MXene / polypropylene composite material as well as preparation method and application thereof

Abstract

The invention discloses an MXene / polypropylene composite material as well as a preparation method and application thereof, and relates to the technical field of high polymer materials. The MXene / polypropylene composite material is prepared from the following components in parts by weight: 100 parts of polypropylene, 4 to 10 parts of MXene, 0.1 to 3 parts of SiO2 nanoparticles and 2 to 10 parts of piperazine modified ammonium polyphosphate, according to the MXene / polypropylene composite material disclosed by the invention, a specific amount of MXene and piperazine modified ammonium polyphosphate are compounded, so that MXene nanosheets anchored by piperazine modified ammonium polyphosphate are more easily and orderly arranged along the direction of a force field when the MXene / polypropylene composite material is subjected to shearing force or interfacial tension of processing, and the barrier property to gas molecules is greatly enhanced, so that the oxygen permeation rate is remarkably reduced. The SiO2 nano-particles can be filled in gaps of MXene lamellas, a permeation blocking path is prolonged, and meanwhile, the rigidity and the stability of the material are enhanced, so that the oxygen permeation rate is remarkably reduced and the mechanical property is improved under the synergistic effect of all the components.

Description

Technical Field

[0001] This application relates to the field of polymer materials, and in particular to an MXene / polypropylene composite material, its preparation method, and its application. Background Technology

[0002] Polypropylene (PP), as one of the five major general-purpose plastics, is widely used due to its simple processing, wide availability, high chemical resistance, heat resistance, and acid and alkali resistance. However, PP's high oxygen and water vapor permeability and poor flame retardancy limit its application in fields such as electronic and electrical packaging.

[0003] MXene, as an emerging 2D nanomaterial, has attracted widespread attention due to its excellent electrical and thermal conductivity, mechanical properties, and abundant surface functional groups. The layered structure of MXene, containing transition metal oxides, can catalyze the reduction of some toxic NOx gases during combustion, thereby reducing smoke emissions; it has great application potential in the field of low-smoke halogen-free flame retardants. However, polypropylene (PP) is a non-polar material with low surface energy, and MXene is prone to severe redeposition and overlap during processing in PP systems. This often requires large amounts of MXene to meet flame retardant performance requirements, leading to a significant decrease in mechanical properties.

[0004] To enhance the flame retardant and mechanical properties of MXene / polypropylene composites, patent CN116656046A provides a flame-retardant and UV-resistant modified lignin-hybrid MXene / polypropylene composite and its preparation method. This method involves phosphorus-nitrogen modified lignin-hybrid MXene to obtain an MX@LNP flame retardant; then, the MX@LNP flame retardant is compounded with ammonium polyphosphate (APP) to obtain a flame retardant MA, which is then melt-composite with polypropylene to achieve a composite material with good flame retardant, UV resistance, and mechanical properties. However, this process requires MXene modification, which is cumbersome and makes it difficult to ensure the stability of the modified MXene structure, making it unsuitable for large-scale production. Furthermore, this solution has not yet improved the gas barrier properties of the MXene / polypropylene composite. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects and shortcomings of the prior art and provide an MXene / polypropylene composite material that, while ensuring the flame retardant rating, also has good mechanical properties and gas barrier properties.

[0006] Another object of the present invention is to provide a method for preparing MXene / polypropylene composite materials.

[0007] Another object of the present invention is to provide an application of MXene / polypropylene composite material in flame-retardant plastics.

[0008] The above-mentioned objective of this invention is achieved through the following technical solution:

[0009] This invention protects an MXene / polypropylene composite material comprising the following components by weight: 100 parts polypropylene, 4-10 parts MXene, 0.1-3 parts SiO2 nanoparticles, and 2-10 parts piperazine-modified ammonium polyphosphate (PAPP).

[0010] The MXene / polypropylene composite material of the present invention uses a specific amount of MXene and piperazine-modified ammonium polyphosphate. When subjected to processing shear force or interfacial tension, the MXene nanosheets anchored by piperazine-modified ammonium polyphosphate are more likely to align in an orderly manner along the force field direction, thereby significantly enhancing the barrier properties against gas molecules. SiO2 nanoparticles can fill the gaps between the MXene sheets, extending the barrier permeation path and enhancing the rigidity and stability of the material. Thus, under the synergistic effect of the components, the oxygen permeation rate is significantly reduced and the mechanical properties are improved.

[0011] Furthermore, the layered structure of MXene provides smoke blocking, and the transition metal oxides can catalyze the reduction of some toxic NOx gases during combustion, thereby reducing smoke release. During combustion, the acidic sites on MXene can catalyze both acidic sites and the cross-linking and carbonization of molecular chain segments. Meanwhile, piperazine-modified ammonium polyphosphate possesses intrinsic properties as both an acid source and a gas source, promoting the formation of a char layer structure in the matrix during combustion. This allows it to synergistically work with MXene sheets to construct a denser, continuous, and higher-strength barrier network structure, enhancing flame retardancy and smoke suppression.

