Fiber reinforced thermoplastic composite pipe

Abstract

The application discloses a kind of fiber reinforced thermoplastic plastic composite pipe, belong to composite material technical field, composite pipe includes inner layer, reinforcing layer and outer layer, the reinforcing layer includes the following weight parts of raw materials: crystallization improvement polypropylene 60-80 parts, core-shell fibrous body 15-25 parts, silicon nitride powder 10-20 parts, metallocene polyethylene 5-15 parts;The application is optimized to the structure of reinforcing layer, uses core-shell fibrous body as raw material, the reinforcing layer prepared is applied between the inner layer and outer layer of composite pipe, and the inner layer structure is optimized, the performance of composite pipe is significantly improved, and the raw material is abundant, and the cost is low with rice hull fiber and coconut shell fiber as raw material, meet the increasing performance demand of pipe.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, specifically to a fiber-reinforced thermoplastic composite pipe. Background Technology

[0002] Composite pipes are pipes based on a composite structure of metal and thermoplastic plastic, with an inner lining of non-metallic materials such as polypropylene, polyethylene, or an outer welded cross-linked polyethylene. They combine the advantages of both metal and non-metal pipes. Composite pipes mainly include metal-plastic composite pipes, plastic-lined composite pipes, and plastic-coated composite pipes. Their installation and connection methods mainly include clamping installation, thermofusion installation, and electrofusion connection.

[0003] To improve strength, current plastic-lined composite pipes typically employ fiber reinforcement. For example, Chinese patent CN108036123A discloses a carbon fiber-glass fiber hybrid composite pipe and its preparation method. This composite pipe uses a carbon fiber bundle reinforcement layer as its central layer, with two or more layers of carbon fiber-glass fiber hybrid reinforcement layers, one or more layers of glass fiber reinforcement layers, and one or more layers of carbon fiber reinforcement layers stacked sequentially. Another example is Chinese patent CN114215971B, which discloses a reinforced and toughened plastic pressure composite pipe and its manufacturing method. The pipe body includes an inner layer, a fiber reinforcement layer, and an outer protective layer arranged sequentially from the inside out. The fiber reinforcement layer is a carbon fiber winding layer, a glass fiber winding layer, or a Kevlar fiber winding layer.

[0004] As people's demands for quality of life increase, they also place higher demands on the performance of pipe materials. The reinforcing fibers in the above-mentioned patents are made of carbon fiber or glass fiber. Pure carbon fiber, glass fiber, or their composites have limited reinforcing performance and are more expensive, which cannot well meet the actual application needs. Summary of the Invention

[0005] The purpose of this invention is to provide a fiber-reinforced thermoplastic composite pipe to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A fiber-reinforced thermoplastic composite pipe includes an inner layer, a reinforcing layer, and an outer layer. The reinforcing layer comprises the following raw materials in parts by weight: 60-80 parts of crystal-improved polypropylene, 15-25 parts of core-shell fiber, 10-20 parts of silicon nitride powder, and 5-15 parts of metallocene polyethylene.

[0008] As a further aspect of the present invention, the core-shell fibrous body is prepared by the following method:

[0009] The shell fiber was placed in deionized water, and then 2-acrylamide-2-methylpropanesulfonic acid was added. The mixture was stirred at 1000-2000 rpm for 1-2 hours to obtain a shell fiber dispersion. Zinc acetate dihydrate was dissolved in deionized water to obtain a metal salt solution, and the obtained metal salt solution was added to the plant fiber dispersion to obtain a mixed solution.

[0010] Nuclear fibers with a particle size of 1-5 μm were added to the mixture and stirred to obtain a suspension slurry with a solid content of 45-55 wt%.

[0011] The suspension slurry was spray-granulated to obtain porous spherical particles with a particle size distribution between 100-200 μm.

[0012] Porous spherical particles are packed into a fluidized bed and heated to the reaction temperature of 800-900℃ in an inert atmosphere. Then, a carbon source is introduced, and the total space velocity of the inert gas and the carbon source is 600-800 h⁻¹. -1 Maintaining the volume ratio of carbon source to inert gas between 1 and 1.5, chemical vapor deposition is performed for a reaction time of 30-50 minutes to obtain core-shell fibrous tissue.

