CN110204868B - Graphene grafted modified epoxy resin and preparation method thereof - Google Patents
Graphene grafted modified epoxy resin and preparation method thereof Download PDFInfo
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 423
- 229910021389 graphene Inorganic materials 0.000 title claims abstract description 422
- 239000003822 epoxy resin Substances 0.000 title claims abstract description 171
- 229920000647 polyepoxide Polymers 0.000 title claims abstract description 171
- 238000002360 preparation method Methods 0.000 title claims abstract description 22
- IISBACLAFKSPIT-UHFFFAOYSA-N bisphenol A Chemical compound C=1C=C(O)C=CC=1C(C)(C)C1=CC=C(O)C=C1 IISBACLAFKSPIT-UHFFFAOYSA-N 0.000 claims abstract description 365
- 239000004850 liquid epoxy resins (LERs) Substances 0.000 claims abstract description 146
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- 238000009775 high-speed stirring Methods 0.000 claims description 6
- JRMUNVKIHCOMHV-UHFFFAOYSA-M tetrabutylammonium bromide Chemical group [Br-].CCCC[N+](CCCC)(CCCC)CCCC JRMUNVKIHCOMHV-UHFFFAOYSA-M 0.000 claims description 6
- GBYIPEFQQCCCJP-UHFFFAOYSA-N Cl.C(C)C1=C(C=CC=C1)P(C1=CC=CC=C1)C1=CC=CC=C1 Chemical compound Cl.C(C)C1=C(C=CC=C1)P(C1=CC=CC=C1)C1=CC=CC=C1 GBYIPEFQQCCCJP-UHFFFAOYSA-N 0.000 claims description 5
- 230000004048 modification Effects 0.000 claims description 5
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- DWGGKKBVZVJZDK-UHFFFAOYSA-N C(C1=CC=CC=C1)C(C=CC=C1)=C1P(C1=CC=CC=C1)C1=CC=CC=C1.Br Chemical compound C(C1=CC=CC=C1)C(C=CC=C1)=C1P(C1=CC=CC=C1)C1=CC=CC=C1.Br DWGGKKBVZVJZDK-UHFFFAOYSA-N 0.000 claims description 3
- YXBSOQIDSJOJRD-UHFFFAOYSA-N C(C=C1)=CC=C1P(C1=CC=CC=C1)(C1=CC=CC=C1)C1=CC=CC=C1.Br Chemical compound C(C=C1)=CC=C1P(C1=CC=CC=C1)(C1=CC=CC=C1)C1=CC=CC=C1.Br YXBSOQIDSJOJRD-UHFFFAOYSA-N 0.000 claims description 3
- KCFOLUKWAIAKFB-UHFFFAOYSA-N CCC(C=CC=C1)=C1P(C1=CC=CC=C1)C1=CC=CC=C1.Br Chemical compound CCC(C=CC=C1)=C1P(C1=CC=CC=C1)C1=CC=CC=C1.Br KCFOLUKWAIAKFB-UHFFFAOYSA-N 0.000 claims description 3
- 229910052698 phosphorus Inorganic materials 0.000 claims description 3
- 239000011574 phosphorus Substances 0.000 claims description 3
- 230000035484 reaction time Effects 0.000 claims description 3
- 238000004821 distillation Methods 0.000 claims description 2
- 150000003856 quaternary ammonium compounds Chemical class 0.000 claims description 2
- 239000000243 solution Substances 0.000 description 69
- 125000003700 epoxy group Chemical group 0.000 description 21
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- 238000007792 addition Methods 0.000 description 5
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- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 238000006555 catalytic reaction Methods 0.000 description 4
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- 229910052760 oxygen Inorganic materials 0.000 description 4
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- 238000007142 ring opening reaction Methods 0.000 description 4
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- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 230000021615 conjugation Effects 0.000 description 3
- LNEPOXFFQSENCJ-UHFFFAOYSA-N haloperidol Chemical class C1CC(O)(C=2C=CC(Cl)=CC=2)CCN1CCCC(=O)C1=CC=C(F)C=C1 LNEPOXFFQSENCJ-UHFFFAOYSA-N 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- OCKGFTQIICXDQW-ZEQRLZLVSA-N 5-[(1r)-1-hydroxy-2-[4-[(2r)-2-hydroxy-2-(4-methyl-1-oxo-3h-2-benzofuran-5-yl)ethyl]piperazin-1-yl]ethyl]-4-methyl-3h-2-benzofuran-1-one Chemical compound C1=C2C(=O)OCC2=C(C)C([C@@H](O)CN2CCN(CC2)C[C@H](O)C2=CC=C3C(=O)OCC3=C2C)=C1 OCKGFTQIICXDQW-ZEQRLZLVSA-N 0.000 description 2
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- BRLQWZUYTZBJKN-UHFFFAOYSA-N Epichlorohydrin Chemical compound ClCC1CO1 BRLQWZUYTZBJKN-UHFFFAOYSA-N 0.000 description 1
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- NJXBVBPTDHBAID-UHFFFAOYSA-M ethyl(triphenyl)phosphanium;chloride Chemical compound [Cl-].C=1C=CC=CC=1[P+](C=1C=CC=CC=1)(CC)C1=CC=CC=C1 NJXBVBPTDHBAID-UHFFFAOYSA-M 0.000 description 1
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/02—Elements
- C08K3/04—Carbon
- C08K3/042—Graphene or derivatives, e.g. graphene oxides
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/04—Oxygen-containing compounds
- C08K5/13—Phenols; Phenolates
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Carbon And Carbon Compounds (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
The invention provides a graphene grafted and modified epoxy resin and a preparation method thereof, wherein the raw material components of the graphene grafted and modified epoxy resin comprise graphene powder, bisphenol A type liquid epoxy resin, bisphenol A, a first catalyst and a second catalyst, and the mass ratio of the graphene powder, the bisphenol A type liquid epoxy resin, the bisphenol A, the first catalyst and the second catalyst is (0.5-5): (70-80): (20-30): (5-50): (0.05-1). The preparation method comprises the following steps: preparing a graphene modified prepolymer, mixing the graphene modified prepolymer with bisphenol A type liquid epoxy resin and bisphenol A, and preparing the graphene grafted modified epoxy resin under the action of a second catalyst. The epoxy resin and the preparation method thereof provided by the invention can improve the grafting efficiency of graphene in the epoxy resin and improve the excellent performance of graphene in the epoxy resin.
Description
Technical Field
The invention belongs to the technical field of epoxy resin synthesis, and relates to graphene modified epoxy resin.
Background
The graphene has the advantages of ultrathin property, ultralight property, ultrahigh strength, ultrahigh electrical conductivity, excellent room-temperature thermal conductivity and structural stability, wide application and huge development prospect, and is one of the key new materials for promoting strategic high-tech development. The composite material has large specific surface area and high mechanical strength, and can form a reinforcing network in the material with a small addition amount, thereby greatly improving the mechanical, electric and heat conductivity properties of the composite material. According to research statistics (Macromolecules 2010,43, 6515-6530), the performance of the polymer composite material can be improved by 50% or even several times by adding 0.1% -3.5% of graphene.
However, the existing research is mainly to add graphene into the polymer material in a blending manner. Because the graphene is incompatible with the polymer, a homogeneous system cannot be formed in the composite material, so that the enhancement effect of the graphene on the polymer composite material is restricted. To solve this problem, chemical grafting of graphene and a high molecular material must be achieved.
In the epoxy resin reinforcement research, a method is generally adopted to chemically modify graphene, and then graphene is added in the process of epoxy resin curing to form a composite material, the method needs to disperse the graphene into the epoxy resin after polymerization in a blending method before curing, and the chemical grafting of the graphene and the epoxy resin cured product is realized by virtue of a group for modifying the graphene. When the method is used, graphene is difficult to be uniformly dispersed in high-viscosity epoxy resin, a large amount of solvent is required, and the graphene is easy to agglomerate, so that the reinforcing effect of the graphene is limited. In addition, in the case of a melt-processed solid epoxy resin system, the dispersion effect of graphene is further poor, and the advantages of graphene cannot be fully exerted.
If graphene is mixed with a monomer in the polymerization process of epoxy resin, chemical grafting of graphene and epoxy resin is realized in the polymerization process, on one hand, graphene is easily dispersed in a low-viscosity monomer, and the dispersibility of graphene is improved; on the other hand, the graphene grafted and modified epoxy resin material can be directly prepared, and can be applied to the fields of coatings, plastics and the like. However, since graphene has low chemical activity and hardly reacts with an epoxy resin monomer, graphene must be chemically modified or modified to ensure grafting efficiency. Otherwise, the graphene is merely dispersed into the resin system during the polymerization of the epoxy resin.
For example, patent CN105837790A discloses a method for preparing graphene modified epoxy resin by using graphene aqueous solution, epichlorohydrin and bisphenol a polymerization. Firstly, the method has no requirement on the used graphene, cannot ensure that the graphene has enough functional groups to perform grafting reaction with the epoxy resin monomer, and essentially only disperses the graphene into the epoxy resin. Secondly, no solvent is added in the preparation process, the reaction temperature is lower than 100 ℃, only low molecular weight epoxy resin can be prepared, and the preparation method is not suitable for preparing high molecular weight solid epoxy resin. Finally, the method adopts the traditional NaOH catalyst to prepare the epoxy resin, needs to increase water to wash products after the reaction is finished, has more reaction waste water, and can not meet the requirement of environmental protection. Patent CN107353587A discloses a method for preparing graphene modified epoxy resin from graphene, low molecular epoxy resin and bisphenol a under the action of a catalyst. The method simply blends the graphene into the epoxy resin monomer, and the grafting reaction efficiency between the graphene and the epoxy resin cannot be ensured.
