Bio-based epoxy resin composites and methods of making the same

Abstract

The application discloses a kind of bio-based epoxy resin composite and preparation method thereof.The bio-based epoxy resin composite includes the following components by weight parts and is prepared by raw materials: epoxy soybean oil 20-35 parts, modified cellulose 25-37 parts, polybasic organic acid 15-25 parts, nucleophilic reagent 10-23 parts, polyol 5-8 parts, curing accelerator 0.1-1 part;The modified cellulose is modified cellulose with carboxyl on the surface;The nucleophilic reagent is a nucleophilic reagent containing aryl group, which contains at least two nucleophilic groups, and the nucleophilic group is hydroxyl and / or carboxyl.The bio-based epoxy resin composite of the application has good mechanical strength, higher tensile strength, Young's modulus and glass transition temperature.

Description

TECHNICAL FIELD

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

[0002] In recent years, epoxy resin is widely used in industry for its unique thermal stability, mechanical strength, creep resistance, electrical insulation and chemical resistance in coatings, adhesives, electronic packaging materials or automotive, aerospace or transportation industries. However, most of the current epoxy thermosetting materials are prepared from non-renewable petrochemical raw materials bisphenol A diglycidyl ether (DGEBA), most of which do not have ductility due to permanent crosslinking structure, are difficult to reprocess or recycle, causing waste and environmental pollution. In addition, the raw materials for producing epoxy resin, bisphenol A and epichlorohydrin, are highly toxic, and the production process has high environmental requirements.

[0003] Epoxy soybean oil is widely used in thermosetting resin plasticization due to its environmental protection, renewable, high yield, high transparency and good chemical stability, and has attracted attention from academia and industry, and is expected to replace or partially replace petrochemical epoxy resin as a bio-based resin. However, the current epoxy soybean oil has the following problems: (1) the epoxy groups in the epoxy soybean oil are located in the middle of the branched chain rather than the end, and the steric hindrance is large, and the group activity is poor; (2) the mechanical strength of the cured epoxy soybean oil molecule is low, and the glass transition temperature is low. The above problems restrict the application of epoxy soybean oil in biomass thermosetting resin, and it is still challenging to obtain a biomass resin with good mechanical properties.

[0004] Therefore, it is of great significance to prepare a bio-based epoxy resin composite material with good mechanical properties and environmental protection for academic exploration and industrial production. SUMMARY

[0005] Based on this, the purpose of the present application is to provide a bio-based epoxy resin composite material with good mechanical properties.

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

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

[0008]

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

[0010] The nucleophile is a nucleophile containing aryl, which contains at least two nucleophilic groups, the nucleophilic groups being hydroxyl and / or carboxyl.

[0011] The modified cellulose is obtained by oxidation after purification of plant fibers; for example, it can be obtained by TEMPO oxidation after grinding, crushing, bleaching and purification of plant fibers.

[0012] The plant fibers can be selected from sugar cane fibers, wheat straw fibers, wood fibers, cotton fibers and the like, and preferably are wheat straw fibers.

[0013] In a second aspect, the application provides a preparation method of the bio-based epoxy resin composite material, comprising the following steps:

[0014] (1) under the atmosphere of inert gas, the epoxy soybean oil, modified cellulose, polybasic organic acid, nucleophile, polyol and solvent are reacted at 70-85℃ for 1-2h, the temperature is kept unchanged, the curing accelerator is added, vacuum is extracted and the reaction is continued for 0.5-1h to obtain a pre-cured product;

[0015] (2) the pre-cured product is compression molded at a temperature of 100-130℃ and a pressure of 0.5-2.5MPa to obtain the bio-based epoxy resin composite material.

[0016] The application has the following beneficial effects:

[0017] The application uses epoxy soybean oil and modified cellulose with carboxyl on the surface as matrix materials, and adds polybasic organic acid, nucleophile containing multiple hydroxyl and / or carboxyl and aryl, and polyol and other components to prepare a biomass epoxy resin composite material with high strength and good mechanical properties.

[0018] The amphiphilicity of the modified cellulose and polyol improves the compatibility of the nucleophile with the epoxy soybean oil; the modified cellulose as a nano filler can enhance the bulk strength of the composite material, the reaction of the carboxyl on the cellulose with the epoxy group can improve the crosslinking degree of the system; the nucleophile has phenolic hydroxyl or carboxyl at both ends, which can participate in the reaction in the epoxy resin curing process, and the introduction of aryl can further improve the strength of the composite material. The synergistic cooperation of the modified cellulose, nucleophile and polybasic acid and other components can significantly improve the mechanical strength of the epoxy soybean oil glassy product, endow the composite material with excellent rigidity, 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, so that the obtained composite material has good toughness.

