Bio-based epoxy resin composite material and preparation method thereof

Abstract

The invention discloses a bio-based epoxy resin composite material and a preparation method thereof. The bio-based epoxy resin composite material is prepared from the following raw materials in parts by weight: 20 to 35 parts of epoxidized soybean oil, 25 to 37 parts of modified cellulose, 15 to 25 parts of polybasic organic acid, 10 to 23 parts of nucleophilic reagent, 5 to 8 parts of polyhydric alcohol and 0.1 to 1 part of curing accelerator, the modified cellulose is modified cellulose with carboxyl on the surface; the nucleophilic reagent is an aryl-containing nucleophilic reagent and contains at least two nucleophilic groups, and the nucleophilic groups are hydroxyl and / or carboxyl. The bio-based epoxy resin composite material disclosed by the invention has good mechanical strength and relatively high tensile strength, Young modulus and glass transition temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of materials, in particular to a composite material, and in particular to a bio-based epoxy resin composite material and a preparation method thereof. Background Art

[0002] In recent years, epoxy resins have been widely used in the industry for coatings, adhesives, electronic packaging materials or the automotive, aerospace or transportation industries due to their unique thermal stability, mechanical strength, creep resistance, electrical insulation and chemical resistance. However, most epoxy thermosetting materials are currently made from non-renewable petrochemical raw materials, bisphenol A diglycidyl ether (DGEBA), most of which are not ductile due to their permanent cross-linked structure and are difficult to reprocess or recycle, resulting in waste and environmental pollution. In addition, the raw materials bisphenol A and epichlorohydrin used in the production of epoxy resins are highly toxic, and the production process has high environmental protection requirements.

[0003] Epoxidized soybean oil is widely used in thermosetting resin plasticization due to its advantages such as environmental friendliness, high yield, high transparency, and good chemical stability. It has attracted the attention of academia and industry and is expected to be used as a bio-based resin to replace or partially replace petrochemical epoxy resins. However, epoxidized soybean oil currently has the following problems: (1) The epoxy groups in epoxidized soybean oil are located in the middle of the branch chain rather than at the end, which results in large steric hindrance and poor group activity; (2) After curing, the epoxidized soybean oil molecules have low mechanical strength and low glass transition temperature. The above problems restrict the application of epoxidized soybean oil in biomass thermosetting resins. It is still challenging to obtain biomass resins with good mechanical properties.

[0004] Therefore, the preparation of an environmentally friendly and renewable biomass epoxy resin composite material with good mechanical properties is of great significance to both academic exploration and industrial production. Summary of the invention

[0005] Based on this, the object of the present invention is to provide a biomass epoxy resin composite material with good mechanical properties.

[0006] In order to achieve the above object, the present invention includes the following technical solutions.

[0007] In a first aspect, the present invention provides a bio-based epoxy resin composite material, which is prepared from raw materials including the following components in parts by weight:

[0008]

[0009] The modified cellulose is a modified cellulose with carboxyl groups on the surface;

[0010] The nucleophilic agent is an aromatic nucleophilic agent containing at least two nucleophilic groups, wherein the nucleophilic groups are hydroxyl groups and / or carboxyl groups.

[0011] The modified cellulose is obtained by oxidizing purified plant fibers; for example, the modified cellulose can be obtained by grinding, pulverizing, bleaching, purifying plant fibers, and then TEMPO oxidation.

[0012] The plant fiber can be selected from plant fibers such as sugarcane fiber, wheat straw fiber, wood fiber, cotton fiber, etc., preferably wheat straw fiber.

[0013] In a second aspect, the present invention provides a method for preparing the bio-based epoxy resin composite material, comprising the following steps:

[0014] (1) In an inert gas atmosphere, the epoxy soybean oil, modified cellulose, polybasic organic acid, nucleophilic reagent, polyol and solvent are reacted at 70° C. to 85° C. for 1 to 2 hours, the temperature is kept constant, the curing accelerator is added, and the reaction is continued for 0.5 to 1 hour under vacuum to obtain a pre-cured product;

[0015] (2) Compression molding the precured material at a temperature of 100° C. to 130° C. and a pressure of 0.5 MPa to 2.5 MPa to obtain the bio-based epoxy resin composite material.

[0016] The present invention has the following beneficial effects:

[0017] The present invention uses epoxy soybean oil and modified cellulose with carboxyl groups on the surface as a matrix material, and adds components such as polybasic organic acid, a nucleophilic reagent containing multiple hydroxyl groups and / or carboxyl groups and aromatic groups, and polyols to prepare a biomass epoxy resin composite material with high strength and good mechanical properties.

