A reinforced toughened carbon nanotube modified polypropylene resin and fiber composite material thereof

Abstract

The application discloses a kind of reinforced toughened carbon nanotube modified polypropylene resin and its fiber composite material, its formula is made of carbon nanotube filler, hexadecyl trimethyl ammonium bromide, chopped glass fiber, polyvinylpyrrolidone, gamma-aminopropyl triethoxysilane, ethylene-octene copolymer, 3,3',5,5'-tetramethyl benzidine and maleic anhydride grafted polypropylene, carbon nanotube filler is surface modified by hexadecyl trimethyl ammonium bromide to form carbon nanotube reinforcement with surface hydrophilic layer, chopped glass fiber is oriented and arranged along the extrusion direction in the melt blending process, and the mechanical strength of polypropylene matrix is synergistically enhanced;Ethylene-octene copolymer forms toughening particles by melt blending, 3,3',5,5'-tetramethyl benzidine induces polypropylene matrix to form rod-shaped long particle β crystal, and the matrix high toughness is synergistically realized;The synthesized polypropylene matrix can be used for preparing fiber composite material.The fiber composite material prepared by the application has excellent mechanical strength, and the toughness and impact resistance are significantly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of polypropylene-based fiber composite materials, in particular to a reinforced and toughened carbon nanotube-modified polypropylene resin and a fiber composite material thereof. Background Art

[0002] Polypropylene is a thermoplastic with a light specific gravity, high surface hardness and high elasticity. It is widely used due to its excellent chemical stability and processing characteristics, and is widely used in automotive parts, household appliances, medical and health fields. However, polypropylene also has defects such as weak low-temperature impact strength, easy aging, and poor electrical and thermal properties, which limit its scope of application. In order to enhance the mechanical properties of current polymer materials, the addition of various inorganic fillers such as talcum powder, mica powder, and glass fiber has become a means of extensive research and application. However, due to the constraints of inorganic particle size and dispersion characteristics, the improvement in the mechanical properties of polymer composites is limited. Compared with inorganic fillers, nanoscale fillers have a relatively high specific surface area and can increase the active interface with the polymer, and are considered to be one of the effective ways to improve the comprehensive performance of polypropylene.

[0003] In the prior art, Chinese Publication No. CN109608669A discloses a carbon nanotube-reinforced polypropylene composite material. This material is obtained by grafting a carbon nanotube array with a polypropylene resin M1 to form modified carbon nanotubes, which are then melt-mixed with a polypropylene resin M2 to produce a polypropylene composite material, effectively improving the mechanical properties of the polypropylene. Chinese Publication No. CN108794885A discloses an anti-aging and impact-resistant modified polypropylene material and its preparation method. The modified polypropylene material is prepared by blending a polypropylene resin, p-alkoxyphenol, polymerized rosin, and nano-titanium dioxide. The synergistic effect of the p-alkoxyphenol and polymerized rosin causes tertiary carbon radicals to migrate to the p-alkoxyphenol, thereby preventing reactions between molecular chains and improving the polypropylene's aging resistance. Furthermore, the material's impact strength is effectively improved by directional crystallization into a β-crystal structure during crystallization. China Publication No. CN 109796679A discloses a two-dimensional ultra-thin titanium dioxide-modified polypropylene nanocomposite material. The prepared ultra-thin titanium dioxide flakes have an ultra-high specific surface area. When used to modify polypropylene, they significantly improve the weather resistance and toughness of the polypropylene matrix, thereby expanding the outdoor service life and application range of polypropylene products.