The statements in the background section are merely prior art as they are known to the inventors and do not, of course, represent prior art in this field.
Disclosure of Invention
Aiming at one or more problems in the prior art, the invention provides a graphene modified prepolymer and a preparation method thereof, and also provides a graphene grafted modified epoxy resin and a preparation method thereof, aiming at improving the chemical grafting efficiency between graphene and epoxy resin, better dispersing graphene in the epoxy resin and further enhancing the performance of the epoxy resin. According to the invention, graphene and bisphenol A are grafted and modified to prepare a prepolymer, and then the prepolymer and epoxy resin are polymerized in situ to prepare the graphene grafted and modified epoxy resin.
In order to achieve the above object, the present invention provides a graphene modified prepolymer, comprising graphene powder, bisphenol a liquid epoxy resin, and bisphenol a, wherein the mass ratio of the graphene powder to the bisphenol a liquid epoxy resin to the bisphenol a is (0.5-5): (1.4-16): (0.2-3).
Preferably, the mass ratio of the graphene powder to the bisphenol a liquid epoxy resin to the bisphenol a is (1-4): (4-12): (0.5-2.5).
Further preferably, the mass ratio of the graphene powder, the bisphenol a type liquid epoxy resin and the bisphenol a is (2-3): (8-10): (1-2).
According to one aspect of the invention, the graphene powder is prepared by a redox method.
Preferably, the redox method comprises a chemical reduction method or a thermal reduction method, so that the prepared graphene powder has epoxy functional groups on the surface.
Preferably, the content of the epoxy functional group on the surface of the graphene powder is more than 0.5 wt%.
Preferably, the content of the epoxy functional group is 1 to 2 wt%.
Further preferably, the temperature of the thermal reduction process is 1500 ℃ or less, preferably 600 ℃ to 1200 ℃.
Partial functional groups are arranged on the surface of the graphene powder prepared by the oxidation-reduction method, and comprise oxygen-containing groups which can be grafted with bisphenol A type liquid epoxy resin better, so that when the graphene powder is prepared by the thermal reduction method, the temperature is required to be below 1500 ℃, partial functional groups are left on the surface of the graphene powder, the temperature is preferably 600-1200 ℃, the content of the functional groups of the graphene powder reaches 1-2wt%, and the grafting reaction is facilitated.
According to one aspect of the invention, the number of layers of the graphene powder is 1-10.
According to one aspect of the invention, the specific surface area of the graphene powder is more than 150m 2 /g。
The specific surface area is less than 150m 2 The number of layers of the reduced graphene oxide powder per gram is more than 10.
Preferably, the sheet diameter of the graphene powder is 1-40 μm.
According to one aspect of the present invention, the bisphenol A type liquid epoxy resin has an epoxy equivalent of 179-208 g/eq. Common commercial liquid epoxy resins are liquid epoxy resins E54 and E51, with an epoxy equivalent of 179-208 g/eq.
Preparing 1-10 layers with specific surface area larger than 150m by oxidation-reduction method 2 When the graphene powder has the sheet diameter of 1-40 mu m, the content of the epoxy functional group on the surface of the graphene powder is more than 0.5wt%, particularly 1-2wt%, and the graphene powder can be grafted with the epoxy resin with the epoxy equivalent of 179-208 g/eq.
The invention also provides a preparation method of the graphene modified prepolymer, which comprises the following steps:
s101: mixing graphene powder and a first catalyst, then carrying out first heating stirring, adding bisphenol A type liquid epoxy resin, and carrying out second heating stirring to obtain a first solution;
s102: adding bisphenol A into the first solution, and heating and stirring for the third time to obtain a second solution;
s103: and distilling the second solution under reduced pressure, and removing the first catalyst to obtain the graphene modified prepolymer.
The bisphenol A type liquid epoxy resin is a monomer for preparing high molecular weight epoxy resin, and graphene is directly added in the polymerization process of the epoxy resin monomer, so that the graphene and the epoxy resin monomer basically do not react due to the low activity of the graphene.
Preparing a graphene modified prepolymer, reacting graphene with bisphenol A type liquid epoxy resin under the catalysis of a first catalyst, and reacting the reacted bisphenol A type liquid epoxy resin with bisphenol A under the catalysis of the first catalyst. Grafting graphene onto bisphenol A liquid epoxy resin to form a graphene modified prepolymer, wherein the graphene modified prepolymer is micromolecular epoxy resin, and finally, the graphene modified prepolymer needs to be subjected to polymerization reaction to form high-molecular-weight epoxy resin.
The first catalyst hardly reacts with the epoxy resin at 100 ℃ or below or in the absence of a transition metal catalyst. The temperature in the process of preparing the graphene modified prepolymer does not exceed 100 ℃, while the temperature in the process of preparing the graphene modified epoxy resin by using the graphene modified prepolymer exceeds 100 ℃, if the first catalyst exists in the process, the first catalyst can react with the epoxy resin to influence subsequent products. Therefore, in step S103, the first catalyst needs to be removed.
According to an aspect of the present invention, in the step S101, the first catalyst is a small molecule alkyl tertiary amine compound.
Preferably, the first catalyst comprises triethylamine or tripropylamine.
According to one aspect of the present invention, in the step S101, the mass ratio of the graphene powder, the bisphenol a type liquid epoxy resin, the bisphenol a, and the first catalyst is (0.5-5): (1.4-16): (0.2-3): (5-50).
Preferably, the mass ratio of the graphene powder, the bisphenol A type liquid epoxy resin, the bisphenol A and the first catalyst is (1-4): (4-12): (0.5-2.5): (10-40); further preferably, the mass ratio is (2-3): (8-10): (1-2): (20-30).
The microscopic reaction principle of the alkyl tertiary amine catalyst is as follows: the alkyl tertiary amine catalyst can promote the ring opening of the graphene epoxy functional group, and the epoxy functional group on the surface of the opened graphene can react with the epoxy group of the bisphenol A liquid epoxy resin more easily; after the bisphenol A is added, the remaining alkyl tertiary amine catalyst promotes the ring opening of the epoxy functional group of the bisphenol A type liquid epoxy resin, so that the epoxy group of the bisphenol A type liquid epoxy resin and the hydroxyl group of the bisphenol A form an ether bond.
The first catalyst is alkyl tertiary amine, on one hand, the p-pi conjugation effect is formed by the micromolecule alkyl tertiary amine and the pi bond of the graphene, and the dispersion and the stability of the graphene are facilitated; on one hand, activating the residual functional groups on the surface of the graphene to graft the functional groups with the epoxy groups of the bisphenol A liquid epoxy resin; on the other hand, the epoxy group of the bisphenol A type liquid epoxy resin is activated, and the bisphenol A type liquid epoxy resin and the bisphenol A are subjected to a crosslinking reaction. The reduced graphene has fewer functional groups on the surface, the graphene has lower activity, and in order to ensure that the functional groups of the graphene are completely reacted, the bisphenol A and the bisphenol A liquid epoxy resin are slightly excessive.
According to an aspect of the present invention, in the step S101, the temperature of the first temperature-raising stirring is 75 to 85 ℃, preferably 80 ℃.
Preferably, the time of the first heating stirring is 1 h.
According to an aspect of the present invention, in the step S101, the temperature of the second temperature-raising stirring is 75 ℃ to 85 ℃, preferably 80 ℃.
Preferably, in the step S101, the second temperature-raising stirring speed is 1500-.
Further preferably, in the step S101, the time for the second stirring is 2 hours.
The bisphenol A liquid epoxy resin is liquid, and after the bisphenol A liquid epoxy resin is added into the solution, under the conditions that the stirring speed is 1500-2500rpm, the stirring time is 2 hours and the temperature is 80 ℃, the graphene powder can be uniformly dispersed in the solution, so that the bisphenol A liquid epoxy resin is dispersed and grafted with the graphene powder.
According to an aspect of the present invention, in the step S102, the third heating and stirring method includes: firstly, stirring at low speed to dissolve the bisphenol A, and then stirring at high speed.
Preferably, in the step S102, the temperature of the third temperature-raising stirring is 75 ℃ to 85 ℃, preferably 80 ℃.
The optimal reaction temperature condition of bisphenol A type liquid epoxy resin and bisphenol A is 80 ℃.
Preferably, in the step S102, the low-speed stirring speed is 300-600 rpm.
Preferably, in the step S102, the high-speed stirring rate is 1500-.
Further preferably, in the step S102, the high-speed stirring time is 2 to 4 hours.
Bisphenol A is solid, and the stirring speed is low at 300-600rpm to dissolve bisphenol A, and if the solid is stirred, the speed is too high, so that the solution is easy to splash. After the bisphenol A is dissolved, stirring at a high speed of 1500-.
The invention also provides graphene graft modified epoxy resin, which comprises the following raw material components in percentage by mass (0.5-5): (70-80): (20-30): (5-50): (0.05-1).
Preferably, the mass ratio of the graphene powder, the bisphenol A type liquid epoxy resin, the bisphenol A, the first catalyst and the second catalyst is (1-4): (72-78): (22-28): (10-40): (0.1-0.8).
Further optionally, the mass ratio of the graphene powder, the bisphenol A type liquid epoxy resin, the bisphenol A, the first catalyst and the second catalyst is (2-3): (74-76): (24-26): (20-30): (0.3-0.6).
The graphene can improve the performance of the epoxy resin, but if the graphene is too much and exceeds the above proportion, the solution viscosity in the preparation process is increased, and the polymerization of the epoxy resin is not uniform.
According to one aspect of the present invention, the graphene powder is prepared by a redox method.
Preferably, the redox method comprises a chemical reduction method or a thermal reduction method, so that the prepared graphene powder has epoxy functional groups on the surface.
Preferably, the content of the epoxy functional group on the surface of the graphene powder is more than 0.5 wt%.
