Ternary nanocomposite flame retardant, flame retardant epoxy resin and method for preparing the same

Abstract

A ternary nanocomposite flame retardant comprises 5 wt.% MXene nanosheets, 45 wt.% layered double metal hydroxide (LDH), and 50 wt.% Cu2O nanocubes. In another aspect, a flame retardant epoxy resin co

Description

TECHNICAL FIELD The present invention relates to the technical field of epoxy resins, and in particular to a ternary nanocomposite flame retardant, a flame retardant epoxy resin and a method for preparing the same. BACKGROUND ART Epoxy resin (EP) has high flammability and can generate a large amount of toxic and harmful gases in the combustion process. The current practice is to add flame retardant to epoxy resin to inhibit the flammability of epoxy resin. The traditional inorganic flame retardant additives, such as aluminum hydroxide and magnesium hydroxide, need to be added in a lot to achieve satisfactory flame retardant effect, and the traditional flame retardant additives can only inhibit the heat release rate of polymeric materials in the combustion process without inhibiting the toxic gases and smoke generated in the combustion process. SUMMARY It is an object of the present invention to provide a ternary nanocomposite flame retardant and a flame retardant epoxy resin, wherein the ternary nanocomposite flame retardant can achieve good flame retardancy of the epoxy resin with a low addition amount (< 6% wt), reduce the heat release rate during the combustion of the epoxy resin, inhibit the generation of toxic and harmful fumes and gases during the combustion, and enhance the mechanical properties of the epoxy resin. The technical solution adopted by the present invention is: A ternary' nanocomposite flame retardant comprises MXene nanosheets, layered double metal hydroxides(LDH), and cuprous oxide nanocubes; in percentage by mass, 5% MXene nanosheets, 45% layered double metal hydroxides, and 50% cuprous oxide nanocubes. Mxene nanosheets have a highly thermally stable layered structure, which can act as a rigid barrier to prevent the transfer of fragments, thereby improving the fire safety of polymers. LDH decomposes endothermically, which reduces the heat release of combustion of the polymer, and the catalytic carbon sequestration effect of cuprous oxide reduces the generation of harmful gases and fumes. All three components produce metal oxides that can reinforce the carbon layer during combustion.Compactcarbon layer can serveas physical barriers, hinder heat and oxygen transfer, and improve flame retardancy. A method for preparing a ternary nanocomposite flame retardant comprising: step 1, preparation of MXene nanosheets; firstly, lithium fluoride powder is dissolved into hydrochloric acid, Tii AIC? powder is added into the mixed solution, kept stirring, and reacted in a water bath; the product is then centrifuged and washed with deionized water; finally, the product is dispersed in deionizedwater for ultrasonic treatment, and then placed in a centrifuge for centrifugal separation to prepare a dispersion of TisCiTx; step 2, preparation of CoNi-LDH / MXene; the Ti3C2Tx dispersion prepared in step 1 and cobalt nitrate hexahydrate are dispersed in deionized water, and are ultrasonically stirred in a three-neck flask, then a methanol solution containing dimethylimidazole is added to the three-neck flask, and is stirred to prepare a ZIF-67 / MXene solution; an ethanol solution containing nickel nitrate hexahydrate is added into the ZIF-67 / MXene solution, stirred, then placed same into a centrifuge for centrifugal treatment, washed with deionizedwater for three times after centrifugation, and washed with ethanol for three times, and vacuum -dried the product to prepare a CoNi-LDH / MXene powder; step 3, preparation of CiuO / CoNi-LDH / MXene; a copper nitrate trihydrate solution and a sodium hydroxide solution are mixed and stirred, then an ascorbic acid aqueous solution is added, stirred under water bath conditions, and then centrifuged to obtain a precipitate, the precipitate is washed with deionized water and ethanol, and finally the product is dried in vacuum to prepare a cuprous oxide CU2O nanocube powder; the CU2O powder and the CoNi-LDH / MXene powder prepared in step 2 are mixed in a mass ratio of 1: 1, dispersed same in deionized water, and the two are combined through hydrothermal treatment; the product is placed into a centrifuge for centrifugal treatment, then the precipitate is taken out, washed with deionizedwater for three times, ethanol for three times, and then vacuum dried to prepare a CuiO / CoNi-LDH / Mxene ternary nanocomposite flame retardant with a structure in which a layered double metal hydroxide grows on MXene nanosheets, and cuprous oxide nanocubes adhere to the surface of the layered double metal hydroxide. The bimetallic hydroxide grows on the MXene nanosheets, and the cuprous oxide nanocubes attach to the layered bimetallic hydroxide surface, forming a unique "sheet + sheet + dot" structure, which can make the three components exert synergistic flame retardant effect and improve the mechanical properties of the polymer. As a preferred example, a method for preparing a ternary' nanocomposite flame retardant comprises: step 1, preparation of MXene nanosheets; Firstly, 1g of lithium fluoride powder is dissolved in 20 mL of hydrochloric acid, with the hydrochloric acid concentration being 9 mol / L, and 1g of TnAIC? powder is added into the mixed solution, kept stirring, and reacted for 24h at 35 °C in a water bath; the product is then centrifuged and washed with deionized water until the pH reached 6-7; finally, the product is dispersed in deionizedwater for ultrasonic treatment for Ih, and then placed in a centrifuge for centrifugal separation at