[0018] Among them, the amphiphilicity of modified cellulose and polyol improves the compatibility of nucleophiles with epoxidized soybean oil; modified cellulose as a nanofiller can enhance the bulk strength of the composite material, and the reaction of the carboxyl group on cellulose with the epoxy group can improve the crosslinking degree of the system; both ends of the nucleophile have phenolic hydroxyl or carboxyl groups, which can participate in the reaction during the curing process of epoxy resin, and the introduction of aromatic groups can further improve the strength of the composite material. The synergistic combination of modified cellulose, nucleophiles and polyacids can significantly improve the mechanical strength of epoxidized soybean oil glass, give the composite material excellent rigidity, and improve its tensile strength, Young's modulus and glass transition temperature. In addition, the components in the system interact through hydrogen bonds or dynamic covalent bonds such as ester groups to increase the crosslinking degree of the crosslinked network of the composite material, thereby achieving toughening and making the resulting composite material have good toughness.

[0019] The raw materials of the bio-based epoxy resin composite material prepared by the present invention are all biomass materials, which are simple and easy to obtain, low in cost, high in yield, green and environmentally friendly, and recyclable. The preparation process is simple to operate, high in yield, does not generate pollutants, and has low energy consumption. The material is safe and non-toxic, has no volatile VOCs components, has good biocompatibility, and can realize the reuse of waste biomass materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of the bio-based epoxy resin composite material of the present invention.

[0021] Figure 2 This is the FT-IR spectrum of the bio-based epoxy resin composite material prepared in Example 1. DETAILED DESCRIPTION

[0022] The technical scheme of the present invention is further illustrated by specific examples below. Those skilled in the art should understand that the examples are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0023] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0024] The terms "including" and "having" and any variations thereof of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, device, product or equipment comprising a series of steps is not limited to the listed steps or modules, but may optionally include steps not listed, or may optionally include other steps inherent to these processes, methods, products or equipment.

[0025] In the present invention, the term "multiple" refers to two or more than two. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0026] Some embodiments of the present invention relate to a bio-based epoxy resin composite material, which is prepared from raw materials including the following components in parts by weight:

[0027]

[0028] The modified cellulose is a modified cellulose with carboxyl groups on the surface;

[0029] The nucleophilic agent is an aromatic nucleophilic agent containing at least two nucleophilic groups, wherein the nucleophilic groups are hydroxyl groups and / or carboxyl groups.

[0030] In some of the embodiments, the bio-based epoxy resin composite material is prepared from raw materials including the following components in parts by weight:

[0031]

[0032] In some embodiments, the modified cellulose is obtained by oxidizing purified plant fibers; for example, the modified cellulose is obtained by TEMPO oxidation of plant fibers after grinding, bleaching and purification.

[0033] In the present invention, the plant fiber can be selected from plant fibers such as sugarcane fiber, wheat straw fiber, wood fiber and cotton fiber.

[0034] In some embodiments, the plant fiber is wheat straw fiber.

[0035] In some embodiments, the method for preparing the modified cellulose comprises the following steps:

[0036] (1) Extraction and purification of cellulose: Plant fiber powder is treated with urea and (NH4)2SO3, and then treated with H2O2 under alkaline conditions to obtain bleached and purified cellulose;

[0037] (2) Oxidation of cellulose: In the presence of 2,2,6,6-tetramethylpiperidinyl oxide and NaBr, the bleached and purified cellulose is oxidized with NaClO under alkaline conditions to obtain the modified cellulose.

[0038] In some embodiments, the method for preparing the modified cellulose comprises the following steps:

[0039] (1) Extraction and purification of cellulose: plant fiber powder, urea and (NH4)2SO3 are added to water, soaked for 4 h to 6 h, reacted at 150°C to 170°C for 0.5 h to 2 h, cooled to room temperature, filtered, washed, and crude cellulose is obtained; the crude cellulose is dispersed in water, NaOH and H2O2 solutions are added, reacted at 70°C to 90°C for 1 h to 3 h, filtered, washed, and bleached and purified cellulose is obtained;

[0040] (2) Oxidation of cellulose: The bleached and purified cellulose is dispersed in water to obtain a cellulose suspension, 2,2,6,6-tetramethylpiperidinyl oxide and NaBr are added, and after mixing evenly, an aqueous NaClO solution is added. The mixture is stirred for 4 h to 6 h at a pH of 9 to 11, and ethanol is added to the reaction solution to obtain an oxidized cellulose precipitate. The precipitate is centrifuged, washed, and dried to obtain the modified cellulose.