[0013] As a further embodiment of the present invention: the shell fiber is rice husk fiber or coconut shell fiber.

[0014] As a further embodiment of the present invention: the nuclear fiber is coconut shell fiber or rice husk fiber.

[0015] As a further embodiment of the present invention, the reinforcing layer is prepared by the following method:

[0016] Weigh the raw materials according to the weight parts, melt-blend and extrude at 180-220℃ to obtain the reinforcing layer.

[0017] As a further embodiment of the present invention: the inner layer comprises a low-density linear polyethylene layer, an ultra-high molecular weight polyethylene layer, and a high-density polyethylene layer.

[0018] As a further aspect of the present invention, the ultra-high molecular weight polyethylene layer has a mesh structure.

[0019] As a further embodiment of the present invention, the mass ratio of the low-density linear polyethylene layer, the ultra-high molecular weight polyethylene layer, and the high-density polyethylene layer is 4:2:4.

[0020] As a further embodiment of the present invention: the outer layer is random copolymer polypropylene, and the mass ratio of the inner layer to the outer layer is 1-2:1.

[0021] A method for preparing a fiber-reinforced thermoplastic composite pipe includes the following steps:

[0022] Fabrication of inner layer, reinforcing layer and outer layer;

[0023] Nest the enhancement layer outside the inner layer;

[0024] The outer layer is nested outside the enhancement layer.

[0025] Compared with the prior art, the beneficial effects of the present invention are: by optimizing the structure of the reinforcing layer and using core-shell fiber as raw material, the reinforcing layer prepared is applied between the inner and outer layers of the composite pipe. Combined with the optimization of the inner layer structure, the performance of the composite pipe is significantly improved. Moreover, using rice husk fiber and coconut shell fiber as raw materials, the raw materials are abundant and the cost is low, which meets the increasingly high performance requirements of pipe materials. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] A fiber-reinforced thermoplastic composite pipe includes an inner layer, a reinforcing layer, and an outer layer. Wherein:

[0029] The inner layer consists of a low-density linear polyethylene layer, a mesh-structured ultra-high molecular weight polyethylene layer, and a high-density polyethylene layer arranged sequentially from the inside out, with a mass ratio of 4:2:4.

[0030] The reinforcing layer comprises the following raw materials: 60 kg of crystal-improved polypropylene, 15 kg of core-shell fiber, 10 kg of silicon nitride powder, and 5 kg of metallocene polyethylene. The core-shell fiber is prepared using the following method:

[0031] Rice husk fiber was placed in deionized water, and then 2-acrylamide-2-methylpropanesulfonic acid was added. The mixture was stirred at 1000 rpm for 2 hours to obtain a husk fiber dispersion. Zinc acetate dihydrate was dissolved in deionized water to obtain a metal salt solution, and the obtained metal salt solution was added to the plant fiber dispersion to obtain a mixed solution.

[0032] Coconut shell fibers with a particle size of 1-5 μm were added to the mixture and stirred to obtain a suspension slurry with a solid content of 45 wt%.

[0033] The suspension slurry was spray-granulated to obtain porous spherical particles with a particle size distribution between 100-200 μm.

[0034] Porous spherical particles were packed into a fluidized bed and heated to a reaction temperature of 8000℃ in an inert atmosphere. Then, a carbon source was introduced, with a total space velocity of 600 h⁻¹ for the inert gas and carbon source. -1 By maintaining a carbon source to inert gas volume ratio of 1:1, chemical vapor deposition is performed for 30 minutes to obtain core-shell fibrous tissue.

[0035] The reinforcing layer was prepared using the following method:

[0036] The raw materials are weighed according to the weight, melt-blended and extruded at 1800℃ to obtain the reinforcing layer.

[0037] The outer layer is random copolymer polypropylene.

[0038] By nesting the reinforcing layer outside the inner layer, and then nesting the outer layer outside the reinforcing layer, a fiber-reinforced thermoplastic composite pipe is obtained, with a mass ratio of 2:1:1 from the inside to the outside.

