A modified PP material, a branched polyethylene elastomer and a preparation method of a bamboo-plastic composite material

Abstract

The application discloses a modified PP material, a branched polyethylene elastomer, a bamboo-plastic composite material and a preparation method thereof, and the modified PP material is composed of the following raw materials in parts by weight: 75-95 parts of polypropylene, 5-25 parts of modified filler and 0.1-0.5 parts of antioxidant; the modified filler is the branched polyethylene elastomer; and the branched polyethylene elastomer is prepared by the following process: Et2AlCl, toluene and a diimine nickel catalyst are added into a polymerization bottle under N2 environment, ethylene gas is filled into a polymerization reaction device, and the branched polyethylene elastomer is obtained through reaction. The application provides a new polyolefin modified PP material and applies the polyolefin modified PP material to preparation of a bamboo-plastic composite material, and mechanical and mechanical properties of the bamboo-plastic composite material are improved. Based on the modified PP material, bamboo powder is used as a filling material to prepare a modified PP bamboo-plastic composite material which is high in cost performance and green and environment-friendly.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and specifically relates to a modified PP material and a method for preparing a high-performance, cost-effective, and environmentally friendly modified PP bamboo-plastic composite material. Background Technology

[0002] Polyolefins are important thermoplastic materials. Due to their abundant raw materials, low price, ease of processing and molding, and excellent comprehensive properties, they are one of the most widely produced and applied polymer materials. Polyethylene and polypropylene are the most important. Major varieties include polyethylene and some ethylene-based copolymers, such as ethylene-vinyl acetate copolymers, ethylene-acrylic acid or acrylate copolymers, as well as polypropylene and some propylene copolymers, poly-1-butene, poly-4-methyl-1-pentene, and cyclic olefin polymers. Polyolefins are widely used in automobiles, home appliances, machinery parts, office supplies, and communication equipment due to their advantages such as light weight, non-toxicity, odorlessness, and good water absorption. However, in some specific material applications, higher physical properties, such as mechanical properties, are required for polyolefins, and ordinary polyolefin materials can no longer meet these requirements.

[0003] Polypropylene (PP) is one of the most widely used general-purpose plastics. Crystalline polypropylene was first produced in 1951, but its high crystallinity resulted in poor low-temperature toughness, high molding shrinkage, and high notch sensitivity, limiting its wider application to some extent. Blending modification is the most effective way to toughen PP, leading to the development of PP / PE blends. This involves mechanically blending two or more polymers with additives at a specific temperature, utilizing the compatibility or reactive blending principle between components, ultimately forming a new material that is macroscopically homogeneous and microscopically phase-separated. Through blending modification of PP, particularly polypropylene, its paper-temperature brittleness, easy aging, and poor weather resistance have been overcome, significantly improving its overall performance. This has allowed it to enter the field of engineering plastics and become a strong competitor to general-purpose engineering plastics and alloys.

[0004] Both PP and PE (polyethylene) are crystalline polymers. They do not form a eutectic and instead crystallize independently, creating a multiphase system with poor compatibility. However, there is a mutual restraint between their crystals, which can disrupt the spherulite structure of PP. PP spherulites are fragmented into crystalline pieces by PE, preventing PP from producing spherulites. As the amount of PE increases, the fragmentation becomes more pronounced, and the PP crystals are refined, resulting in smaller PP crystal sizes and improved impact strength in the PP / PE blend system.

[0005] Chinese patent application CN112574505A discloses a modified PP material made from the following raw materials in weight percentages: 70.75%–79.25% PP resin, 19%–25% calcium carbonate, 1%–3% color masterbatch, and 0.75%–1.25% lubricant, which has the advantage of good wear resistance. However, the mechanical properties and impact strength of the modified PP material in this patent still need further improvement. Summary of the Invention

[0006] The technical problem to be solved by this invention is how to address the poor mechanical properties of existing modified PP materials.