[0041] In some embodiments, the method for preparing the modified cellulose comprises the following steps:

[0042] (1) Extraction and purification of cellulose: plant fiber powder, urea and (NH4)2SO3 are added to water, soaked for 4.5 h to 5.5 h, reacted at 155°C to 165°C for 0.8 h to 1.2 h, cooled to room temperature, filtered, washed, and crude cellulose is obtained; the crude cellulose is dispersed in water, NaOH and H2O2 solutions are added, reacted at 75°C to 85°C for 1.5 h to 2.5 h, filtered, washed, and bleached and purified cellulose is obtained;

[0043] (2) Oxidation of cellulose: The bleached and purified cellulose is dispersed in water to obtain a cellulose suspension, 2,2,6,6-tetramethylpiperidinyl oxide and NaBr are added, and after mixing evenly, an aqueous NaClO solution is added. The mixture is stirred at a pH of 10 for 4.5 h to 5.5 h, and ethanol is added to the reaction solution to obtain an oxidized cellulose precipitate. The precipitate is centrifuged, washed, and dried to obtain the modified cellulose.

[0044] In some embodiments, the plant fiber powder has a mesh size of 80-120.

[0045] In some of the embodiments, the mass ratio of the plant fiber powder, urea and (NH4)2SO3 is 100:5-7:18-22.

[0046] In some of the embodiments, the ratio of the plant fiber powder to the water is 180g-220g:1L.

[0047] In some of the embodiments, the ratio of the crude cellulose, water, NaOH and H2O2 solution is 1 g: 3 mL~5 mL: 0.03 g~0.05 g: 0.3 mL~0.5 mL.

[0048] In some embodiments, the mass fraction of the H2O2 solution is 25-40%, preferably 28-35%.

[0049] In some embodiments, the mass fraction of the cellulose suspension is 3-5%.

[0050] In some of the embodiments, the ratio of the cellulose suspension, 2,2,6,6-tetramethylpiperidinyl oxide, NaBr and NaClO aqueous solution is 1L: 0.6g-0.7g: 3g-5g: 110mL-130mL.

[0051] In some embodiments, the mass fraction of the NaClO aqueous solution is 8-12%.

[0052] In some embodiments, the polybasic organic acid is selected from at least one of oxalic acid, citric acid, malic acid, tartaric acid, maleic acid, fumaric acid, phthalic acid, and terephthalic acid, preferably citric acid and / or malic acid, and more preferably citric acid.

[0053] In some embodiments, the nucleophilic reagent is selected from at least one of catechol, hydroquinone, phthalic acid and terephthalic acid; or the nucleophilic reagent is obtained by reacting p-aminophenol with a nucleophilic organic acid, the nucleophilic organic acid is an organic acid containing an aromatic group, the nucleophilic organic acid contains at least two nucleophilic groups, the nucleophilic groups are hydroxyl groups and / or carboxyl groups, and at least one nucleophilic group in the nucleophilic organic acid is a carboxyl group.

[0054] In some embodiments, the nucleophilic organic acid is selected from at least one of salicylic acid, p-hydroxybenzoic acid, L-tyrosine, gallic acid, phthalic acid, and terephthalic acid, more preferably p-hydroxybenzoic acid, gallic acid, or terephthalic acid, and more preferably gallic acid.

[0055] In some embodiments, the molar ratio of p-aminophenol to nucleophilic organic acid is 1:1-1.3.

[0056] In some embodiments, the nucleophilic reagent is obtained by reacting p-aminophenol with a nucleophilic organic acid, and the preparation method thereof comprises the following steps:

[0057] The p-aminophenol reacts with the nucleophilic organic acid under the catalysis of 4-dimethylaminopyridine to obtain the product.

[0058] In some embodiments, the reaction is carried out in an organic solvent, and the organic solvent is preferably acetonitrile.

[0059] In some embodiments, the molar ratio of the p-aminophenol to the 4-dimethylaminopyridine is 1:0.04-0.06.

[0060] In some of the embodiments, the reaction temperature is 35° C. to 45° C., and the reaction time is 6 h to 10 h.

[0061] In some embodiments, the reaction is carried out under an inert gas atmosphere.

[0062] In some embodiments, the polyol is selected from at least one of ethylene glycol, propylene glycol, glycerol, diethylene glycol, triethylene glycol, sorbitol, xylitol and pentaerythritol, preferably ethylene glycol or glycerol, more preferably ethylene glycol.

[0063] In some embodiments, the curing accelerator is selected from at least one of imidazole derivatives, hexadecyltrimethylammonium bromide, and DMP-30, preferably an imidazole derivative, and more preferably 1,2-dimethylimidazole.