[0004] However, the polypropylene composite materials prepared above generally have disadvantages such as single performance improvement, limited improvement, poor dispersion of fillers, etc., and the operation is complex and the conditions are harsh, which seriously affects their application and promotion. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a reinforced and toughened carbon nanotube-modified polypropylene resin, which effectively improves the problem of high viscosity of the polypropylene matrix in the molten state causing difficulty in impregnation, while at the same time providing sufficient melting time to eliminate most internal defects such as pores and cracks in the fiber composite material.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A reinforced and toughened carbon nanotube-modified polypropylene resin is prepared by the following steps. The formula is calculated by weight: 0.5-2 parts of carbon nanotube filler (solid), 1-6 parts of polyvinyl pyrrolidone (solid, dispersant), 0.5-2 parts of hexadecyltrimethylammonium bromide (liquid, surfactant), 0.5-1.5 parts of γ-aminopropyltriethoxysilane (silane coupling agent), 2-6 parts of chopped glass fibers (solid), 0.5-1.5 parts of ethylene-octene copolymer (solid, toughening agent), 0.05-0.15 parts of 3,3',5,5'-tetramethylbenzidine (solid, toughening agent) and 90-100 parts of maleic anhydride-grafted polypropylene (solid).

[0008] Step 1: Preparing a carbon nanotube reinforcement: polyvinyl pyrrolidone, γ-aminopropyltriethoxysilane, and anhydrous ethanol are stirred and mixed according to a ratio, a carbon nanotube filler is added to the mixed solution, and the mixed solution is ultrasonically treated until a uniform mixed solution is obtained to obtain a carbon nanotube dispersion liquid I; hexadecyltrimethylammonium bromide is added, and the carbon nanotube dispersion liquid I is dispersed by high-speed centrifugation, and allowed to stand to obtain a layered carbon nanotube dispersion liquid II; the upper layer solution is extracted to obtain a carbon nanotube dispersion liquid III placed in a lower layer; the carbon nanotube dispersion liquid III is filtered through a membrane filter, and the precipitate is washed and dried to obtain a carbon nanotube reinforcement liquid IV adsorbed and modified by hexadecyltrimethylammonium bromide;

[0009] Step 2: Preparation of reinforced and toughened carbon nanotube-modified polypropylene resin: Ethylene-octene copolymer, maleic anhydride grafted polypropylene, chopped glass fiber, and 3,3',5,5'-tetramethylbenzidine are added to a twin-screw extruder according to the ratio, uniformly mixed in the hopper of the twin-screw extruder, and the carbon nanotube reinforcement IV is added, and melt-blended and extruded to obtain a reinforced and toughened carbon nanotube-modified polypropylene resin.

[0010] Preferably, the carbon nanotube filler is a carboxyl carbon nanotube with a size of 5-20 nm; and the length of the chopped glass fiber is in the range of 10-50 μm.

[0011] Preferably, the carbon nanotube dispersion I is a mixed dispersion of carbon nanotube fillers in polyvinyl pyrrolidone and anhydrous ethanol. Polyvinyl pyrrolidone is easily soluble in anhydrous ethanol due to its similar polarity. The formed mixed solution provides a dispersion medium for the carboxyl carbon nanotube fillers, and the carbon nanotube fillers are evenly dispersed in combination with ultrasonic treatment; the power of the ultrasound is 200-400W, and the time is 0.5-1h.

[0012] Preferably, hexadecyltrimethylammonium bromide modifies carbon nanotubes through π-π bonds and hydrogen bonds. The carbon nanotube solid particles carry a negative charge in a hydrophilic medium. Hexadecyltrimethylammonium bromide interacts with the π electrons on the surface of the carbon nanotubes to form a strong adsorption layer on the surface of the carbon nanotubes, thereby forming modified carbon nanotubes. Excess hexadecyltrimethylammonium bromide is dispersed in anhydrous ethanol solvent. The centrifugal dispersion time is 10-60 minutes, and the centrifugal speed is 8000-20000 rpm.

[0013] Preferably, the upper layer solution of the carbon nanotube dispersion II is anhydrous ethanol, and the lower layer solution is a mixed dispersion of carbon nanotube filler, hexadecyltrimethylammonium bromide and polyvinylpyrrolidone.