[0007] The present invention solves the above-mentioned technical problems through the following technical means:

[0008] The first aspect of the present invention provides a modified PP material, which is composed of the following raw materials in parts by weight: 75-95 parts of polypropylene, 5-25 parts of modified filler and 0.1-0.5 parts of antioxidant; wherein the modified filler is a branched polyethylene elastomer; the branched polyethylene elastomer is obtained by the following process: Et2AlCl, toluene and nickel diimide catalyst are added to a polymerization bottle under N2 environment, ethylene gas is introduced into a polymerization reactor, and the reaction is carried out to obtain the branched polyethylene elastomer.

[0009] Beneficial effects: This invention provides a new polyolefin-modified PP material and applies it to the preparation of bamboo-plastic composite materials, thereby improving its mechanical properties.

[0010] Preferably, the antioxidant is Irganox1010.

[0011] Preferably, the chemical formula of the nickel diimine catalyst is as follows:

[0012] in

[0013] A second aspect of the present invention provides a method for preparing the above-mentioned modified PP material, comprising the following steps:

[0014] (1) Polypropylene, modified filler and antioxidant are thoroughly mixed according to the weight ratio to obtain a mixture;

[0015] Note: It is understood that the purpose of thorough mixing here is to mix the raw materials evenly. The mixing method and time are not specifically limited, as long as the purpose of mixing evenly is achieved.

[0016] (2) The mixture is added to a twin-screw extruder, melted and extruded to obtain modified PP material.

[0017] Note: It is understood that the processing parameters of a twin-screw extruder, such as temperature and speed, can be adjusted according to different matrix materials and raw materials, so no specific limitations are required.

[0018] Preferably, the melting temperature is 160-180°C.

[0019] Preferably, the screw rotation speed is 130-180 r / min.

[0020] A third aspect of the present invention provides a modified PP bamboo-plastic composite material, which is composed of the following raw materials in parts by weight: 65-100 parts of the above-mentioned modified PP material, 5-30 parts of bamboo powder and 0.1-0.5 parts of antioxidant.

[0021] Preferably, the antioxidant is Irganox168.

[0022] The fourth aspect of the present invention provides a method for preparing the above-mentioned modified PP bamboo-plastic composite material, comprising the following steps: mixing the modified PP material, bamboo powder and antioxidant according to the weight ratio, melting and extruding to obtain the composite material.

[0023] The fifth aspect of this invention provides a method for preparing the above-mentioned nickel diimine catalyst, which is obtained through the following steps:

[0024] (1) Mix 4-tert-butylbromobenzene, n-butyllithium, ethyl formate and solvent, concentrate the solvent after reaction, add n-hexane to precipitate solid, and obtain compound (I);

[0025] (2) 2-bromo-4-methylaniline, 4-methylphenylboronic acid and potassium carbonate were added to a suspension of toluene and water. The suspension was bubbled by blowing N2. Then, a toluene solution of Pd(PPh3)4 was added to the suspension and heated to react, to obtain compound (II).

[0026] (3) Mix compound (I) and compound (II), heat, and then add concentrated hydrochloric acid solution of zinc chloride to react and obtain compound (III);

[0027] (4) Dissolve acenaphthene and compound (III) in a mixed solution of acetonitrile and acetic acid, and heat to react to obtain compound (IV);

[0028] (5) Compound (IV) was reacted with (DME)NiBr2 in a solvent to obtain a diimine nickel complex (V) of the acenaphthoquinone skeleton.

[0029] The technical approach is as follows:

[0030]

[0031] The sixth aspect of the present invention provides a diimine nickel catalyst prepared by the above-described method for preparing diimine nickel catalyst.

[0032] The seventh aspect of the present invention provides a method for preparing the above-mentioned modified filler (branched polyethylene elastomer), comprising the following steps: adding Et2AlCl, toluene, and nickel diimide catalyst into a polymerization bottle under N2 environment, purging ethylene gas into a polymerization reactor, and reacting to obtain branched polyethylene elastomer.