[0064] Some embodiments of the present invention also involve a method for manufacturing the bio-based epoxy resin composite material, comprising the following steps:

[0065] (1) reacting the epoxidized soybean oil, modified cellulose, polybasic organic acid, nucleophilic reagent, polyol and solvent at 70° C. to 85° C. for 1 to 2 hours under an inert gas atmosphere, keeping the temperature constant, adding the curing accelerator, removing the solvent by vacuum, and continuing the reaction for 0.5 to 1 hour to obtain a precured product;

[0066] (2) Compression molding the precured material at a temperature of 100° C. to 130° C. and a pressure of 0.5 MPa to 2.5 MPa to obtain the bio-based epoxy resin composite material.

[0067] In some embodiments, the solvent is selected from at least one of water, 1,4-dioxane, ethyl acetate, tetrahydrofuran, methanol, ethanol, acetonitrile and tetrahydrofuran, preferably ethanol.

[0068] In some embodiments, the weight portion of the solvent is preferably 2 to 4 parts, more preferably 3 to 4 parts.

[0069] In some embodiments, the compression molding time is 0.5 to 6 hours, preferably 0.8 to 2 hours.

[0070] In some embodiments, the temperature in step (2) is 105° C. to 115° C., and the pressure is 0.8 MPa to 1.5 MPa.

[0071] The following are specific embodiments.

[0072] The experimental environment temperature in the following examples is 25° C. and the relative humidity is 50% RH. There is no special restriction on the raw materials used, and they are all commercially available products unless otherwise specified.

[0073] In the following Examples 1-11 and Comparative Examples 2-3, the preparation method of the modified cellulose used is as follows:

[0074] (1) Extraction and purification of cellulose: After drying the wheat straw fiber in a vacuum drying oven, cut it into pieces, grind it mechanically, and sieve it to obtain a 100-mesh fiber powder. Take 200g of the sieved fiber powder, 12g (200mmol) urea, and 40g (400mmol) (NH4)2SO3 and add them to 1L deionized water, soak for 5h, then put it into a high-pressure reactor, react at 160℃ for 1h, cool to room temperature, filter, and wash to obtain crude cellulose; disperse 50g of crude cellulose in 200mL deionized water, add 2g (500mmol) NaOH and 20mL of 30% H2O2 solution, and react at 80℃ for 2h. Filter and wash to obtain bleached and purified cellulose.

[0075] (2) Preparation of modified cellulose: Take the bleached and purified cellulose and add it to water. Use a high-speed disperser to disperse it at 1500 rpm for 10 minutes to obtain a 4% cellulose suspension. Add 0.64g (4mmol) 2,2,6,6-tetramethylpiperidinoxide (TEMPO) and 4g (40mmol) NaBr to 1L of 4% cellulose suspension. After mixing evenly, slowly add 120mL of 10% NaClO aqueous solution. Use Na2CO3 / NaHCO3 buffer to adjust pH to 10 and stir at room temperature for 5h. Add 200mL of ethanol to the reaction solution to obtain oxidized cellulose precipitation. Centrifuge the precipitation, wash it with 75% ethanol, and vacuum dry it at room temperature to obtain modified cellulose with carboxyl groups on the surface.

[0076] Example 1

[0077] 1. Preparation of nucleophilic reagents:

[0078] 21.8 g (200 mmol) of p-aminophenol was dissolved in 100 mL of acetonitrile, and 30.4 g (220 mmol) of p-hydroxybenzoic acid was added. The mixture was stirred at 40°C for 15 min under nitrogen until the solution was uniformly mixed. 1.22 g (10 mmol) of 4-dimethylaminopyridine catalyst was added, and the mixture was reacted at 40°C for 8 h. 100 mL of deionized water was added to obtain a precipitate, which was filtered and washed with deionized water, recrystallized with ethanol, and dried to obtain the nucleophilic reagent AP-HA.

[0079] 2. Preparation of bio-based epoxy resin composites:

[0080] (1) Using a one-pot method, 37 g of epoxidized soybean oil, 30 g of modified cellulose, 14 g of citric acid, 13 g of nucleophilic reagent AP-HA, 2 g of glycerol, and 3.8 g of ethanol were added under a nitrogen atmosphere, and a high-speed disperser was used to react at a dispersion rate of 2500 rpm at 80°C for 1 h. The temperature was kept constant, and 0.2 g of 1,2-dimethylimidazole was added. After stirring for 5 min until 1,2-dimethylimidazole was fully dissolved, the solvent was removed by vacuum (-0.09 MPa), and the reaction was continued for 1 h. After degassing, a pre-cured material was obtained.

