Temperature-resistant high-strength PE composite pipe and preparation method thereof

Abstract

The application discloses a kind of temperature-resistant high-strength PE composite pipe and preparation method thereof, it is related to high polymer material synthesis technical field;The temperature-resistant high-strength PE composite pipe of the application includes the following weight parts of raw materials: non-crosslinking heat-resistant polyethylene 75-105 parts, modified ultra-high molecular weight polyethylene fiber 10-15 parts, functional elastomer 10-20 parts, composite nanoparticles 8-12 parts, lubricant 1-2 parts, anti-aging agent 0.5-0.8 parts, flame retardant 3-5 parts, dispersing agent 2-3 parts;The temperature-resistant high-strength PE composite pipe prepared by the application has good temperature resistance, strong heat expansion resistance, and excellent mechanical performance.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of high polymer material synthesis, in particular to a temperature-resistant high-strength PE composite pipe and a preparation method thereof. BACKGROUND

[0002] The PE composite pipe plays an increasingly important role in modern pipeline systems. Traditional PE pipes are widely used in urban water supply, gas supply, industrial transportation and other fields due to their excellent corrosion resistance, chemical medium resistance, lightness, simple forming and processing and other advantages. However, with the expansion of application scenarios, especially in complex environments such as high temperature, high pressure and strong corrosive medium, the single PE material gradually shows limitations, such as insufficient thermal stability, weak creep performance, limited mechanical impact resistance, decreased long-term bearing capacity and insufficient temperature resistance. These problems are particularly prominent in geothermal systems, hot water reuse, steam transportation, chemical media and high temperature and high pressure environments, directly affecting the safety, stability and service life of the pipeline system. The long-term use temperature of ordinary PE pipes is usually not more than 60 DEG C, and the pipes are prone to softening deformation in high temperature environments and have insufficient anti-creep ability, so they are difficult to meet the needs of high temperature and high pressure working conditions such as petroleum and chemical industry and industrial heat transportation. Most of the existing technologies adopt a layered design to set multiple functional layers to solve these problems, but at the same time, the problem of serious interlayer non-uniform thermal expansion and decreased mechanical properties is also caused, so it is necessary to develop a high-temperature-resistant and high-strength specialized composite pipe. SUMMARY

[0003] The application aims to provide a temperature-resistant high-strength PE composite pipe and a preparation method thereof, and solve the following technical problems:

[0004] Most of the existing PE composite pipe technologies adopt a layered design, which causes the problem of serious interlayer non-uniform thermal expansion and decreased mechanical properties.

[0005] The application can be achieved by the following technical solutions:

[0006] A temperature-resistant high-strength PE composite pipe, characterized in that the pipe comprises the following raw materials in parts by weight: non-crosslinked heat-resistant polyethylene 75-105 parts, modified ultra-high molecular weight polyethylene fiber 10-15 parts, functionalized elastomer 10-20 parts, composite nanoparticles 8-12 parts, lubricant 1-2 parts, anti-aging agent 0.5-0.8 parts, flame retardant 3-5 parts, dispersant 2-3 parts; the functionalized elastomer is a polyolefin elastomer obtained by copolymerization of long-chain alpha-olefin monomer containing siloxane and ethylene; the composite nanoparticles are nano-tetrairon oxide composite nano-titanium dioxide, and the modified ultra-high molecular weight polyethylene fiber is an ultra-high molecular weight polyethylene fiber modified by catechol and amino silane for the second time.

[0007] As a further scheme of the present application: the functionalized elastomer preparation method comprises the following steps:

[0008] A1, vinyl trimethoxysilane, 1-octene, second generation Grubbs catalyst are blended, and reaction is carried out at 90-95 DEG C for 1-2 h in a nitrogen or argon atmosphere to obtain long-chain alpha-olefin monomer;

[0009] A2, under vacuum, cyclohexane and long-chain alpha-olefin monomer are added into a reaction kettle, nitrogen is introduced, and after the reaction kettle is filled with nitrogen, ethylene is continuously introduced, and the temperature is increased to 60 DEG C at a rate of 5 DEG C / min, and triethylaluminum is added to start stirring, and after stirring for 1-3 min, the temperature is increased to 120 DEG C at a rate of 5 DEG C / min, and the composite catalyst and deionized water are added, and the reaction is carried out under the stirring of 2.5 MPa ethylene pressure for 10-20 min; after the reaction is completed, anhydrous ethanol is added, and vacuum drying is carried out to obtain a functionalized elastomer.