[0014] Preferably, the carbon nanotube reinforcement IV is obtained by washing the carbon nanotube dispersion II with distilled water to obtain a precipitate by filtration, and then drying it at 25-80° C. for 18-30 hours.

[0015] Preferably, in step 2, the rotation speed of the twin-screw extruder high-speed mechanical shearing stirring is 1000-3000 rpm, the stirring temperature is 190-240°C, and the nozzle temperature is 190-200°C.

[0016] Preferably, in step 2, the ethylene-octene copolymer is distributed in the continuous phase polypropylene matrix in the form of microfibrillated particles, and the 3,3',5,5'-tetramethylbenzidine induces the polypropylene matrix to form β crystals during the cooling process of melt blending, generating slender rod-shaped crystals; when subjected to impact damage, the applied impact stress is evenly diffused along the toughening particles, thereby reducing the stress acting on the brittle polypropylene matrix, inducing a large number of silver streaks and shear bands in the matrix, thereby absorbing most of the impact kinetic energy and achieving matrix toughening of the fiber composite material.

[0017] Another object of the present invention is to provide a polypropylene-based fiber composite material prepreg, which is prepared by a reinforced and toughened carbon nanotube-modified polypropylene resin as described above, and its preparation method is as follows: continuous fibers are driven by a traction system to pass through a creel, and are dispersed into continuous fiber monofilaments through dispersion, preheating and desizing, and yarn spreading treatment; the molten reinforced and toughened carbon nanotube-modified polypropylene resin extruded by a twin-screw extruder is spread flat on the surface of the fiber filaments, and the resin is impregnated into the fiber through a melt impregnation mold; and the polypropylene-based fiber composite material prepreg is obtained through calendering treatment.

[0018] Preferably, the continuous fibers are glass fibers, carbon fibers or basalt fibers, with a heating and melting temperature of 230-270° C. and a pulling rate of 0.1-0.5 m / min.

[0019] Another object of the present invention is to provide a polypropylene-based fiber composite material, which is prepared by a polypropylene-based fiber composite material prepreg tape as described above, and the preparation method is as follows: the polypropylene-based fiber composite material prepreg tape is passed through a creel under the drive of a traction system, heated and melted in a melting mold, cooled and shaped, and pultruded to obtain a polypropylene-based fiber composite material.

[0020] Preferably, the molding temperature is 200-250° C., the cooling temperature is 80-150° C., and the pulling rate is 0.1-0.5 m / min.

[0021] Preferably, the polypropylene-based fiber composite material is pultruded into a fiber composite material profile of corresponding shape and specification according to the shape at the outlet of the internal cavity of the melting mold.

[0022] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0023] 1. Uniform dispersion of carbon nanotube particles within a polypropylene resin matrix is ​​achieved through the synergistic effect of non-covalent modification with hexadecyltrimethylammonium bromide and grafting with γ-aminopropyltriethoxysilane. The cationic surfactant, hexadecyltrimethylammonium bromide, is a polar molecule containing a hydrophobic alkyl end and a hydrophilic ammonium bromide end. It strongly adsorbs to the surface of carbon nanotube particles through π-π electrostatic interactions, forming a hydrophilic layer on the surface and hydrogen bonding between the hydrophilic ends and polar solvents. Furthermore, γ-aminopropyltriethoxysilane hydrolyzes the end groups of the carbon nanotube filler and grafts onto the surface, generating hydroxyl and amino groups on the surface. These groups also form hydrogen bonds with the polar solvent, jointly promoting the dissolution and uniform dispersion of the carbon nanotube filler.

[0024] 2. The flow characteristics of the polypropylene matrix during melt blending cause the chopped glass fibers to align, with the majority of the chopped glass fibers tending to align along the direction of the extruded melt flow, which is beneficial for strengthening the polypropylene matrix along the extrusion direction. The uniform dispersion of the carbon nanotube filler improves the adhesion of the carbon nanotube-polypropylene interface, reduces stress concentration within the matrix, and limits the slippage and chain recombination of the polypropylene molecular chains through physical barriers. Overall, the present invention uses carbon nanotube fillers and chopped glass fibers to synergistically reinforce the polypropylene resin matrix at multiple scales, significantly improving the overall mechanical properties of the fiber composite material.