[0039] Example 2

[0040] A fiber-reinforced thermoplastic composite pipe includes an inner layer, a reinforcing layer, and an outer layer. Wherein:

[0041] The inner layer consists of a low-density linear polyethylene layer, a mesh-structured ultra-high molecular weight polyethylene layer, and a high-density polyethylene layer arranged sequentially from the inside out, with a mass ratio of 4:2:4.

[0042] The reinforcing layer comprises the following raw materials: 65 kg of crystal-improved polypropylene, 18 kg of core-shell fiber, 12 kg of silicon nitride powder, and 8 kg of metallocene polyethylene. The core-shell fiber is prepared using the following method:

[0043] Rice husk fiber was placed in deionized water, and then 2-acrylamide-2-methylpropanesulfonic acid was added. The mixture was stirred at 1250 rpm for 1.2 h to obtain a husk fiber dispersion. Zinc acetate dihydrate was dissolved in deionized water to obtain a metal salt solution, and the obtained metal salt solution was added to the plant fiber dispersion to obtain a mixed solution.

[0044] Coconut shell fibers with a particle size of 1-4 μm were added to the mixture and stirred to obtain a suspension slurry with a solid content of 48 wt%.

[0045] The suspension slurry was spray-granulated to obtain porous spherical particles with a particle size distribution between 120-180μm.

[0046] Porous spherical particles were packed into a fluidized bed and heated to a reaction temperature of 825°C in an inert atmosphere. Then, a carbon source was introduced, and the total space velocity of the inert gas and the carbon source was 650 h⁻¹. -1By maintaining a carbon source to inert gas volume ratio of 1.2:1, chemical vapor deposition was performed for 35 minutes to obtain core-shell fibrous tissue.

[0047] The reinforcing layer was prepared using the following method:

[0048] The raw materials are weighed according to the weight, melt-blended and extruded at 190℃ to obtain the reinforcing layer.

[0049] The outer layer is random copolymer polypropylene.

[0050] By nesting the reinforcing layer outside the inner layer, and then nesting the outer layer outside the reinforcing layer, a fiber-reinforced thermoplastic composite pipe is obtained, with a mass ratio of 1.5:1:1 from the inside to the outside.

[0051] Example 3

[0052] A fiber-reinforced thermoplastic composite pipe includes an inner layer, a reinforcing layer, and an outer layer. Wherein:

[0053] The inner layer consists of a low-density linear polyethylene layer, a mesh-structured ultra-high molecular weight polyethylene layer, and a high-density polyethylene layer arranged sequentially from the inside out, with a mass ratio of 4:2:4.

[0054] The reinforcing layer comprises the following raw materials: 70 kg of crystal-improved polypropylene, 20 kg of core-shell fiber, 15 kg of silicon nitride powder, and 10 kg of metallocene polyethylene. The core-shell fiber is prepared using the following method:

[0055] Rice husk fiber was placed in deionized water, and then 2-acrylamide-2-methylpropanesulfonic acid was added. The mixture was stirred at 150 rpm for 1.5 h to obtain a husk fiber dispersion. Zinc acetate dihydrate was dissolved in deionized water to obtain a metal salt solution, and the obtained metal salt solution was added to the plant fiber dispersion to obtain a mixed solution.

[0056] Coconut shell fibers with a particle size of 2-4 μm were added to the mixture and stirred to obtain a suspension slurry with a solid content of 50 wt%.

[0057] The suspension slurry was spray-granulated to obtain porous spherical particles with a particle size distribution between 140-160μm.

[0058] Porous spherical particles were packed into a fluidized bed and heated to a reaction temperature of 850°C in an inert atmosphere. Then, a carbon source was introduced, with a total space velocity of 700 h⁻¹ for the inert gas and carbon source. -1 By maintaining a carbon source to inert gas volume ratio of 1.3:1, chemical vapor deposition was carried out for 40 minutes to obtain core-shell fibrous tissue.

[0059] The reinforcing layer was prepared using the following method:

[0060] The raw materials are weighed according to the weight, melt-blended and extruded at 200℃ to obtain the reinforcing layer.