[0010] As a further scheme of the present application: the second generation Grubbs catalyst in A1 is composed of benzylidene [1,3-bis (trimethylphenyl) -2-imidazoline] dichloride (tricyclohexylphosphine) ruthenium,

[0011] The mass ratio of the addition of vinyl trimethoxysilane, 1-octene, second generation Grubbs catalyst is 150-165:105-120:0.05;

[0012] The composite catalyst in A2 is a mixed solution of methyl aluminoxane and a single-metallocene titanium catalyst, and the volume ratio of the addition is 1:3,

[0013] The addition ratio of cyclohexane, long-chain alpha-olefin monomer, triethylaluminum, composite catalyst, and deionized water is 100 mL:230-245 g:7-10 mL:25 mL:10 mL.

[0014] As a further scheme of the present application: the preparation method of the composite nanoparticles comprises the following steps:

[0015] The nano Fe3O4, anhydrous ethanol and oleic acid are mixed and ultrasonically dispersed for 45 min-1 h, titanium tetrabutoxide, deionized water and NH3·H2O are added and stirred for 1-2 h, filtered, washed with anhydrous ethanol, and the washed product is dispersed in an ethanol aqueous solution, a small amount of NH3·H2O is added, transferred into a reaction kettle, and reacted at 160-165 DEG C for 18-20 h to obtain composite nanoparticles.

[0016] As a further scheme of the present application: the concentration of the aqueous ethanol solution is 75 vol%, the adding ratio of the nano Fe3O4, the anhydrous ethanol, the oleic acid, the tetrabutyl titanate, the deionized water, the NH3H2O, the aqueous ethanol solution is 0.3-0.5g: 100mL: 15mL: 3-5mL: 5mL: 0.3-0.5mL: 125mL.

[0017] As a further scheme of the present application: the preparation method of the modified ultra-high molecular weight polyethylene fiber comprises the following steps:

[0018] Tris(hydroxymethyl) aminomethane, catechol, distilled water are mixed, the pH is adjusted to 8.5 by using a standard HCl solution, the ultra-high molecular weight fiber is placed in the mixed solution, and is subjected to shock treatment at room temperature for 35-40h, and then is washed by distilled water and dried; the KH550 aqueous solution is ultrasonically treated for 30min, the fiber is placed in the solution, and is subjected to stirring reaction for 1-2h, and then is taken out, washed by distilled water, and placed in an oven to be baked at 110 DEG C for 1h and dried at 60 DEG C for 1h to obtain the modified ultra-high molecular weight polyethylene fiber.

[0019] As a further scheme of the present application: the concentration of the standard HCl solution is 0.36wt%, the concentration of the KH550 aqueous solution is 3wt%, and the adding ratio of the tris(hydroxymethyl) aminomethane, the catechol, the distilled water, the ultra-high molecular weight fiber, the KH550 aqueous solution is 0.7-1.1g: 4-6g: 500mL: 50g: 500mL.

[0020] As a further scheme of the present application: the lubricant is polyethylene wax;

[0021] The anti-aging agent is primary antioxidant 1010 and auxiliary antioxidant 168, and the mixing mass ratio is 1:2;

[0022] The flame retardant is bisphenol A-bis(diphenyl phosphate) and polydimethylsiloxane, and the mixing mass ratio is 3:1;

[0023] The dispersant is stearate.

[0024] As a further scheme of the present application: the preparation method of the temperature-resistant high-strength PE composite pipe comprises the following steps:

[0025] The non-crosslinking heat-resistant polyethylene, the functionalized elastomer, the composite nanoparticles, the modified ultra-high molecular weight polyethylene fiber, the lubricant, the anti-aging agent, the flame retardant and the dispersant are mixed to obtain a mixture, the mixture is extruded to a mold plate through a double-screw extruder, is first air-cooled at 80 DEG C for 1h, then air-cooled at 50 DEG C for 20-30min, and finally water-cooled at 25 DEG C for 40min-1h, and dried to obtain the temperature-resistant high-strength PE composite pipe.

