranched polymer with a yield of 89.2%. The molecular weight was 1122 g / mol as determined by GPC.

[0090] (2) 156 g of terminal hydroxyl hyperbranched polymer, 60 g of mercaptopropionic acid, 200 g of toluene and 0.42 g of p-toluenesulfonic acid were mixed uniformly and stirred at 100° C. for 10 h. After the reaction, the mixture was washed with a 5% sodium bicarbonate aqueous solution until the pH value was 7. The organic layer was decompressed to remove the organic solvent to obtain 203 g of terminal mercapto hyperbranched polyester with a yield of 93.9%. The molecular weight of the polyester was 1650 g / mol as measured by GPC.

[0091] (3) 100 g of carbon fiber cloth was immersed in 300 g of dichloromethane containing 200 g of terminal thiol hyperbranched polyester and 1 g of benzoin dimethyl ether, and a thiol-olefin click reaction was carried out under a UV curing apparatus with a power of 500 W for 2 minutes, and then dried at 100° C. for 1 hour to obtain 150 g of thiol-functionalized carbon fiber cloth.

[0092] (4) 61 g of terminal thiol hyperbranched polyester and 14 g of isocyanate monomer are mixed and coated on the surface of the above-mentioned thiol-functionalized carbon fiber cloth to obtain 225 g of carbon fiber cloth prepreg; 12 layers of carbon fiber cloth prepreg are neatly stacked and placed in a flat vulcanizer and hot-pressed and cured at 100°C and 10 MPa for 2 hours to obtain a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material.

[0093] (5) 5 g of the hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material was placed in 320 ml of a 16 wt% alcohol and dichloromethane mixed solution, and degraded at room temperature and pressure for 5 h, and then the carbon fiber and the degradation liquid were separated.

[0094] (6) The separated carbon fiber cloth was dried at 75° C. for 3 h to obtain a regenerated carbon fiber cloth. The organic solvent was removed from the degradation solution under reduced pressure to obtain 1.9 g of recovered terminal mercapto group hyperbranched polyester.

[0095] (7) The recycled terminal mercapto hyperbranched polyester and 1.3 g of isocyanate monomer were mixed and coated on the surface of the above-mentioned regenerated carbon fiber cloth to obtain a recycled carbon fiber cloth prepreg; 12 layers of regenerated carbon fiber cloth prepreg were neatly stacked and placed in a flat vulcanizer and hot-pressed and cured at 90°C and 10 MPa to obtain a recycled carbon fiber composite material; the tensile strength, interlaminar shear strength, and single fiber tensile strength are shown in Table 1.

[0096] Example 6

[0097] A method for preparing a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material and recycling the same, the steps of which are as follows:

[0098] (1) 117 g of hydroxyethyl hexahydro-s-triazine, 60 g of succinic acid, 60 g of N'N-dimethylformamide and 0.39 g of p-toluenesulfonic acid were mixed at 100° C. and stirred for reaction for 5 h. After the reaction, the organic solvent was removed under reduced pressure to obtain 158 g of a terminal hydroxyl hyperbranched polymer with a yield of 89.2%. The molecular weight was 1122 g / mol as determined by GPC.

[0099] (2) 156 g of terminal hydroxyl hyperbranched polymer, 60 g of mercaptopropionic acid, 200 g of toluene and 0.42 g of p-toluenesulfonic acid were mixed uniformly and stirred at 100° C. for 10 h. After the reaction, the mixture was washed with a 5% sodium bicarbonate aqueous solution until the pH value was 7. The organic layer was decompressed to remove the organic solvent to obtain 203 g of terminal mercapto hyperbranched polyester with a yield of 94.0%. The molecular weight was 1650 g / mol as measured by GPC.

[0100] (3) 100 g of carbon fiber cloth was immersed in 300 g of dichloromethane containing 200 g of terminal thiol hyperbranched polyester and 1 g of benzoin dimethyl ether, and a thiol-olefin click reaction was carried out under a UV curing apparatus with a power of 500 W for 2 minutes, and then dried at 100° C. for 1 hour to obtain 150 g of thiol-functionalized carbon fiber cloth.