[0019] The raw materials of the prepared bio-based epoxy resin composite material are all biomass materials, the raw materials are simple and easy to obtain, low in cost, large in yield, green and environmentally friendly, and the raw materials can be recycled. The preparation process is simple to operate, high in yield, free of pollutants, and low in energy consumption. The material is safe, non-toxic, free of volatile VOCs components, and good in biocompatibility, and the recycling of waste biomass materials can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 A structure diagram of the bio-based epoxy resin composite material of the present application.

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

[0022] The technical solutions of the present application will be further described below through specific examples. Those skilled in the art should understand that the examples are only for the purpose of understanding the present application and should not be regarded as specific limitations of the present application.

[0023] Unless otherwise defined, all technical and scientific terms used in the present application have the same meanings as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing specific examples and should not be used to limit the present application.

[0024] The terms "comprising" and "having" and any variations thereof in the present application are intended to cover non-exclusive inclusion. For example, a process, method, device, product or equipment comprising a series of steps is not limited to the listed steps or modules, but can optionally further comprise steps not listed, or can optionally further comprise other steps inherent to the process, method, product or equipment.

[0025] In the present application, "a plurality of" refers to two or more. "And / or", which describes the association relationship of the associated objects, means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. The character " / " generally represents that the associated objects before and after it are in an "or" relationship.

[0026] In some embodiments of the present application, a bio-based epoxy resin composite material is prepared from raw materials including the following components by weight:

[0027]

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

[0029] The nucleophile is an aryl-containing nucleophile, which contains at least two nucleophilic groups, the nucleophilic groups being hydroxyl and / or carboxyl.

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

[0031]

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

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

[0034] In some embodiments, the plant fibers are wheat straw fibers.

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

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

[0037] (2) Oxidation of cellulose: oxidizing the bleached and purified cellulose with NaClO under alkaline conditions in the presence of 2,2,6,6-tetramethylpiperidine oxide and NaBr 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: adding plant fiber powder, urea and (NH4)2SO3 into water, soaking for 4h-6h, reacting at 150℃-170℃ for 0.5h-2h, cooling to room temperature, filtering, washing to obtain crude cellulose; dispersing the crude cellulose in water, adding NaOH and H2O2 solution, reacting at 70℃-90℃ for 1h-3h, filtering, washing to obtain bleached and purified cellulose;

[0040] (2) Oxidation of cellulose: dispersing the bleached and purified cellulose in water to obtain a cellulose suspension, adding 2,2,6,6-tetramethylpiperidine oxide and NaBr, uniformly mixing, then adding NaClO aqueous solution under the condition of pH 9-11, stirring for 4h-6h, adding ethanol into the reaction solution to obtain oxidized cellulose precipitate, centrifuging, washing, drying 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 4.5h-5.5h, reacted at 155℃-165℃ for 0.8h-1.2h, cooled to room temperature, filtered, washed, and the crude cellulose is obtained; the crude cellulose is dispersed in water, NaOH and H2O2 solution are added, reacted at 75℃-85℃ for 1.5h-2.5h, filtered, washed, and the 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-tetramethylpiperidine oxide and NaBr are added, and after uniform mixing, an aqueous NaClO solution is added, stirred at pH 10 for 4.5h-5.5h, ethanol is added to the reaction solution to obtain an oxidized cellulose precipitate, 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 embodiments, the mass ratio of the plant fiber powder, urea and (NH4)2SO3 is 100:5-7:18-22.

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

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

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

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

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

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

[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, terephthalic acid, more preferably p-hydroxybenzoic acid, gallic acid or terephthalic acid, more preferably gallic acid.

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

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

[0057] The p-aminophenol is reacted with the nucleophilic organic acid under catalysis of 4-dimethylaminopyridine.

[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 embodiments, the reaction temperature is 35-45°C, and the reaction time is 6-10h.

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

[0062] In some embodiments, the polyhydric alcohol 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 derivative, cetyltrimethylammonium bromide, DMP-30, preferably imidazole derivative, more preferably 1,2-dimethylimidazole.