[0081] (2) Transfer the pre-cured material to a polytetrafluoroethylene mold (100×100×0.5mm 3 ) and compression molded at 110 °C and a pressure of 1.0 MPa for 1 h to obtain a bio-based epoxy resin composite material.

[0082] The FT-IR spectrum of the bio-based epoxy resin composite material prepared in this example is as follows: Figure 1 Shown: 1740 and 1680cm -1 The absorption peaks of ester and amide groups are 1226 and 1154 cm, respectively, representing the participation of carboxyl groups in epoxy ring opening and the introduction of nucleophilic reagent AP-HA. -1 The ether bond absorption peak at 1085cm further indicates that organic acid and nucleophilic reagent participate in the curing of epoxidized soybean oil system. -1 It is the absorption peak of cellulose glycosidic bond, representing the introduction of cellulose.

[0083] Example 2

[0084] 1. Preparation of nucleophilic reagents:

[0085] The steps are the same as those in Example 1, except that the organic acid added is 37.4 g (220 mmol) of gallic acid, and the other raw materials and preparation method are the same as those in Example 1, to obtain a nucleophilic reagent AP-GA.

[0086] 2. Preparation of bio-based epoxy resin composites:

[0087] The preparation method is the same as that of Example 1, and the raw materials are as follows: 37 g of epoxidized soybean oil, 30 g of modified cellulose, 14 g of citric acid, 13 g of nucleophilic reagent AP-GA, 2 g of glycerol, 3.8 g of ethanol and 0.2 g of 1,2-dimethylimidazole.

[0088] Example 3

[0089] 1. Preparation of nucleophilic reagents:

[0090] The steps are the same as those in Example 1, except that the organic acid added is 14.9 g (90 mmol) of terephthalic acid, and the other raw materials and preparation method are the same as those in Example 1, to obtain a nucleophilic reagent 2AP-PA.

[0091] 2. Preparation of bio-based epoxy resin composites:

[0092] The preparation method is the same as that of Example 1, and the raw materials are as follows: 37 g of epoxidized soybean oil, 30 g of modified cellulose, 14 g of citric acid, 13 g of nucleophilic reagent 2AP-PA, 2 g of glycerol, 3.8 g of ethanol and 0.2 g of 1,2-dimethylimidazole.

[0093] Example 4

[0094] The preparation methods of the nucleophilic reagent and the bio-based epoxy resin composite material provided in this embodiment are the same as those in Example 1.

[0095] The raw materials for preparing the bio-based epoxy resin composite material are different from those in Example 1 in that the citric acid in Example 1 is replaced by an equal amount of malic acid, specifically as follows: 37 g of epoxidized soybean oil, 30 g of modified cellulose, 14 g of malic acid, 13 g of nucleophilic reagent AP-HA, 2 g of glycerol, 3.8 g of ethanol and 0.2 g of 1,2-dimethylimidazole.

[0096] Example 5

[0097] The preparation methods of the nucleophilic reagent and the bio-based epoxy resin composite material provided in this embodiment are the same as those in Example 2.

[0098] The raw materials for preparing the bio-based epoxy resin composite material are different from those in Example 2 in that the citric acid in Example 2 is replaced by an equal amount of malic acid, specifically as follows: 37 g of epoxidized soybean oil, 30 g of modified cellulose, 14 g of malic acid, 13 g of nucleophilic reagent AP-GA, 2 g of glycerol, 3.8 g of ethanol and 0.2 g of 1,2-dimethylimidazole.

[0099] Example 6

[0100] The preparation methods of the nucleophilic reagent and the bio-based epoxy resin composite material provided in this embodiment are the same as those in Example 3.

[0101] The raw materials for preparing the bio-based epoxy resin composite material are different from those in Example 3 in that the citric acid in Example 3 is replaced by an equal amount of malic acid, specifically as follows: 37 g of epoxidized soybean oil, 30 g of modified cellulose, 14 g of malic acid, 13 g of nucleophilic reagent 2AP-PA, 2 g of glycerol, 3.8 g of ethanol and 0.2 g of 1,2-dimethylimidazole.

[0102] Example 7

[0103] The preparation methods of the nucleophilic reagent and the bio-based epoxy resin composite material provided in this embodiment are the same as those in Example 1.

[0104] The raw materials for preparing the bio-based epoxy resin composite material are different from those in Example 1 in that the glycerol in Example 1 is replaced by an equal amount of ethylene glycol, specifically as follows: 37 g of epoxidized soybean oil, 30 g of modified cellulose, 14 g of citric acid, 13 g of nucleophilic reagent AP-HA, 2 g of ethylene glycol, 3.8 g of ethanol and 0.2 g of 1,2-dimethylimidazole.