[0026] The present application has the following beneficial effects:

[0027] (1) The present application introduces Si-O-C bond into long-chain α-olefin monomer by using vinyl trimethoxysilane, and then polymerizes the long-chain α-olefin monomer with ethylene to obtain a functionalized elastomer. Since the molecular structure of the functionalized elastomer is similar to that of the matrix, the compatibility is good, the particle size of the dispersed phase of the blend is small, and the dispersion is uniform, the toughening effect of the blend is good, and the elongation at break is higher. At the same time, during the copolymerization stage, the silicon trimethoxyl group will hydrolyze to produce silanol group or hydrolysis intermediate, and then condense to form Si-O-Si bond. The Si-O-Si skeleton network has high bond energy, and it can also tightly fix the polyethylene molecular chain like an "anchor", greatly hindering the movement ability of the molecular chain and segment when heated. The introduction of Si-O-Si skeleton network improves the high temperature resistance, thermal stability and thermal expansion resistance of the material.

[0028] (2) The present application adds nano-tetrairon oxide composite nano-titanium dioxide. The nano-titanium dioxide has a wide band gap, strongly absorbs ultraviolet light, prevents thermal oxidation aging caused by ultraviolet light, and has a high refractive index to reflect infrared heat, reduce thermal expansion, and improve thermal stability. Nano-tetrairon oxide has high thermal conductivity, and the nano-particles form a heat conduction network in the matrix to improve thermal stability. In addition, it also has high activity, and the Fe 2+ / Fe 3+ redox pair can capture free radicals generated by thermal degradation of polyethylene, interrupt chain oxidation reaction, and inhibit thermal oxidation aging. By coating nano-tetrairon oxide with nano-titanium dioxide to form a core-shell structure, the agglomeration of nano-tetrairon oxide is prevented, and the nano-tetrairon oxide can be uniformly dispersed in the Si-O-Si skeleton network by using a dispersant. Through the synergistic effect of light-heat-three-dimensional structure, the thermal performance of the material is significantly improved.

[0029] (3) The present application uses modified ultra-high molecular weight polyethylene fiber as the outer material of PE composite pipe. The raw material polyethylene has a molecular weight of 1 million to 5 million, and the fiber formed has high crystallinity and high orientation, thereby having high modulus, high strength, friction resistance, impact resistance, and cutting resistance. However, the surface of the unmodified fiber is smooth and chemically inert, and the interfacial adhesion between the fiber and the polyethylene blend system is weak. The surface of the fiber is modified by catechol and amino silane, which increases the surface roughness of the fiber and introduces a large number of active groups, thereby improving the reactivity of the fiber and the blend system, and further improving the bonding performance. The interfacial shear strength of the fiber-blend system can be greatly improved without affecting the mechanical properties of the fiber, so that the combination is stable, and the tensile properties are slightly improved.

[0030] (4) The present application uses a segmented cooling process to reduce stress and improve the tensile strength of the composite pipe. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0032] The method for preparing the functionalized elastomer in the embodiment 1 comprises the following steps:

[0033] A1, 150 g of vinyltrimethoxysilane, 112 g of 1-octene, and 0.05 g of the second-generation Grubbs catalyst are blended, and the mixture is reacted at 90°C for 2 h in a nitrogen atmosphere to obtain a long-chain α-olefin monomer;

[0034] A2, 100 mL of cyclohexane and 240 g of the long-chain α-olefin monomer are added to a reaction kettle under vacuum, nitrogen is introduced, and after the reaction kettle is filled with nitrogen, ethylene is continuously introduced. The temperature is increased to 60°C at a rate of 5°C / min, 8 mL of triethylaluminum is added to start stirring, the temperature is increased to 120°C at a rate of 5°C / min after stirring for 1-3 min, and a mixed solution of methyl aluminoxane and a single-metallocene titanium catalyst in a volume ratio of 1:3, 25 mL, and 10 mL of deionized water are added. The mixture is stirred and reacted at 2.5 MPa of ethylene pressure for 20 min. After the reaction is completed, anhydrous ethanol is added, and the mixture is vacuum dried to obtain the functionalized elastomer.