a rotation speed of 3500 rpm to prepare a dispersion of ThCiTyi step 2, preparation of CoNi-LDH / MXene; the TisCiTx dispersion prepared in step 1 and 5g of cobalt nitrate hexahydrate are dispersed in 200 mL of deionized water, ultrasonically stirred lOmin in a three-neck flask, wherein the Ti3C2Tx dispersion comprises 0.2g TnCiTx. then 200 mL of a methanol solution containing 6g of dimethylimidazole is added to the three-neck flask, and is stirred for 12h to prepare a ZIF-67 / MXene solution; 200 mL of an ethanol solution containing 5g of nickel nitrate hexahydrate is added into the ZIF-67 / MXene solution, stirred for 1011, then placed same into a centrifuge for centrifugal treatment, with the centrifugal rotation speed being 10000 rpm, washed with deionizedwater for three times after centrifugation, and washed with ethanol for three times, and vacuum-dried the product to prepare a CoNi-LDH / MXene powder; step 3, preparation of CmO / CoNi-LDH / MXcnc; 300 mL of a 0.01 mol / L copper nitrate trihydrate solution and 60 mL of a 1 mol / L sodium hydroxide solution are mixed, stirred for 30 min, then 60 mL of a 0.5 mol / L ascorbic acid aqueous solution is added, stirred for 3h at 50 °C under water bath conditions, centrifuged at the rotation speed of 10000 rpm to obtain a precipitate, the precipitate is washed with deionized water and ethanol, and finally the product is dried in vacuum at 60 °C to prepare a cuprous oxide G12O nanocube powder; the CuzO powder and the CoNi-LDH / MXene powder prepared in step 2 are mixed in a mass ratio of 1: 1, dispersed same in deionized water, and the two are combined through a hydrothermal treatment at 120 °C; the product is placed into a centrifuge for centrifugal treatment at the rotation speed of 10000 rpm, then the precipitate is taken out, washed with deionizedwater for three times, ethanol for three times, and then vacuum-dried to prepare a Cu2O / CoNi-LDH / MXene nanocomposite flame retardant material, namely, preparing CLMXene with the mass ratio of MXene nanosheets, layered double metal hydroxide and cuprous oxide nanocubes being 1: 9: 10. A flame retardant epoxy resin comprises a ternary nanocomposite flame retardant or a single component thereof, an epoxy resin and a curing agent, in percentage by mass, the ternary nanocomposite flame retardant or a single component thereof accounts for 2%, the epoxy resin accounts for 80.4% and the curing agent accounts for 17.6%, and the components of the ternary nanocomposite flame retardant comprises 5% MXene nanosheets, 45% layered double metal hydroxide and 50% cuprous oxide nanocubes. The epoxy resin incorporated with 2% CLMXene composite flame retardant had the best comprehensive performance, increased the combustion residual carbon rate and the limiting oxygen index of epoxy resin, reduced the maximum mass loss rate, and reduced the corresponding temperature. Preferably, the curing agent is 4, 4’diaminodiphenyl methane, which is capable of imparting excellent electrical properties, corrosion resistance, heat resistance, impact resistance and the like to the epoxy resin. A method for preparing a flame retardant epoxy resin specifically comprises: dispersing a powder of CLMXene or CU2O or CoNi-LDH or MXene in acetone, after ultrasonic treatment in a flask, adding an epoxy resin for stirring, placing the flask in an oil bath for stirring, evaporating the acetone, adding a curing agent in a molten state for stirring, pouring the mixture into a mould, placing the mould in an oven for curing, and then naturally cooling to prepare a flame retardant epoxy resin. Specifically, CLMXene is incorporated in an amount of 2% to 6% by mass. The high flame retardancy of epoxy resin can be achieved with lower content (< 6% wt). The residual carbon rate and limiting oxygen index at 2%, 4% and 6% are increased, the maximum mass loss rate and the temperature corresponding to the maximum mass loss rate are decreased. The tensile strength, elongation at break, flexural strength and flexural modulus are increased. As a preferred example, the CLMXene is incorporated in an amount of 2% by mass, namely, CLMXene: (epoxy resin + curing agent) = 2: 98, wherein the mass ratio of epoxy resin to curing agent is 4.58: 1. The composite flame retardant incorporated with 2% CLMXene showed better flame retardancy and mechanical properties than the composite flame retardant with 2% single-component CU2O or CoNi-LDH or MXene. When 4% and 6% CLMXene incorporated in the composite flame retardant, the flame retardancy was better, but more flame retardant could destroy the network structure of epoxy resin, resulting in the decrease of mechanical properties. Specifically, the mold is placed in an oven and cured by: the temperature was maintained at 100 °C for 2h and then increased to 150 °C for 2h. Advantageous effects of the present invention are: 1. According to the method for preparing the composite flame retardant of the present invention, a CuiO / CoNi-LDH / MXene flame retardant with a "sheet + sheet + dot" structure is prepared, and the composite flame retardant has a very good flame retardant effect on an epoxy resin, can greatly increase the combustion residual carbon rate and the limiting oxygen index of the epoxy resin, lower the decomposition rate of the epoxy resin, and can also improve the mechanical properties of the epoxy resin, including tensile strength and flexural strength, and can also greatly inhibit the release of heat and toxic fumes when the epoxy resin is burned. 