[0105] Example 8

[0106] The preparation methods of the nucleophilic reagent and the bio-based epoxy resin composite material provided in this embodiment are the same as those in Example 2.

[0107] The raw material preparation of the bio-based epoxy resin composite material is different from that of Example 2 in that the glycerol in Example 2 is replaced by an equal amount of ethylene glycol, specifically as follows: 37 g of epoxidized soybean oil, 30 g of modified cellulose, 14 g of citric acid, 13 g of nucleophilic reagent AP-GA, 2 g of ethylene glycol, 3.8 g of ethanol and 0.2 g of 1,2-dimethylimidazole.

[0108] Example 9

[0109] The preparation methods of the nucleophilic reagent and the bio-based epoxy resin composite material provided in this embodiment are the same as those in Example 3.

[0110] The raw materials for preparing the bio-based epoxy resin composite material are different from those in Example 3 in that the glycerol in Example 3 is replaced by an equal amount of ethylene glycol, specifically as follows: 37 g of epoxidized soybean oil, 30 g of modified cellulose, 14 g of citric acid, 13 g of nucleophilic reagent 2AP-PA, 2 g of ethylene glycol, 3.8 g of ethanol and 0.2 g of 1,2-dimethylimidazole.

[0111] Example 10

[0112] The preparation method of the bio-based epoxy resin composite material provided in this embodiment is the same as that in Example 1. The difference between the preparation raw materials and those in Example 1 is that the nucleophilic reagent AP-HA in Example 1 is replaced by hydroquinone, which is as follows: 37 g of epoxidized soybean oil, 30 g of modified cellulose, 14 g of citric acid, 13 g of hydroquinone, 2 g of glycerol, 3.8 g of ethanol and 0.2 g of 1,2-dimethylimidazole.

[0113] Embodiment 11

[0114] The preparation method of the bio-based epoxy resin composite material provided in this embodiment is the same as that in Example 1. The difference between the preparation raw materials and those in Example 1 is that terephthalic acid is used to replace the nucleophilic reagent AP-HA in Example 1, specifically as follows: 37 g of epoxy soybean oil, 30 g of modified cellulose, 14 g of citric acid, 13 g of terephthalic acid, 2 g of glycerol, 3.8 g of ethanol and 0.2 g of 1,2-dimethylimidazole.

[0115] Comparative Example 1

[0116] The preparation method of the bio-based epoxy resin composite material provided in this comparative example is the same as that in Example 1. The difference between the preparation raw materials and those in Example 1 is that no modified cellulose is added, which are as follows: 54 g of epoxy soybean oil, 21 g of citric acid, 19 g of AP-HA, 2 g of glycerol, 3.8 g of ethanol and 0.2 g of 1,2-dimethylimidazole.

[0117] Comparative Example 2

[0118] The preparation method of the bio-based epoxy resin composite material provided in this comparative example is the same as that in Example 1. The difference between the preparation raw materials and those in Example 1 is that no nucleophilic reagent AP-HA is added, which is as follows: 37 g of epoxy soybean oil, 30 g of modified cellulose, 27 g of citric acid, 2 g of glycerol, 3.8 g of ethanol and 0.2 g of 1,2-dimethylimidazole.

[0119] Comparative Example 3

[0120] The preparation method of the bio-based epoxy resin composite material provided in this comparative example is the same as that in Example 1. The difference between the preparation raw materials and those in Example 1 is that no citric acid is added, which are as follows: 37 g of epoxy soybean oil, 30 g of modified cellulose, 27 g of AP-HA, 2 g of glycerol, 3.8 g of ethanol and 0.2 g of 1,2-dimethylimidazole.

[0121] Comparative Example 4

[0122] The preparation method of the bio-based epoxy resin composite material provided in this comparative example is the same as that in Example 1. The difference between the preparation raw materials and those in Example 1 is that the cellulose used is different, specifically as follows: 37 g of epoxy soybean oil, 30 g of cellulose, 14 g of citric acid, 13 g of nucleophilic reagent AP-HA, 2 g of glycerol, 3.8 g of ethanol and 0.2 g of 1,2-dimethylimidazole.

[0123] Wherein, the preparation method of cellulose is as follows:

[0124] The wheat straw fiber was dried in a vacuum drying oven, cut into pieces, mechanically ground and sieved to obtain 100 mesh fiber powder. 200g of the sieved fiber powder, 12g (200mmol) urea, 40g (400mmol) (NH4)2SO3 were added to 1L deionized water, soaked for 5h, then placed in a high-pressure reactor, reacted at 160℃ for 1h, cooled to room temperature, filtered, washed, and crude cellulose was obtained; 50g of crude cellulose was dispersed in 200mL deionized water, 2g (500mmol) NaOH and 20mL of 30% H2O2 solution were added, and reacted at 80℃ for 2h. Filtered and washed to obtain bleached and purified cellulose.