[0012] In some embodiments, the MXene content that enables the achievement of the present invention can be any range between any two of any two of 4, 5, 6, 7, 8, 9, and 10 parts.

[0013] In some embodiments, the SiO2 nanoparticle content that enables the achievement of the present invention can be any range between any two of any one of 0.1 parts, 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, and 3 parts.

[0014] In some embodiments, the piperazine-modified ammonium polyphosphate content that enables the achievement of the present invention can be any one or more of 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, and 10 parts, or any two of them.

[0015] In some embodiments, the polypropylene content in the MXene / polypropylene composite is not less than 80 wt%.

[0016] In some embodiments, the following components are included by weight: 5-8 parts MXene and 3-6 parts piperazine-modified ammonium polyphosphate.

[0017] In some embodiments, the D50 particle size of the SiO2 nanoparticles is 1-40 nm, preferably 5-20 nm; more preferably 10-14 nm. The D50 particle size is determined using image analysis, specifically by scanning electron microscopy (SEM) to examine the surface morphology and measure the particle size. The testing procedure is as follows: SiO2 powder is dispersed in anhydrous ethanol and ultrasonically treated in an ice-water bath for 10-30 minutes using a probe-type ultrasonic disruptor (power 200-500W) to obtain fully dispersed individual primary particles. Subsequently, images are acquired using SEM, and 50 independently dispersed SiO2 nanoparticles are selected for particle size measurement to calculate the D50 particle size.

[0018] In some embodiments, the weight of MXene accounts for 3-10 wt% of the total weight of the MXene / polypropylene composite; preferably, the weight ratio of MXene is 4.5-7.1%.

[0019] Preferably, the weight of MXene accounts for a range of 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10% of the total weight of the MXene / polypropylene composite material, or between any two of these components.

[0020] In some embodiments, the piperazine-modified ammonium polyphosphate accounts for 1.5-8 wt% of the total weight of the MXene / polypropylene composite material; preferably, the weight ratio of the piperazine-modified ammonium polyphosphate is 2.7-5.4%.

[0021] Preferably, the weight of the piperazine-modified ammonium polyphosphate accounts for a range between any two of the following components: 1.5%, 2%, 3%, 4%, 5%, 6%, 7%, and 8% of the total weight of the MXene / polypropylene composite material.

[0022] Preferably, the mass of SiO2 nanoparticles accounts for 0.2 to 3 wt% of the total weight of the MXene / polypropylene composite material; preferably, the weight ratio of SiO2 nanoparticles is 0.6 to 1.3%.

[0023] Preferably, the weight of the SiO2 nanoparticles accounts for a range between any two of the following percentages of the total weight of the MXene / polypropylene composite material: 0.2%, 0.4%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, and 3%.

[0024] Specifically, the surface of SiO2 nanoparticles has organosilane compounds, which may be, but are not limited to, organosilanes (HMDS), dimethyldichlorosilane (DDS), etc.

[0025] In some embodiments, the polypropylene is homopolymer polypropylene and / or copolymer polypropylene.

[0026] In some embodiments, the polypropylene has a melt flow rate of 5-40 g / 10 min at 230°C and 2.16 kg. The melt flow rate is tested according to ASTM D1238.

[0027] In some embodiments, the MXene has the structural formula M n+1 X n T x Wherein, M is selected from at least one of Ti, Zr and Cr, X is selected from C and / or N, T is selected from at least one of F, Cl, O and -OH, n is 1 to 3, and x is 1 to 15; Preferably, the structural formula of the MXene is Ti3C2T. x T is selected from at least one of F, Cl, O and -OH, and x is 1 to 15.

[0028] In some embodiments, the modification method of the piperazine-modified ammonium polyphosphate includes the following steps: mixing and dispersing piperazine, ammonium polyphosphate and an alcohol solvent evenly, and reacting at 80-100°C for 4-6 hours to obtain the piperazine-modified ammonium polyphosphate.

[0029] In some embodiments, the mass ratio of piperazine to ammonium polyphosphate in the piperazine-modified ammonium polyphosphate is (0.2-0.6):1.

[0030] Optionally, the alcohol solvent is selected from at least one of ethanol, n-propanol, and isopropanol.

[0031] This invention protects a method for preparing an MXene / polypropylene composite material, comprising the following steps: mixing the components evenly, performing internal melting and blending, and pressing and molding to obtain the MXene / polypropylene composite material.