Preferably, the content of the epoxy functional group is 1 to 2 wt%.
Further preferably, the temperature of the thermal reduction process is 1500 ℃ or less, preferably 600 ℃ to 1200 ℃.
Partial functional groups are arranged on the surface of the graphene powder prepared by the oxidation-reduction method, and comprise oxygen-containing groups which can be grafted with bisphenol A type liquid epoxy resin better, so that when the graphene powder is prepared by the thermal reduction method, the temperature is required to be below 1500 ℃, partial functional groups are left on the surface of the graphene powder, the temperature is preferably 600-1200 ℃, the content of the functional groups of the graphene powder reaches 1-2wt%, and the grafting reaction is facilitated.
According to one aspect of the invention, the number of layers of the graphene powder is 1-10.
According to one aspect of the invention, the specific surface area of the graphene powder is more than 150m 2 /g。
Preferably, the sheet diameter of the graphene powder is 1-40 μm.
According to one aspect of the invention, the epoxy equivalent of the bisphenol A liquid epoxy resin is 179-208 g/eq. Common commercial liquid epoxy resins are liquid epoxy resins E54 and E51, with an epoxy equivalent of 179-208 g/eq.
Preparing 1-10 layers by oxidation-reduction method, and the specific surface area is more than 150m 2 When the graphene powder with the sheet diameter of 1-40 mu m is used, the content of the epoxy functional group on the surface of the graphene powder is more than 0.5wt%, particularly 1-2wt%, and the graphene powder can be connected with the epoxy resin with the epoxy equivalent of 179-208g/eqThe branches are more sufficient.
Preferably, the first catalyst is a small molecule alkyl tertiary amine compound.
Further preferably, the first catalyst comprises triethylamine or tripropylamine.
Preferably, the second catalyst adopts a tertiary amine compound, a quaternary ammonium compound or a phosphorus compound.
Further preferably, the second catalyst is tetrabutylammonium bromide, triphenylphosphine, ethyltriphenylphosphine acetate, ethyltriphenylphosphine chloride, ethyltriphenylphosphine bromide, tetraphenylphosphine bromide or benzyltriphenylphosphine bromide.
The invention also provides a preparation method of the graphene grafted and modified epoxy resin, which adopts the raw material components of the graphene grafted and modified epoxy resin and comprises the following steps:
s201: preparing the graphene modified prepolymer according to the preparation method of the graphene modified prepolymer;
s202: mixing the graphene modified prepolymer with the rest of bisphenol A liquid epoxy resin, and stirring to obtain a third solution;
s203: adding the rest bisphenol A into the third solution, and heating and stirring to obtain a fourth solution;
s204: and adding a second catalyst into the fourth solution, introducing gas, heating and stirring to enable the fourth solution to react under the action of the second catalyst, and cooling to obtain the graphene grafted modified epoxy resin.
In the process of preparing the graphene grafted modified epoxy resin, the bisphenol A and the bisphenol A type liquid epoxy resin are respectively added twice, and the purpose of adding the bisphenol A and the bisphenol A type liquid epoxy resin twice is different.
For two additions of bisphenol a: in step S201, a hydroxyl group of bisphenol a and an epoxy group of the bisphenol a liquid epoxy resin on which the graphene powder is grafted form an ether bond, thereby generating a graphene modified prepolymer with a small molecular weight. In step S203, the bisphenol a is added to react with the bisphenol a type liquid epoxy resin and the graphene modified prepolymer to form a high molecular weight epoxy resin.
For the two-stage addition of bisphenol a type liquid epoxy resin: in step S201, epoxy groups of the bisphenol a liquid epoxy resin react with epoxy groups on the surface of the open-loop graphene powder, so as to graft the graphene powder onto the bisphenol a liquid epoxy resin, thereby generating a graphene modified prepolymer. In step S202, the bisphenol a type liquid epoxy resin is polymerized with the bisphenol a added in step S203 and the graphene modified prepolymer prepared in step S201 to obtain the graphene modified high molecular weight epoxy resin.
The bisphenol A type liquid epoxy resin is a small molecular epoxy resin which has been polymerized and has an epoxy group. The polymerization reaction refers to: under the catalytic action of a second catalyst, epoxy groups of the bisphenol A epoxy resin react with hydroxyl groups of the bisphenol A, the bisphenol A epoxy resin is combined with the bisphenol A through ether bonds, and the molecular weight chain extension generates macromolecular epoxy resin with a linear structure.
According to an aspect of the present invention, in the step S202, the temperature of the graphene modified prepolymer is 50 to 70 ℃.
The temperature condition of 50 to 70 ℃ is selected because the graphene-modified prepolymer undergoes a side reaction with the newly added bisphenol a type liquid epoxy resin if the temperature of the graphene-modified prepolymer exceeds 70 ℃, and the viscosity of the graphene-modified prepolymer is too high if the temperature of the graphene-modified prepolymer is less than 50 ℃.
Preferably, in the step S202, the stirring speed is 1500-.
Further preferably, in the step S202, the stirring time is 1 h.
And adding the graphene modified prepolymer into bisphenol A liquid epoxy resin, wherein the solution contains two substances, namely the bisphenol A liquid epoxy resin and the bisphenol A epoxy resin grafted with graphene. The two materials were mixed together and dispersed uniformly by stirring at a stirring speed of 1500-2500rpm for 1 h.
According to an aspect of the present invention, in the step S203, the temperature of the temperature rise is 75 to 85 ℃. 75-85 ℃ is the optimum temperature for better dissolution of bisphenol A in solution.
Preferably, in the step S203, the stirring speed is 300-600 rpm.
Preferably, in the step S203, the stirring time is 1 h.
The stirring speed of 300-600rpm and the stirring time of 1 hour were selected in order to sufficiently dissolve the solid bisphenol A.
According to an aspect of the present invention, in the step S204, the gas is nitrogen.
In the process of polymerization reaction, nitrogen can protect reaction products under high temperature from being oxidized, and before the high temperature reaction is carried out, nitrogen needs to replace air in a reaction bottle to protect a reaction system.
Preferably, in the step S204, the temperature is increased slowly.
The polymerization reaction process can automatically release heat, the temperature is easy to lose control when the temperature rises too fast, the reaction is slow when the temperature rises too slow, and the temperature is slowly raised, so that the control of the polymerization reaction temperature is facilitated.
Further preferably, in the step S204, the temperature of the temperature rise is 110-130 DEG C
Preferably, in the step S204, the stirring speed is 1500-.
Preferably, in the step S204, the reaction temperature of the fourth solution and the second catalyst is controlled within the range of 160-190 ℃.
Further preferably, the method for controlling the reaction temperature of the fourth solution and the second catalyst is heating in an oil bath.
Preferably, in the step S204, the reaction time of the fourth solution is 1.5 h.
At high temperature, the bisphenol A type liquid epoxy resin and the graphene modified prepolymer can fully react to form high-molecular epoxy resin. However, if the self-heating temperature of the fourth solution is too high, which exceeds 190 ℃, side reactions may occur, and the prepared epoxy resin may generate branches or have too wide a molecular weight distribution, so that the purity of the epoxy resin may be insufficient, and the use properties may be deteriorated during the use.
The invention also provides graphene grafted and modified epoxy resin, which is prepared by the preparation method of the graphene grafted and modified epoxy resin. The graphene grafted modified epoxy resin with different epoxy equivalent can be prepared according to different proportions of the molecular weight of the bisphenol A type liquid epoxy resin and the molecular weight of the bisphenol A during preparation, so as to adapt to different application fields. The method comprises the steps of firstly preparing a graphene modified prepolymer, carrying out graft modification on graphene powder and bisphenol A type liquid epoxy resin, then adding a small amount of bisphenol A, wherein in the graphene modified prepolymer, the graphene powder is easily dispersed in the low-viscosity bisphenol A type epoxy resin, and opening an epoxy functional group on the surface of the graphene powder through a first catalyst to graft the graphene powder onto the bisphenol A type liquid epoxy resin.
In order to prepare graphene modified epoxy resin with higher grafting efficiency of graphene and epoxy resin, in the process of polymerizing an epoxy resin monomer into high molecular weight epoxy resin, a graphene modified prepolymer is added to prepare epoxy resin with more uniform graphene dispersion and higher grafting efficiency, so that the epoxy resin can fully exert the advantages of graphene in the epoxy resin in the fields of paint, plastics and the like.
The advantages of the present invention are illustrated by the following three points:
(1) according to the invention, the graphene prepared by the oxidation-reduction method is selected, and part of functional groups are remained on the surface of the graphene, so that the activity of the graphene can be improved, and the grafting reaction of the graphene and the epoxy resin is ensured.
(2) The micromolecular alkyl tertiary amine is selected as a catalyst, on one hand, the amino group of the micromolecular alkyl tertiary amine and the pi bond of the graphene form a p-pi conjugation effect, and the dispersion and the stability of the graphene in the catalyst are facilitated; in the second aspect, the catalyst can also activate functional groups remaining on the surface of the graphene, so that epoxy groups of the ring-opened graphene powder react with epoxy groups of the bisphenol A type liquid epoxy resin, and finally the graphene graft modified epoxy resin is realized; in a third aspect, the catalyst is capable of catalyzing the reaction of the epoxy groups of the bisphenol A type liquid epoxy resin and the hydroxyl groups of bisphenol A. The micromolecule alkyl tertiary amine can be separated and recovered in a reduced pressure distillation mode, and is reusable and environment-friendly in process.
(3) The chemically grafted graphene is provided with an epoxy molecular chain, the polarity of the epoxy molecular chain is consistent with that of a reaction system, and graphene agglomeration cannot occur due to incompatibility, so that the graphene can be uniformly and stably dispersed.