[0125] The bio-based epoxy resin composite materials prepared in Examples 1-11 and Comparative Examples 1-4 were subjected to the following performance tests:

[0126] Tensile strength: Tested according to the method specified in "GB / T 528-2009, Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber".

[0127] Elongation at break: Tested according to the method specified in "GB / T 528-2009, Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber".

[0128] Young's modulus: tested according to the method specified in "GB / T 1447-2005, Test method for tensile properties of fiber reinforced plastics".

[0129] Glass transition temperature: The glass transition temperature is measured by thermomechanical analysis (TMA) in a temperature range of 25 to 200°C, at a heating rate of 5°C / min, and at the temperature point at the half-height of the glass transition process.

[0130] The test results are shown in Table 1 below:

[0131] Table 1. Performance test results of bio-based epoxy resin composites

[0132]

[0133]

[0134] It can be seen from the data in Table 1 that the present invention can endow the epoxidized soybean oil bio-based epoxy resin with ideal mechanical properties through the synergistic combination of polybasic organic acid, specific nucleophilic reagent and modified cellulose, so that it has higher tensile strength, Young's modulus and glass transition temperature.

[0135] Comparative Example 1 did not add modified cellulose, Comparative Example 2 did not add nucleophilic reagents, and Comparative Example 3 did not add polybasic organic acids, resulting in a significant decrease in the tensile strength, modulus and glass transition temperature of the obtained bio-based epoxy resin composite material. It can be seen that polybasic organic acids, nucleophilic reagents and modified cellulose are indispensable and have the effect of synergistically improving the mechanical strength of bio-based epoxy resin composite materials. Among them, organic acids affect the curing of the epoxidized soybean oil system and have the greatest impact on the performance of the composite material.

[0136] Although the unoxidized cellulose added in Comparative Example 4 can also enhance the strength of the composite material, the effect is obviously not as good as that of the oxidized modified cellulose.

[0137] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0138] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A bio-based epoxy resin composite material, characterized in that: The composition is prepared from the following raw materials in parts by weight: The modified cellulose is a modified cellulose with carboxyl groups on the surface; The nucleophilic agent is an aromatic nucleophilic agent containing at least two nucleophilic groups, wherein the nucleophilic groups are hydroxyl groups and / or carboxyl groups.

2. The bio-based epoxy resin composite material according to claim 1, characterized in that: The composition is prepared from the following raw materials in parts by weight:

3. The bio-based epoxy resin composite material according to claim 1 or 2, characterized in that: The modified cellulose is obtained by purifying plant fibers and then oxidizing them; Preferably, the modified cellulose is prepared by TEMPO oxidation method after grinding, bleaching and purification of plant fibers; Preferably, the plant fiber is selected from sugarcane fiber, wheat straw fiber, wood fiber, cotton fiber, preferably wheat straw fiber.

4. The bio-based epoxy resin composite material according to claim 3, characterized in that: The preparation method of the modified cellulose comprises the following steps: (1) Extraction and purification of cellulose: Plant fiber powder is treated with urea and (NH4)2SO3, and then treated with H2O2 under alkaline conditions to obtain bleached and purified cellulose; (2) cellulose oxidation: oxidizing the bleached and purified cellulose with NaClO under alkaline conditions in the presence of 2,2,6,6-tetramethylpiperidinyl oxide and NaBr to obtain the modified cellulose; Preferably, the method for preparing the modified cellulose comprises the following steps: (1) Extraction and purification of cellulose: plant fiber powder, urea and (NH4)2SO3 are added to water, soaked for 4 h to 6 h, reacted at 150°C to 170°C for 0.5 h to 2 h, cooled to room temperature, filtered, washed, and crude cellulose is obtained; the crude cellulose is dispersed in water, NaOH and H2O2 solutions are added, reacted at 70°C to 90°C for 1 h to 3 h, filtered, washed, and bleached and purified cellulose is obtained; (2) Oxidation of cellulose: The bleached and purified cellulose is dispersed in water to obtain a cellulose suspension, 2,2,6,6-tetramethylpiperidinyl oxide and NaBr are added, and after mixing evenly, an aqueous NaClO solution is added. The mixture is stirred for 4 h to 6 h at a pH of 9 to 11, and ethanol is added to the reaction solution to obtain an oxidized cellulose precipitate. The precipitate is centrifuged, washed, and dried to obtain the modified cellulose.