[0064] The application also relates to a method for preparing the bio-based epoxy resin composite material, comprising the following steps:

[0065] (1) reacting the epoxy soybean oil, modified cellulose, polybasic organic acid, nucleophile, polyhydric alcohol and solvent at 70-85°C for 1-2h under an inert gas atmosphere, keeping the temperature unchanged, adding the curing accelerator, removing the solvent by vacuum, and continuing to react for 0.5-1h to obtain a pre-cured product;

[0066] (2) compression molding the pre-cured product at a temperature of 100-130°C and a pressure of 0.5-2.5MPa 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 of the solvent is preferably 2-4 parts, more preferably 3-4 parts.

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

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

[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, and the raw materials used are not specially limited, and are all commercially available products unless otherwise specified.

[0073] In the following examples 1-11 and comparative examples 2-3, the modified cellulose is prepared according to the following method:

[0074] (1) Extraction and purification of cellulose: After drying the wheat straw fibers using a vacuum drying oven, cutting, mechanical grinding, sieving, 100 mesh fiber powder was obtained. 200 g of sieved fiber powder, 12 g (200 mmol) of urea, 40 g (400 mmol) of (NH4)2SO3 was added to 1 L of deionized water, soaked for 5 h, then put into a high-pressure reaction tank, 160 ℃ for 1 h, cooled to room temperature, filtered, washed, and obtained crude cellulose; 50 g of crude cellulose was dispersed in 200 mL of deionized water, 2 g (500 mmol) of NaOH and 20 mL of 30% H2O2 solution were added, and the mixture was reacted at 80 ℃ for 2 h. Filter, wash, and obtain bleached and purified cellulose.

[0075] (2) Preparation of modified cellulose: The bleached and purified cellulose was added to water, and a high-speed disperser was used to disperse at 1500 rpm for 10 min to obtain a 4% cellulose suspension. To 1 L of 4% cellulose suspension, 0.64 g (4 mmol) of 2,2,6,6-tetramethylpiperidine oxide (TEMPO) and 4 g (40 mmol) of NaBr were added, and the mixture was mixed uniformly. Then 120 mL of 10% NaClO aqueous solution was slowly added dropwise, and the pH was adjusted to 10 using Na2CO3 / NaHCO3 buffer. The mixture was stirred at room temperature for 5 h. 200 mL of ethanol was added to the reaction solution to precipitate the oxidized cellulose, which was then centrifuged and washed with 75% ethanol. The mixture was dried at room temperature under vacuum to obtain modified cellulose with carboxyl groups on the surface.

[0076] Example 1

[0077] 1. Preparation of nucleophile:

[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 ℃ under nitrogen for 15 min until the solution was uniformly mixed. Then 1.22 g (10 mmol) of 4-dimethylaminopyridine catalyst was added, and the mixture was reacted at 40 ℃ for 8 h. 100 mL of deionized water was added to obtain a precipitate, which was filtered and washed with deionized water. The precipitate was recrystallized with ethanol and dried to obtain the nucleophile AP-HA.

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

[0080] (1) One-pot method was adopted, 37 g of epoxidized soybean oil, 30 g of modified cellulose, 14 g of citric acid, 13 g of nucleophile AP-HA, 2 g of glycerol, 3.8 g of ethanol were added under nitrogen atmosphere, and a high-speed dispersion machine was used to react at 80°C for 1 h at a dispersion rate of 2500 rpm. After keeping the temperature unchanged, 0.2 g of 1,2-dimethylimidazole was added, and after stirring for 5 min to dissolve the 1,2-dimethylimidazole, the solvent was removed by vacuum (-0.09 MPa), and the reaction was continued for 1 h. After degassing, a pre-cured product was obtained.

[0081] (2) The pre-cured product was transferred to a polytetrafluoroethylene mold (100 x 100 x 0.5 mm 3 ), and compression molding was performed 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 shown in Figure 1 : 1740 and 1680 cm -1 are ester and amide absorption peaks, respectively, representing the participation of carboxyl in the ring opening of epoxy and the introduction of nucleophile AP-HA. The ether bond absorption peaks at 1226 and 1154 cm -1 further indicate that the organic acid and the nucleophile participate in the curing of the epoxidized soybean oil system. The cellulose glycosidic bond absorption peak at 1085 cm -1 represents the introduction of cellulose.