As can be seen from fig. 3 to 6, the graphene in the graphene grafted modified epoxy resin product prepared by the method of the present invention is uniformly dispersed, and no aggregated or clustered graphene appears.
As can be seen from fig. 7 and 8, the graphene in the graphene grafted and modified epoxy resin product prepared by the method of the present invention has a lamellar structure and a relatively thin thickness, which indicates that the graphene is well dispersed in the epoxy resin.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a Raman spectrum of graphene grafted modified epoxy resin and common epoxy resin, wherein the abscissa represents the difference of the number of waves (cm) of scattered light relative to the incident light -1 ) The ordinate represents the intensity of scattered light;
fig. 2 is a graph of thermal weight loss of graphene graft-modified epoxy resin and common epoxy resin, wherein the abscissa represents temperature (deg.c) and the ordinate represents weight ratio (%);
3-6 are SEM images of the graphene grafted and modified epoxy resin product of the invention;
FIGS. 7-8 are TEM images of the graphene graft-modified epoxy resin product of the present invention;
wherein 1 — the graphene graft modified epoxy resin of example 1, 2 is the graphene graft modified epoxy resin of example 2, 3 is the graphene graft modified epoxy resin of example 3, 4 is the graphene graft modified epoxy resin of example 4, and 5 is a common epoxy resin.
Detailed Description
In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.
In the description of the present invention, it is to be understood that the terms "first", "second" and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Moreover, the present invention may repeat reference numerals and/or reference letters in the various examples, which have been repeated for purposes of simplicity and clarity and do not in themselves dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or uses of other materials.
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it should be understood that they are presented herein only to illustrate and explain the present invention and not to limit the present invention.
According to a first embodiment of the invention, a graphene modified prepolymer is shown, which comprises graphene powder, bisphenol a liquid epoxy resin and bisphenol a, wherein the mass ratio of the graphene powder to the bisphenol a liquid epoxy resin to the bisphenol a is (0.5-5): (1.4-16): (0.2-3), for example: 0.5:1.4:0.2, 1:2:1, 2:3:1.5, 3:5:2, 4:10:2.5, 4.5:15:2.8, 5:16:3, etc. In a preferred embodiment, the mass ratio of the graphene powder, the bisphenol a liquid epoxy resin and the bisphenol a is (1-4): (4-12): (0.5-2.5), for example: 1:4:0.5, 2:6:1, 3:8:1.5, 3.5:10:2, 4:12:2.5, etc. In a most preferred embodiment, the mass ratio of the graphene powder, the bisphenol a type liquid epoxy resin and the bisphenol a is (2-3): (8-10): (1-2), for example: 2:8:1, 2.5:9:1.5, 3:10:2, etc.
The graphene powder is prepared by a redox method, wherein the redox method comprises a chemical reduction method or a thermal reduction method, so that the surface of the prepared graphene powder is provided with an epoxy functional group. The content of the epoxy functional group on the surface of the graphene powder is 0.5wt% or more, for example: 0.5wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, 1.8 wt%, 2wt%, 2.2 wt%, 2.5 wt%, 3 wt%, etc. As a preferred embodiment, the content of epoxy functional groups is from 1 to 2% by weight, for example: 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2wt%, etc. The temperature of the thermal reduction process is 1500 ℃ or less, for example: 200 ℃, 210 ℃, 220 ℃, 250 ℃, 300 ℃, 350 ℃, 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃, 750 ℃, 800 ℃, 810 ℃, 820 ℃, 850 ℃, 880 ℃, 900 ℃, 950 ℃, 1000 ℃, 1050 ℃, 1100 ℃, 1150 ℃, 1200 ℃, 1250 ℃, 1300 ℃, 1350 ℃, 1400 ℃, 1450 ℃, 1480 ℃, 1490 ℃, 1500 ℃, etc. As a preferred embodiment, the temperature of the thermal reduction process is from 600 ℃ to 1200 ℃, for example: 600 deg.C, 610 deg.C, 620 deg.C, 630 deg.C, 640 deg.C, 650 deg.C, 700 deg.C, 750 deg.C, 800 deg.C, 850 deg.C, 900 deg.C, 950 deg.C, 1000 deg.C, 1050 deg.C, 1100 deg.C, 1150 deg.C, 1160 deg.C, 1170 deg.C, 1180 deg.C, 1190 deg.C, 1200 deg.C, etc. Partial functional groups are arranged on the surface of the graphene powder prepared by the oxidation-reduction method, and comprise oxygen-containing groups which can be grafted with bisphenol A type liquid epoxy resin better, so that when the graphene powder is prepared by the thermal reduction method, the temperature is required to be below 1500 ℃, partial functional groups are left on the surface of the graphene powder, the temperature is preferably 600-1200 ℃, the content of the functional groups of the graphene powder reaches 1-2wt%, and the grafting reaction is facilitated. The number of layers of the graphene powder is 1 to 10, for example: 1Layer, 2 layers, 3 layers, 4 layers, 5 layers, 6 layers, 7 layers, 8 layers, 9 layers, 10 layers, etc. The specific surface area of the graphene powder is more than 150m 2 G, for example: 150m 2 /g、160m 2 /g、170m 2 /g、180m 2 /g、190m 2 /g、200m 2 /g、220m 2 /g、250m 2 /g、280m 2 /g、300m 2 /g、320m 2 /g、350m 2 /g、380m 2 /g、390m 2 /g、400m 2 And/g, etc. The sheet diameter of the graphene powder is 1 to 40 μm, for example, 1 μm, 2 μm, 3 μm, 5 μm, 8 μm, 10 μm, 15 μm, 18 μm, 20 μm, 25 μm, 28 μm, 30 μm, 35 μm, 38 μm, 40 μm, and the like. The epoxy equivalent of the bisphenol A type liquid epoxy resin is 179-208g/eq, for example: 179g/eq, 180g/eq, 181g/eq, 183g/eq, 185g/eq, 187g/eq, 189g/eq, 190g/eq, 192g/eq, 193g/eq, 195g/eq, 198g/eq, 199g/eq, 200g/eq, 201g/eq, 202g/eq, 203g/eq, 204g/eq, 205g/eq, 206g/eq, 207g/eq, 208g/eq, etc. Common commercial liquid epoxy resins are liquid epoxy resins E54 and E51, with an epoxy equivalent of 179-208 g/eq. Preparing 1-10 layers by oxidation-reduction method, and the specific surface area is more than 150m 2 When the graphene powder has the sheet diameter of 1-40 mu m, the content of the epoxy functional group on the surface of the graphene powder is more than 0.5wt%, particularly 1-2wt%, and the graphene powder can be grafted with the epoxy resin with the epoxy equivalent of 179-208 g/eq.
According to a second embodiment of the present invention, there is shown a method for preparing a graphene modified prepolymer according to the first embodiment of the present invention, comprising the steps of:
s101: mixing graphene powder and a first catalyst, then carrying out first heating stirring, adding bisphenol A type liquid epoxy resin, and carrying out second heating stirring to obtain a first solution;
s102: adding bisphenol A into the first solution, and heating and stirring for the third time to obtain a second solution;
s103: and distilling the second solution under reduced pressure, and removing the first catalyst to obtain the graphene modified prepolymer.
The bisphenol A type liquid epoxy resin is a monomer for preparing high molecular weight epoxy resin, and graphene is directly added in the polymerization process of the epoxy resin monomer, so that the graphene and the epoxy resin monomer basically do not react due to the low activity of the graphene. Preparing a graphene modified prepolymer, reacting graphene with bisphenol A type liquid epoxy resin under the catalysis of a first catalyst, and reacting the reacted bisphenol A type liquid epoxy resin with bisphenol A under the catalysis of the first catalyst. Grafting graphene onto bisphenol A liquid epoxy resin to form a graphene modified prepolymer, wherein the graphene modified prepolymer is micromolecular epoxy resin, and finally, the graphene modified prepolymer needs to be subjected to polymerization reaction to form high-molecular-weight epoxy resin.
In the step S101, the first catalyst is a small-molecular alkyl tertiary amine compound and comprises triethylamine or tripropylamine. The mass ratio of the graphene powder to the bisphenol A type liquid epoxy resin to the bisphenol A to the first catalyst is (0.5-5): (1.4-16): (0.2-3): (5-50), for example: 0.5:1.4:0.2:5, 1:2:1:10, 2:3:1.5:20, 3:5:2:30, 4:10:2.5:40, 4.5:15:2.8:45, 5:16:3:50, etc. In a preferred embodiment, the mass ratio of the graphene powder, the bisphenol a type liquid epoxy resin, the bisphenol a, and the first catalyst is (1-4): (4-12): (0.5-2.5): (10-40), for example: 1:4:0.5:10, 2:6:1:20, 3:8:1.5:30, 3.5:10:2:35, 4:12:2.5:40, etc. In a most preferred embodiment, the mass ratio of the graphene powder, the bisphenol a type liquid epoxy resin, the bisphenol a, and the first catalyst is (2-3): (8-10): (1-2): (20-30), for example: 2:8:1:20, 2.5:9:1.5:25, 3:10:2:30, etc.
The microscopic reaction principle of the alkyl tertiary amine catalyst is as follows: the alkyl tertiary amine catalyst can promote the ring opening of the epoxy functional group, and the epoxy functional group on the surface of the opened graphene can react with the epoxy group of the bisphenol A liquid epoxy resin more easily; after the bisphenol A is added, the residual alkyl tertiary amine catalyst promotes the ring opening of the epoxy functional group of the bisphenol A type liquid epoxy resin, so that the epoxy group of the bisphenol A type liquid epoxy resin and the hydroxyl group of the bisphenol A form ether bond. The first catalyst is alkyl tertiary amine, on one hand, the p-pi conjugation effect is formed by the micromolecule alkyl tertiary amine and the pi bond of the graphene, and the dispersion and the stability of the graphene are facilitated; on one hand, activating the residual functional groups on the surface of the graphene to graft the functional groups with the epoxy groups of the bisphenol A liquid epoxy resin; on the other hand, the epoxy group of the bisphenol A type liquid epoxy resin is activated, and the bisphenol A type liquid epoxy resin and the bisphenol A are subjected to a crosslinking reaction. The reduced graphene has fewer functional groups on the surface, the graphene has lower activity, and in order to ensure that the functional groups of the graphene are completely reacted, the bisphenol A and the bisphenol A type liquid epoxy resin are slightly excessive.