[0025] 3. The toughening agent, ethylene-octene copolymer, is distributed as microfibrillated particles ("islands") within the continuous phase polypropylene matrix ("sea"), forming a "sea-island" structure. 3,3',5,5'-Tetramethylbenzidine induces the formation of β crystals within the polypropylene matrix during the cooling process of melt blending, resulting in slender rod-shaped crystals. When subjected to impact damage, the uniform distribution of ethylene-octene copolymer particles within the brittle polypropylene matrix disperses the applied impact stress evenly across its spherical surface, reducing the stress acting on the brittle matrix. As the impact stress increases further, the toughening agent particles, acting as stress concentration areas, induce numerous silver crazing and shear bands within the brittle matrix. This process absorbs significant energy, thereby enhancing the toughness and impact resistance of the polypropylene resin matrix.

[0026] 4. The present invention has mild preparation conditions, a wide range of applications, and high product molding quality. The fiber composite material is secondary molded using a prepreg melt pultrusion process, which effectively improves the problem of difficulty in impregnation caused by the high viscosity of the polypropylene matrix in the molten state. At the same time, sufficient melting time eliminates most internal defects such as pores and cracks in the fiber composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart of a high-strength and high-toughness carbon nanotube-modified polypropylene-based fiber composite material and a preparation method thereof of the present invention.

[0028] Figure 2 These are the microscopic morphologies of the radial cross-section of polypropylene-based fiber composites before and after carbon nanotube modification, (a) before modification, (b) after modification. DETAILED DESCRIPTION

[0029] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] Example 1:

[0031] In this example, a reinforced and toughened carbon nanotube-modified polypropylene resin was synthesized. The amounts of each formula were as follows: 23.0 g of carbon nanotube filler, 92.0 g of polyvinyl pyrrolidone, 34.5 g of cetyltrimethylammonium bromide, 27.6 g of γ-aminopropyltriethoxysilane, 91.9 g of chopped glass fiber, 23.0 g of ethylene-octene copolymer, 1.8 g of 3,3',5,5'-tetramethylbenzidine, and 2180 g of maleic anhydride-grafted polypropylene.

[0032] Furthermore, the preparation of a polypropylene-based glass fiber composite rod using the aforementioned reinforced and toughened carbon nanotube-modified polypropylene resin comprises the following steps:

[0033] Step 1: preparing carbon nanotube reinforcement;

[0034] Step 2: preparing reinforced and toughened polypropylene resin;

[0035] Step 3: preparing a polypropylene-based fiber composite prepreg tape;

[0036] Step 4: Prepare polypropylene-based fiber composite material.

[0037] Furthermore, in step 1, preparing a carbon nanotube reinforcement includes:

[0038] A formulated amount of polyvinyl pyrrolidone and a formulated amount of anhydrous ethanol are stirred and mixed, a formulated amount of carbon nanotube filler is added to the mixed solution, and ultrasonic dispersion is performed for 0.5 h under ultrasonic assistance with a power of 200 W to obtain a carbon nanotube dispersion liquid I; a formulated amount of hexadecyltrimethylammonium bromide is added, and the carbon nanotube dispersion liquid I is dispersed by high-speed centrifugation at 10,000 rpm for 20 minutes, and allowed to stand to obtain a stratified carbon nanotube dispersion liquid II; the upper layer solution is extracted to obtain a carbon nanotube dispersion liquid III placed in a lower layer; the carbon nanotube dispersion liquid III is filtered through a membrane filter, and the precipitate is washed and dried to obtain a carbon nanotube reinforcement body IV.