[0083] Example 2

[0084] 1. Preparation of nucleophile:

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

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

[0087] The preparation method is the same as in Example 1, and the preparation raw materials are as follows: 37 g of epoxidized soybean oil, 30 g of modified cellulose, 14 g of citric acid, 13 g of nucleophile 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 nucleophile:

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

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

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

[0093] Example 4

[0094] The nucleophile and the preparation method of the bio-based epoxy resin composite material provided in this example are the same as those of Example 1.

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

[0096] Example 5

[0097] The nucleophile and the preparation method of the bio-based epoxy resin composite material provided in this example are the same as those of Example 2.

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

[0099] Example 6

[0100] The nucleophile and the preparation method of the bio-based epoxy resin composite material provided in this example are the same as those of Example 3.

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

[0102] Example 7

[0103] The nucleophile and the preparation method of the bio-based epoxy resin composite material provided in this example are the same as those of Example 1.

[0104] The preparation of the bio-based epoxy resin composite material in this example is the same as that in Example 1, except that the glycerol in Example 1 is replaced with an equal amount of ethylene glycol, as follows: 37 g of epoxy soybean oil, 30 g of modified cellulose, 14 g of citric acid, 13 g of nucleophile 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 nucleophile and the method for preparing a bio-based epoxy resin composite material provided in this example are the same as those in Example 2.

[0107] The preparation of the bio-based epoxy resin composite material in this example is the same as that in Example 2, except that the glycerol in Example 2 is replaced with an equal amount of ethylene glycol, as follows: 37 g of epoxy soybean oil, 30 g of modified cellulose, 14 g of citric acid, 13 g of nucleophile 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 nucleophile and the method for preparing a bio-based epoxy resin composite material provided in this example are the same as those in Example 3.

[0110] The preparation of the bio-based epoxy resin composite material in this example is the same as that in Example 3, except that the glycerol in Example 3 is replaced with an equal amount of ethylene glycol, as follows: 37 g of epoxy soybean oil, 30 g of modified cellulose, 14 g of citric acid, 13 g of nucleophile 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 method for preparing a bio-based epoxy resin composite material provided in this example is the same as that in Example 1, except that the nucleophile AP-HA in Example 1 is replaced with hydroquinone, as follows: 37 g of epoxy 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] Example 11

[0114] The method for preparing a bio-based epoxy resin composite material provided in this example is the same as that in Example 1, except that the nucleophile AP-HA in Example 1 is replaced with terephthalic acid, 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 provided by the present comparative example is the same as that of Example 1, and the difference between the raw materials for preparation and Example 1 is that no modified cellulose is added, and the specific preparation method is 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 provided by the present comparative example is the same as that of Example 1, and the difference between the raw materials for preparation and Example 1 is that no nucleophile AP-HA is added, and the specific preparation method 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 provided by the present comparative example is the same as that of Example 1, and the difference between the raw materials for preparation and Example 1 is that no citric acid is added, and the specific preparation method is 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 provided by the present comparative example is the same as that of Example 1, and the difference between the raw materials for preparation and Example 1 is that the cellulose used is different, and the specific preparation method is as follows: 37 g of epoxy soybean oil, 30 g of cellulose, 14 g of citric acid, 13 g of nucleophile AP-HA, 2 g of glycerol, 3.8 g of ethanol, and 0.2 g of 1,2-dimethylimidazole.

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

[0124] After the wheat straw fibers are dried in a vacuum drying oven, they are cut, mechanically ground and crushed, sieved, and 100-mesh fiber powder is obtained. 200 g of sieved fiber powder, 12 g (200 mmol) of urea, and 40 g (400 mmol) of (NH4)2SO3 are added to 1 L of deionized water, soaked for 5 h, then placed in a high-pressure reaction tank, and reacted at 160°C for 1 h. After cooling to room temperature, filtration and washing are performed to obtain crude cellulose; 50 g of crude cellulose is dispersed in 200 mL of deionized water, 2 g (500 mmol) of NaOH and 20 mL of 30% H2O2 solution are added, and the mixture is reacted at 80°C for 2 h. After filtration and washing, bleached and purified cellulose is obtained.

[0125] The bio-based epoxy resin composites prepared from 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 or thermoplastic rubbers".

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

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

[0129] Glass transition temperature: the glass transition temperature was measured by thermal mechanical analysis (TMA) at a temperature range of 25-200℃ and a temperature rising rate of 5℃ / min, and the temperature point at the half height of the glass transition process was taken.

