A modified polytetrafluoroethylene pipe and its preparation method

Abstract

The present invention relates to the technical field of pipe materials, and particularly relates to a modified polytetrafluoroethylene pipe and a preparation method thereof. The modified polytetrafluoroethylene pipe is obtained by extrusion molding and sintering of modified carbon nanotubes, hydroxylated polytetrafluoroethylene powder and polytetrafluoroethylene powder. The modified carbon nanotubes are obtained by modifying carbon nanotubes with γ-(2,3-epoxypropoxy)propyltrimethoxysilane and tridecafluorooctyltriethoxysilane. The modified polytetrafluoroethylene pipe provided by the present invention has excellent mechanical properties, especially the notched impact strength, so that it can be widely used in dynamic load and high-impact environments.

Description

Technical Field

[0001] The present invention relates to the technical field of pipe materials, and particularly to a modified polytetrafluoroethylene pipe and a preparation method thereof. Background Art

[0002] Polytetrafluoroethylene (PTFE) is a high-performance polymer formed by the polymerization of tetrafluoroethylene, and is well-known for its excellent chemical inertness, high temperature resistance, and low friction coefficient. PTFE remains stable within a wide temperature range and can resist the erosion of most chemicals, so it is widely used in fields such as chemical industry, electronics, machinery, and aerospace. However, the inherent mechanical properties of PTFE are insufficient, especially its low impact strength and elongation at break, which limit its use in some high-stress applications.

[0003] Traditional PTFE pipes are prone to fracture or damage when subjected to external forces or impacts, which may lead to serious consequences in some critical applications. Although PTFE has many excellent properties, the deficiency of its mechanical properties limits its application in dynamic load and high-impact environments.

[0004] In recent years, with the development of nanotechnology, nanomaterials such as carbon nanotubes have been introduced into PTFE in order to improve its mechanical properties. Carbon nanotubes have excellent mechanical properties and electrical conductivity, and can significantly improve the strength and toughness of composite materials. However, due to the non-polar characteristics of PTFE, the dispersion and compatibility of carbon nanotubes in the PTFE matrix are poor, which limits their strengthening effect. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a modified polytetrafluoroethylene pipe to solve the problem that polytetrafluoroethylene pipes are difficult to be applied in dynamic load and high-impact environments.

[0006] Based on the above purpose, the present invention provides a modified polytetrafluoroethylene pipe, which is obtained by extrusion molding and sintering from the following raw materials by weight: 1-3 parts of modified carbon nanotubes, 5-20 parts of hydroxylated polytetrafluoroethylene powder, and 80-120 parts of polytetrafluoroethylene powder.

[0007] Further, the modified carbon nanotubes are obtained by modifying carbon nanotubes with γ-(2,3-epoxypropoxy) propyltrimethoxysilane and tridecafluorooctyltriethoxysilane.

[0008] Further, the weight ratio of γ-(2,3-epoxypropoxy) propyltrimethoxysilane, tridecafluorooctyltriethoxysilane, and carbon nanotubes is 0.1-0.3:0.2-1:10-30.

[0009] Further, the preparation method of the hydroxylated polytetrafluoroethylene is as follows:

[0010] (1) Add polytetrafluoroethylene powder into tetrahydrofuran, ultrasonicate for 10 - 30 min. Under nitrogen protection, add sodium naphthalene treatment solution, stir for 5 - 20 min, then add deionized water to terminate the activation reaction, and purify to obtain activated polytetrafluoroethylene powder;

[0011] (2) Add the activated polytetrafluoroethylene powder into deionized water, ultrasonicate for 10 - 30 min. Under nitrogen protection, add ammonium persulfate, heat up to 45 - 55 °C, then add 2 - hydroxyethyl methacrylate, continue to stir for 10 - 20 h, and purify to obtain hydroxylated polytetrafluoroethylene powder.

[0012] Preferably, in the step (1), the weight ratio of polytetrafluoroethylene powder, tetrahydrofuran, sodium naphthalene treatment solution and deionized water is 8 - 12:40 - 60:2 - 4:1 - 2.

[0013] Preferably, the addition amount of deionized water in the step (1) is 0.5 - 1 times the weight of the sodium naphthalene treatment solution.

[0014] Preferably, in the step (2), the weight ratio of activated polytetrafluoroethylene powder, deionized water and 2 - hydroxyethyl methacrylate is 8 - 12:20 - 40:1 - 3.