[0061] The outer layer is random copolymer polypropylene.

[0062] By nesting the reinforcing layer outside the inner layer, and then nesting the outer layer outside the reinforcing layer, a fiber-reinforced thermoplastic composite pipe is obtained, with a mass ratio of 1:1:1 from the inside to the outside.

[0063] Example 4

[0064] A fiber-reinforced thermoplastic composite pipe includes an inner layer, a reinforcing layer, and an outer layer. Wherein:

[0065] The inner layer consists of a low-density linear polyethylene layer, a mesh-structured ultra-high molecular weight polyethylene layer, and a high-density polyethylene layer arranged sequentially from the inside out, with a mass ratio of 4:2:4.

[0066] The reinforcing layer comprises the following raw materials: 75 kg of crystal-improved polypropylene, 23 kg of core-shell fiber, 17 kg of silicon nitride powder, and 12 kg of metallocene polyethylene. The core-shell fiber is prepared using the following method:

[0067] Rice husk fiber was placed in deionized water, and then 2-acrylamide-2-methylpropanesulfonic acid was added. The mixture was stirred at 1800 rpm for 1.8 h to obtain a husk fiber dispersion. Zinc acetate dihydrate was dissolved in deionized water to obtain a metal salt solution, and the obtained metal salt solution was added to the plant fiber dispersion to obtain a mixed solution.

[0068] Coconut shell fibers with a particle size of 2-5 μm were added to the mixture and stirred to obtain a suspension slurry with a solid content of 52 wt%.

[0069] The suspension slurry was spray-granulated to obtain porous spherical particles with a particle size distribution between 130-170 μm.

[0070] Porous spherical particles were packed into a fluidized bed and heated to a reaction temperature of 875°C in an inert atmosphere. Then, a carbon source was introduced, and the total space velocity of the inert gas and the carbon source was 750 h⁻¹. -1 By maintaining a carbon source to inert gas volume ratio of 1.4:1, chemical vapor deposition was carried out for 45 minutes to obtain core-shell fibrous tissue.

[0071] The reinforcing layer was prepared using the following method:

[0072] The raw materials are weighed according to the weight, melt-blended and extruded at 210℃ to obtain the reinforcing layer.

[0073] The outer layer is random copolymer polypropylene.

[0074] By nesting the reinforcing layer outside the inner layer, and then nesting the outer layer outside the reinforcing layer, a fiber-reinforced thermoplastic composite pipe is obtained, with a mass ratio of 2:1:2 from the inside to the outside.

[0075] Example 5

[0076] A fiber-reinforced thermoplastic composite pipe includes an inner layer, a reinforcing layer, and an outer layer. Wherein:

[0077] The inner layer consists of a low-density linear polyethylene layer, a mesh-structured ultra-high molecular weight polyethylene layer, and a high-density polyethylene layer arranged sequentially from the inside out, with a mass ratio of 4:2:4.

[0078] The reinforcing layer comprises the following raw materials: 80 kg of crystal-improved polypropylene, 25 kg of core-shell fiber, 20 kg of silicon nitride powder, and 15 kg of metallocene polyethylene. The core-shell fiber is prepared using the following method:

[0079] Rice husk fiber was placed in deionized water, and then 2-acrylamide-2-methylpropanesulfonic acid was added. The mixture was stirred at 2000 rpm for 2 hours to obtain a husk fiber dispersion. Zinc acetate dihydrate was dissolved in deionized water to obtain a metal salt solution, and the obtained metal salt solution was added to the plant fiber dispersion to obtain a mixed solution.

[0080] Coconut shell fibers with a particle size of 1-5 μm were added to the mixture and stirred to obtain a suspension slurry with a solid content of 55 wt%.

[0081] The suspension slurry was spray-granulated to obtain porous spherical particles with a particle size distribution between 100-200 μm.

[0082] Porous spherical particles were packed into a fluidized bed and heated to a reaction temperature of 900°C in an inert atmosphere. Then, a carbon source was introduced, and the total space velocity of the inert gas and the carbon source was 800 h⁻¹. -1 By maintaining a carbon source to inert gas volume ratio of 1.5:1, chemical vapor deposition was performed for 50 minutes to obtain core-shell fibrous tissue.