5. The bio-based epoxy resin composite material according to claim 4, characterized in that: The mesh size of the plant fiber powder is 80 to 120 meshes; and / or, the mass ratio of the plant fiber powder, urea and (NH4)2SO3 is 100:5-7:18-22; And / or, the ratio of the plant fiber powder to the water is 180g-220g:1L; and / or, the ratio of the crude cellulose, water, NaOH and H2O2 solution is 1 g: 3 mL to 5 mL: 0.03 g to 0.05 g: 0.3 mL to 0.5 mL; And / or, the mass fraction of the H2O2 solution is 25-40%; And / or, the mass fraction of the cellulose suspension is 3-5%; and / or, the ratio of the cellulose suspension, 2,2,6,6-tetramethylpiperidinyl oxide, NaBr and NaClO aqueous solution is 1L: 0.6g-0.7g: 3g-5g: 110mL-130mL; And / or, the mass fraction of the NaClO aqueous solution is 8-12%.

6. The bio-based epoxy resin composite material according to claim 1 or 2, characterized in that: The polybasic organic acid is selected from at least one of oxalic acid, citric acid, malic acid, tartaric acid, maleic acid, fumaric acid, phthalic acid and terephthalic acid, preferably citric acid and / or malic acid.

7. The bio-based epoxy resin composite material according to claim 1 or 2, characterized in that: The nucleophile is selected from at least one of catechol, hydroquinone, phthalic acid and terephthalic acid; Alternatively, the nucleophilic reagent is obtained by reacting p-aminophenol with a nucleophilic organic acid, the nucleophilic organic acid is an organic acid containing an aromatic group, the nucleophilic organic acid contains at least two nucleophilic groups, the nucleophilic groups are hydroxyl groups and / or carboxyl groups, and at least one nucleophilic group in the nucleophilic organic acid is a carboxyl group; Preferably, the nucleophilic organic acid is selected from at least one of salicylic acid, p-hydroxybenzoic acid, L-tyrosine, gallic acid, phthalic acid, and terephthalic acid, more preferably p-hydroxybenzoic acid, gallic acid, or terephthalic acid; Preferably, the molar ratio of p-aminophenol to nucleophilic organic acid is 1:1 to 1.

3.

8. The bio-based epoxy resin composite material according to claim 7, characterized in that: The nucleophilic reagent is obtained by reacting p-aminophenol with a nucleophilic organic acid, and its preparation method comprises the following steps: The p-aminophenol reacts with the nucleophilic organic acid under the catalysis of 4-dimethylaminopyridine to obtain; Preferably, the reaction is carried out in an organic solvent, and the organic solvent is preferably acetonitrile; Preferably, the molar ratio of the p-aminophenol to the 4-dimethylaminopyridine is 1:0.04-0.06; Preferably, the reaction temperature is 35°C to 45°C, and the reaction time is 6h to 10h; Preferably, the reaction is carried out under an inert gas atmosphere.

9. The bio-based epoxy resin composite material according to claim 1 or 2, characterized in that: The polyol is at least one selected from ethylene glycol, propylene glycol, glycerol, diethylene glycol, triethylene glycol, sorbitol, xylitol and pentaerythritol, preferably ethylene glycol or glycerol; And / or, the curing accelerator is selected from at least one of imidazole derivatives, hexadecyltrimethylammonium bromide, and DMP-30, preferably an imidazole derivative, and more preferably 1,2-dimethylimidazole.

10. A method for preparing the bio-based epoxy resin composite material according to any one of claims 1 to 9, characterized in that: The steps include: (1) reacting the epoxidized soybean oil, modified cellulose, polybasic organic acid, nucleophilic reagent, polyol and solvent at 70° C. to 85° C. for 1 to 2 hours under an inert gas atmosphere, keeping the temperature constant, adding the curing accelerator, removing the solvent by vacuum, and continuing the reaction for 0.5 to 1 hour to obtain a precured product; (2) compressing the precured material at a temperature of 100° C. to 130° C. and a pressure of 0.5 MPa to 2.5 MPa to obtain the bio-based epoxy resin composite material; Preferably, the solvent is selected from at least one of water, 1,4-dioxane, ethyl acetate, tetrahydrofuran, methanol, ethanol, acetonitrile and tetrahydrofuran, preferably ethanol; Preferably, the weight portion of the solvent is preferably 2 to 4 parts; Preferably, the compression molding time is 0.5 to 6 hours, preferably 0.8 to 2 hours; Preferably, the temperature in step (2) is 105° C. to 115° C., and the pressure is 0.8 MPa to 1.5 MPa.

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