In the step S101, the temperature for the first heating and stirring is 75-85 ℃, for example: 75 deg.C, 76 deg.C, 77 deg.C, 78 deg.C, 79 deg.C, 80 deg.C, 81 deg.C, 82 deg.C, 83 deg.C, 84 deg.C, 85 deg.C, etc. In a preferred embodiment, the temperature of the first temperature-raising stirring is 80 ℃. The time for the first heating and stirring is 1 h. The temperature of the second heating and stirring is 75-85 ℃, for example: 75 deg.C, 76 deg.C, 77 deg.C, 78 deg.C, 79 deg.C, 80 deg.C, 81 deg.C, 82 deg.C, 83 deg.C, 84 deg.C, 85 deg.C, etc. In a preferred embodiment, the temperature of the second temperature-raising stirring is 80 ℃. The second heating stirring speed is 1500-: 1500rpm, 1600rpm, 1700rpm, 1800rpm, 1900rpm, 2000rpm, 2100rpm, 2200rpm, 2300rpm, 2400rpm, 2500rpm, and the like. The time of the second heating and stirring is 2 h. The bisphenol A liquid epoxy resin is liquid, and after the bisphenol A liquid epoxy resin is added into the solution, under the conditions that the stirring speed is 1500-2500rpm, the stirring time is 2 hours and the temperature is 80 ℃, the graphene powder can be uniformly dispersed in the solution, so that the bisphenol A liquid epoxy resin is dispersed and grafted with the graphene powder.
In the step S102, the third heating and stirring method includes: firstly stirring at a low speed to dissolve the bisphenol A, and then stirring at a high speed. The temperature of the third heating stirring is 75-85 ℃, for example: 75 deg.C, 76 deg.C, 77 deg.C, 78 deg.C, 79 deg.C, 80 deg.C, 81 deg.C, 82 deg.C, 83 deg.C, 84 deg.C, 85 deg.C, etc. In a preferred embodiment, the temperature for the third heating and stirring is 80 ℃, and 80 ℃ is the optimal reaction temperature condition of the graphene powder and the bisphenol A. The low speed stirring rate is 300-: 300rpm, 310rpm, 320rpm, 330rpm, 340rpm, 350rpm, 380rpm, 400rpm, 420rpm, 450rpm, 480rpm, 500rpm, 530rpm, 550rpm, 560rpm, 570rpm, 580rpm, 590rpm, 600rpm, and the like. The high-speed stirring rate is 1500-: 1500rpm, 1600rpm, 1700rpm, 1800rpm, 1900rpm, 2000rpm, 2100rpm, 2200rpm, 2300rpm, 2400rpm, 2500rpm, and the like. The high speed stirring time is 2-4h, for example: 2h, 2.2h, 2.5h, 2.8h, 3h, 3.2h, 3.5h, 3.8h and 4 h. Bisphenol A is solid, and the stirring speed is low at 300-600rpm to dissolve bisphenol A, and if the solid is stirred, the speed is too high, so that the solution is easy to splash. After the bisphenol A is dissolved, stirring at a high speed of 1500-.
According to a third embodiment of the invention, a graphene graft modified epoxy resin is shown, which comprises the following raw material components of graphene powder, bisphenol a type liquid epoxy resin, bisphenol a, a first catalyst and a second catalyst, wherein the mass ratio of the graphene powder, the bisphenol a type liquid epoxy resin, the bisphenol a, the first catalyst and the second catalyst is (0.5-5): (70-80): (20-30): (5-50): (0.05-1), for example: 0.5:70:20:5:0.05, 1:72:22:10:0.1, 2:75:25:20:0.5, 3:75:25:35:0.8, 4:78:28:45:0.8, 5:80:30:50:1, and so on. In a preferred embodiment, the mass ratio of the graphene powder, the bisphenol a liquid epoxy resin, the bisphenol a, the first catalyst and the second catalyst is (1-4): (72-78): (22-28): (10-40): (0.1-0.8), for example: 1:72:22:28:10:0.1, 2:74:24:20:0.2, 3:76:26:30:0.5, 3:76:26:30:0.6, 4:78:28:40:0.8, etc. In a preferred embodiment, the mass ratio of the graphene powder, the bisphenol a type liquid epoxy resin, the bisphenol a, the first catalyst and the second catalyst is (2-3): (74-76): (24-26): (20-30): (0.3-0.6), for example: 2:74:24:20:0.3, 2.5:75:25: 0.5, 3:76:26:30:0.6, etc. The graphene can improve the performance of the epoxy resin, but if the graphene is too much and exceeds the proportion, the viscosity of the solution in the preparation process is increased, and the polymerization of the epoxy resin is not uniform; if the amount of graphene is too small, the amount is lower than the above ratio, the graphene cannot exert its advantages in epoxy resin. The graphene powder is prepared by a redox method, wherein the redox method comprises a chemical reduction method or a thermal reduction method, so that the surface of the prepared graphene powder is provided with an epoxy functional group.The content of the epoxy functional group on the surface of the graphene powder is 0.5wt% or more, for example: 0.5wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, 1.8 wt%, 2wt%, 2.2 wt%, 2.5 wt%, 3 wt%, etc. As a preferred embodiment, the content of epoxy functional groups is from 1 to 2% by weight, for example: 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2wt%, etc. The temperature of the thermal reduction process is 1500 ℃ or less, for example: 200 ℃, 210 ℃, 220 ℃, 250 ℃, 300 ℃, 350 ℃, 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃, 750 ℃, 800 ℃, 810 ℃, 820 ℃, 850 ℃, 880 ℃, 900 ℃, 950 ℃, 1000 ℃, 1050 ℃, 1100 ℃, 1150 ℃, 1200 ℃, 1250 ℃, 1300 ℃, 1350 ℃, 1400 ℃, 1450 ℃, 1480 ℃, 1490 ℃, 1500 ℃, etc. As a preferred embodiment, the temperature of the thermal reduction process is from 600 ℃ to 1200 ℃, for example: 600 deg.C, 610 deg.C, 620 deg.C, 630 deg.C, 640 deg.C, 650 deg.C, 700 deg.C, 750 deg.C, 800 deg.C, 850 deg.C, 900 deg.C, 950 deg.C, 1000 deg.C, 1050 deg.C, 1100 deg.C, 1150 deg.C, 1160 deg.C, 1170 deg.C, 1180 deg.C, 1190 deg.C, 1200 deg.C, etc. Partial functional groups are arranged on the surface of the graphene powder prepared by the oxidation-reduction method, and comprise oxygen-containing groups which can be grafted with bisphenol A type liquid epoxy resin better, so that when the graphene powder is prepared by the thermal reduction method, the temperature is required to be below 1500 ℃, partial functional groups are left on the surface of the graphene powder, the temperature is preferably 600-1200 ℃, the content of the functional groups of the graphene powder reaches 1-2wt%, and the grafting reaction is facilitated. The number of layers of the graphene powder is 1 to 10, for example: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. The specific surface area of the graphene powder is more than 150m 2 G, for example: 150m 2 /g、160m 2 /g、170m 2 /g、180m 2 /g、190m 2 /g、200m 2 /g、220m 2 /g、250m 2 /g、280m 2 /g、300m 2 /g、320m 2 /g、350m 2 /g、380m 2 /g、390m 2 /g、400m 2 And/g, etc. The graphene powder has a sheet diameter of 1-40 μm, for example 1 μm2 μm, 3 μm, 5 μm, 8 μm, 10 μm, 15 μm, 18 μm, 20 μm, 25 μm, 28 μm, 30 μm, 35 μm, 38 μm, 40 μm, and the like. The epoxy equivalent of the bisphenol A liquid epoxy resin is 179-208g/eq, for example: 179g/eq, 180g/eq, 181g/eq, 183g/eq, 185g/eq, 187g/eq, 189g/eq, 190g/eq, 192g/eq, 193g/eq, 195g/eq, 198g/eq, 199g/eq, 200g/eq, 201g/eq, 202g/eq, 203g/eq, 204g/eq, 205g/eq, 206g/eq, 207g/eq, 208g/eq, etc. The first catalyst is a small molecule alkyl tertiary amine compound, including triethylamine or tripropylamine. The second catalyst adopts tertiary amine compound, quaternary ammonium salt compound or phosphorus compound. As a preferred embodiment, the second catalyst is tetrabutylammonium bromide, triphenylphosphine, ethyltriphenylphosphine acetate, ethyltriphenylphosphine chloride, ethyltriphenylphosphine bromide, tetraphenylphosphine bromide or benzyltriphenylphosphine bromide.
According to a fourth embodiment of the present invention, a method for preparing a graphene graft modified epoxy resin is presented, wherein the method adopts the raw material components of the graphene graft modified epoxy resin of the third embodiment, and comprises the following steps:
s201: preparing a graphene modified prepolymer by adopting the preparation method of the graphene modified prepolymer in the second embodiment of the invention;
s202: mixing the graphene modified prepolymer with the rest of bisphenol A liquid epoxy resin, and stirring to obtain a third solution;
s203: adding the rest bisphenol A into the third solution, and heating and stirring to obtain a fourth solution;
s204: and adding a second catalyst into the fourth solution, introducing gas, heating and stirring to enable the fourth solution to react under the action of the second catalyst, and cooling to obtain the graphene grafted modified epoxy resin.