[0101] (4) 56 g of terminal mercapto hyperbranched polyester and 19 g of hexamethylene diisocyanate were mixed and coated on the surface of the above-mentioned mercapto-functionalized carbon fiber cloth to obtain 225 g of carbon fiber cloth prepreg; 12 layers of carbon fiber cloth prepreg were neatly stacked and placed in a flat vulcanizer and hot-pressed and cured at 100°C and 10 MPa for 2 h to obtain a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material.

[0102] (5) 5 g of the hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material was placed in 100 ml of a 27 wt % alcohol and dichloromethane mixed solution, and after degradation at room temperature and pressure for 5 h, the carbon fiber and the degradation liquid were separated.

[0103] (6) The separated carbon fiber cloth was dried at 75° C. for 3 h to obtain a regenerated carbon fiber cloth. The organic solvent was removed from the degradation solution under reduced pressure to obtain 2.8 g of recovered terminal mercapto group hyperbranched polyester.

[0104] (7) The recovered terminal mercapto hyperbranched polyester and 1.9 g of isocyanate monomer were mixed and coated on the surface of the above-mentioned regenerated carbon fiber cloth to obtain a regenerated carbon fiber cloth prepreg; 12 layers of regenerated carbon fiber cloth prepreg were neatly stacked and placed in a flat vulcanizer and hot-pressed and cured at 90°C and 10 MPa to obtain a regenerated carbon fiber composite material; the tensile strength, interlaminar shear strength, and single fiber tensile strength are shown in Table 1.

[0105] Example 7

[0106] A method for preparing a carbon fiber reinforced polyurea composite material of a thiol-terminated monomer, the steps of which are as follows:

[0107] (1) 100 g of carbon fiber cloth was completely immersed in 50 g of dichloromethane dissolved with 50 g of ethylene glycol bis(thioglycolate) monomer and 0.5 g of dimethyl benzoate, and a thiol-olefin click reaction was performed in a UV curing apparatus with a power of 500 W for 1 minute, and then dried at 90° C. for 1 hour to obtain 125 g of carbon fiber cloth with surface thiol functionalization.

[0108] (2) 25 g of ethylene glycol bisthioglycolate monomer and 20 g of hexamethylene diisocyanate were mixed and coated on the carbon fiber cloth prepreg obtained above.

[0109] (3) Twelve layers of prepreg obtained in step (2) are neatly stacked and placed in a flat-plate vulcanizer for hot pressing and curing at a certain pressure and temperature for 2 hours to obtain a carbon fiber composite material.

[0110] (4) 5 g of the carbon fiber composite material was placed in 25 g of 1.0 mol / L acidic DMF solvent, and the carbon fiber and the degradation liquid were separated after degradation for 1 hour under normal pressure of 25°C.

[0111] (5) The separated carbon fiber cloth was dried at 60°C for 1 h to obtain 4.5 g of regenerated carbon fiber cloth.

[0112] (6) 22.5 g of degradation liquid and 8 ml of 40% formaldehyde aqueous solution were mixed and coated on the surface of the above-mentioned regenerated carbon fiber cloth to obtain a regenerated carbon fiber cloth prepreg; 10 layers of regenerated carbon fiber cloth prepreg were neatly stacked and placed in a flat vulcanizer and hot-pressed and cured at 80°C and 10 MPa for 2 h to obtain a regenerated carbon fiber composite material; the tensile strength, interlaminar shear strength, and single fiber tensile strength are shown in Table 1.

[0113] Table 1 Performance test results of carbon fiber composite materials of various embodiments

[0114]

[0115] It can be seen from Table 1 that the tensile strength, interlaminar shear strength and single filament tensile strength of the composite materials of Examples 1 to 6 of the present invention are greater than the composite material of Example 7 without adding the terminal mercapto hyperbranched polyester, indicating that Examples 1 to 6 have good mechanical properties. It can be seen that the terminal mercapto hyperbranched polyester of the present invention can be used to modify carbon fibers well.

[0116] In addition, the tensile strength, interlaminar shear strength, and single-filament tensile strength of the carbon fiber and the regenerated carbon fiber in Examples 1 to 6 were compared, respectively, indicating that the carbon fiber has high performance retention.