[0083] The reinforcing layer was prepared using the following method:

[0084] The raw materials are weighed according to the weight, melt-blended and extruded at 220℃ to obtain the reinforcing layer.

[0085] The outer layer is random copolymer polypropylene.

[0086] By nesting the reinforcing layer outside the inner layer, and then nesting the outer layer outside the reinforcing layer, a fiber-reinforced thermoplastic composite pipe is obtained, with a mass ratio of 2:2:1 from the inside to the outside.

[0087] Example 6

[0088] The difference between this embodiment and Embodiment 1 is that this embodiment uses coconut shell fiber to replace the rice husk fiber in Embodiment 1, and uses rice husk fiber to replace the coconut shell fiber in Embodiment 1.

[0089] Example 7

[0090] The difference between this embodiment and embodiment 2 is that this embodiment uses coconut shell fiber to replace the rice husk fiber in embodiment 2.

[0091] Example 8

[0092] The difference between this embodiment and embodiment 3 is that this embodiment uses coconut shell fiber to replace the rice husk fiber in embodiment 3, and uses rice husk fiber to replace the coconut shell fiber in embodiment 3.

[0093] Example 9

[0094] The difference between this embodiment and embodiment 4 is that this embodiment uses coconut shell fiber to replace the rice husk fiber in embodiment 4, and rice husk fiber to replace the coconut shell fiber in embodiment 4.

[0095] Example 10

[0096] The difference between this embodiment and embodiment 5 is that this embodiment uses coconut shell fiber to replace the rice husk fiber in embodiment 5, and rice husk fiber to replace the coconut shell fiber in embodiment 5.

[0097] Comparative Example 1

[0098] The difference between this embodiment and embodiment 3 is that the reinforcing layer in this embodiment is carbon fiber.

[0099] Comparative Example 2

[0100] The difference between this embodiment and embodiment 8 is that the reinforcing layer in this embodiment is glass fiber.

[0101] Comparative Example 3

[0102] A fiber-reinforced thermoplastic composite pipe includes an inner layer, a reinforcing layer, and an outer layer. Wherein:

[0103] The inner layer is a low-density linear polyethylene layer.

[0104] The reinforcing layer is made of carbon fiber.

[0105] The outer layer is random copolymer polypropylene.

[0106] The reinforcing layer is nested outside the inner layer, and then the outer layer is nested outside the reinforcing layer to obtain a composite pipe, with the mass ratio from the inside to the outside being 1:1:1.

[0107] Comparative Example 4

[0108] A fiber-reinforced thermoplastic composite pipe includes an inner layer, a reinforcing layer, and an outer layer. Wherein:

[0109] The inner layer is a high-density linear polyethylene layer.

[0110] The reinforcing layer is made of glass fiber.

[0111] The outer layer is random copolymer polypropylene.

[0112] The reinforcing layer is nested outside the inner layer, and then the outer layer is nested outside the reinforcing layer to obtain a composite pipe, with the mass ratio from the inside to the outside being 1:1:1.

[0113] Experimental Example 1

[0114] The composite tubes of Examples 3, 8 and Comparative Examples 1-4 were subjected to performance tests. Each group was measured 5 times, and the average value of the results was taken. The test results and test standards are detailed in Table 1 below.

[0115] Table 1

[0116] Test Project Tensile strength (MPa) Bending strength (MPa) Flexural modulus (MPa) <![CDATA[Impact strength (KJ / m 2 )]]> Test Standards GB / T 1040 GB / T 9341 GB / T 9341 GB / T 1043.1-2008 Example 3 37.7 47.8 2351 61.0 Example 8 38.5 49.4 2443 62.8 Comparative Example 1 31.3 41.5 1921 54.7 Comparative Example 2 30.9 40.7 1857 52.5 Comparative Example 3 27.5 37.4 1512 48.6 Comparative Example 4 26.2 35.8 1483 47.4