[0039] Furthermore, in step 2, preparing a reinforced and toughened carbon nanotube-modified polypropylene resin comprises:

[0040] The formulated amount of ethylene-octene copolymer, maleic anhydride grafted polypropylene, and chopped fibers were added to a twin-screw extruder. The speed of the twin-screw extruder's high-speed mechanical shearing and stirring was 2000 rpm, the stirring temperature was 230°C, and the nozzle temperature was 190°C. The carbon nanotube reinforcement IV was added by side feeding, and the mixture was melt-blended and extruded to obtain a reinforced and toughened carbon nanotube-modified polypropylene resin V.

[0041] Furthermore, in step 3, preparing a polypropylene-based fiber composite material prepreg tape includes:

[0042] Driven by a traction system, continuous glass fibers are passed through a creel and expanded into continuous fiber monofilaments through dispersion, preheating, desizing, and yarn spreading. The molten reinforced and toughened polypropylene resin V extruded from a twin-screw extruder is spread flat on the surface of the fiber filaments, and the resin is impregnated into the fiber through a melt impregnation mold. The heating temperature is set to 250°C. After calendering, a polypropylene-based fiber composite material prepreg tape VI is obtained.

[0043] Preferably, in step 4, preparing the polypropylene-based fiber composite material rod comprises:

[0044] 23 bundles of polypropylene-based fiber composite prepreg tapes VI with a width of 10 mm were driven by a traction system and passed through a creel, heated and melted in a melting mold, and cooled to shape. The heating and cooling temperatures of the molding mold were 230°C and 110°C, respectively, and the traction rate was 0.3 m / min. The polypropylene-based fiber composite rod VII with a diameter of 10 mm was obtained by pultrusion.

[0045] Example 2:

[0046] In this example, a reinforced and toughened carbon nanotube-modified polypropylene resin was synthesized. The amounts of each formula were as follows: 46.0 g of carbon nanotube filler, 92.0 g of polyvinyl pyrrolidone, 34.5 g of cetyltrimethylammonium bromide, 27.6 g of γ-aminopropyltriethoxysilane, 91.9 g of chopped glass fiber, 23.0 g of ethylene-octene copolymer, 1.8 g of 3,3',5,5'-tetramethylbenzidine, and 2180 g of maleic anhydride-grafted polypropylene.

[0047] Furthermore, a polypropylene-based glass fiber composite rod is prepared using the reinforced and toughened carbon nanotube-modified polypropylene resin as described above, and the specific implementation method is the same as that of Example 1.

[0048] Example 3:

[0049] In this example, a reinforced and toughened carbon nanotube-modified polypropylene resin was synthesized. The amounts of each formula were as follows: 11.5 g of carbon nanotube filler, 92.0 g of polyvinyl pyrrolidone, 34.5 g of cetyltrimethylammonium bromide, 27.6 g of γ-aminopropyltriethoxysilane, 91.9 g of chopped glass fiber, 23.0 g of ethylene-octene copolymer, 1.8 g of 3,3',5,5'-tetramethylbenzidine, and 2180 g of maleic anhydride-grafted polypropylene.

[0050] Furthermore, a polypropylene-based glass fiber composite rod is prepared using the reinforced and toughened carbon nanotube-modified polypropylene resin as described above, and the specific implementation method is the same as that of Example 1.

[0051] Comparative Example 1:

[0052] This comparative example provides a polypropylene-based fiber composite material that is not modified with carbon nanotubes. The resin matrix thereof is only maleic anhydride-grafted polypropylene. The specific implementation method is the same as steps 3 and 4 of Example 1.

[0053] Comparative Example 2:

[0054] This comparative example synthesized a reinforced and toughened carbon nanotube-modified polypropylene resin using the same method as Example 1, except that chopped glass fiber was omitted. The following amounts were used in the formulation: 23.0g carbon nanotube filler, 92.0g polyvinyl pyrrolidone, 34.5g cetyltrimethylammonium bromide, 27.6g γ-aminopropyltriethoxysilane, 23.0g ethylene-octene copolymer, 1.8g 3,3',5,5'-tetramethylbenzidine, and 2180g maleic anhydride-grafted polypropylene.