[0033] The advantages of this invention are:

[0034] 1. This invention provides a new polyolefin-modified PP material and applies it to the preparation of bamboo-plastic composite materials, thereby improving its mechanical properties.

[0035] 2. The polyolefin composite material in this invention utilizes high-density thermoplastic polyethylene (HDPE) blended into polypropylene (PP) to form a macroscopically homogeneous, microscopically phase-separated polyolefin composite material. Due to the mutual restraint between the crystals of the two materials, the spherulite structure of PP is disrupted. The PP spherulites are segmented into wafers by PE, preventing PP from producing spherulites. As the amount of PE increases, the segmentation becomes more significant, and the PP crystals are refined, resulting in smaller PP crystal sizes and improved impact strength of the PP / PE blend system.

[0036] 3. Based on modified PP material, this invention uses bamboo powder as a filler to blend and prepare a high-performance, cost-effective, green and environmentally friendly modified PP bamboo-plastic composite material. Attached Figure Description

[0037] Figure 1 Compound (III) of Example 13 of this invention 1 H NMR spectrum;

[0038] Figure 2 Compound (III) of Example 13 of this invention 13 C NMR spectrum;

[0039] Figure 3 Compound (IV) of Example 13 of this invention 1 H NMR spectrum;

[0040] Figure 4 Compound (IV) of Example 13 of this invention 13 C NMR spectrum;

[0041] Figure 5 X-ray crystallography of compound (V) in Example 13 of this invention;

[0042] Figure 6The image shows the cyclic stress-strain curve of the branched polyethylene elastomer prepared in Example 1 of this invention.

[0043] Figure 7 This is a physical image of the modified PP material cantilever beam notched impact strength spline prepared in Example 1 of the present invention;

[0044] Figure 8 This is a photograph of the modified PP material tensile strength test strip prepared in Example 1 of the present invention.

[0045] Figure 9 This is a photograph of the branched polyethylene elastomer reciprocating test strip prepared in Example 1 of the present invention.

[0046] Figure 10 The branched polyethylene elastomer prepared in Example 1 of this invention 1 H NMR spectrum;

[0047] Figure 11 The branched polyethylene elastomer prepared in Example 1 of this invention 13 C NMR spectrum;

[0048] Figure 12 The figures show a comparison of the tensile and impact resistance test results of the materials prepared in Examples 1-5 and Comparative Example 1 of the present invention. (a) is a tensile test result figure; (b) is a test result figure of impact resistance and tensile strength, where the black bars represent tensile strength and the red bars represent impact strength. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0051] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0052] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0053] (I) The preparation process of the above modified PP material is as follows:

[0054] The performance testing conditions for the products obtained in the following embodiments and comparative examples are as follows:

[0055] The tensile specimen used for the tensile strength test is (50.0±5.0)mm*(4.0±0.5)mm*(2.5±0.2)mm, and the tensile rate is 50mm / min;

[0056] The notched impact strength test specimen used for the cantilever beam is of the following size: (80.0±5.0)mm*(10.0±0.5)mm*(4.0±0.2)mm. The notch is machined by a milling machine and the notch depth is (2.0±0.2)mm.

[0057] Example 1

[0058] Preparation of modified PP material: Weigh 75 parts by weight of polypropylene, 25 parts by weight of modified filler (branched polyethylene elastomer), and 0.2 parts by weight of antioxidant Irganox 1010, add them to a mixer and mix for 10 minutes to obtain a mixture.