In the process of preparing the graphene grafted modified epoxy resin, the bisphenol A and the bisphenol A type liquid epoxy resin are respectively added twice, and the purpose of adding the bisphenol A and the bisphenol A type liquid epoxy resin twice is different.
For two additions of bisphenol a: in step S201, a hydroxyl group of bisphenol a and an epoxy group of the bisphenol a liquid epoxy resin on which the graphene powder is grafted form an ether bond, thereby generating a graphene modified prepolymer with a small molecular weight. In step S203, the bisphenol a is added to react with the bisphenol a type liquid epoxy resin and the graphene modified prepolymer to form a high molecular weight epoxy resin.
For the two-stage addition of bisphenol a type liquid epoxy resin: in step S201, epoxy groups of the bisphenol a liquid epoxy resin react with epoxy groups on the surface of the open-ring graphene powder, so as to graft the graphene powder onto the bisphenol a liquid epoxy resin, thereby generating a graphene modified prepolymer. In step S202, the bisphenol a type liquid epoxy resin is polymerized with the bisphenol a added in step S203 and the graphene modified prepolymer prepared in step S201 to obtain the graphene modified high molecular weight epoxy resin.
The bisphenol A type liquid epoxy resin is a small molecular epoxy resin which has been polymerized and has an epoxy group. The polymerization reaction refers to: under the catalytic action of a second catalyst, epoxy groups of the bisphenol A epoxy resin react with hydroxyl groups of the bisphenol A, the bisphenol A epoxy resin is combined with the bisphenol A through ether bonds, and the molecular weight chain extension generates macromolecular epoxy resin with a linear structure.
In the step S202, the temperature of the graphene modified prepolymer is 50 to 70 ℃, for example: 50 ℃, 51 ℃, 52 ℃, 53 ℃, 55 ℃, 58 ℃, 60 ℃, 62 ℃, 64 ℃,65 ℃, 67 ℃, 68 ℃, 69 ℃, 70 ℃ and the like. The temperature condition of 50 to 70 ℃ is selected because the graphene-modified prepolymer undergoes a side reaction with the newly added bisphenol a type liquid epoxy resin if the temperature of the graphene-modified prepolymer exceeds 70 ℃, and the viscosity of the graphene-modified prepolymer is too high if the temperature of the graphene-modified prepolymer is less than 50 ℃. The stirring speed is 1500-: 1500rpm, 1600rpm, 1700rpm, 1800rpm, 1900rpm, 2000rpm, 2100rpm, 2200rpm, 2300rpm, 2400rpm, 2500rpm, and the like. The stirring time was 1 h. And adding the graphene modified prepolymer into bisphenol A liquid epoxy resin, wherein the solution contains two substances, namely the bisphenol A liquid epoxy resin and the bisphenol A epoxy resin grafted with graphene. The two materials were mixed together and dispersed uniformly by stirring at a stirring speed of 1500-2500rpm for 1 h.
In step S203, the temperature of the temperature rise is 75 to 85 ℃, for example: 75 deg.C, 76 deg.C, 77 deg.C, 78 deg.C, 79 deg.C, 80 deg.C, 81 deg.C, 82 deg.C, 83 deg.C, 84 deg.C, 85 deg.C, etc. The stirring speed is 300-600rpm, for example: 300rpm, 310rpm, 320rpm, 330rpm, 340rpm, 350rpm, 380rpm, 400rpm, 420rpm, 450rpm, 480rpm, 500rpm, 530rpm, 550rpm, 560rpm, 570rpm, 580rpm, 590rpm, 600rpm, and the like. The stirring time was 1 h. The stirring speed of 300-600rpm and the stirring time of 1 hour were selected in order to sufficiently dissolve the solid bisphenol A.
In the step S204, the gas is nitrogen, and in the process of the polymerization reaction, the nitrogen can protect the reaction product at high temperature from being oxidized, and before the high temperature reaction, the nitrogen needs to replace the air in the reaction bottle to protect the reaction system. The temperature raising method is to raise the temperature slowly, the temperature raising temperature is 110-: 1500rpm, 1600rpm, 1700rpm, 1800rpm, 1900rpm, 2000rpm, 2100rpm, 2200rpm, 2300rpm, 2400rpm, 2500rpm, and the like. Controlling the reaction temperature of the fourth solution and the second catalyst within the range of 160-190 ℃, for example: 160 ℃, 161 ℃, 162 ℃, 163 ℃, 165 ℃, 168 ℃, 170 ℃, 172 ℃, 175 ℃, 178 ℃, 180 ℃, 182 ℃, 185 ℃, 188 ℃, 190 ℃ and the like. The polymerization reaction process can automatically release heat, the temperature is easy to lose control when the temperature rises too fast, the reaction is slow when the temperature rises too slow, and the temperature is increased slowly, so that the control of the polymerization reaction temperature is facilitated. The method for controlling the reaction temperature of the fourth solution and the second catalyst is oil bath heating. The reaction time of the fourth solution was 1.5 h. At high temperature, the bisphenol A type liquid epoxy resin and the graphene modified prepolymer can fully react to form high-molecular epoxy resin. However, if the self-elevating temperature of the fourth solution is too high, exceeding 190 ℃, side reactions may occur and the prepared epoxy resin may generate branches or have too wide a molecular weight distribution.
According to a fifth embodiment of the present invention, a graphene graft modified epoxy resin is shown, which is prepared by the method for preparing a graphene graft modified epoxy resin according to the fourth embodiment, and graphene graft modified epoxy resins with different epoxy equivalent weights can be prepared according to different ratios of the molecular weights of bisphenol a type liquid epoxy resin and bisphenol a during preparation, so as to adapt to different application fields.
The advantages of the present invention are explained in detail below with reference to examples and comparative examples:
example 1A:
this example shows a method for preparing a graphene-modified prepolymer, comprising the following steps:
s101: mixing and stirring graphene powder and triethylamine, adding bisphenol A type liquid epoxy resin, raising the temperature to 80 ℃, and stirring for 2 hours at a stirring speed of 1500rpm to obtain a first solution; the mass ratio of the graphene powder to the bisphenol A type liquid epoxy resin to the bisphenol A to the triethylamine is 5:16:3: 50; the graphene powder is prepared by a chemical reduction method; the epoxy equivalent of the bisphenol A type liquid epoxy resin is 179 g/eq;
s102: adding bisphenol A into the first solution, heating the mixed solution to 80 ℃, stirring at 300rpm, and when the bisphenol A is completely dissolved, increasing the stirring speed to 1500rpm, and stirring for 4 hours to obtain a second solution;
s103: and distilling the second solution under reduced pressure to remove triethylamine, thereby obtaining the graphene modified prepolymer.
In the graphene modified prepolymer, the mass ratio of graphene powder, bisphenol A type liquid epoxy resin and bisphenol A is 5:16: 3.
Example 1B:
this example illustrates a process for preparing a graphene graft-modified epoxy resin, which includes the method of preparing the graphene-modified prepolymer of example 1A. The raw material components of the graphene grafted and modified epoxy resin comprise graphene powder, bisphenol A type liquid epoxy resin, bisphenol A, triethylamine and tetrabutylammonium bromide, wherein the mass ratio of the graphene powder to the bisphenol A type liquid epoxy resin to the bisphenol A to the triethylamine to the tetrabutylammonium bromide is 5:75:25:50: 0.1.
The preparation process of the graphene grafted and modified epoxy resin comprises the following steps:
s201: preparing a graphene modified prepolymer according to the method for preparing the graphene modified prepolymer in the embodiment 1A;
s202: mixing the graphene modified prepolymer (with the temperature of 70 ℃) with the rest bisphenol A type liquid epoxy resin, and stirring at the stirring speed of 1500rpm for 1h to obtain a third solution;
s203: adding the rest bisphenol A into the third solution, raising the temperature to 75 ℃, and stirring for 1h at the stirring speed of 300rpm to obtain a fourth solution;
s204: adding tetrabutylammonium bromide into the fourth solution, introducing nitrogen, slowly raising the temperature to 130 ℃, stirring at the rotating speed of 1500rpm for 1.5h, and controlling the reaction temperature within the range of 160-190 ℃ to obtain the graphene grafted modified epoxy resin.
The epoxy equivalent of the graphene grafted and modified epoxy resin prepared by the method for preparing the graphene grafted and modified epoxy resin is 484g/eq, and the content of graphene is 4.76%.
Example 2A:
this example shows a method for preparing a graphene-modified prepolymer, comprising the following steps:
s101: mixing and stirring graphene powder and tripropylamine, adding bisphenol A type liquid epoxy resin, raising the temperature to 80 ℃, and stirring for 2 hours at a stirring speed of 2500rpm to obtain a first solution; wherein the mass ratio of the graphene powder to the bisphenol A type liquid epoxy resin to the bisphenol A to the tripropylamine is 2.5:10:2.5: 40; the graphene powder is prepared by a thermal reduction method at 1500 ℃; the epoxy equivalent of the bisphenol A type liquid epoxy resin is 208 g/eq;
s102: adding bisphenol A into the first solution, heating the mixed solution to 80 ℃, stirring at 600rpm, and when the bisphenol A is completely dissolved, increasing the stirring speed to 2500rpm, and stirring for 2 hours to obtain a second solution;
s103: and distilling the second solution under reduced pressure to remove tripropylamine, thereby obtaining the graphene modified prepolymer.
In the graphene modified prepolymer, the mass ratio of graphene powder, bisphenol A type liquid epoxy resin and bisphenol A is 2.5:10: 2.5.