2. The flame retardant epoxy resin of the present invention can achieve high flame retardancy at a relatively low addition amount of flame retardant (< 6% wt), and the flame retardant epoxy resin obtained by the preparation method has good flame retardancy, a slow heat release rate during combustion, less toxic smoke generation, excellent performance in reducing polymer fire toxicity, and high tensile strength and flexural strength. BRIEF DESCRIPTION OF THEFIGURES Fig. 1 shows a scanning electron microscope image of a ternary nanocomposite flame retardant and its intermediates; wherein Fig. 1 (a) shows the structure of MXene; Fig. 1 (b) shows the structure of CoNi-LDH / MXene; Fig. 1 (c) shows the overall structure of CLMXene; Fig. 1 (d) shows a partially enlarged structure of FIG. 1 (c); Fig. 1 (e) shows a partially enlarged structure of FIG. 1 (d); Fig. 1 (f) shows an energy spectrum scan of CLMXene. Fig. 2 is a thermogravimetric curve under nitrogen of a commercially available epoxy resin and a flame retardant epoxy resin prepared in Comparative Examples 1 to 3 and Examples 2 to 4, respectively; wherein, Fig. 2 (a) is a TG curve under nitrogen of the above epoxy resin; Fig. 2 (b) is a DTG plot under nitrogen of the above epoxy resin. Fig. 3 shows the results of limiting oxygen index tests of commercially available epoxy resins and flame retardant epoxy resins prepared in Comparative Examples 1 to 3 and Examples 2 to 4, respectively. Fig. 4 shows results of mechanical property tests of commercially available epoxy resins and flame retardant epoxy resins prepared in Comparative Examples 1 to 3 and Examples 2 to 4, respectively; wherein Fig. 4 (a) shows the tensile strength; Fig. 4 (b) is a bar graph of flexural strength and flexural modulus, where the left column is flexural strength and the right column is flexural modulus. Fig. 5 is a graph showing cone calorimetiy test results of commercially available epoxy resins and flame retardant epoxy resins prepared in Comparative Examples 1 to 3 and Examples 2 to 4, respectively; wherein, Fig. 5 (a) shows the maximum heat release rate; Fig. 5 (b) shows the total heat release; Fig. 5 (c) shows the maximum smoke production rate; Fig. 5 (d) shows the total smoke production. DETAILED DESCRIPTION OF THE EMBODIMENTS The invention will be explained in further detail with reference to the accompanying drawings and detailed description, but it should be understood that the scope of the present invention is not limited to the detailed description. Example 1 This example is a method for preparing a ternary nanocomposite flame retardant, specifically comprising: step 1, preparation of MXene nanosheets; wherein the molecular formula of the MXene nanosheets isTijCzTx. Firstly, 1g of lithium fluoride powder is dissolved in 20 mL of hydrochloric acid, with the hydrochloric acid concentration being 9 mol / L, and 1g of TijAlCi powder is added into the mixed solution, kept stirring, and reacted for 24h at 35 °C in a water bath; the product is then centrifuged and washed with deionized water until the pH reached 6-7; finally, the product is dispersed in deionizedwater for ultrasonic treatment for Ih, and then placed in a centrifuge for centrifugal separation at a rotation speed of 3500 rpm to prepare a dispersion of TrLM^ Step 2, preparation of CoNi-LDH / MXene; wherein CoNi-LDH is a CoNi layer bimetallic hydroxide. The TigCzTx dispersion prepared in step 1 (containing 0.2g TisCzTx) and 5g of cobalt nitrate hexahydrate are dispersed in 200 mL of deionized water, ultrasonically stirred lOmin in a three-neck flask, and then 200 mL of a methanol solution containing 6g of dimethylimidazole is added to the three-neck flask and stirred for 12h to prepare a ZIF-67 / MXene solution. 200 mL of an ethanol solution containing 5g of nickel nitrate hexahydrate is added into the ZIF-67 / MXene solution, stirred for lOh, then placed same into a centrifuge for centrifugal treatment, with the centrifugal rotation speed being 10000 rpm, washed withdeionized water for three times after centrifugation, and washed with ethanol for three times, and vacuum dryied the product to prepare a CoNi-LDH / MXene powder. Step 3, preparation of CmO / CoNi-LDH / MXene 300 mL of a 0.01 mol / L copper nitrate trihydrate solution and 60 mL of a 1 mol / L sodium hydroxide solution are mixed, stirred for 30 min, then 60 mL of a 0.5 mol / L ascorbic acid aqueous solution is added, stirred for 3h at 50 °C under water bath conditions, centrifuged at the rotation speed of 10000 rpm to obtain a precipitate, the precipitate is washed with deionized water and ethanol, and finally the product is dried in vacuum at 60 °C to prepare a cuprous oxide nanocube powder. The CujO powder and the CoNi-LDH / MXene powder prepared in step 2 are mixed in a mass ratio of 1: 1, dispersed same in deionized water, and the two are combined through a hydrothermal treatment at 120 °C; the product is placed into a centrifuge for centrifugal treatment at the rotation speed of 10000 rpm, then the precipitate is taken out, washed with deionizedwater for three times, ethanol for three times, and then vacuum-dried to prepare a GuO / CoNi-LDH / MXene nanocomposite flame retardant material, namely, preparing CLMXene with the mass ratio of MXene nanosheets, layered double metal hydroxide and cuprous oxide nanocubes being 1:9: 10. The layered double metal hydroxide grows on the MXene nanosheets, and the cuprous oxide nanocubes adhere to the surface of the layered double metal hydroxide, forming a unique "sheet + sheet + dot" structure. As shown in Fig. 1, the scanning electron microscope images of ternary nanocomposite flame retardants are shown, wherein (a) is MXene nanosheets, (b) is bimetallic hydroxides grown on MXene nanosheets, and the layered structure of LDH can be clearly seen, and (c) to (f) are structural enlargement and energy spectrum scanning images of CLMXene, and the LDH structure and cuprous oxide nanocubes on MXene nanosheets can be seen. Example 2 This example is a method for preparing a flame