[0059] The mixture was added to a twin-screw extruder, melted, and extruded to obtain a modified PP material, denoted as PE-25%. The temperatures and screw speeds in each zone of the twin-screw extruder were as follows: upper chamber temperature 160℃, lower chamber temperature 180℃, and screw speed 130–180 r / min. (Test specimens are prepared as follows...) Figure 7-8 (As shown)

[0060] Preparation method of branched polyethylene elastomer: In a typical experiment, a 350 mL thick-walled glass pressure vessel is loaded with the required amounts of Et2AlCl (600 μmol), toluene (28 mL), and a magnetic stir bar in a glove box. The pressure vessel is connected to a high-pressure polymerization line to degas the solution. The vessel is heated to 25 °C using an oil bath and allowed to equilibrate for 5 minutes. Diimide nickel catalyst (2 μmol) in CH2Cl2 (2 mL) is injected into the vessel using a syringe. The reactor is pressurized under rapid stirring and maintained at 8.0 atm for ethylene. After 0.3 h, the vessel is vented, and the polymer is precipitated in acidified ethanol (ethanol / HCl = 50:1 (volume ratio)) and dried under vacuum at 50 °C for 24 h. Branched polyethylene elastomer is obtained. 1 H NMR spectrum, 13 CNMR spectrum as shown Figure 10 , Figure 11 As shown, its cyclic stress-strain curve is as follows: Figure 6 As shown, the sample underwent 10 cyclic tests, with a maximum strain of 300%. The test specimen is shown below. Figure 9 (As shown)

[0061] Note: The branched polyethylene elastomer used in this embodiment was prepared using a sterically hindered nickel diimine catalyst (chemical formula: [chemical formula not provided]). in As we have seen in previous studies, branched polyethylene elastomers prepared with nickel catalysts with similar structures also possess certain elastomer properties and can be used to prepare modified PP materials. However, the polyethylene prepared with the catalyst structure described in this paper exhibits superior elastomer properties.

[0062] The modified filler (branched polyethylene elastomer) used in the following examples is the same as that in Example 1.

[0063] Example 2

[0064] Preparation of modified PP material: Weigh 80 parts by weight of polypropylene, 20 parts by weight of modified filler (branched polyethylene elastomer), and 0.2 parts by weight of antioxidant Irganox 1010, add them to a mixer and mix for 10 minutes to obtain a mixture;

[0065] The mixture is added to a twin-screw extruder, melted, and extruded to obtain a modified PP material, denoted as PE-20%. The temperature and screw speed of each zone of the twin-screw extruder are as follows: upper cavity plate temperature 160℃, lower cavity plate temperature 180℃, and screw speed 130~180r / min.

[0066] Example 3

[0067] Preparation of modified PP material: Weigh 85 parts by weight of polypropylene, 15 parts by weight of modified filler (branched polyethylene elastomer), and 0.2 parts by weight of antioxidant Irganox 1010, add them to a mixer and mix for 10 minutes to obtain a mixture.

[0068] The mixture is added to a twin-screw extruder, melted, and extruded to obtain a modified PP material, denoted as PE-15%. The temperatures and screw speeds of each zone of the twin-screw extruder are as follows: upper chamber temperature 160℃, lower chamber temperature 180℃, and screw speed 130~180r / min.

[0069] Example 4

[0070] Preparation of modified PP material: Weigh 90 parts by weight of polypropylene, 10 parts by weight of modified filler (branched polyethylene elastomer), and 0.2 parts by weight of antioxidant Irganox 1010, add them to a mixer and mix for 10 minutes to obtain a mixture.

[0071] The mixture is added to a twin-screw extruder, melted, and extruded to obtain a modified PP material, denoted as PE-10%. The temperature and screw speed of each zone of the twin-screw extruder are as follows: upper cavity plate temperature 160℃, lower cavity plate temperature 180℃, and screw speed 130~180r / min.

[0072] Example 5

[0073] Preparation of modified PP material: Weigh 95 parts by weight of polypropylene, 5 parts by weight of modified filler (branched polyethylene elastomer), and 0.2 parts by weight of antioxidant Irganox 1010, add them to a mixer and mix for 10 minutes to obtain a mixture.

[0074] The mixture is added to a twin-screw extruder, melted, and extruded to obtain a modified PP material, denoted as PE-5%. The temperature and screw speed of each zone of the twin-screw extruder are as follows: upper cavity plate temperature 160℃, lower cavity plate temperature 180℃, and screw speed 130~180r / min.