Example 2B:
this example illustrates a process for preparing a graphene graft-modified epoxy resin, which includes the method of preparing the graphene-modified prepolymer of example 2A. The raw material components of the graphene grafted modified epoxy resin comprise graphene powder, bisphenol A type liquid epoxy resin, bisphenol A, tripropylamine and triphenylphosphine, wherein the mass ratio of the graphene powder to the bisphenol A type liquid epoxy resin to the bisphenol A, to the tripropylamine to the triphenylphosphine is 2.5:80:29:40: 0.2.
The method for grafting and modifying the epoxy resin by the graphene comprises the following steps:
s201: preparing a graphene modified prepolymer according to the method for preparing the graphene modified prepolymer in the embodiment 2A;
s202: mixing the graphene modified prepolymer (with the temperature of 65 ℃) with the rest bisphenol A type liquid epoxy resin, and stirring for 1h at the stirring speed of 2500rpm to obtain a third solution;
s203: adding the rest bisphenol A into the third solution, raising the temperature to 85 ℃, and stirring for 1h at the stirring speed of 600rpm to obtain a fourth solution;
s204: and adding triphenylphosphine into the fourth solution, introducing nitrogen, slowly raising the temperature to 120 ℃, stirring at the rotating speed of 2500rpm for 1.5h, and controlling the reaction temperature within the range of 160-190 ℃ to obtain the graphene grafted modified epoxy resin.
The epoxy equivalent of the graphene grafted and modified epoxy resin prepared by the method for preparing the graphene grafted and modified epoxy resin is 843g/eq, and the content of graphene is 2.24%.
Example 3A:
this example shows a method for preparing a graphene-modified prepolymer, comprising the following steps:
s101: mixing and stirring graphene powder and triethylamine, adding bisphenol A type liquid epoxy resin, raising the temperature to 80 ℃, and stirring for 2 hours at a stirring speed of 2000rpm to obtain a first solution; wherein the mass ratio of the graphene powder to the bisphenol A type liquid epoxy resin to the bisphenol A to the triethylamine is 2:8:1.5: 30; the graphene powder is prepared by a thermal reduction method at 600 ℃; the epoxy equivalent of the bisphenol A type liquid epoxy resin is 200 g/eq;
s102: adding bisphenol A into the first solution, heating the mixed solution to 75 ℃, stirring at 400rpm, and when the bisphenol A is completely dissolved, increasing the stirring speed to 2000rpm, and stirring for 3.5 hours to obtain a second solution;
s103: and distilling the second solution under reduced pressure to remove triethylamine, thereby obtaining the graphene modified prepolymer.
In the graphene modified prepolymer, the mass ratio of graphene powder, bisphenol A type liquid epoxy resin and bisphenol A is 2:8: 1.5.
Example 3B:
this example illustrates a process for preparing a graphene graft modified epoxy resin, which includes the method of example 3A for preparing a graphene modified prepolymer. The graphene grafted and modified epoxy resin comprises the raw material components of graphene powder, bisphenol A type liquid epoxy resin, bisphenol A, triethylamine and ethyl triphenyl phosphine acetate, wherein the mass ratio of the graphene powder to the bisphenol A type liquid epoxy resin to the bisphenol A to the triethylamine to the ethyl triphenyl phosphine acetate is 2:70:30:30: 0.2.
The method for grafting and modifying the epoxy resin by the graphene comprises the following steps:
s201: preparing a graphene modified prepolymer according to the method for preparing the graphene modified prepolymer in example 3A;
s202: mixing the graphene modified prepolymer (with the temperature of 60 ℃) with the rest bisphenol A type liquid epoxy resin, and stirring at the stirring speed of 2000rpm for 1h to obtain a third solution;
s203: adding the rest bisphenol A into the third solution, raising the temperature to 80 ℃, and stirring for 1h at the stirring speed of 400rpm to obtain a fourth solution;
s204: and adding ethyl triphenyl phosphine acetate into the fourth solution, introducing nitrogen, slowly raising the temperature to 120 ℃, stirring at the rotating speed of 2000rpm for 1.5h, and controlling the reaction temperature within the range of 160-190 ℃ to obtain the graphene grafted modified epoxy resin.
The epoxy equivalent of the graphene grafted and modified epoxy resin prepared by the method for preparing the graphene grafted and modified epoxy resin is 1106g/eq, and the content of graphene is 1.96%.
Example 4A:
this example shows a method for preparing a graphene-modified prepolymer, comprising the following steps:
s101: mixing and stirring graphene powder and triethylamine, adding bisphenol A type liquid epoxy resin, raising the temperature to 80 ℃, and stirring for 2 hours at a stirring speed of 1800rpm to obtain a first solution; wherein the mass ratio of the graphene powder to the bisphenol A type liquid epoxy resin to the bisphenol A to the triethylamine is 0.5:4:0.5: 10; the graphene powder is prepared by a thermal reduction method at 1200 ℃; the epoxy equivalent of the bisphenol A type liquid epoxy resin is 190 g/eq;
s102: adding bisphenol A into the first solution, heating the mixed solution to 85 ℃, stirring at 400rpm, and when the bisphenol A is completely dissolved, increasing the stirring speed to 1800rpm, and stirring for 2.5 hours to obtain a second solution;
s103: and distilling the second solution under reduced pressure to remove triethylamine, thereby obtaining the graphene modified prepolymer.
In the graphene modified prepolymer, the mass ratio of graphene powder to bisphenol A liquid epoxy resin to bisphenol A is 0.5:4: 0.5.
Example 4B:
this example illustrates a process for preparing a graphene graft modified epoxy resin, which includes the method of example 4A for preparing a graphene modified prepolymer. The raw material components of the graphene grafted modified epoxy resin comprise graphene powder, bisphenol A type liquid epoxy resin, bisphenol A, triethylamine and ethyl triphenyl phosphine chloride, wherein the mass ratio of the graphene powder to the bisphenol A type liquid epoxy resin to the bisphenol A to the triethylamine to the ethyl triphenyl phosphine chloride is 0.5:70:21:10: 0.1.
The method for grafting and modifying the epoxy resin by the graphene comprises the following steps:
s201: preparing a graphene modified prepolymer according to the method for preparing the graphene modified prepolymer in example 4A;
s202: mixing the graphene modified prepolymer (with the temperature of 55 ℃) with the rest bisphenol A type liquid epoxy resin, and stirring at the stirring speed of 1800rpm for 1h to obtain a third solution;
s203: adding the rest bisphenol A into the third solution, raising the temperature to 80 ℃, and stirring for 1h at the stirring speed of 400rpm to obtain a fourth solution;
s204: and adding ethyl triphenyl phosphonium chloride into the fourth solution, introducing nitrogen, slowly raising the temperature to 125 ℃, stirring at the rotation speed of 1800rpm for 1.5h, and controlling the reaction temperature within the range of 160-190 ℃ to obtain the graphene grafted modified epoxy resin.
The epoxy equivalent of the graphene grafted and modified epoxy resin prepared by the method for preparing the graphene grafted and modified epoxy resin is 447g/eq, and the content of graphene is 0.55%.
Four examples are described above, and the superiority of the prepared graphene graft modified epoxy resin is illustrated by the following drawings:
as shown in FIG. 1, FIG. 1 is a Raman spectrum of graphene grafted modified epoxy resin and common epoxy resin, wherein the D peak is a Raman characteristic peak of carbon atom crystal, which represents defects of carbon atom lattice at 1300cm -1 The graphene grafted and modified epoxy resins prepared in examples 1B-4B have D peaks characteristic of reduced graphene oxide, while the ordinary epoxy resins do not have D peaks.
As shown in fig. 2, fig. 2 is a graph of the thermal weight loss of the graphene graft modified epoxy resin and the common epoxy resin, and the thermal stability of the graphene graft modified epoxy resin is obviously improved compared with the common epoxy resin.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described above, or equivalents may be substituted for elements thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (56)
1. The graphene modified prepolymer is characterized by comprising the following raw material components in percentage by mass (0.5-5): (1.4-16): (0.2-3), mixing graphene powder and a first catalyst, then carrying out first heating stirring, adding bisphenol A type liquid epoxy resin, carrying out second heating stirring, opening an epoxy functional group on the surface of the graphene powder through the first catalyst, grafting the graphene powder onto the bisphenol A type liquid epoxy resin, and carrying out reduced pressure distillation to remove the first catalyst, wherein the first catalyst is a small molecular alkyl tertiary amine compound, and the content of the epoxy functional group on the surface of the graphene powder is more than 0.5 wt%;
the preparation method of the graphene modified prepolymer comprises the following steps:
s101: mixing graphene powder and a first catalyst, then carrying out first heating stirring, adding bisphenol A type liquid epoxy resin, and carrying out second heating stirring to obtain a first solution, wherein the first heating stirring temperature is 75-85 ℃, and the second heating stirring temperature is 75-85 ℃;
s102: adding bisphenol A into the first solution, and heating and stirring for the third time to obtain a second solution, wherein the temperature for heating and stirring for the third time is 75-85 ℃;
s103: and distilling the second solution under reduced pressure, and removing the first catalyst to obtain the graphene modified prepolymer.
2. The graphene modified prepolymer according to claim 1, wherein the mass ratio of the graphene powder to the bisphenol A liquid epoxy resin to the bisphenol A is (1-4): (4-12): (0.5-2.5).
3. The graphene modified prepolymer according to claim 2, wherein the mass ratio of the graphene powder to the bisphenol a liquid epoxy resin to the bisphenol a is (2-3): (8-10): (1-2).
4. The graphene-modified prepolymer according to claim 1, wherein the graphene powder is prepared by a redox method.
5. The graphene modified prepolymer according to claim 4, wherein the redox method comprises a chemical reduction method or a thermal reduction method, so that the prepared graphene powder has an epoxy functional group on the surface.