[0055] Furthermore, a polypropylene-based glass fiber composite rod is prepared using the reinforced and toughened carbon nanotube-modified polypropylene resin as described above. The specific implementation method is the same as steps 3 and 4 of Example 1.

[0056] Comparative Example 3:

[0057] This comparative example synthesized a reinforced and toughened carbon nanotube-modified polypropylene resin using the same method as Example 1, except that the ethylene-octene copolymer and 3,3',5,5'-tetramethylbenzidine were omitted. The following amounts were used in the formulation: 23.0g carbon nanotube filler, 92.0g polyvinyl pyrrolidone, 34.5g cetyltrimethylammonium bromide, 27.6g γ-aminopropyltriethoxysilane, 91.9g chopped glass fiber, and 2180g maleic anhydride-grafted polypropylene.

[0058] Furthermore, a polypropylene-based glass fiber composite rod is prepared using the reinforced and toughened carbon nanotube-modified polypropylene resin as described above. The specific implementation method is the same as steps 3 and 4 of Example 1.

[0059] The tensile properties, bending properties and short beam shear properties of polypropylene-based fiber composite materials were tested. The test results of mechanical properties are shown in Table 1.

[0060] Table 1 Performance test results of high-strength and high-toughness carbon nanotube-modified polypropylene-based fiber composites

[0061]

[0062] From the above, it can be seen that the present invention uses carbon nanotube fillers and short glass fibers to synergistically reinforce the polypropylene matrix at multiple scales, effectively achieving an improvement in the mechanical strength of the fiber composite material. Compared with Comparative Example 1, the tensile strength, flexural strength, and short beam shear strength of Example 1 increased by 12.4%, 11.8%, and 10.6%, respectively, with an increase of more than 10%. This shows that the carbon nanotube fillers are evenly dispersed through surface modification and grafting, promoting the improvement of the stiffness of the polypropylene matrix, which is macroscopically manifested as an enhancement of the mechanical strength of the fiber composite material. The mechanical indicators of Example 2 are slightly lower than those of Example 1. This is because too much carbon nanotube filler agglomerates in the polypropylene matrix and is difficult to disperse. The elongation at break of each group of examples is significantly higher than that of Comparative Example 3, indicating that the synergistic effect of ethylene-octene copolymer and 3,3',5,5'-tetramethylbenzidine achieves high toughness of the polypropylene resin matrix. Figure 2 The microscopic morphology of the radial cross-section of the fiber composite rod before and after modification shows that the defects inside the fiber composite are significantly reduced after modification, and the degree of fiber impregnation is improved, indicating that the high-strength and high-toughness modification significantly improves the molding quality of the fiber composite.

[0063] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the claims of the present invention.