[0075] Comparative Example 1 (without modified filler)

[0076] Preparation of comparative sample material: Weigh 100 parts by weight of polypropylene and 0.2 parts by weight of antioxidant Irganox 1010, add them to a mixer and mix for 10 minutes to obtain a mixture;

[0077] The mixture is added to a twin-screw extruder, melted, and extruded to produce PP. The temperature and screw speed of each zone of the twin-screw extruder are as follows: upper cavity plate temperature 160℃, lower cavity plate temperature 180℃, and screw speed 130~180r / min.

[0078] The materials obtained in Examples 1-5 and Comparative Example 1 were injection molded into specimens using an injection molding machine for performance testing. The results of the tensile and impact resistance tests are as follows: Figure 12 As shown.

[0079] (II) The preparation process of the above-mentioned modified PP bamboo-plastic composite material is as follows:

[0080] Example 6

[0081] Preparation of bamboo-plastic composite material of modified PP: 65 parts by weight of modified PP material, 35 parts by weight of bamboo powder, and 0.2 parts by weight of antioxidant Irganox168 were weighed and added to a mixer for 10 min to obtain a mixture. The mixture was then added to a twin-screw extruder and melted and extruded to obtain the bamboo-plastic composite material of modified PP. The temperature and screw speed of each zone of the twin-screw extruder were as follows: upper cavity plate temperature 140℃, lower cavity plate temperature 160℃, and screw speed 130~180r / min.

[0082] Example 7

[0083] The difference between this embodiment and embodiment 6 is that: 70 parts of modified PP material, 30 parts of bamboo powder, and 0.2 parts of antioxidant Irganox 1680 are used, while the other steps are the same as in embodiment 6.

[0084] Example 8

[0085] The difference between this embodiment and embodiment 6 is that: 75 parts of modified PP material, 25 parts of bamboo powder, and 0.2 parts of antioxidant Irganox 1680 are used, while the other steps are the same as in embodiment 6.

[0086] Example 9

[0087] The difference between this embodiment and embodiment 6 is that: 80 parts of modified PP material, 20 parts of bamboo powder, and 80.2 parts of antioxidant Irganox 16 are used, while the other steps are the same as in embodiment 6.

[0088] Example 10

[0089] The difference between this embodiment and embodiment 6 is that: 85 parts of modified PP material, 15 parts of bamboo powder, and 0.2 parts of antioxidant Irganox 1680 are used, while the other steps are the same as in embodiment 6.

[0090] Example 11

[0091] The difference between this embodiment and embodiment 6 is that: 90 parts of modified PP material, 10 parts of bamboo powder, and 0.2 parts of antioxidant Irganox 1680 are used, while the other steps are the same as in embodiment 6.

[0092] Example 12

[0093] The difference between this embodiment and embodiment 6 is that: 95 parts of modified PP material, 5 parts of bamboo powder, and 0.2 parts of antioxidant Irganox 1680 are used, while the other steps are the same as in embodiment 6.

[0094] Bamboo-plastic composites with modified PP doped with 5%, 10%, 15%, 20%, 25%, 30%, and 35% were obtained. Analysis of the blending results showed that when the bamboo powder content was below 30%, the composite material maintained a good morphology. However, when the doping content reached 35%, the composite material exhibited problems such as flaking, uneven mixing, and poor compatibility, making sample preparation and testing impossible. The materials obtained in Examples 6-12 were injection molded into strips for tensile property testing. The test results are shown in the table below. In the table, “—” indicates that the morphology is poor at 35℃, making sample preparation and testing impossible.