retardant epoxy resin, specifically comprising: 2g of CuzO / CoNi-LDH / MXene powder is dispersed in acetone, after ultrasonic treatment for Ih in a flask, 80.4g of epoxy resin is added, stirred for 30min, the flask is placed in a 90 °C oil bath for stirring, acetone is evaporated, 17.6g of molten 4, 4’ diaminodiphenyl methane is added, stirred for 30s, the mixture is poured into a mould, the mould is placed in an oven for curing, the curing temperature is 100 °C and maintained for 2h, then the temperature is increased to 150 °C and maintained for 2h, and the temperature is naturally decreased to prepare a flame retardant epoxy resin. The curing agent in this example is 4, 4’diaminodiphenyl methane. In this example, the mass percent incorporation of CLMXene is 2%, namely, CLMXene: (epoxy resin + curing agent) = 2: 98, wherein the mass ratio of epoxy resin to curing agent is 4.58: 1. Example 3 This example is also a method for preparing a flame retardant epoxy resin, which differs from Example 2 in that CLMXene is incorporated in a mass percentage of 4%, specifically: 4g of Cu2O / CoNi-LDH / MXene powder is dispersed in acetone, after ultrasonic treatment for Ih in a flask, 78.8g of epoxy resin is added, stirred for 30min, the flask is placed in a 90 °C oil bath for stirring, acetone is evaporated, 17.2g of molten 4, 4’ diaminodiphenyl methane is added, stirred for 30s, the mixture is poured into a mould, the mould is placed in an oven for curing, the curing temperature is 100 °C and maintained for 2h, then the temperature is increased to 150 °C and maintained for 2h, and the temperature is naturally decreased to prepare a flame retardant epoxy resin. Example 4 This example is also a method for preparing a flame retardant epoxy resin, which differs from Example 2 in that CLMXene is incorporated in a mass percentage of 6%, specifically: 6g of CmO / CoNi-LDH / MXcnc powder is dispersed in acetone, after ultrasonic treatment for Ih in a flask, 77.2g of epoxy resin is added, stirred for 30min. the flask is placed in a 90 °C oil bath for stirring, the acetone is evaporated, 16.8g of 4, 4’ diaminodiphenyl methane in a molten state is added, stirred for 30s, the mixture is poured into a mould, the mould is placed in an oven for curing, the curing temperature is 100 °C, the temperature is maintained for 2h, then the temperature is increased to 150 °C, the temperature is maintained for 2h, and the temperature is naturally decreased to prepare a flame retardant epoxy resin. Comparative Example 1 This example is also a method for preparing a flame retardant epoxy resin, which differs from Example 2 in that CmO is incorporated into the epoxy resin, the mass percentage of incorporation of C112O being 2%, and the specific method is as follows: 2g of CuiO powder is dispersed in acetone; after ultrasonic treatment for Ih in a flask, 80.4g of epoxy resin is added, stirred for 30mm; tire flask is placed in a 90 °C oil bath and stirred; acetone is evaporated; 17.6g of 4, 4’ diaminodiphenyl methane in a molten state is added, and stirred for 30s; the mixture is poured into a mould, and the mould is placed in an oven for curing; the curing temperature is 100 °C and maintained for 2h; then the temperature is increased to 150 °C and maintained for 2h; finally, a flame-retardant epoxy resin is prepared by naturally cooling. Comparative Example 2 This example is also a method for preparing a flame-retardant epoxy resin, and differs from Example 2 in that CoNi-LDH is incorporated into an epoxy resin for preparation, wherein the mass percentage of incorporation of CoNi-LDH is 2%, and the specific method is as follows: 2g of CoNi-LDH powder is dispersed in acetone; after ultrasonic treatment for Ih in a flask. 80.4g of epoxy resin is added, stirred for 30mm; the flask is placed in a 90 °C oil bath and stirred; acetone is evaporated; 17.6g of 4, 4’ diaminodiphenyl methane in a molten state is added, and stirred for 30s; the mixture is poured into a mould, and the mould is placed in an oven for curing; the curing temperature is 100 °C and maintained for 2h; then the temperature is increased to 150 °C and maintained for 2h; finally, a flame-retardant epoxy resin is prepared by naturally cooling. Comparative Example 3 This example is also a method for preparing a flame retardant epoxy resin, which differs from example 2 in that MXene is incorporated into the epoxy resin, the mass percentage of incorporation of MXene being 2%, and the specific method is as follows: 2g of MXene powder is dispersed in acetone; after ultrasonic treatment for Ih in a flask, 80.4g of epoxy resin is added, stirred for 30min; the flask is placed in a 90 °C oil bath and stirred; acetone is evaporated; 17.6g of 4, 4’ diaminodiphenyl methane in a molten state is added, and stirred for 30s; the mixture is poured into a mould, and the mould is placed in an oven for curing; the curing temperature is 100 °C and maintained for 2h; then the temperature is increased to 150 °C and maintained for 2h; finally, a flame-retardant epoxy resin is prepared by naturally cooling. Comparison and analysis of examples and comparative examples: Thermogravimetric analysis under nitrogen was carried out on the epoxy resin without ternary nanocomposite flame retardant and the flame retardant epoxy resin samples prepared in comparative Examples 1, 2, 3, examples 2, 3 and 4, respectively. The thermal degradation process of the samples under nitrogen was studied and the limiting oxygen index of the samples was tested. The data are shown in Table 1. Table 1 Thermogravimetric analysis and limiting oxygen index of epoxy resin samples under nitrogen atmosphere Sample Residual carbon rate (wt%) Maximum mass loss (% / °C) Temperature corresponding to maximum mass loss (°C) Limiting oxygen index (%) EP 13.82 1.52 403 24.6 2%Mxene 15.57 1.37 398.67 27.3 2%LDH 12.22 1.68 377.33 28.8 2%Cu2O 18.95 1.06 399.33 26.5 2%CLMMXene 18.38 1.27 387.33 28.1 4%CLMXene 19.78 1.35 382 29.3 6%CLMXene 21.32 1.13 381 30 It can be seen from Table 1 that the addition of the flame retardant increases the combustion residual carbon rate and the limiting oxygen index of the epoxy resin, especially the addition of the ternary nanocomposite flame retardant greatly increases the combustion residual carbon rate and the limiting oxygen index of the epoxy resin, which indicates that the ternary nanocomposite flame retardant catalyzes the decomposition of the epoxy resin, resulting in a decrease in the temperature corresponding to the maximum mass loss rate, and the carbon formed by the catalytic decomposition acts as a barrier to hinder the transfer of heat and debris. The residual carbon rate of EP with 2% CLMXene reaches 18.38%, which is higher than that of EP with 2% Mxene and 2% CoNi-LDH, only slightly lower than that of EP with 2% CmO (18.96%). The residual carbon rate of EP with 4% CLMXene and 6% CLMXene are improved to 19.78% and 21.32%, respectively. As shown in the DTG curve of Fig. 2, the maximum mass loss rate decreased from 1.52% / °C for the pure epoxy resin to 1.27% / °C with the addition of 2% CLMXene, indicating that the addition of 2% CLMXene flame retardant can inhibit the decomposition rate of epoxy resin. The temperature corresponding to the maximum mass loss decreased from 403 °C to 387.33 °C for the pure epoxy resin, indicating that the addition of 2% CLMXene flame retardant can greatly inhibit the heat release during the combustion of epoxy resin. As shown in Fig. 3, the limiting oxygen index of epoxy resin with 2% CLMXene is 28.1%, which was higher than that of epoxy resin with 2% Mxene and 2% Cu2O alone, indicating that the flame retardant with 2% CLMXene can effectively improve the combustion difficulty of epoxy resin. Although the limiting oxygen index of epoxy resin added with 2% CoNi-LDH is the highest, the thermal gravimetric analysis results of 2% CoNi-LDH epoxy resin are not good, the residual carbon rate is the lowest, and the maximum mass loss rate is also the highest due to the easy decomposition of LDH and rapid collapse of structure. In conclusion, the flame retardant effect of ternary nanocomposite flame retardant is better than that of singly adding one component, and the effect of epoxy resin with 2% CLMXene is better. The addition of CLMXene can also enhance the mechanical properties of EP, including tensile 5 strength and flexural strength. The results of mechanical tests are shown in Table 2 and Fig. 4. The mechanical property of the CLMXene composite flame retardant is improved by more than that of a single-component flame retardant by the same addition amount of 2%, and compared with pure epoxy resin, the tensile strength and the flexural strength are respectively improved by 44.97% and 14.72% by adding 2% of CLMXene. The advantage of adding 2% CLMXene was 10 proved. Table 2 Mechanical property data of epoxy resin samples Sample Tensile strength (MPa) Elongation at break (%) Flexural strength (MPa) Flexural modulus (MPa) EP 45.19 12.62 87.69 1234 2%Mxene 35.53 7.9 69.3 2310 2%LDH 50.02 13.75 84 2363 2%Cu2O 56.17 13.1 95.11 2548 2%CLMXene 65.51 14.1 100.6 3592 4%CLMXene 62.57 14.98 109.8 3776 6%CLMXene 51.18 13.53 125.6 3425 The effect of CLMXene composite flame retardants on the combustion hazard of epoxy resins was further investigated by cone calorimetry testing and the results are shown in Fig. 5 and Table 15 3. Table 3 Cone calorimetry test data for epoxy resin Samples Sample Maximum heat release rate (Kw / m2) Total heat release (MJ / nr) Maximum smoke production Total smoke production (m2) rate (m2 / s) EP 2171.73 128.13 0.46 27.44 2%CLMXene 1509.29 98.97 0.42 21.14 4%CLMXene 1340.92 94.85 0.35 18.4 6%CLMXene 1228.80 88.12 0.27 15.88 The maximum heat release rate and total heat release of pure epoxy resin were 2171.73 kW / nr and 128 MJ / m2, respectively. When 2% CLMXene was added, the maximum heat release rate was 1509.29 kW / m2 and total heat release was 98.97 MJ / m2, which decreased by 30.47% and 22.76%, respectively. With the addition of 4% and 6% CLMXene, the maximum heat release rate decreased by 38.26% and 43.42%, respectively, and the total heat release decreased by 25.97% and 31.22%, respectively, indicating that the addition of CLMXene can greatly inhibit the heat release during the combustion of epoxy resin. Many studies indicate that in real fires, the release of large amounts of smoke and toxic gases is a major fatal hazard. Therefore, more attention should be paid to the inhibition of toxic volatiles. The maximum smoke production rate and total smoke production of epoxy resin were 0.46 m2 / s and 27.44 m2, respectively. When 2% CLMXene was added, the maximum smoke production rate was 0.42 m2 / s and total smoke production was 21.14 m2, which decreased by 8.7% and 23%, respectively. With the addition of 4% and 6% CLMXene, the maximum smoke production rate decreased by 23.91% and 41.3%, respectively, and the total smoke production decreased by 32.94% and 42.13%, respectively, indicating that the addition of CLMXene flame retardant can reduce the emission of toxic smoke during the combustion of epoxy resin, excellent performance in reducing polymer fire toxicity. The non-illustrated parts involved in the present invention are the same as or implemented using the prior art. The foregoing is merely a preferred example of the present invention and the present invention is not limited to the details of the example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the invention, and any changes and modifications made are within the scope of the invention.