6. The graphene-modified prepolymer according to claim 5, wherein the epoxy functional group is present in an amount of 1-2 wt%.
7. The graphene-modified prepolymer according to claim 5, wherein the temperature of the thermal reduction process is 1500 ℃ or lower.
8. The graphene-modified prepolymer according to claim 7, wherein the temperature of the thermal reduction process is 600 ℃ to 1200 ℃.
9. The graphene modified prepolymer according to claim 4, wherein the number of graphene powder layers is 1-10.
10. The graphene modified prepolymer of claim 4, wherein the graphene powder has a specific surface area greater than 150m 2 /g。
11. The graphene modified prepolymer of claim 4, wherein the graphene powder has a platelet size of 1-40 μm.
12. The graphene modified prepolymer according to claim 4, wherein the bisphenol A type liquid epoxy resin has an epoxy equivalent of 179-208 g/eq.
13. A method for preparing the graphene-modified prepolymer according to any one of claims 1 to 12, comprising the steps of:
s101: mixing graphene powder and a first catalyst, then carrying out first heating stirring, adding bisphenol A type liquid epoxy resin, carrying out second heating stirring to obtain a first solution, wherein the first catalyst is a micromolecular alkyl tertiary amine compound, opening an epoxy functional group on the surface of the graphene powder through the first catalyst to graft the graphene powder onto the bisphenol A type liquid epoxy resin, and the mass ratio of the graphene powder to the bisphenol A type liquid epoxy resin to the bisphenol A type first catalyst is (0.5-5): (1.4-16): (0.2-3): (5-50), wherein the content of the epoxy functional groups on the surface of the graphene powder is more than 0.5wt%, the temperature for first heating and stirring is 75-85 ℃, and the temperature for second heating and stirring is 75-85 ℃;
s102: adding bisphenol A into the first solution, and heating and stirring for the third time to obtain a second solution, wherein the temperature for heating and stirring for the third time is 75-85 ℃;
s103: and distilling the second solution under reduced pressure to remove the first catalyst, thereby obtaining the graphene modified prepolymer.
14. The method according to claim 13, wherein in S101, the first catalyst is triethylamine or tripropylamine.
15. The method for preparing the graphene modified prepolymer according to claim 13, wherein the mass ratio of the graphene powder, the bisphenol a liquid epoxy resin, the bisphenol a and the first catalyst is (1-4): (4-12): (0.5-2.5): (10-40).
16. The method for preparing the graphene modified prepolymer according to claim 15, wherein the mass ratio of the graphene powder, the bisphenol a type liquid epoxy resin, the bisphenol a and the first catalyst is (2-3): (8-10): (1-2): (20-30).
17. The method for preparing the graphene modified prepolymer according to claim 13, wherein the temperature of the first temperature-raising stirring is 80 ℃.
18. The method for preparing the graphene modified prepolymer according to claim 13, wherein the time for the first temperature-raising stirring is 1 hour.
19. The method for preparing the graphene modified prepolymer according to claim 13, wherein the temperature of the second heating and stirring is 80 ℃.
20. The method for preparing the graphene modified prepolymer according to claim 13, wherein the second temperature-raising stirring speed is 1500-.
21. The method for preparing the graphene modified prepolymer according to claim 13, wherein the time for the second temperature-raising stirring is 2 hours.
22. The method for preparing the graphene modified prepolymer according to claim 13, wherein in S102, the third heating and stirring method includes: firstly, stirring at low speed to dissolve the bisphenol A, and then stirring at high speed.
23. The method for preparing the graphene modified prepolymer according to claim 13, wherein the temperature of the third temperature-raising stirring is 80 ℃.
24. The method for preparing the graphene modified prepolymer according to claim 22, wherein the low-speed stirring speed is 300-600 rpm.
25. The method for preparing the graphene modified prepolymer according to claim 22, wherein the high-speed stirring speed is 1500-2500 rpm.
26. The method for preparing the graphene modified prepolymer according to claim 22, wherein the high-speed stirring time is 2-4 h.
27. The graphene grafted and modified epoxy resin is characterized by comprising the following raw material components in percentage by mass (0.5-5): (70-80): (20-30): (5-50): (0.05-1), the first catalyst is a micromolecular alkyl tertiary amine compound, and the graphene powder is grafted to the bisphenol A liquid epoxy resin by opening the epoxy functional groups on the surface of the graphene powder through the first catalyst;
the preparation method of the graphene grafted and modified epoxy resin comprises the following steps:
s201: preparing a graphene modified prepolymer according to any one of claims 13-26;
s202: mixing the graphene modified prepolymer with the rest of bisphenol A liquid epoxy resin, and stirring to obtain a third solution;
s203: adding the rest bisphenol A into the third solution, and heating and stirring to obtain a fourth solution;
s204: and adding a second catalyst into the fourth solution, introducing gas, heating and stirring to enable the fourth solution to react under the action of the second catalyst, cooling to obtain the graphene grafted modified epoxy resin, and controlling the reaction temperature of the fourth solution and the second catalyst within the range of 160-190 ℃.
28. The graphene graft modification epoxy resin according to claim 27, wherein the mass ratio of the graphene powder, the bisphenol a type liquid epoxy resin, the bisphenol a, the first catalyst and the second catalyst is (1-4): (72-78): (22-28): (10-40): (0.1-0.8).
29. The graphene graft modification epoxy resin according to claim 28, wherein the mass ratio of the graphene powder, the bisphenol a type liquid epoxy resin, the bisphenol a, the first catalyst and the second catalyst is (2-3): (74-76): (24-26): (20-30): (0.3-0.6).
30. The graphene grafted and modified epoxy resin according to claim 27, wherein the graphene powder is prepared by a redox method.
31. The graphene grafted and modified epoxy resin of claim 30, wherein the redox method is a chemical reduction method or a thermal reduction method, and the prepared graphene powder has an epoxy functional group on the surface.
32. The graphene graft modified epoxy resin according to claim 30, wherein the content of the epoxy functional group on the surface of the graphene powder is 0.5wt% or more.
33. The graphene graft modified epoxy resin according to claim 32, wherein the content of the epoxy functional group is 1 to 2 wt%.
34. The graphene graft modified epoxy resin according to claim 31, wherein the temperature of the thermal reduction method is 1500 ℃ or lower.
35. The graphene graft modified epoxy resin according to claim 31, wherein the temperature of the thermal reduction method is 600 ℃ to 1200 ℃.
36. The graphene grafted and modified epoxy resin of claim 30, wherein the number of graphene powder layers is 1-10.
37. The graphene grafted and modified epoxy resin of claim 30, wherein the specific surface area of the graphene powder is greater than 150m 2 /g。
38. The graphene grafted and modified epoxy resin of claim 30, wherein the sheet diameter of the graphene powder is 1-40 μm.
39. The graphene graft modified epoxy resin as claimed in claim 30, wherein the epoxy equivalent of the bisphenol a type liquid epoxy resin is 179-208 g/eq.
40. The graphene graft modified epoxy resin according to claim 27, wherein the first catalyst is triethylamine or tripropylamine.
41. The graphene graft modified epoxy resin according to claim 27, wherein the second catalyst is a tertiary amine compound, a quaternary ammonium compound or a phosphorus compound.
42. The graphene graft modified epoxy resin of claim 41, wherein the second catalyst is tetrabutylammonium bromide, triphenylphosphine, ethyltriphenylphosphine acetate, ethyltriphenylphosphine chloride, ethyltriphenylphosphine bromide, tetraphenylphosphine bromide or benzyltriphenylphosphine bromide.
43. A preparation method of graphene grafted and modified epoxy resin is characterized by adopting the raw material components in claim 28 and comprising the following steps:
s201: preparing a graphene modified prepolymer according to any one of claims 13-26;
s202: mixing the graphene modified prepolymer with the rest of bisphenol A liquid epoxy resin, and stirring to obtain a third solution;
s203: adding the rest bisphenol A into the third solution, and heating and stirring to obtain a fourth solution;
s204: and adding a second catalyst into the fourth solution, introducing gas, heating and stirring to enable the fourth solution to react under the action of the second catalyst, cooling to obtain the graphene grafted and modified epoxy resin, and controlling the reaction temperature of the fourth solution and the second catalyst within the range of 160-190 ℃.
44. The method for preparing the graphene graft modified epoxy resin according to claim 43, wherein in S202, the temperature of the graphene modified prepolymer is 50-70 ℃.
45. The method as claimed in claim 43, wherein in S202, the stirring speed is 1500-2500 rpm.
46. The method for preparing the graphene graft modified epoxy resin according to claim 43, wherein in S202, the stirring time is 1 h.
47. The method for preparing the graphene graft-modified epoxy resin according to claim 43, wherein the temperature for increasing the temperature in S203 is 75-85 ℃.
48. The method as claimed in claim 43, wherein in S203, the stirring speed is 300-600 rpm.
49. The method for preparing the graphene graft modified epoxy resin according to claim 43, wherein in S203, the stirring time is 1 h.
50. The method according to claim 43, wherein in S204, the gas is nitrogen.
51. The method for preparing the graphene graft modified epoxy resin according to claim 43, wherein in S204, the temperature is slowly increased.
52. The method of claim 51, wherein in S204, the temperature is increased to 110-130 ℃.
53. The method as claimed in claim 43, wherein in S204, the stirring speed is 1500-2500 rpm.
54. The method for preparing the graphene grafted and modified epoxy resin according to claim 43, wherein the method for controlling the reaction temperature of the fourth solution and the second catalyst is oil bath heating.
55. The method of claim 43, wherein in S204, the reaction time of the fourth solution is 1.5 h.
56. A graphene graft-modified epoxy resin, which is characterized in that the graphene graft-modified epoxy resin is prepared by the method for preparing the graphene graft-modified epoxy resin according to any one of claims 43 to 55.
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