[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] As can be seen from the data in Table 1, the present application can impart ideal mechanical properties to the bio-based epoxy resin of epoxidized soybean oil through the synergistic cooperation of the polybasic organic acid, the specific nucleophilic reagent and the modified cellulose, so that it has high tensile strength, Young's modulus and glass transition temperature.

[0135] Comparative Example 1 does not add modified cellulose, Comparative Example 2 does not add a nucleophilic reagent, and Comparative Example 3 does not add a polybasic organic acid, resulting in a significant decrease in the tensile strength, modulus and glass transition temperature of the obtained bio-based epoxy resin composite. It can be seen that the polybasic organic acid, the nucleophilic reagent and the modified cellulose are indispensable, and have a synergistic effect of improving the mechanical strength of the bio-based epoxy resin composite, among which the organic acid has the greatest influence on the performance of the composite material by affecting the curing of the epoxidized soybean oil system.

[0136] Comparative Example 4 adds unoxidized cellulose, which can also enhance the strength of the composite material, but the effect is significantly less than that of the oxidized and modified cellulose.

[0137] Any combination of the technical features in the above-described embodiments can be made, and for the sake of brevity, not all possible combinations are described, however, as long as the combination of the technical features does not exist in contradiction, it shall be considered within the scope of the present disclosure.

[0138] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it shall not be understood as a limitation on the patent scope of the present application. It shall be pointed out that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these shall be within the protection scope of the present application. Therefore, the protection scope of the present application patent shall be subject to the appended claims.

Claims

1. A bio-based epoxy resin composite material, characterized in that, It is prepared from raw materials comprising the following components, in parts by weight: 20-40 parts of epoxidized soybean oil 25-37 parts of modified cellulose, 10-25 parts of polybasic organic acids 10-23 parts of nucleophilic reagent, 1-5 parts of polyol, Curing accelerator 0.1~1 part; The modified cellulose is modified cellulose with carboxyl groups on its surface; The modified cellulose is obtained by grinding, bleaching and purifying plant fibers and then oxidizing them using the TEMPO oxidation method. The nucleophile is an aryl nucleophile containing at least two nucleophilic groups, wherein the nucleophilic groups are hydroxyl and / or carboxyl groups.

2. The bio-based epoxy resin composite material according to claim 1, characterized in that, It is prepared from raw materials comprising the following components, in parts by weight: 35-40 parts of epoxidized soybean oil 28-32 parts of modified cellulose, 13-15 parts of polybasic organic acids 12-15 parts of nucleophilic reagent, 1-3 parts of polyol, 0.1 to 0.3 parts of curing accelerator.

3. The bio-based epoxy resin composite material according to claim 1 or 2, characterized in that, The plant fibers are selected from sugarcane fiber, wheat straw fiber, wood fiber, and cotton fiber.

4. The bio-based epoxy resin composite material according to claim 3, characterized in that, The plant fiber is wheat straw fiber.

5. The bio-based epoxy resin composite material according to claim 3, characterized in that, The method for preparing the modified cellulose includes the following steps: (1) Extraction and purification of cellulose: Plant fiber powder was treated with urea and (NH4)2SO3, and then treated with H2O2 under alkaline conditions to obtain bleached and purified cellulose; (2) Oxidation of cellulose: The bleached and purified cellulose was oxidized with NaClO under alkaline conditions in the presence of 2,2,6,6-tetramethylpiperidine oxide and NaBr to obtain the modified cellulose.

6. The bio-based epoxy resin composite material according to claim 5, characterized in that, The method for preparing the modified cellulose includes the following steps: (1) Extraction and purification of cellulose: Plant fiber powder, urea and (NH4)2SO3 were added to water and soaked for 4h~6h. The mixture was reacted at 150 ℃~170 ℃ for 0.5 h~2h, cooled to room temperature, filtered and washed to obtain crude cellulose. The crude cellulose was dispersed in water, NaOH and H2O2 solution were added, and the mixture was reacted at 70 ℃~90 ℃ for 1h~3h. The mixture was filtered and washed to obtain bleached and purified cellulose. (2) Oxidation of cellulose: The bleached and purified cellulose is dispersed in water to obtain a cellulose suspension. 2,2,6,6-Tetramethylpiperidine oxide and NaBr are added and mixed evenly. Then, NaClO aqueous solution is added and stirred for 4-6 hours at pH 9-11. Ethanol is added to the reaction solution to obtain oxidized cellulose precipitate. The precipitate is centrifuged, washed, and dried to obtain the modified cellulose.