[0032] In some embodiments, the internal melting blending process is carried out at a processing temperature of 180-190°C, a rotation speed of 20-80 rpm, and a mixing time of 20-35 min.

[0033] In some embodiments, the pressing process is as follows: hot pressing at 8-12 MPa and 170-180°C for 250-400 seconds, followed by cold pressing at 4-7 MPa and 18-25°C for 100-200 seconds.

[0034] This invention protects the application of an MXene / polypropylene composite material in flame-retardant plastics.

[0035] Specifically, the MXene / polypropylene composite material of the present invention can be applied in the fields of electronic appliances, new energy vehicle battery packs, and building insulation materials.

[0036] Compared with the prior art, the beneficial effects of the present invention are: This invention provides an MXene / polypropylene composite material, which uses a specific amount of MXene and a specific type of piperazine-modified ammonium polyphosphate. Under processing shear force or interfacial tension, the MXene nanosheets anchored by the piperazine-modified ammonium polyphosphate are more likely to align orderly along the force field direction, significantly enhancing the barrier properties against gas molecules and thus significantly reducing the oxygen permeation rate. SiO2 nanoparticles can fill the gaps between the MXene sheets, extending the barrier permeation path and enhancing the rigidity and stability of the material. Therefore, through the synergistic effect of the components, the oxygen permeation rate is significantly reduced and the mechanical properties are improved. Detailed Implementation

[0037] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way.

[0038] The raw materials used in the following examples and comparative examples are: Polypropylene: PP-1: Homopolymer polypropylene, with a melt flow rate (ASTM D1238) of 36.0 g / 10 min at 230°C and 2.16 kg; ExxonMobi PP3155E3, ExxonMobil.

[0039] PP-2: Homopolymer polypropylene, with a melt flow rate (ASTM D1238) of 6 g / 10 min at 230°C and 2.16 kg; ExxonMobi PPT0170F, ExxonMobil.

[0040] PP-3: Copolymer polypropylene, with a melt flow rate (ASTM D1238) of 24 g / 10 min at 230°C and 2.16 kg; Excee PP9074MED, ExxonMobil.

[0041] Nano SiO2 particles-1: D50 particle size is 7nm, Evonik Industries, AEROSIL® R812S.

[0042] Nano SiO2 particles-2: D50 particle size is 16nm, Evonik Industries, AEROSIL® R972.

[0043] Nano SiO2 particles-3: D50 particle size is 12nm, Evonik Industries, AEROSIL® R974.

[0044] PAPP-1: Piperazine and ammonium polyphosphate in a mass ratio of 0.43:1, prepared in-house.

[0045] PAPP-2: Piperazine and ammonium polyphosphate in a mass ratio of 0.55:1, prepared in-house.

[0046] The method for preparing the piperazine-modified ammonium polyphosphate includes the following steps: Weigh out the required amounts of anhydrous piperazine and ammonium polyphosphate, mix them thoroughly, and add the mixture to a compound solvent of anhydrous ethanol and deionized water (v / v, 85:2) at a mass ratio of 1:10. Disperse the mixture evenly and react at 90°C for 5 hours, then cool to room temperature. The resulting white solid is then repeatedly washed with anhydrous ethanol to remove impurities, and finally dried in a vacuum drying oven to constant weight to obtain the piperazine-modified ammonium polyphosphate.

[0047] The preparation method of MXene includes the following steps: (1) Pour 2.0g LiF into a polytetrafluoroethylene reaction flask containing 40ml 9mol / L HCl solution and stir at 40℃ for 30min to obtain HCl-LiF etching solution.

[0048] (2) Take 2.0 g of titanium aluminum carbide powder (MAX) and add it to the HCl-LiF etching solution. Stir and react at 38 °C for 48 h. Wash the product after the reaction is completed three times by centrifugation at 8000 rpm with 1 mol / L HCl solution and 1 mol / L LiCl solution respectively. Remove the supernatant and add deionized water. Centrifuge several times until the supernatant is neutral.

[0049] (3) The washed black precipitate was dispersed in a 250 ml round-bottom flask and sonicated at room temperature for 1 h. After sonication, the dispersion was centrifuged at 3500 rpm for 1 h. The upper liquid was taken to obtain the MXene nano aqueous dispersion. The dispersion was frozen in a refrigerator to form a solid shape, and then dried in a vacuum freeze dryer. The dried product was then ground into powder to obtain MXene powder.

[0050] The following examples and comparative methods for preparing MXene / polypropylene composite materials include the following steps: (1) PAPP, MXene, nano SiO2 particles and polypropylene were dried in an 80℃ drying oven for 12h.