Claims

1. A ternary nanocomposite flame retardant, characterized by comprising MXene nanosheets, layered double metal hydroxides, and cuprous oxide nanocubes; in percentage by mass, 5% MXene nanosheets, 45% layered double metal hydroxides, and 50% cuprous oxide nanocubes.

2. The method for preparing a ternary nanocomposite flame retardant according to claim 1, characterized by comprising:step 1, preparation of MXene nanosheets;firstly, lithium fluoride powder is dissolved into hydrochloric acid, Tn A1C powder is added into the mixed solution, kept stirring, and reacted in a water bath; the product is then centrifuged and washed with deionized water; finally, the product is dispersed in deionizedwater for ultrasonic treatment, and then placed in a centrifuge for centrifugal separation to prepare a dispersion of Ti3C2Tx;step 2, preparation of CoNi-LDH / MXene;the TisCiTx dispersion prepared in step 1 and cobalt nitrate hexahydrate are dispersed in deionized water, and are ultrasonically stirred in a three-neck flask, then a methanol solution containing dimethylimidazole is added to the three-neck flask, and is stirred to prepare a ZIF-67 / MXene solution; an ethanol solution containing nickel nitrate hexahydrate is added into the ZIF-67 / MXene solution, stirred, then placed same into a centrifuge for centrifugal treatment, washed with deionizedwater for three times after centrifugation, and washed with ethanol for three times, and vacuum-dried the product to prepare a CoNi-LDH / MXene powder;step 3, preparation of CmO / CoNi-LDH / MXene;a copper nitrate trihydrate solution and a sodium hydroxide solution are mixed and stirred, then an ascorbic acid aqueous solution is added, stirred under water bath conditions, and then centrifuged to obtain a precipitate, the precipitate is washed with deionized water and ethanol, and finally the product is dried in vacuum to prepare a cuprous oxide CtoO nanocube powder;the CmO powder and the CoNi-LDH / MXene powder prepared in step 2 are mixed in a mass ratio of 1: 1, dispersed same in deionized water, and the two are combined through hydrothermal treatment; the product is placed into a centrifuge for centrifugal treatment, then the precipitate is taken out, washed with deionizedwater for three times, ethanol for three times, and then vacuumdried to prepare a Cu2O / CoNi-LDH / Mxene ternary nanocomposite flame retardant with a structure in which a layered double metal hydroxide grows on MXene nanosheets, and cuprous oxide nanocubes adhere to the surface of the layered double metal hydroxide.

3. The method for preparing a ternary nanocomposite flame retardant according to claim 2, characterized in that the ternary nanocomposite flame retardant comprises 5% MXene nanosheets, 45% layered double metal hydroxide and 50% cuprous oxide nanocubes in percentage by mass.