[0035] The method for preparing the composite nanoparticles in the embodiment 2 comprises the following steps:

[0036] The 0.4 g of nano Fe3O4, 100 mL of anhydrous ethanol, and 15 mL of oleic acid are mixed, ultrasonically dispersed for 1 h, 4 mL of tetrabutyl titanate, 5 mL of deionized water, and 0.4 mL of NH3·H2O are added, and the mixture is stirred for 2 h. The mixture is filtered, washed with anhydrous ethanol, dispersed in 125 mL of a 75 vol% ethanol aqueous solution, and 0.1 mL of NH3·H2O is added to the mixture. The mixture is transferred into a reaction kettle, reacted at 160°C for 20 h, and the composite nanoparticles are obtained.

[0037] The method for preparing the modified ultrahigh molecular weight polyethylene fiber in the embodiment 3 comprises the following steps:

[0038] 0.9g tris(hydroxymethyl)aminomethane, 5g catechol, 500mL distilled water are mixed, 0.36wt% HCl standard solution is used to adjust pH to 8.5, 50g ultra-high molecular weight fiber is placed in the mixed solution, and is treated by oscillation at room temperature for 40h, is washed with distilled water, and is dried; 500mL 3wt% KH550 aqueous solution is ultrasonically treated for 30min, the fiber is placed in the solution, is stirred to react for 2h, is taken out, is washed with distilled water, and is placed in an oven to be baked at 110°C for 1h and dried at 60°C for 1h to obtain the modified ultra-high molecular weight polyethylene fiber.

[0039] Example 4 A temperature-resistant high-strength PE composite pipe comprises the following raw materials by weight: non-crosslinked heat-resistant polyethylene 75 parts, modified ultra-high molecular weight polyethylene fiber 10 parts, functionalized elastomer 10 parts, composite nanoparticles 8 parts, polyethylene wax 1 part, primary antioxidant 1010 0.2 parts, secondary antioxidant 168 0.3 parts, bisphenol A-bis(diphenyl phosphate) 2.3 parts, polydimethylsiloxane 0.7 parts, and stearate 2 parts; the functionalized elastomer is prepared by the method in Example 1, the composite nanoparticles are prepared by the method in Example 2, and the modified ultra-high molecular weight polyethylene fiber is prepared by the method in Example 3; the preparation method of the temperature-resistant high-strength PE composite pipe comprises the following steps:

[0040] The non-crosslinked heat-resistant polyethylene, the functionalized elastomer, the composite nanoparticles, the modified ultra-high molecular weight polyethylene fiber, the polyethylene wax, the primary antioxidant 1010, the secondary antioxidant 168, the bisphenol A-bis(diphenyl phosphate), the polydimethylsiloxane, and the stearate are mixed to obtain a mixture, the mixture is extruded to a mold plate through a double-screw extruder, is first air-cooled at 80°C for 1h, is then air-cooled at 50°C for 20min, and is finally water-cooled at 25°C for 40min, and is dried to obtain the temperature-resistant high-strength PE composite pipe.

[0041] Example 5 A temperature-resistant high-strength PE composite pipe comprises the following raw materials by weight: non-crosslinked heat-resistant polyethylene 90 parts, modified ultra-high molecular weight polyethylene fiber 13 parts, functionalized elastomer 15 parts, composite nanoparticles 10 parts, polyethylene wax 1.5 parts, primary antioxidant 1010 0.25 parts, secondary antioxidant 168 0.5 parts, bisphenol A-bis(diphenyl phosphate) 3 parts, polydimethylsiloxane 1 part, and stearate 2.5 parts; the functionalized elastomer is prepared by the method in Example 1, the composite nanoparticles are prepared by the method in Example 2, and the modified ultra-high molecular weight polyethylene fiber is prepared by the method in Example 3; the preparation method of the temperature-resistant high-strength PE composite pipe comprises the following steps:

[0042] The non-crosslinking heat-resistant polyethylene, the functionalized elastomer, the composite nanoparticles, the modified ultra-high molecular weight polyethylene fiber, the polyethylene wax, the primary antioxidant 1010, the auxiliary antioxidant 168, the bisphenol A-bis(diphenyl phosphate), the polydimethylsiloxane and the stearate are mixed to obtain a mixture, and the mixture is extruded to a mold plate through a double screw extruder; air cooling at 80 DEG C for 1 h, air cooling at 50 DEG C for 20 min, and finally water cooling at 25 DEG C for 40 min, and drying to obtain the heat-resistant high-strength PE composite pipe.