[0117] As can be seen from the table above, the composite pipes prepared in Examples 3 and 8 of this invention are significantly superior to those in Comparative Examples 1-4 in terms of tensile strength, flexural strength, flexural modulus, and impact strength. Specifically, Comparative Examples 1 and 2 differ from Comparative Examples 3 and 4 only in their inner layer structure; that is, the performance of the composite pipe is altered by changing the inner layer structure. Specifically, the tensile strength is improved by approximately 15%, the flexural strength by approximately 12%, the flexural modulus by approximately 25%, and the impact strength by approximately 10%. In other words, this invention can significantly improve the performance of the composite pipe through optimization of the inner layer structure. Furthermore, Examples 3 and 8 differ from Comparative Examples 1 and 2 only in their reinforcing layer structure; that is, the performance of the composite pipe is altered by changing the reinforcing layer structure. Specifically, the tensile strength is improved by approximately 22%, the flexural strength by approximately 18%, the flexural modulus by approximately 25%, and the impact strength by approximately 16%. In other words, this invention significantly improves the performance of the composite pipe through optimization of the inner layer structure and the reinforcing layer structure.

[0118] Example 11

[0119] A fiber-reinforced thermoplastic composite pipe includes an inner layer, a reinforcing layer, and an outer layer. Wherein:

[0120] The inner layer consists of a low-density linear polyethylene layer, a mesh-structured ultra-high molecular weight polyethylene layer, and a high-density polyethylene layer arranged sequentially from the inside out, with a mass ratio of 4:2:4.

[0121] The reinforcing layer comprises the following raw materials: 70 kg of crystal-improved polypropylene, 20 kg of core-shell fiber, 15 kg of silicon nitride powder, and 10 kg of metallocene polyethylene. The core-shell fiber is prepared using the following method:

[0122] Rice husk fiber was placed in deionized water, and then 2-acrylamide-2-methylpropanesulfonic acid was added. The mixture was stirred at 150 rpm for 1.5 h to obtain a husk fiber dispersion. Zinc acetate dihydrate was dissolved in deionized water to obtain a metal salt solution, and the obtained metal salt solution was added to the plant fiber dispersion to obtain a mixed solution.

[0123] Coconut shell fibers with a particle size of 2-4 μm were added to the mixture and stirred to obtain a suspension slurry with a solid content of 50 wt%.

[0124] The suspension slurry was spray-granulated to obtain porous spherical particles with a particle size distribution between 140-160μm.

[0125] Porous spherical particles were packed into a fluidized bed and heated to a reaction temperature of 850°C in an inert atmosphere. Then, a carbon source was introduced, with a total space velocity of 700 h⁻¹ for the inert gas and carbon source. -1 By maintaining a carbon source to inert gas volume ratio of 1.3:1, chemical vapor deposition was carried out for 40 minutes to obtain core-shell fibrous tissue.

[0126] The reinforcing layer was prepared using the following method:

[0127] The raw materials are weighed according to the weight, melt-blended and extruded at 200℃ to obtain the reinforcing layer.

[0128] The outer layer is random copolymer polypropylene.

[0129] The reinforcing layer is nested outside the inner layer through an adhesive layer, and then the outer layer is nested outside the reinforcing layer to obtain a fiber-reinforced thermoplastic composite pipe. The mass ratio of the inner layer, reinforcing layer and outer layer is 1:1:1. The adhesive layer is coconut shell cellulose / chitosan aerogel with a thickness of 1 mm.

[0130] Example 12

[0131] A fiber-reinforced thermoplastic composite pipe includes an inner layer, a reinforcing layer, and an outer layer. Wherein:

[0132] The inner layer consists of a low-density linear polyethylene layer, a mesh-structured ultra-high molecular weight polyethylene layer, and a high-density polyethylene layer arranged sequentially from the inside out, with a mass ratio of 4:2:4.