[0015] Preferably, the addition amount of ammonium persulfate in the step (2) is 0.05% - 0.2% of the weight of 2 - hydroxyethyl methacrylate.

[0016] Preferably, the average particle size of the polytetrafluoroethylene powder is 100 - 300 μm.

[0017] Preferably, the outer diameter of the carbon nanotubes is 10 - 20 nm and the length is 0.5 - 2 μm.

[0018] Preferably, the preparation method of the modified carbon nanotubes is as follows: Disperse the carbon nanotubes in a mixed solution of ethanol and deionized water, add γ-(2,3 - epoxypropoxy) propyltrimethoxysilane and tridecafluorooctyltriethoxysilane, heat up to 55 - 65 °C, stir and react for 6 - 7 h, and purify to obtain modified carbon nanotubes.

[0019] Preferably, the weight ratio of ethanol to deionized water is 3:2.

[0020] Furthermore, the present invention also provides a method for preparing a modified polytetrafluoroethylene pipe, comprising the following steps: melting and mixing modified carbon nanotubes, hydroxylated polytetrafluoroethylene powder, and polytetrafluoroethylene powder at 400 - 450 °C, extruding and granulating to obtain a modified polytetrafluoroethylene masterbatch, then loading the modified polytetrafluoroethylene masterbatch into a mold for preforming to form a cylindrical blank, then putting the cylindrical blank into an extruder to extrude and form a tubular material, and finally sintering the tubular material at 350 - 370 °C for 2.5 - 3.5 h and cooling to obtain a modified polytetrafluoroethylene pipe.

[0021] Advantages of the present invention:

[0022] By modifying polytetrafluoroethylene, the present invention significantly improves the mechanical properties of the material, especially achieving remarkable progress in elongation at break and impact strength. First of all, although the tensile strength of the modified polytetrafluoroethylene pipe slightly decreases, this change is not significant and still meets the basic requirements of most applications. More importantly, the modified material has achieved a substantial increase in elongation at break and impact strength, especially the notched impact strength has increased by more than three times. This enhanced notched impact strength means that the material is less likely to break or be damaged when subjected to external forces or impacts, thus significantly improving the durability and service life of the pipe.

[0023] By performing hydroxyl modification on the surface of polytetrafluoroethylene powder, the present invention enhances its compatibility and dispersibility with carbon nanotubes. This modification enables hydroxyl groups to form chemical bonds with epoxy groups on the surface of carbon nanotubes, thereby improving the elongation at break and impact strength of the material. In addition, the introduction of epoxy groups and fluorine chains on the surface of carbon nanotubes effectively regulates the mechanical properties of the polytetrafluoroethylene pipe. While maintaining the tensile strength, it greatly increases the elongation at break and synergistically improves the impact performance, especially the notched impact performance. This improvement in performance is mainly attributed to the chemical crosslinking between epoxy groups and the surface of polytetrafluoroethylene and the physical entanglement between fluorine chains and the molecular chains of polytetrafluoroethylene.

[0024] In summary, through dual modification means of chemistry and physics, the present invention significantly improves the mechanical properties of polytetrafluoroethylene pipes, making them show higher reliability and durability in a wider range of applications. This modification strategy not only improves the performance of the material but also provides new possibilities for the use of polytetrafluoroethylene in high - demand applications. Detailed implementation manners

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the following further elaborates on the present invention in conjunction with specific embodiments.

[0026] In the specific implementation manner of the present invention, the polytetrafluoroethylene powder was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with the product number P434336 and an average particle size of 200 μm. The naphthalene sodium treatment solution was purchased from Dongguan Yihe Chemical Co., Ltd., with the model number YH-891. The carbon nanotubes were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with the product number C369044, an outer diameter of 10 - 20 nm, and a length of 0.5 - 2 μm. Example 1:

[0027] (1) Add 80 g of polytetrafluoroethylene powder to 400 g of tetrahydrofuran, ultrasonic for 10 min. Under nitrogen protection, add 20 g of naphthalene sodium treatment solution, stir for 5 min, then add 10 g of deionized water to terminate the activation reaction. Then wash with acetone and perform vacuum filtration 3 times, and dry in vacuum to obtain activated polytetrafluoroethylene powder;

[0028] (2) Add 80 g of activated polytetrafluoroethylene powder to 200 g of deionized water, ultrasonic for 10 min. Under nitrogen protection, add 0.01 g of ammonium persulfate, heat up to 45 °C, then add 10 g of 2-hydroxyethyl methacrylate, continue to stir for 10 h, then wash with deionized water and perform vacuum filtration 3 times, and dry in vacuum to obtain hydroxylated polytetrafluoroethylene powder;