[0043] In one embodiment, a heat-resistant high-strength PE composite pipe includes the following raw materials by weight: 105 parts of non-crosslinking heat-resistant polyethylene, 15 parts of modified ultra-high molecular weight polyethylene fiber, 20 parts of functionalized elastomer, 12 parts of composite nanoparticles, 2 parts of polyethylene wax, 0.3 parts of primary antioxidant 1010, 0.5 parts of auxiliary antioxidant 168, 4 parts of bisphenol A-bis(diphenyl phosphate), 1 part of polydimethylsiloxane, and 3 parts of stearate; the functionalized elastomer is prepared by the method in Example 1, the composite nanoparticles are prepared by the method in Example 2, and the modified ultra-high molecular weight polyethylene fiber is prepared by the method in Example 3; and the preparation method of the heat-resistant high-strength PE composite pipe includes the following steps:

[0044] The non-crosslinking heat-resistant polyethylene, the functionalized elastomer, the composite nanoparticles, the modified ultra-high molecular weight polyethylene fiber, the polyethylene wax, the primary antioxidant 1010, the auxiliary antioxidant 168, the bisphenol A-bis(diphenyl phosphate), the polydimethylsiloxane and the stearate are mixed to obtain a mixture, and the mixture is extruded to a mold plate through a double screw extruder; air cooling at 80 DEG C for 1 h, air cooling at 50 DEG C for 20 min, and finally water cooling at 25 DEG C for 40 min, and drying to obtain the heat-resistant high-strength PE composite pipe.

[0045] In one embodiment, a PE composite pipe includes the following raw materials by weight: 90 parts of non-crosslinking heat-resistant polyethylene, 13 parts of modified ultra-high molecular weight polyethylene fiber, 10 parts of composite nanoparticles, 1.5 parts of polyethylene wax, 0.25 parts of primary antioxidant 1010, 0.5 parts of auxiliary antioxidant 168, 3 parts of bisphenol A-bis(diphenyl phosphate), 1 part of polydimethylsiloxane, and 2.5 parts of stearate; the composite nanoparticles are prepared by the method in Example 2, and the modified ultra-high molecular weight polyethylene fiber is prepared by the method in Example 3; and the preparation method of the PE composite pipe includes the following steps:

[0046] The non-crosslinking heat-resistant polyethylene, the functionalized elastomer, the composite nanoparticles, the modified ultra-high molecular weight polyethylene fiber, the polyethylene wax, the primary antioxidant 1010, the auxiliary antioxidant 168, the bisphenol A-bis(diphenyl phosphate), the polydimethylsiloxane and the stearate are mixed to obtain a mixture, and the mixture is extruded to a mold plate through a double screw extruder; air cooling at 80 DEG C for 1 h, air cooling at 50 DEG C for 20 min, and finally water cooling at 25 DEG C for 40 min, and drying to obtain the heat-resistant high-strength PE composite pipe.

[0047] Comparative Example 2 A PE composite pipe comprises the following raw materials by weight: non-crosslinked heat-resistant polyethylene 90 parts, modified ultra-high molecular weight polyethylene fiber 13 parts, functionalized elastomer 15 parts, polyethylene wax 1.5 parts, primary antioxidant 1010 0.25 parts, secondary antioxidant 168 0.5 parts, bisphenol A-bis(diphenyl phosphate) 3 parts, polydimethylsiloxane 1 part, stearate 2.5 parts; the functionalized elastomer is prepared by the method in Example 1, and the modified ultra-high molecular weight polyethylene fiber is prepared by the method in Example 3; the preparation method of the PE composite pipe comprises the following steps:

[0048] The non-crosslinked heat-resistant polyethylene, the functionalized elastomer, the modified ultra-high molecular weight polyethylene fiber, the polyethylene wax, the primary antioxidant 1010, the secondary antioxidant 168, the bisphenol A-bis(diphenyl phosphate), the polydimethylsiloxane, and the stearate are mixed to obtain a mixture, and the mixture is extruded to a mold plate by a double-screw extruder; air cooling at 80°C for 1 h, air cooling at 50°C for 20 min, and water cooling at 25°C for 40 min in sequence, and drying to obtain the PE composite pipe.