7. The bio-based epoxy resin composite material according to claim 6, characterized in that, The mesh size of the plant fiber powder is 80-120 mesh; 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 1g: 3mL~5mL: 0.03g~0.05g: 0.3mL~0.5mL; And / or, the mass fraction of the H2O2 solution is 25-40%; And / or, the cellulose suspension has a mass fraction of 3-5%; And / or, the ratio of the cellulose suspension, 2,2,6,6-tetramethylpiperidine oxide, NaBr and NaClO aqueous solution is 1 L: 0.6 g~0.7 g: 3 g~5 g: 110 mL~130 mL; And / or, the mass fraction of the NaClO aqueous solution is 8-12%.

8. 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.

9. The bio-based epoxy resin composite material according to claim 8, characterized in that, The polybasic organic acid is citric acid and / or malic acid.

10. 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 nucleophile is obtained by reacting p-aminophenol with a nucleophilic organic acid, wherein the nucleophilic organic acid is an organic acid containing an aryl group, the nucleophilic organic acid contains at least two nucleophilic groups, the nucleophilic groups being hydroxyl and / or carboxyl groups, and at least one nucleophilic group in the nucleophilic organic acid is a carboxyl group.

11. The bio-based epoxy resin composite material according to claim 10, characterized in that, 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.

12. The bio-based epoxy resin composite material according to claim 11, characterized in that, The nucleophilic organic acid is p-hydroxybenzoic acid, gallic acid, or terephthalic acid.

13. The bio-based epoxy resin composite material according to claim 10, characterized in that, The molar ratio of p-aminophenol to nucleophilic organic acid is 1:1 to 1.

3.

14. The bio-based epoxy resin composite material according to claim 10, characterized in that, The nucleophilic reagent is obtained by reacting p-aminophenol with a nucleophilic organic acid, and its preparation method includes the following steps: The p-aminophenol is reacted with the nucleophilic organic acid under the catalysis of 4-dimethylaminopyridine to obtain the product.

15. The bio-based epoxy resin composite material according to claim 14, characterized in that, The reaction is carried out in an organic solvent, namely acetonitrile.

16. The bio-based epoxy resin composite material according to claim 14, characterized in that, The molar ratio of p-aminophenol to 4-dimethylaminopyridine is 1:0.04~0.

06.

17. The bio-based epoxy resin composite material according to claim 14, characterized in that, The reaction is carried out at a temperature of 35℃ to 45℃ for a duration of 6 to 10 hours.

18. The bio-based epoxy resin composite material according to claim 14, characterized in that, The reaction is carried out in an inert gas atmosphere.

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

20. The bio-based epoxy resin composite material according to claim 19, characterized in that, The polyol is ethylene glycol or glycerol.

21. The bio-based epoxy resin composite material according to claim 19, characterized in that, The curing accelerator is 1,2-dimethylimidazole.

22. A method for preparing a bio-based epoxy resin composite material according to any one of claims 1-21, characterized in that, Includes the following steps: (1) Under an inert gas atmosphere, the epoxidized soybean oil, modified cellulose, polybasic organic acid, nucleophile, polyol and solvent are reacted at 70℃~85℃ for 1~2 h, the temperature is kept constant, the curing accelerator is added, the solvent is removed by vacuum, and the reaction is continued for 0.5~1 h to obtain the pre-cured product; (2) The pre-cured material is compressed and molded under a temperature of 100℃~130℃ and a pressure of 0.5MPa~2.5MPa to obtain the bio-based epoxy resin composite material.

23. The method for preparing the bio-based epoxy resin composite material according to claim 22, characterized in that, The solvent is selected from at least one of water, 1,4-dioxane, ethyl acetate, tetrahydrofuran, methanol, ethanol, acetonitrile, and tetrahydrofuran.

24. The method for preparing the bio-based epoxy resin composite material according to claim 22, characterized in that, The solvent is present in 2 to 4 parts by weight.

25. The method for preparing the bio-based epoxy resin composite material according to claim 22, characterized in that, The compression molding time is 0.5~6 h.

26. The method for preparing the bio-based epoxy resin composite material according to claim 25, characterized in that, The compression molding time is 0.8~2 hours.

27. The method for preparing the bio-based epoxy resin composite material according to claim 22, characterized in that, The temperature in step (2) is 105℃~115℃ and the pressure is 0.8MPa~1.5MPa.

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