4. The method for preparing a ternary nanocomposite flame retardant according to claim 3, characterized by comprising:step 1, preparation of MXene nanosheets;Firstly, 1g of lithium fluoride powder is dissolved in 20 ml of hydrochloric acid, with the hydrochloric acid concentration being 9 mol / L, and 1g of TisAlCi powder is added into the mixed solution, kept stirring, and reacted for 24h at 35 °C in a water bath; the product is then centrifuged and washed with deionized water until the pH reached 6-7; finally, the product is dispersed in deionizedwater for ultrasonic treatment for Ih, and then placed in a centrifuge for centrifugal separation at a rotation speed of 3500 rpm to prepare a dispersion of Ti3C2Tx;step 2, preparation of CoNi-LDH / MXene;the TisC2Tx dispersion prepared in step 1 and 5g of cobalt nitrate hexahydrate are dispersed in 200 mL of deionized water, and are ultrasonically stirred in a three-neck flask for 10 min, wherein the TisCzTx dispersion comprises 0.2g Ti3C2Tx, then 200 mL of a methanol solution containing 6g of dimethylimidazole is added in the three-neck flask, and is stirred for 12h to prepare a ZIF-67 / MXene solution; 200 mL of an ethanol solution containing 5g of nickel nitrate hexahydrate is added into the ZIF-67 / MXene solution, stirred for lOh, then placed same into a centrifuge for centrifugal treatment, with the centrifugal rotation speed being 10000 rpm, washed with deionizedwater for three times after centrifugation, and washed with ethanol for three times, and vacuum dryied the product to prepare a CoNi-LDH / MXene powder;step 3, preparation of Cu2O / CoNi-LDH / MXene;300 mL of a 0.01 mol / L copper nitrate trihydrate solution and 60 mL of a 1 mol / L sodium hydroxide solution are mixed, stirred for 30min, then 60 mL of a 0.5 mol / L ascorbic acid aqueous solution is added, stirred for 3h at 50 °C in a water bath, and centrifuged at the rotationspeed of 10000 rpm to obtain a precipitate, the precipitate is washed with deionized water and ethanol, and finally the product is dried in vacuum at 60 °C to prepare a cuprous oxide Cu?O nanocube powder.the CuiO powder and the CoNi-LDH / MXene powder prepared in step 2 are mixed in a mass ratio of 1: 1, dispersed same in deionized water, and the two are combined through a hydrothermal treatment at 120 °C; the product is placed into a centrifuge for centrifugal treatment at the rotation speed of 10000 rpm, then the precipitate is taken out, washed with deionizedwater for three times, ethanol for three times, and then vacuum dried to prepare a Cu2O / CoNi-LDH / MXene nanocomposite flame retardant material, namely, preparing CLMXene with the mass ratio of MXene nanosheets, layered double metal hydroxide and cuprous oxide nanocubes being 1: 9: 10.

5. A flame retardant epoxy resin, characterized by comprising a ternary nanocomposite flame retardant or a single component thereof, an epoxy resin and a curing agent; in percentage by mass, the ternary' nanocomposite flame retardant or a single component thereof accounts for 2%, the epoxy resin accounts for 80.4% and the curing agent accounts for 17.6%, and the components of the ternary nanocomposite flame retardant comprise 5% MXene nanosheets, 45% layered double metal hydroxide and 50% cuprous oxide nanocubes.

6. A flame retardant epoxy resin according to claim 5, characterized in that the curing agent is 4, 4’diaminodiphenyl methane.

7. The method for preparing a flame retardant epoxy resin according to claim 5, characterized by specifically comprising: dispersing a powder of CLMXene or CmO or CoNi-LDH or MXene in acetone, after ultrasonic treatment in a flask, adding an epoxy resin for stirring, placing the flask in an oil bath for stirring, evaporating the acetone, adding a curing agent in a molten state for stirring, pouring the mixture into a mould, placing the mould in an oven for curing, and then naturally cooling to prepare a flame retardant epoxy resin.

8. The method for preparing a flame retardant epoxy resin according to claim 7, characterized in that the CLMXene is incorporated in an amount of 2% to 6% by mass.

9. The method for preparing a flame retardant epoxy resin according to claim 8, characterized in that the CLMXene is incorporated in an amount of 2% by mass, namely, CLMXene: (epoxy resin + curing agent) = 2: 98, wherein the mass ratio of epoxy resin to curing agent is 4.58: 1.

10. The method for preparing a flame retardant epoxy resin according to claim 7, characterized in that the mold is placed in an oven and cured by: the temperature was maintained at 100 °C for 2h and then increased to 150 °C for 2h.12 01 24AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS:Amended Claims (clean version)1. A ternary nanocomposite flame retardant, denoted as CLMXene, characterized by comprising MXene nanosheets, layered double metal hydroxides, and cuprous oxide nanocubes; in percentage by mass, 5% MXene nanosheets, 45% layered double metal hydroxides, and 50% 5 cuprous oxide nanocubes.

2. A method for preparing the ternary nanocomposite flame retardant according to claim 1, characterized by comprising:step 1, preparation of MXene nanosheets;10 firstly, lithium fluoride powder is dissolved into hydrochloric acid, TisAlC2 powder is added into the mixed solution, kept stirring, and reacted in a water bath; the product is then centrifuged and washed with deionized water; finally, the product is dispersed in deionizedwater for ultrasonic treatment, and then placed in a centrifuge for centrifugal separation to prepare a dispersion of TisCsTx,15 step 2, preparation of CoNi-LDH / MXene;the Ti3C2Tx dispersion prepared in step 1 and cobalt nitrate hexahydrate are dispersed in deionized water, and are ultrasonically stirred in a three-neck flask, then a methanol solution containing dimethylimidazole is added to the three-neck flask, and is stirred to prepare a ZIF-67 / MXene solution; an ethanol solution containing nickel nitrate hexahydrate is added into 20 the ZIF-67 / MXene solution, stirred, then placed same into a centrifuge for centrifugal treatment, washed with deionizedwater for three times after centrifugation, and washed with ethanol for three times, and vacuum-dried the product to prepare a CoNi-LDH / MXene powder;step 3, preparation of Cu2O / CoNi-LDH / MXene;a copper nitrate trihydrate solution and a sodium hydroxide solution are mixed and stirred, then 25 an ascorbic acid aqueous solution is added, stirred under water bath conditions, and then centrifuged to obtain a precipitate, the precipitate is washed with deionized water and ethanol, and finally the product is dried in vacuum to prepare a cuprous oxide CU2O nanocube powder;the CU2O powder and the CoNi-LDH / MXene powder prepared in step 2 are mixed in a mass ratio of 1: 1, dispersed same in deionized water, and the two are combined through hydrothermal 30 treatment; the product is placed into a centrifuge for centrifugal treatment, then the precipitate istaken out, washed with deionizedwater for three times, ethanol for three times, and then vacuum dried to prepare a Cu2O / CoNi-LDH / Mxene ternary nanocomposite flame retardant with a structure in which a layered double metal hydroxide grows on MXene nanosheets, and cuprous oxide nanocubes adhere to the surface of the layered double metal hydroxide.