[0049] Comparative Example 3 A PE composite pipe comprises the following raw materials by weight: non-crosslinked heat-resistant polyethylene 90 parts, functionalized elastomer 15 parts, composite nanoparticles 10 parts, polyethylene wax 1.5 parts, primary antioxidant 1010 0.25 parts, secondary antioxidant 168 0.5 parts, bisphenol A-bis(diphenyl phosphate) 3 parts, polydimethylsiloxane 1 part, stearate 2.5 parts; the functionalized elastomer is prepared by the method in Example 1, and the composite nanoparticles are prepared by the method in Example 2; the preparation method of the PE composite pipe comprises the following steps:

[0050] The non-crosslinked heat-resistant polyethylene, the functionalized elastomer, the composite nanoparticles, the polyethylene wax, the primary antioxidant 1010, the secondary antioxidant 168, the bisphenol A-bis(diphenyl phosphate), the polydimethylsiloxane, and the stearate are mixed to obtain a mixture, and the mixture is extruded to a mold plate by a double-screw extruder; air cooling at 80°C for 1 h, air cooling at 50°C for 20-30 min, and water cooling at 25°C for 50 min in sequence, and drying to obtain the PE composite pipe.

[0051] Comparative Example 4 A PE composite pipe comprises the following raw materials by weight: non-crosslinked heat-resistant polyethylene 90 parts, modified ultra-high molecular weight polyethylene fiber 13 parts, polyethylene wax 1.5 parts, primary antioxidant 1010 0.25 parts, secondary antioxidant 168 0.5 parts, bisphenol A-bis(diphenyl phosphate) 3 parts, polydimethylsiloxane 1 part, stearate 2.5 parts; the composite nanoparticles are prepared by the method in Example 2, and the modified ultra-high molecular weight polyethylene fiber is prepared by the method in Example 3; the preparation method of the PE composite pipe comprises the following steps:

[0052] The non-crosslinking heat-resistant polyethylene, modified ultra-high molecular weight polyethylene fiber, polyethylene wax, main antioxidant 1010, auxiliary antioxidant 168, bisphenol A-bis(diphenyl phosphate), polydimethylsiloxane, stearate were mixed to obtain a mixture, and the mixture was extruded to a mold plate through a double screw extruder; first air cooling at 80°C for 1h, then air cooling at 50°C for 20min, and finally water cooling at 25°C for 40min, and drying to obtain a PE composite pipe.

[0053] Performance detection:

[0054] 1. Tensile strength and elongation at break: according to GB / T 8804-2003 "Determination of tensile properties of thermoplastics pipes"; a sample with a length of 150mm was cut from the wall of the temperature-resistant high-strength PE composite pipe, the sample was longitudinally parallel to the pipe axis, the sample was installed on a tensile testing machine and the axis was consistent with the tensile stress direction, the stress-strain curve of the sample was recorded until the sample was broken, and the tensile strength and elongation at break were calculated, respectively, and the results are shown in Table 1.

[0055] Table 1 Tensile strength and elongation at break data table of samples prepared in Examples 4-6 and Comparative Examples 1-3

[0056]

[0057] As can be seen from the table, the mechanical properties of Examples 4-6 are excellent; Comparative Example 1 lacks a functional elastomer, and the elongation at break is significantly lower than Examples and the rest of the comparative examples; Comparative Example 2 lacks composite nanoparticles, and the tensile strength is slightly lower than Examples 4-6 and Comparative Example 1; Comparative Example 3 lacks modified ultra-high molecular weight polyethylene fiber, and the tensile strength is significantly lower than Examples and the rest of the comparative examples, and the elongation at break is also lower than Examples 4-6 and Comparative Example 2 to some extent; Comparative Example 4 lacks both functional elastomer and composite nanoparticles, resulting in a certain degree of decrease in tensile strength and elongation at break compared with Examples 4-6.