[0029] (3) Disperse 10 g of carbon nanotubes in a mixed solution of 120 g of ethanol and 80 g of deionized water, add 0.1 g of γ-(2,3-epoxypropoxy) propyltrimethoxysilane and 0.2 g of trifluorooctyltriethoxysilane, heat up to 55 °C, stir and react for 5 h, wash with water, and dry to obtain modified carbon nanotubes;

[0030] (4) Melt and mix 10 g of modified carbon nanotubes, 50 g of hydroxylated polytetrafluoroethylene powder, and 800 g of polytetrafluoroethylene powder at 400 °C, extrude and granulate to obtain modified polytetrafluoroethylene masterbatch. Then load the modified polytetrafluoroethylene masterbatch into a mold for preforming to form a cylindrical blank. Then put the cylindrical blank into an extruder to extrude and form a tubular material. Finally, sinter the tubular material at 350 °C for 2.5 h and cool to obtain a modified polytetrafluoroethylene pipe. Example 2:

[0031] (1) Add 100 g of polytetrafluoroethylene powder to 500 g of tetrahydrofuran, ultrasonic for 20 min. Under nitrogen protection, add 30 g of naphthalene sodium treatment solution, stir for 10 min, then add 15 g of deionized water to terminate the activation reaction. Then wash with acetone and perform vacuum filtration 3 times, and dry in vacuum to obtain activated polytetrafluoroethylene powder;

[0032] (2) Add 100 g of activated polytetrafluoroethylene powder to 300 g of deionized water, ultrasonicate for 20 min, under nitrogen protection, add 0.02 g of ammonium persulfate, heat up to 50 °C, then add 20 g of 2-hydroxyethyl methacrylate, continue stirring for 15 h, then wash with deionized water and filter under reduced pressure 3 times, and dry in vacuum to obtain hydroxylated polytetrafluoroethylene powder;

[0033] (3) Disperse 20 g of carbon nanotubes in a mixed solution of 120 g of ethanol and 80 g of deionized water, add 0.2 g of γ-(2,3-epoxypropoxy) propyltrimethoxysilane and 0.5 g of tridecafluorooctyltriethoxysilane, heat up to 60 °C, stir and react for 6 h, wash with water, and dry to obtain modified carbon nanotubes;

[0034] (4) Melt and mix 20 g of modified carbon nanotubes, 100 g of hydroxylated polytetrafluoroethylene powder and 1000 g of polytetrafluoroethylene powder at 420 °C, extrude and pelletize to obtain modified polytetrafluoroethylene masterbatch, then put the modified polytetrafluoroethylene masterbatch into a mold for preforming to form a cylindrical blank, then put the cylindrical blank into an extruder to extrude into a tubular material, and finally sinter the tubular material at 360 °C for 3 h and cool to obtain a modified polytetrafluoroethylene pipe. Example 3:

[0035] (1) Add 120 g of polytetrafluoroethylene powder to 600 g of tetrahydrofuran, ultrasonicate for 30 min, under nitrogen protection, add 40 g of sodium naphthalene treatment solution, stir for 20 min, then add 40 g of deionized water to terminate the activation reaction, then wash with acetone and filter under reduced pressure 3 times, and dry in vacuum to obtain activated polytetrafluoroethylene powder;

[0036] (2) Add 120 g of activated polytetrafluoroethylene powder to 400 g of deionized water, ultrasonicate for 30 min, under nitrogen protection, add 0.06 g of ammonium persulfate, heat up to 55 °C, then add 30 g of 2-hydroxyethyl methacrylate, continue stirring for 20 h, then wash with deionized water and filter under reduced pressure 3 times, and dry in vacuum to obtain hydroxylated polytetrafluoroethylene powder;

[0037] (3) Disperse 30 g of carbon nanotubes in a mixed solution of 120 g of ethanol and 80 g of deionized water, add 0.3 g of γ-(2,3-epoxypropoxy) propyltrimethoxysilane and 1 g of tridecafluorooctyltriethoxysilane, heat up to 65 °C, stir and react for 7 h, wash with water, and dry to obtain modified carbon nanotubes;

[0038] (4) Melt and mix 30 g of modified carbon nanotubes, 200 g of hydroxylated polytetrafluoroethylene powder, and 1200 g of polytetrafluoroethylene powder at 450 °C, extrude and pelletize to obtain a modified polytetrafluoroethylene masterbatch. Then, load the modified polytetrafluoroethylene masterbatch into a mold for preforming to form a cylindrical blank. Next, place the cylindrical blank into an extruder to extrude into a tubular material. Finally, sinter the tubular material at 370 °C for 3.5 h and cool to obtain a modified polytetrafluoroethylene pipe.