[0117] In addition, by comparing the tensile strength, interlaminar shear strength and single-filament tensile strength of the carbon fiber and recycled carbon fiber in Examples 1 to 6, it can be seen that: the advantage of recycling method one is that the retention rates of various properties of its recycled carbon fiber composite materials are all above 95%, among which the single-filament tensile strength retention rate of the carbon fiber composite material reaches 99.25%; the advantage of recycling method two is that the retention rates of various properties of its recycled carbon fiber composite materials are all above 94%, among which the interlaminar shear strength retention rate of the carbon fiber composite material reaches 99.18%; the advantage of recycling method three is that the retention rates of various properties of its recycled carbon fiber composite materials are all above 95%, among which the tensile strength retention rate of the carbon fiber composite material reaches 98.48%.

[0118] 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 terminal mercapto group hyperbranched polyester, the structural formula of which is as follows: in, R', R'', and R''' are the same or different and are independently represented by the structure of general formula (2), general formula (3) or general formula (4): R1 is represented by the general formula (5), wherein * represents the position of connection with R2: R2 is represented by one of the general formula (6), general formula (7), general formula (8), and general formula (9), wherein ** represents the position connected to R1: R3 is represented by the general formula (10), (11) wherein *** indicates the position of connection with R2:

2. A method for preparing a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material, characterized in that: The following steps are involved: 1) completely immersing the carbon fiber cloth in an organic solvent containing the terminal thiol hyperbranched polyester and a photoinitiator according to claim 1, performing a thiol-olefin click reaction in a UV curing apparatus with a power of 300W to 800W for 1 to 2 minutes, and then drying at 80 to 100°C for 0.5 to 2 hours to obtain a carbon fiber cloth with surface thiol functionalization; 2) mixing the terminal mercapto hyperbranched polyester and isocyanate monomer described in claim 1 and coating the mixture on the carbon fiber cloth with surface mercapto functionalization obtained in step 1) to obtain a carbon fiber cloth prepreg, wherein the isocyanate monomer is a diisocyanate compound; 3) 8-12 layers of the prepreg obtained in step 2) are neatly stacked and placed in a flat vulcanizer for hot pressing and curing at a certain pressure and temperature for 1-2 hours to obtain a high-performance degradable polyurea-type hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material.

3. The method for preparing a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material according to claim 2, characterized in that: In step 1), the carbon fiber cloth is one or more of commercially available T300, T600, T700 or T800; the photoinitiator is one or more of benzoin dimethyl ether, photoinitiator 651, 4-dimethylaminopyridine or benzophenone; the organic solvent is one or more of N'N-dimethylformamide, 1,4-dioxane, tetrahydrofuran, ethyl acetate or dichloromethane; the terminal thiol hyperbranched polyester is one or more with different terminal groups, and its molar mass is 1482-8652g / mol; the drying condition is 80-100°C for 0.5-2 hours; the mass ratio of the terminal thiol hyperbranched polyester, the photoinitiator, the organic solvent and the carbon fiber cloth is 2:0.01:(2-5):1; In step 2), the mass ratio of the terminal mercapto group hyperbranched polyester, the isocyanate monomer and the surface mercapto group functionalized carbon fiber cloth is (4-4.5):(1-1.5):11; The hot pressing curing conditions in step 3) are: hot pressing curing at 5-20 MPa and 80-100° C. for 1-2 hours.

4. A hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material prepared according to the preparation method according to claim 2 or 3.

5. A degradation and recycling method for a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material, characterized in that: The following steps are involved: 1) soaking the hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material to be degraded as claimed in claim 4 in an acidic organic solvent, and degrading it at normal pressure and 25-90° C. for 1-2 hours to obtain a carbon fiber cloth and a degradation liquid; 2) drying the carbon fiber cloth obtained in step 1) at 60° C.-80° C. for 1 h-3 h to obtain a recycled carbon fiber cloth; 3) The degradation liquid obtained in step 1) and a 35%-40% formaldehyde aqueous solution are mixed and coated on the surface of the regenerated carbon fiber cloth obtained in step 2) to obtain a regenerated carbon fiber cloth prepreg; 8-12 layers of the regenerated carbon fiber cloth prepreg are neatly stacked and placed in a flat vulcanizer and hot-pressed for 1-2 hours at 80-100° C. and 5-20 MPa to obtain a regenerated carbon fiber composite material.