[0058] 2. Vicat softening temperature: according to GB / T 1633-2000 "Determination of Vicat softening temperature (VST) of thermoplastics"; the sample was taken as a cylinder with a diameter of 10mm and a height of 5mm, a thermal deformation Vicat softening point temperature tester was used, and the oil bath temperature measured by the sensor when the depth of the pressure needle penetrating into the sample exceeded the starting position by 1mm±0.01mm was recorded, and the results are shown in Table 2.

[0059] 3. Thermal expansion rate: according to GB / T 36800.2-2018 "Plastics - Thermomechanical analysis - Part 2: Test for linear thermal expansion coefficient and glass transition temperature", the sample was taken as a cylinder with a diameter of 5mm and a height of 50mm, a thermal mechanical analyzer was used to record the temperature-length curve, and the linear thermal expansion coefficient was calculated, and the results are shown in Table 2.

[0060] Table 2 Vicat softening temperature and thermal expansion data of samples prepared in Examples 4-6 and Comparative Examples 1-3

[0061]

[0062] From the table, it can be seen that Examples 4-6 and Comparative Example 3 have excellent thermal performance; Comparative Example 1 has poor temperature resistance and high thermal expansion because of the lack of functional elastomer, and Comparative Example 2 has poor temperature resistance and high thermal expansion because of the lack of composite nanoparticles, and the lack of composite nanoparticles has a greater impact on the thermal expansion of the PE composite pipe than the lack of functional elastomer; Comparative Example 4 has the worst temperature resistance and thermal expansion among all groups because it lacks both functional elastomer and composite nanoparticles, and the impact on thermal expansion is greater than the sum of each group, indicating that functional elastomer and composite nanoparticles have a synergistic effect on thermal stability.

[0063] The above embodiments of the present application have been described in detail, but the content described is only the preferred embodiments of the present application and cannot be considered as limiting the scope of the present application. Any equivalent changes and improvements made in accordance with the scope of the present application should still be attributed to the scope of the present patent.

Claims

1. A high-strength, temperature-resistant PE composite pipe, characterized in that, The high-strength, heat-resistant PE composite pipe comprises the following raw materials in parts by weight: 75-105 parts of non-crosslinked heat-resistant polyethylene, 10-15 parts of modified ultra-high molecular weight polyethylene fiber, 10-20 parts of functionalized elastomer, 8-12 parts of composite nanoparticles, 1-2 parts of lubricant, 0.5-0.8 parts of anti-aging agent, 3-5 parts of flame retardant, and 2-3 parts of dispersant; the functionalized elastomer is a polyolefin elastomer obtained by copolymerizing a long-chain α-olefin monomer containing siloxane with ethylene; the composite nanoparticles are nano-iron oxide composite nano-titanium dioxide; and the modified ultra-high molecular weight polyethylene fiber is ultra-high molecular weight polyethylene fiber with secondary surface modification by catechol and aminosilane. The method for preparing the functionalized elastomer includes the following steps: A1. Vinyltrimethoxysilane, 1-octene, and second-generation Grubbs catalyst are blended and reacted at 90-95℃ for 1-2 hours in a nitrogen or argon atmosphere to obtain long-chain α-olefin monomers. A2. Under vacuum conditions, cyclohexane and long-chain α-olefin monomers are added to a reactor, nitrogen is introduced, and after the reactor is filled with nitrogen, ethylene is continuously introduced. The temperature is raised to 60°C at a rate of 5°C / min, triethylaluminum is added and stirring is started. After stirring for 1-3 min, the temperature is raised to 120°C at a rate of 5°C / min, composite catalyst and deionized water are added, and the reaction is carried out under 2.5 MPa ethylene pressure with stirring for 10-20 min. After the reaction is completed, anhydrous ethanol is added, and the mixture is dried under vacuum to obtain the functionalized elastomer.