[0039] Comparative Example 1:

[0040] The difference between Comparative Example 1 and Example 2 is that the polytetrafluoroethylene powder was not hydroxylated.

[0041] The specific steps are as follows:

[0042] (1) Disperse 20 g of carbon nanotubes in a mixed solution of 120 g of ethanol and 80 g of deionized water, add 0.2 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 0.5 g of tridecafluorooctyltriethoxysilane, heat to 60 °C, stir and react for 6 h, wash with water, and dry to obtain modified carbon nanotubes.

[0043] (2) Melt and mix 20 g of modified carbon nanotubes and 1100 g of polytetrafluoroethylene powder at 420 °C, extrude and pelletize to obtain a modified polytetrafluoroethylene masterbatch. Then, load the modified polytetrafluoroethylene masterbatch into a mold for preforming to form a cylindrical blank. Next, place the cylindrical blank into an extruder to extrude into a tubular material. Finally, sinter the tubular material at 360 °C for 3 h and cool to obtain a polytetrafluoroethylene pipe.

[0044] Comparative Example 2:

[0045] The difference between Comparative Example 2 and Example 2 is that only γ-(2,3-epoxypropoxy)propyltrimethoxysilane was grafted onto the surface of the carbon nanotubes.

[0046] The specific steps are as follows:

[0047] (1) Add 100 g of polytetrafluoroethylene powder to 500 g of tetrahydrofuran, ultrasonicate for 20 min, under nitrogen protection, add 30 g of sodium naphthalene treatment solution, stir for 10 min, then add 15 g of deionized water to terminate the activation reaction, and then wash with acetone and filter under reduced pressure 3 times, and dry in vacuo to obtain activated polytetrafluoroethylene powder.

[0048] (2) Add 100 g of activated polytetrafluoroethylene powder to 300 g of deionized water, ultrasonicate for 20 min, under nitrogen protection, add 0.02 g of ammonium persulfate, heat to 50 °C, then add 20 g of 2-hydroxyethyl methacrylate, continue to stir for 15 h, and then wash with deionized water and filter under reduced pressure 3 times, and dry in vacuo to obtain hydroxylated polytetrafluoroethylene powder.

[0049] (3) Disperse 20 g of carbon nanotubes in a mixed solution of 120 g of ethanol and 80 g of deionized water, add 0.7 g of γ-(2,3-epoxypropoxy) propyltrimethoxysilane, heat up to 60 °C, stir and react for 6 h, wash with water, and dry to obtain modified carbon nanotubes;

[0050] (4) Melt and mix 20 g of modified carbon nanotubes, 100 g of hydroxylated polytetrafluoroethylene powder and 1000 g of polytetrafluoroethylene powder at 420 °C, extrude and granulate to obtain a modified polytetrafluoroethylene masterbatch. Then, put the modified polytetrafluoroethylene masterbatch into a mold for preforming to form a cylindrical blank. Next, put the cylindrical blank into an extruder to extrude and form a tubular material. Finally, sinter the tubular material at 360 °C for 3 h and cool to obtain a polytetrafluoroethylene pipe.

[0051] Comparative Example 3:

[0052] The difference between Comparative Example 3 and Example 2 is that only tridecafluorooctyltriethoxysilane is grafted on the surface of the carbon nanotubes;

[0053] The specific steps are as follows:

[0054] (1) Add 100 g of polytetrafluoroethylene powder to 500 g of tetrahydrofuran, ultrasonicate for 20 min, under nitrogen protection, add 30 g of sodium naphthalide treatment solution, stir for 10 min, then add 15 g of deionized water to terminate the activation reaction, and then wash with acetone and filter under reduced pressure 3 times, and dry in vacuum to obtain activated polytetrafluoroethylene powder;

[0055] (2) Add 100 g of activated polytetrafluoroethylene powder to 300 g of deionized water, ultrasonicate for 20 min, under nitrogen protection, add 0.02 g of ammonium persulfate, heat up to 50 °C, then add 20 g of 2-hydroxyethyl methacrylate, continue to stir for 15 h, then wash with deionized water and filter under reduced pressure 3 times, and dry in vacuum to obtain hydroxylated polytetrafluoroethylene powder;