Claims

1. A reinforced and toughened carbon nanotube-modified polypropylene resin, characterized in that: The preparation is carried out according to the following steps, wherein the formula is calculated by weight: 0.5-2 parts of carbon nanotube filler, 1-6 parts of polyvinyl pyrrolidone, 0.5-2 parts of hexadecyltrimethylammonium bromide, 0.5-1.5 parts of γ-aminopropyltriethoxysilane, 2-6 parts of chopped glass fibers, 1-3 parts of ethylene-octene copolymer, 0.05-0.15 parts of 3,3',5,5'-tetramethylbenzidine and 90-100 parts of maleic anhydride grafted polypropylene. Step S1: preparing a carbon nanotube reinforcement: polyvinyl pyrrolidone, γ-aminopropyltriethoxysilane, and anhydrous ethanol are stirred and mixed according to a ratio, carbon nanotube filler is added to the mixed solution, and ultrasonic treatment is performed until the mixed solution is uniform to obtain a carbon nanotube dispersion liquid I; hexadecyltrimethylammonium bromide is added, and the carbon nanotube dispersion liquid I is dispersed by high-speed centrifugation, and allowed to stand to obtain a layered carbon nanotube dispersion liquid II; the upper layer solution is extracted to obtain a carbon nanotube dispersion liquid III placed in a lower layer; the carbon nanotube dispersion liquid III is filtered through a membrane filter, and the precipitate is washed and dried to obtain a carbon nanotube reinforcement body IV modified by adsorption of hexadecyltrimethylammonium bromide; Step S2: Preparing a reinforced and toughened carbon nanotube-modified polypropylene resin: adding ethylene-octene copolymer, maleic anhydride grafted polypropylene, chopped glass fiber, and 3,3',5,5'-tetramethylbenzidine into a twin-screw extruder according to a proportion, uniformly mixing them in the hopper of the twin-screw extruder, and adding the carbon nanotube reinforcement IV, and melt-blending and extruding to obtain a reinforced and toughened carbon nanotube-modified polypropylene resin.

2. The reinforced and toughened carbon nanotube-modified polypropylene resin according to claim 1, wherein: The carbon nanotube filler is a carboxyl carbon nanotube with a size of 5-20 nm; the particle size of the chopped glass fiber is in the range of 10-50 μm.

3. The reinforced and toughened carbon nanotube-modified polypropylene resin according to claim 1, wherein: In step S1, the ultrasonic power is 200–400 W, the time is 0.5–1 h, the centrifugal dispersion time is 10–60 min, and the centrifugal speed is 8000–20000 rpm.

4. The reinforced and toughened carbon nanotube-modified polypropylene resin according to claim 1, wherein: In step S1, the upper layer solution of the carbon nanotube dispersion II is anhydrous ethanol, and the lower layer solution is a mixed dispersion of carbon nanotube filler, hexadecyltrimethylammonium bromide and polyvinylpyrrolidone; the carbon nanotube reinforcement IV is obtained by washing the precipitate obtained by filtering the carbon nanotube dispersion III with distilled water and then drying it at 25-80°C for 18-30 hours.

5. The reinforced and toughened carbon nanotube-modified polypropylene resin according to claim 1, wherein: In step S2, the main screw speed of the twin-screw extruder is 100-300 rpm, the feeding screw speed is 10-50 rpm, the extrusion temperature during the extrusion process adopts a temperature combination with a temperature range of 190-240°C and a sequentially increasing temperature combination, and the head temperature is 190-200°C.

6. A polypropylene-based fiber composite material prepreg tape, characterized in that: The preparation method is as follows: continuous fibers are driven by a traction system to pass through a creel, and are dispersed into continuous fiber monofilaments through dispersion, preheating and desizing, and yarn spreading treatment; a molten reinforced and toughened carbon nanotube-modified polypropylene resin as described in any one of claims 1 to 5 extruded by a twin-screw extruder is spread flat on the surface of the fiber filaments, and the resin is impregnated into the fiber through a melt impregnation mold; and a polypropylene-based fiber composite material prepreg tape is obtained through calendering treatment.

7. The polypropylene-based fiber composite material prepreg tape according to claim 6, characterized in that: The continuous fiber is glass fiber, carbon fiber or basalt fiber, the heating melting temperature of the melt impregnation mold is 200-300°C, and the pulling speed is 0.1-1 m / min.

8. A polypropylene-based fiber composite material, characterized in that: The preparation method is as follows: the polypropylene-based fiber composite material prepreg tape according to claim 6 is passed through a creel under the drive of a traction system, heated and melted in a melting mold, cooled and shaped, and pultruded to obtain a polypropylene-based fiber composite material.

9. The polypropylene-based fiber composite material according to claim 8, characterized in that: The heating melting temperature of the molten mold is 200–300°C, the cooling temperature is 80–150°C, and the pulling speed is 0.1–1 m / min.

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