2. The high-strength, high-temperature resistant PE composite pipe according to claim 1, characterized in that, The second-generation Grubbs catalyst in A1 is composed of benzenemethyl[1,3-bis(trimethylphenyl)-2-imidazolinide]dichloro(tricyclohexylphosphine)ruthenium. The mass ratio of vinyltrimethoxysilane, 1-octene, and second-generation Grubbs catalyst added is 140-160:105-120:0.05; In A2, the composite catalyst is a mixed solution of methylalumina and monotitanium phosphate catalyst, with a volume ratio of 1:

3. The addition ratio of cyclohexane, long-chain α-olefin monomer, triethylaluminum, composite catalyst, and deionized water is 100mL: 230-245g: 7-10mL: 25mL: 10mL.

3. The high-strength, high-temperature resistant PE composite pipe according to claim 1, characterized in that, The method for preparing the composite nanoparticles includes the following steps: Nano Fe3O4, anhydrous ethanol, and oleic acid were mixed and ultrasonically dispersed for 45 min-1 h. Tetrabutyl titanate, deionized water, and NH3·H2O were added and stirred for 1-2 h. The mixture was filtered, washed with anhydrous ethanol, and the washed product was dispersed in an ethanol-water solution. A small amount of NH3·H2O was added to the solution, and the mixture was transferred to a reaction vessel and kept at 160-165℃ for 18-20 h to obtain composite nanoparticles. The concentration of the ethanol aqueous solution is 75 vol%. The addition ratio of nano Fe3O4, anhydrous ethanol, oleic acid, tetrabutyl titanate, deionized water, NH3·H2O and ethanol aqueous solution is 0.3-0.5 g: 100 mL: 15 mL: 3-5 mL: 5 mL: 0.3-0.5 mL: 125 mL.

4. The high-strength, high-temperature resistant PE composite pipe according to claim 1, characterized in that, The method for preparing the modified ultra-high molecular weight polyethylene fiber includes the following steps: Tris(hydroxymethyl)aminomethane, catechol, and distilled water were mixed together, and the pH was adjusted to 8.5 with HCl standard solution. Ultra-high molecular weight fibers were placed in the mixed solution and shaken at room temperature for 35-40 hours. The fibers were then rinsed with distilled water and dried. KH550 aqueous solution was sonicated for 30 minutes, and the fibers were placed in the solution and stirred for 1-2 hours. The fibers were then removed, washed with distilled water, and placed in an oven to bake at 110℃ for 1 hour and then dried at 60℃ for 1 hour to obtain modified ultra-high molecular weight polyethylene fibers.

5. The high-strength, high-temperature resistant PE composite pipe according to claim 4, characterized in that, The concentration of the HCl standard solution is 0.36 wt%, the concentration of the KH550 aqueous solution is 3 wt%, and the addition ratio of tris(hydroxymethyl)aminomethane, catechol, distilled water, ultra-high molecular weight fiber, and KH550 aqueous solution is 0.7-1.1 g: 4-6 g: 500 mL: 50 g: 500 mL.

6. The high-strength, high-temperature resistant PE composite pipe according to claim 1, characterized in that, The lubricant is polyethylene wax; The anti-aging agent is mainly antioxidant 1010 and auxiliary antioxidant 168, with a mixing mass ratio of 1:

2. The flame retardant is bisphenol A-bis(diphenyl phosphate) and polydimethylsiloxane, with a mixing mass ratio of 3:1; The dispersant is stearate.

7. The high-strength, high-temperature resistant PE composite pipe according to claim 1, characterized in that, The preparation method of the high-strength, heat-resistant PE composite pipe includes the following steps: Non-crosslinked heat-resistant polyethylene, functionalized elastomer, composite nanoparticles, modified ultra-high molecular weight polyethylene fiber, lubricant, anti-aging agent, flame retardant, and dispersant are mixed to obtain a compound. The compound is then extruded into a template using a twin-screw extruder. It is first air-cooled at 80℃ for 1 hour, then air-cooled at 50℃ for 20-30 minutes, and finally water-cooled at 25℃ for 40 minutes to 1 hour. After drying, a high-strength, heat-resistant PE composite pipe is obtained.

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