[0056] (3) Disperse 20 g of carbon nanotubes in a mixed solution of 120 g of ethanol and 80 g of deionized water, add 0.7 g of tridecafluorooctyltriethoxysilane, heat up to 60 °C, stir and react for 6 h, wash with water, and dry to obtain modified carbon nanotubes;

[0057] (4) Melt and mix 20 g of modified carbon nanotubes, 100 g of hydroxylated polytetrafluoroethylene powder and 1000 g of polytetrafluoroethylene powder at 420 °C, extrude and granulate to obtain a modified polytetrafluoroethylene masterbatch. Then, put the modified polytetrafluoroethylene masterbatch into a mold for preforming to form a cylindrical blank. Next, put the cylindrical blank into an extruder to extrude and form a tubular material. Finally, sinter the tubular material at 360 °C for 3 h and cool to obtain a polytetrafluoroethylene pipe.

[0058] Comparative Example 4:

[0059] The difference between Comparative Example 4 and Example 2 is that the carbon nanotubes were not modified;

[0060] The specific steps are as follows:

[0061] (1) Add 100 g of polytetrafluoroethylene powder to 500 g of tetrahydrofuran, ultrasonicate for 20 min, under nitrogen protection, add 30 g of sodium naphthalide treatment solution, stir for 10 min, then add 15 g of deionized water to terminate the activation reaction, and then wash with acetone and filter under reduced pressure 3 times, and dry in vacuum to obtain activated polytetrafluoroethylene powder;

[0062] (2) Add 100 g of activated polytetrafluoroethylene powder to 300 g of deionized water, ultrasonicate for 20 min, under nitrogen protection, add 0.02 g of ammonium persulfate, heat up to 50 °C, then add 20 g of 2-hydroxyethyl methacrylate, continue to stir for 15 h, and then wash with deionized water and filter under reduced pressure 3 times, and dry in vacuum to obtain hydroxylated polytetrafluoroethylene powder;

[0063] (3) Melt and mix 20 g of carbon nanotubes, 100 g of hydroxylated polytetrafluoroethylene powder and 1000 g of polytetrafluoroethylene powder at 420 °C, extrude and granulate to obtain a modified polytetrafluoroethylene masterbatch, then put the modified polytetrafluoroethylene masterbatch into a mold for preforming to form a cylindrical blank, then put the cylindrical blank into an extruder to extrude into a tubular material, and finally sinter the tubular material at 360 °C for 3 h and cool to obtain a polytetrafluoroethylene pipe.

[0064] Comparative Example 5:

[0065] Comparative Example 5 is a polytetrafluoroethylene pipe;

[0066] The specific steps are as follows:

[0067] Melt and mix polytetrafluoroethylene powder at 420 °C, extrude and granulate to obtain a modified polytetrafluoroethylene masterbatch, then put the modified polytetrafluoroethylene masterbatch into a mold for preforming to form a cylindrical blank, then put the cylindrical blank into an extruder to extrude into a tubular material, and finally sinter the tubular material at 360 °C for 3 h and cool to obtain a polytetrafluoroethylene pipe.

[0068] Performance test:

[0069] Tensile property test: Conducted on a universal testing machine and tested according to GB / T 1040—1992.

[0070] Impact strength test: Conducted on an impact testing machine and tested according to ISO 180:2000.

[0071] Table 1 Performance Test Results

[0072]

[0073] Data analysis:

[0074] It can be seen from the data of Examples 1-3 and Comparative Example 5 in Table 1 that, compared with traditional polytetrafluoroethylene pipes, the modified polytetrafluoroethylene pipes prepared by the present invention show a slight decrease in tensile strength, but the difference is not significant. The elongation at break and impact strength are greatly improved. Most importantly, the notched impact strength is increased by more than 3 times. The enhanced notched impact strength means that the material is less likely to break or be damaged when subjected to external force or impact, thus improving the durability and service life of the pipes.

[0075] It can be seen from the data of Example 2 and Comparative Example 1 in Table 1 that the hydroxyl modification on the surface of polytetrafluoroethylene powder helps to improve the elongation at break and impact strength. This is because the hydroxyl groups on the surface of polytetrafluoroethylene powder can form chemical bonds with the epoxy groups on the surface of carbon nanotubes, thereby improving the compatibility and dispersion of carbon nanotubes in polytetrafluoroethylene.