[0133] The reinforcing layer comprises the following raw materials: 70 kg of crystal-improved polypropylene, 20 kg of core-shell fiber, 15 kg of silicon nitride powder, and 10 kg of metallocene polyethylene. The core-shell fiber is prepared using the following method:

[0134] Coconut shell fiber was placed in deionized water, and then 2-acrylamide-2-methylpropanesulfonic acid was added. The mixture was stirred at 150 rpm for 1.5 h to obtain a shell fiber dispersion. Zinc acetate dihydrate was dissolved in deionized water to obtain a metal salt solution, and the obtained metal salt solution was added to the plant fiber dispersion to obtain a mixed solution.

[0135] Rice husk fibers with a particle size of 2-4 μm were added to the mixture and stirred to obtain a suspension slurry with a solid content of 50 wt%.

[0136] The suspension slurry was spray-granulated to obtain porous spherical particles with a particle size distribution between 140-160μm.

[0137] Porous spherical particles were packed into a fluidized bed and heated to a reaction temperature of 850°C in an inert atmosphere. Then, a carbon source was introduced, with a total space velocity of 700 h⁻¹ for the inert gas and carbon source. -1 By maintaining a carbon source to inert gas volume ratio of 1.3:1, chemical vapor deposition was carried out for 40 minutes to obtain core-shell fibrous tissue.

[0138] The reinforcing layer was prepared using the following method:

[0139] The raw materials are weighed according to the weight, melt-blended and extruded at 200℃ to obtain the reinforcing layer.

[0140] The outer layer is random copolymer polypropylene.

[0141] The reinforcing layer is nested outside the inner layer, and then the outer layer is nested outside the reinforcing layer through an adhesive layer to obtain a fiber-reinforced thermoplastic composite pipe. The mass ratio of the inner layer, reinforcing layer and outer layer is 1:1:1. The adhesive layer is coconut shell cellulose / chitosan aerogel with a thickness of 5 mm.

[0142] Example 13

[0143] A fiber-reinforced thermoplastic composite pipe includes an inner layer, a reinforcing layer, and an outer layer. Wherein:

[0144] The inner layer consists of a low-density linear polyethylene layer, a mesh-structured ultra-high molecular weight polyethylene layer, and a high-density polyethylene layer arranged sequentially from the inside out, with a mass ratio of 4:2:4.

[0145] The reinforcing layer comprises the following raw materials: 70 kg of crystal-improved polypropylene, 20 kg of core-shell fiber, 15 kg of silicon nitride powder, and 10 kg of metallocene polyethylene. The core-shell fiber is prepared using the following method:

[0146] Coconut shell fiber was placed in deionized water, and then 2-acrylamide-2-methylpropanesulfonic acid was added. The mixture was stirred at 150 rpm for 1.5 h to obtain a shell fiber dispersion. Zinc acetate dihydrate was dissolved in deionized water to obtain a metal salt solution, and the obtained metal salt solution was added to the plant fiber dispersion to obtain a mixed solution.

[0147] Rice husk fibers with a particle size of 2-4 μm were added to the mixture and stirred to obtain a suspension slurry with a solid content of 50 wt%.

[0148] The suspension slurry was spray-granulated to obtain porous spherical particles with a particle size distribution between 140-160μm.

[0149] Porous spherical particles were packed into a fluidized bed and heated to a reaction temperature of 850°C in an inert atmosphere. Then, a carbon source was introduced, with a total space velocity of 700 h⁻¹ for the inert gas and carbon source. -1 By maintaining a carbon source to inert gas volume ratio of 1.3:1, chemical vapor deposition was carried out for 40 minutes to obtain core-shell fibrous tissue.

[0150] The reinforcing layer was prepared using the following method:

[0151] The raw materials are weighed according to the weight, melt-blended and extruded at 200℃ to obtain the reinforcing layer.

[0152] The outer layer is random copolymer polypropylene.

[0153] The reinforcing layer is nested outside the inner layer through an adhesive layer, and then the outer layer is nested outside the reinforcing layer through an adhesive layer to obtain a fiber-reinforced thermoplastic composite pipe. The mass ratio of the inner layer, reinforcing layer and outer layer is 1:1:1. The adhesive layer is coconut shell cellulose / chitosan aerogel with a thickness of 3 mm.

[0154] Experimental Example 2

[0155] The composite layers prepared in Examples 11-13 were subjected to performance tests, and the test results are shown in Table 2 below.