[0095] (III) The above-mentioned nickel diimine catalyst The synthesis process is as follows:

[0096] Example 13:

[0097] Preparation of nickel diimine catalyst:

[0098] Step (1) Synthesis of compound (I): Under a nitrogen atmosphere, 4-tert-butylbromobenzene (2.12 g, 10.0 mmol) was added to a solvent and placed in a -78°C low-temperature stirrer. Then, n-butyllithium (6 ml, 12.0 mmol) was added and stirred for 3 h. Next, ethyl formate (2.22 g, 22.0 mmol) was added to the solution. After reacting for 4 h, the solvent was concentrated, and n-hexane was added to precipitate a solid. The solid was dried under vacuum to obtain the desired product. The reaction formula is as follows:

[0099]

[0100] Step (2) Synthesis of compound (II): A mixture of 2-bromo-4-methylaniline (1.86 g, 10.0 mmol), 4-methylphenylboronic acid (1.77 g, 13.0 mmol), and K2CO3 (2.76 g, 20.0 mmol) was added to a suspension of toluene / water = 3 / 1 (volume ratio). The suspension was bubbled by blowing N2 for 20 minutes. After sealing the reaction system, a toluene solution of Pd(PPh3)4 (0.23 g, 0.2 mmol) was added to the suspension. The suspension was stirred at 90 °C for 24 hours. The reaction mixture was cooled to room temperature and extracted with CH2Cl2. The combined organic layers were washed with brine and dried with anhydrous Na2SO4. The solvent was removed under reduced pressure to obtain the crude product, which was then purified by flash silica chromatography (EA / PE = 1 / 10 (volume ratio)). The desired product was obtained by the following reaction:

[0101]

[0102] Step (3) Synthesis of compound (III): Take compound (II) (1.97 g, 10.0 mmol) and compound (I) (3.55 g, 12.0 mmol), heat to 120 °C, slowly add zinc chloride (1.08 g, 8.0 mmol) in concentrated hydrochloric acid (0.60 g, 16 mmol), then heat to 160 °C and react for 30 min. Cool the reaction mixture to room temperature, extract three times with CH2Cl2, and dry with anhydrous magnesium sulfate. Filter off the magnesium sulfate, concentrate the filtrate, and add ethanol to precipitate the solid, which is product (III). The reaction formula is as follows: (The reaction formula of compound (III) is as follows: 1 H NMR spectrum, 13 The C NMR spectrum is as follows Figure 1 , Figure 2 (As shown)

[0103]

[0104] Step (4) Synthesis of compound (IV): Dissolve acenaphthene (0.96 g, 5.0 mmol) and compound (III) (4.75 g, 10.0 mmol) in acetonitrile-acetic acid. Stir and reflux at 95 °C for 12 h. Cool to room temperature, concentrate the solution, add methanol to precipitate the solid, filter, wash with methanol to obtain the product, compound (IV). The reaction formula is as follows: (The reaction formula of compound (IV) is as follows) 1 HNMR spectrum, 13 The C NMR spectrum is as follows Figure 3 , Figure 4 (As shown)

[0105]

[0106] Step (5) Synthesis of Complex (V): Under a nitrogen atmosphere, compound (IV) (1.10 g, 1.0 mmol) synthesized in step (4) was reacted with (DME)NiBr2 (0.31 g, 1.0 mmol) in CH2Cl2 (20 mL) solvent for 6-12 h. After filtration, washing, and drying, the diimine nickel complex (V) of the acenaphthoquinone skeleton was synthesized. The reaction formula is as follows:

[0107]

[0108] X-ray crystallography of compound (V) is shown below. Figure 5 As shown.

[0109] (CCDC:2298550):Selected bond lengths and angles[deg]:Br(1)-Ni(1)=2.3418(13),Br(2)-Ni(1)=2.3168(15),Ni(1)-N(1)=2.057(5),N i(1)-N(2)=2.037(4), N(1)-C(28)=1.437(7), N(1)-C(36)=1.288(7), N(2)-C(46)=1.297(8), N(2)-C(47)=1.417(7); Br(2)-Ni(1)-Br(1)=116.73(5),N(1)-Ni(1)-Br(1)=118.46(15),N(1 )-Ni(1)-Br(2)=110.55(14), N(1)-Ni(1)Br(2)=110.55(14), N(2)-Ni(1)-Br(2)=113.26(14),