6. The degradation recycling method according to claim 5, characterized in that: In step 1), the concentration of the acidic organic solution is between 0.1-1.0 mol / L, the acid is one or more of formic acid, phosphoric acid or acetic acid, and the solvent is one of dichloromethane, ethyl acetate, dioxane, and N,N-dimethylformamide; the mass ratio of the carbon fiber composite material to the acidic solution is 1:(2-5); In step 3), the mass ratio of the degradation liquid, 35%-40% formaldehyde aqueous solution and the regenerated carbon fiber cloth is (3-5):(1.6-1.8):

1.

7. A degradation and recycling method for a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material, characterized in that: The following steps are involved: 1) placing the hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material to be degraded as described in claim 4 in an organic solvent of the terminal thiol hyperbranched polyester as described in claim 1, degrading for 1-12 hours under normal pressure and temperature conditions, and separating the carbon fiber cloth and the degradation liquid; 2) rinsing and drying the carbon fiber cloth separated in step 1) to obtain a regenerated carbon fiber cloth; 3) The recycled terminal mercapto hyperbranched polyester and isocyanate monomer are mixed and coated on the surface of the above-mentioned recycled carbon fiber cloth to obtain a recycled carbon fiber cloth prepreg; 8-12 layers of recycled carbon fiber cloth prepreg are neatly stacked and placed in a flat vulcanizer for hot pressing and curing at 80-100° C. and 5-20 MPa for 1-2 hours to obtain a recycled carbon fiber composite material.

8. The degradation recycling method according to claim 7, characterized in that: The organic solvent in step 1) is one or more of acetone, N'N-dimethylformamide, 1,4-dioxane, tetrahydrofuran, chloroform or ethyl acetate; the terminal mercapto hyperbranched polyester is one or more of two with different numbers of terminal groups; the mass ratio of the carbon fiber composite material, the terminal mercapto hyperbranched polyester and the organic solvent is 1:18:(30-45); In step 3), the stoichiometric ratio of the isocyanate to the thiol functional group concentration in the terminal mercapto hyperbranched polyester is r<0.5; the isocyanate monomers are mixed to form a diisocyanate compound; and the mass ratio of the recovered terminal mercapto hyperbranched polyester, the isocyanate monomer and the recycled carbon fiber cloth is (1.5-1.7):(0.8-1):

5.

9. A degradation and recycling method for a hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material, characterized in that: The following steps are involved: 1) placing the hyperbranched polymer dynamically cross-linked degradable carbon fiber composite material to be degraded as claimed in claim 4 in a mixed solution of 16wt%-27wt% alcohol and an organic solvent, degrading at room temperature and pressure for 1-12h, and separating the carbon fiber cloth from the degradation solution; 2) drying the carbon fiber cloth separated in step 1) at 70° C.-80° C. for 2 h-4 h to obtain a regenerated carbon fiber cloth; 3) The recycled terminal mercapto hyperbranched polyester and isocyanate monomer are mixed and coated on the surface of the above-mentioned recycled carbon fiber cloth to obtain a recycled carbon fiber cloth prepreg; 8-12 layers of recycled carbon fiber cloth prepreg are neatly stacked and placed in a flat vulcanizer and hot-pressed and cured at 80-100° C. and 5-20 MPa for 1-2 hours to obtain a recycled carbon fiber composite material.

10. The degradation recycling method according to claim 9, characterized in that: The alcohol used in step 1) is methanol; the organic solvent is one of dichloromethane and N,N-dimethylformamide; the mass ratio of the mixed solvent of the carbon fiber composite material and the alcohol is 1:(93-156); The isocyanate monomer used in step 3) is one of toluene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate; the stoichiometric ratio of the isocyanate to the thiol functional group concentration in the terminal mercapto hyperbranched polyester is r<0.5; the isocyanate monomers are mixed to form a dibasic isocyanate compound; the mass ratio of the recovered terminal mercapto hyperbranched polyester, the isocyanate monomer and the recycled carbon fiber cloth is (2-3):(1.4-2):5.

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