[0156] Table 2

[0157] Test Project Tensile strength (MPa) Bending strength (MPa) Flexural modulus (MPa) <![CDATA[Impact strength (KJ / m 2 )]]> Test Standards GB / T 1040 GB / T 9341 GB / T 9341 GB / T 1043.1-2008 Example 11 38.1 48.3 2374 61.7 Example 12 39.4 50.4 2498 63.9 Example 13 40.5 51.9 2566 65.9

[0158] The results showed that adding adhesive layers improved the tensile strength, flexural strength, flexural modulus, and impact strength to varying degrees. Specifically, adding adhesive layers to one side of the reinforcement layer improved the overall performance by more than 1%, and the improvement was minimal with increasing adhesive layer thickness. When adhesive layers were added to both sides of the reinforcement layer, the performance was significantly improved compared to adding adhesive layers to one side, with an overall performance improvement of approximately 5%. This means that even without a significant increase in overall weight, the overall performance was still improved, demonstrating a clear improvement effect.

[0159] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0160] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A fiber-reinforced thermoplastic composite pipe, comprising an inner layer, a reinforcing layer, and an outer layer, characterized in that, The reinforcing layer comprises the following raw materials in parts by weight: 60-80 parts of crystal-improved polypropylene, 15-25 parts of core-shell fiber, 10-20 parts of silicon nitride powder, and 5-15 parts of metallocene polyethylene. The core-shell fibrous body was prepared by the following method: Shell fibers were placed in deionized water, and then 2-acrylamide-2-methylpropanesulfonic acid was added. The mixture was stirred at 1000-2000 rpm for 1-2 hours to obtain a shell fiber dispersion. Zinc acetate dihydrate was dissolved in deionized water to obtain a metal salt solution, and the obtained metal salt solution was added to the shell fiber dispersion to obtain a mixture. Nuclear fibers with a particle size of 1-5 μm were added to the mixture and stirred to obtain a suspension slurry with a solid content of 45-55 wt%. The suspension slurry was spray-granulated to obtain porous spherical particles with a particle size distribution between 100-200 μm. Porous spherical particles are packed into a fluidized bed and heated to the reaction temperature of 800-900℃ in an inert atmosphere. Then, a carbon source is introduced, and the total space velocity of the inert gas and the carbon source is 600-800 h⁻¹. -1 Maintaining the volume ratio of carbon source to inert gas between 1 and 1.5, chemical vapor deposition is performed for a reaction time of 30-50 minutes to obtain core-shell fibrous tissue. The shell fiber is rice husk fiber, and the kernel fiber is coconut shell fiber; or The shell fiber is coconut shell fiber, and the kernel fiber is rice husk fiber.

2. The fiber-reinforced thermoplastic composite pipe according to claim 1, characterized in that, The reinforcing layer is prepared using the following method: Weigh the raw materials according to the weight parts, melt-blend and extrude at 180-220℃ to obtain the reinforcing layer.

3. The fiber-reinforced thermoplastic composite pipe according to claim 1, characterized in that, The inner layer comprises a low-density linear polyethylene layer, an ultra-high molecular weight polyethylene layer, and a high-density polyethylene layer.

4. The fiber-reinforced thermoplastic composite pipe according to claim 3, characterized in that, The ultra-high molecular weight polyethylene layer has a mesh structure.

5. The fiber-reinforced thermoplastic composite pipe according to claim 3, characterized in that, The mass ratio of the low-density linear polyethylene layer, the ultra-high molecular weight polyethylene layer, and the high-density polyethylene layer is 4:2:

4.

6. The fiber-reinforced thermoplastic composite pipe according to claim 1, characterized in that, The outer layer is random copolymer polypropylene, and the mass ratio of the inner layer to the outer layer is 1-2:

1.

7. The method for preparing fiber-reinforced thermoplastic composite pipe according to any one of claims 1-6, characterized in that, Includes the following steps: Fabrication of inner layer, reinforcing layer and outer layer; Nest the enhancement layer outside the inner layer; The outer layer is nested outside the enhancement layer.