[0110] N(2)-Ni(1)-N(1)=83.32(18),C(28)-N(1)-Ni(1)=130.6(3),C(36)-N(1)-Ni(1)=110.0(4),C(36)-N(1)-C(28)

[0111] =119.4(5), C(46)-N(2)-Ni(1)=110.6(3), C(46)-N(2)-C(47)=120.1(4), C(47)-N(2)-Ni(1)=129.1(4)

[0112]

[0113]

[0114] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A modified PP material, characterized in that: It is composed of the following raw materials in parts by weight: 75-95 parts polypropylene, 5-25 parts modified filler, and 0.1-0.5 parts antioxidant; the modified filler is branched polyethylene elastomer; the branched polyethylene elastomer is obtained by the following process: Et2AlCl, toluene, and nickel diimide catalyst are added to a polymerization bottle under N2 atmosphere, and ethylene gas is introduced into the polymerization reactor to react and obtain the branched polyethylene elastomer; the chemical formula of the nickel diimide catalyst is […]. ,in .

2. The modified PP material according to claim 1, characterized in that: The antioxidant is designated as Irganox1010.

3. The modified PP material according to claim 1, characterized in that: It is composed of the following raw materials in parts by weight: 75 parts polypropylene, 25 parts modified filler and 0.2 parts antioxidant.

4. The method for preparing the modified PP material according to any one of claims 1-3, characterized in that: Includes the following steps: (1) Polypropylene, modified filler and antioxidant are thoroughly mixed according to the weight ratio to obtain a mixture; (2) The mixture is added to a twin-screw extruder, melted and extruded to obtain modified PP material.

5. The method for preparing the modified PP material according to claim 4, characterized in that: The melting temperature is 160-180℃.

6. A bamboo-plastic composite material made of modified PP, characterized in that: It is composed of the following raw materials in parts by weight: 65-100 parts of the modified PP material as described in any one of claims 1-3, 5-30 parts of bamboo powder, and 0.1-0.5 parts of antioxidant.

7. The method for preparing the modified PP bamboo-plastic composite material according to claim 6, characterized in that: Modified PP material, bamboo powder, and antioxidant are mixed according to the weight ratio, melted, and extruded to obtain the final product.

8. A method for preparing a nickel diimine catalyst, characterized in that: (1) 4-tert-butylbromobenzene, n-butyllithium, ethyl formate, and solvent were mixed. After the reaction, the solvent was concentrated, and n-hexane was added to precipitate a solid, yielding compound (I); the structure of compound (I) is as follows: ; (2) 2-Bromo-4-methylaniline, 4-methylphenylboronic acid, and potassium carbonate were added to a suspension of toluene and water. The suspension was bubbled by blowing N2, and then a toluene solution of Pd(PPh3)4 was added to the suspension. The mixture was heated to react and yield compound (II). The structural formula of compound (II) is: ; (3) Compound (I) and compound (II) are mixed, heated, and then a concentrated hydrochloric acid solution of zinc chloride is added to react and give compound (III); the structural formula of compound (III) is as follows: ; (4) Dissolve acenaphthene and compound (III) in a mixed solution of acetonitrile and acetic acid, and heat to react, to obtain compound (IV); the structural formula of compound (IV) is as follows: ; (5) Compound (IV) was reacted with (DME)NiBr2 in a solvent to obtain a nickel diimine complex (V) with a acenaphthoquinone skeleton; the structural formula of the nickel diimine complex (V) with a acenaphthoquinone skeleton is as follows: .

9. The nickel diimine catalyst prepared by the method of claim 8.

10. A method for preparing a branched polyethylene elastomer, characterized in that: The process includes the following steps: adding Et2AlCl, toluene, and the nickel diimide catalyst as described in claim 8 into a polymerization flask under N2 environment, purging the polymerization reactor with ethylene gas, and reacting to obtain branched polyethylene elastomer.

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