[0076] It can be seen from the data of Example 2 and Comparative Examples 2-4 in Table 1 that the epoxy groups and fluorine chains on the surface of carbon nanotubes effectively regulate the mechanical properties of polytetrafluoroethylene pipes. While maintaining the tensile strength, the elongation at break is greatly improved, and moreover, the impact performance, especially the notched impact performance, is synergistically improved. This is due to the chemical cross-linking between the epoxy groups and the surface of polytetrafluoroethylene and the physical entanglement between the fluorine chains and the molecular chains of polytetrafluoroethylene.

[0077] Those of ordinary skill in the art should understand that: the discussion of any above embodiments is only exemplary and is not intended to imply that the scope of the present invention is limited to these examples; under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A modified polytetrafluoroethylene pipe, characterized in that: The following raw materials are extruded and sintered to obtain the modified carbon nanotubes by weight: 1-3 parts, hydroxylated polytetrafluoroethylene powder by weight 5-20 parts and polytetrafluoroethylene powder by weight 80-120 parts; The modified carbon nanotubes are obtained by modifying carbon nanotubes with γ-(2,3-epoxypropyloxy)propyltrimethoxysilane and tridecafluorooctyltriethoxysilane; The weight ratio of the γ-(2,3-epoxypropoxy)propyltrimethoxysilane, tridecafluorooctyltriethoxysilane and carbon nanotubes is 0.1-0.3:0.2-1:10-30; The preparation method of the hydroxylated polytetrafluoroethylene is as follows: (1) Add polytetrafluoroethylene powder to tetrahydrofuran, ultrasonicate for 10-30 minutes, add sodium naphthalene treatment solution under nitrogen protection, stir for 5-20 minutes, then add deionized water to terminate the activation reaction, purify, and obtain activated polytetrafluoroethylene powder; (2) Add activated polytetrafluoroethylene powder to deionized water, ultrasonicate for 10-30 minutes, add ammonium persulfate under nitrogen protection, heat to 45-55°C, add hydroxyethyl methacrylate, continue stirring for 10-20 hours, and purify to obtain hydroxylated polytetrafluoroethylene powder; In the step (1), the weight ratio of polytetrafluoroethylene powder, tetrahydrofuran, sodium naphthalene treatment solution and deionized water is 8-12:40-60:2-4:1-2; In the step (2), the weight ratio of activated polytetrafluoroethylene powder, deionized water and hydroxyethyl methacrylate is 8-12:20-40:1-3.

2. The modified polytetrafluoroethylene pipe according to claim 1, characterized in that: The average particle size of the polytetrafluoroethylene powder is 100-300 μm.

3. The modified polytetrafluoroethylene pipe according to claim 1, characterized in that: The outer diameter of the carbon nanotube is 10-20 nm, and the length is 0.5-2 μm.

4. The modified polytetrafluoroethylene pipe according to claim 1, characterized in that: The preparation method of the modified carbon nanotubes is as follows: dispersing carbon nanotubes in a mixed solution of ethanol and deionized water, adding γ-(2,3-epoxypropoxy)propyltrimethoxysilane and tridecafluorooctyltriethoxysilane, heating to 55-65° C., stirring and reacting for 65-7 hours, and purifying to obtain modified carbon nanotubes.

5. The modified polytetrafluoroethylene pipe according to claim 4, characterized in that: The weight ratio of the ethanol to deionized water is 3:

2.

6. The modified polytetrafluoroethylene pipe according to claim 1, characterized in that: The amount of deionized water added in step (1) is 0.5-1 times the weight of the sodium naphthalene treatment solution.

7. The modified polytetrafluoroethylene pipe according to claim 1, characterized in that: The amount of ammonium persulfate added in step (2) is 0.05%-0.2% of the weight of hydroxyethyl methacrylate.

8. A method for preparing a modified polytetrafluoroethylene pipe according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: melting and mixing modified carbon nanotubes, hydroxylated polytetrafluoroethylene powder and polytetrafluoroethylene powder at 400-450°C, extruding and granulating to obtain modified polytetrafluoroethylene masterbatch, then loading the modified polytetrafluoroethylene masterbatch into a mold for preforming to form a cylindrical blank, then putting the cylindrical blank into an extruder and extruding to form a tubular material, and finally sintering the tubular material at 350-370°C for 2.5-3.5h and cooling to obtain a modified polytetrafluoroethylene tube.

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