3. The method for preparing the ternary nanocomposite flame retardant according to claim 2, comprising:step 1, preparation of MXene nanosheets;Firstly, 1g of lithium fluoride powder is dissolved in 20 mL of hydrochloric acid, with the hydrochloric acid concentration being 9 mol / L, and 1g of Ti3AlC2 powder is added into the mixed solution, kept stirring, and reacted for 24h at 35 °C in a water bath; the product is then centrifuged and washed with deionized water until the pH reached 6-7; finally, the product is dispersed in deionizedwater for ultrasonic treatment for Ih, and then placed in a centrifuge for centrifugal separation at a rotation speed of 3500 rpm to prepare a dispersion of KiCjTx, step 2, preparation of CoNi-LDH / MXene;the Ti3C2Tx dispersion prepared in step 1 and 5g of cobalt nitrate hexahydrate are dispersed in 200 mL of deionized water, and are ultrasonically stirred in a three-neck flask for 10 min, wherein the TisC2Tx dispersion comprises 0.2g TisCsK, then 200 mL of a methanol solution containing 6g of dimethylimidazole is added in the three-neck flask, and is stirred for 12h to prepare a ZIF-67 / MXene solution; 200 mL of an ethanol solution containing 5g of nickel nitrate hexahydrate is added into the ZIF-67 / MXene solution, stirred for lOh, then placed same into a centrifuge for centrifugal treatment, with the centrifugal rotation speed being 10000 rpm, washed with deionizedwater for three times after centrifugation, and washed with ethanol for three times, and vacuum dryied the product to prepare a CoNi-LDH / MXene powder;step 3, preparation of Cu2O / CoNi-LDH / MXene;300 mL of a 0.01 mol / L copper nitrate trihydrate solution and 60 mL of a 1 mol / L sodium hydroxide solution are mixed, stirred for 30min, then 60 mL of a 0.5 mol / L ascorbic acid aqueous solution is added, stirred for 3h at 50 °C in a water bath, and centrifuged at the rotation speed of 10000 rpm to obtain a precipitate, the precipitate is washed with deionized water and ethanol, and finally the product is dried in vacuum at 60 °C to prepare a cuprous oxide CU2Onanocube powder;the CU2O powder and the CoNi-LDH / MXene powder prepared in step 2 are mixed in a mass ratio of 1: 1, dispersed same in deionized water, and the two are combined through a hydrothermal treatment at 120 °C; the product is placed into a centrifuge for centrifugal 5 treatment at the rotation speed of 10000 rpm, then the precipitate is taken out, washed with deionizedwater for three times, ethanol for three times, and then vacuum dried to prepare a Cu2O / CoNi-LDH / MXene nanocomposite flame retardant material, namely, preparing CLMXene with the mass ratio of MXene nanosheets, layered double metal hydroxide and cuprous oxide nanocubes being 1: 9: 10.

104. A flame retardant epoxy resin, characterized by comprising the ternary nanocomposite flame retardant according to claim 1, an epoxy resin and a curing agent; in percentage by mass, the ternary nanocomposite flame retardant accounts for 2% to 6%.CM15 5. The flame retardant epoxy resin according to claim 4, wherein in percentage by mass, theternary nanocomposite flame retardant accounts for 2%, the epoxy resin accounts for 80.4% and CM the curing agent accounts for 17.6%.I-6. The flame retardant epoxy resin according to claim 4 or 5, wherein the curing agent is 4, 20 4’diaminodiphenyl methane.

7. A method for preparing the flame retardant epoxy resin according to claim 4, characterized by comprising: dispersing a powder of CLMXene in acetone, after ultrasonic treatment in a flask, adding an epoxy resin for stirring, placing the flask in an oil bath for stirring, evaporating the 25 acetone, adding a curing agent in a molten state for stirring, pouring the mixture into a mould, placing the mould in an oven for curing, and then naturally cooling to prepare a flame retardant epoxy resin.

8. The method for preparing the flame retardant epoxy resin according to claim 7, wherein the 30 CLMXene is incorporated in an amount of 2% by mass.

9. The method for preparing the flame retardant epoxy resin according to claim 8, wherein the CLMXene is incorporated in an amount of 2% by mass, namely, CLMXene: (epoxy resin + curing agent) = 2: 98, wherein the mass ratio of epoxy resin to curing agent is 4.58: 1.

10. The method for preparing the flame retardant epoxy resin according to claim 7, wherein the mold is placed in an oven and cured by: the temperature was maintained at 100 °C for 2h and then increased to 150 °C for 2h.

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