[0051] (2) The processing temperature of each section of the multifunctional torque rheometer was set to 185℃, the rotation speed to 50 rpm, and the mixing time to 25 minutes. When the processing temperature of each section remained stable, polypropylene was first poured into the internal mixer and melted for 3 minutes. Then, PAPP, MXene and nano-SiO2 particles were added, and the mixture was melted and blended for another 10 minutes. The sample obtained from the internal mixing was placed in a mold and hot-pressed in a flat vulcanizer at 10 MPa and 175℃ for 300 s, and then cold-pressed at 5 MPa and 20℃ for 120 s to prepare the MXene / polypropylene composite material.

[0052] The performance testing standards for the following examples and comparative examples are as follows: Tensile strength: Tested according to the method of ASTM D638.

[0053] Oxygen permeability: The gas permeability tester was used in accordance with the method of ASTM D3985-17; the square sample was 100mm × 100mm and the thickness was 1mm.

[0054] Examples 1-12 This embodiment provides a series of MXene / polypropylene composite materials. The components and performance test results of each embodiment by mass are shown in Table 1.

[0055] Table 1. Raw material composition and test results of Examples 1-12

[0056] Comparative Examples 1-5 This comparison provides a series of MXene / polypropylene composite materials. The components and performance test results of each comparative example by mass are shown in Table 2.

[0057] Table 2. Raw material composition and test results of Comparative Examples 1-5

[0058] The samples from Examples 1-12 were tested for UL-94 according to the method of ASTM D3801-20 (sample thickness 4 mm). The results showed that the samples from Examples 1-12 achieved UL-94 level V-1, indicating high flame retardant performance.

[0059] As shown in Table 1, the MXene / polypropylene composite material of the present invention not only meets the requirements of mechanical properties, but also has good gas barrier properties; the results show that its oxygen permeability is ≤2385cm³ / m²·24h·atm and its tensile strength is ≥24MPa.

[0060] As shown in Tables 1-2, compared to Example 7, Comparative Example 1, which does not contain nano-SiO2 particles, has a higher oxygen permeability and lower material rigidity. Comparative Example 2, which does not contain PAPP, exhibits decreased gas barrier properties and mechanical properties.

[0061] Compared to Example 2, when the PAPP content in Comparative Example 3 was insufficient, its oxygen permeability and tensile strength were poor.

[0062] Compared to Example 7, in Comparative Example 4, the excess of nano-SiO2 particles led to a decrease in gas barrier properties; in Comparative Example 5, the excess of MXene had limited effect on improving barrier properties and resulted in a significant decrease in mechanical properties.

[0063] The above embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An MXene / polypropylene composite material, characterized in that, The composition includes the following components by weight: 100 parts polypropylene, 4-10 parts MXene, 0.1-3 parts SiO2 nanoparticles, and 2-10 parts piperazine-modified ammonium polyphosphate.

2. The MXene / polypropylene composite material according to claim 1, characterized in that, The product contains the following components by weight: 5-8 parts MXene and 3-6 parts piperazine-modified ammonium polyphosphate.

3. The MXene / polypropylene composite material according to claim 1, characterized in that, The D50 particle size of the SiO2 nanoparticles is 1-40 nm, preferably 5-20 nm.

4. The MXene / polypropylene composite material according to claim 1, characterized in that: The polypropylene is either homopolymer polypropylene or copolymer polypropylene.

5. The MXene / polypropylene composite material according to claim 1 or 4, characterized in that: The melt flow rate of the polypropylene at 230℃ and 2.16Kg is 5-40g / 10min.

6. The MXene / polypropylene composite material according to claim 1, characterized in that: The structural formula of MXene is M n+ 1X n T x Wherein, M is selected from at least one of Ti, Zr, and Cr, X is selected from C and / or N, T is selected from at least one of F, Cl, O, and -OH, n is 1 to 3, and x is 1 to 15; preferably, the structural formula of the MXene is Ti3C2T. x T is selected from at least one of F, Cl, O and -OH, and x is 1 to 15.

7. The MXene / polypropylene composite material according to any one of claims 1-6, characterized in that: The modification method of the piperazine-modified ammonium polyphosphate includes the following steps: mixing and dispersing piperazine, ammonium polyphosphate and an alcohol solvent evenly, and reacting at 80-100℃ to obtain the piperazine-modified ammonium polyphosphate.

8. The MXene / polypropylene composite material according to claim 1, characterized in that: The mass ratio of piperazine to ammonium polyphosphate in the piperazine-modified ammonium polyphosphate is (0.2-0.6):

1.

9. A method for preparing the MXene / polypropylene composite material according to any one of claims 1-8, characterized in that: Includes the following steps: The components are mixed evenly, melt-blended and pressed into shape to obtain the MXene / polypropylene composite material.

10. The use of the MXene / polypropylene composite material according to any one of claims 1-8 in flame-retardant plastics.

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