Multi-end feeding twin-screw extrusion pipeline and preparation method of high-temperature-resistant polyethylene glycol oxalate

Abstract

The invention relates to the technical field of high-temperature-resistant pipeline production, in particular to a multi-end feeding twin-screw extrusion pipeline and a preparation method of high-temperature-resistant polyethylene glycol oxalate. Comprising a corrosion-resistant layer, a pipeline layer and a thermal insulation layer, the corrosion-resistant layer is made of vinyl ester resin, and the vinyl ester resin is sprayed on the inner surface of the pipeline layer; the pipeline layer is made of high-temperature-resistant polyethylene glycol oxalate, particles are softened at high temperature, and the pipeline layer is formed through extrusion of a mold; the heat preservation layer is made of ceramic fiber felt, the outer surface of the pipeline layer is evenly coated with a high-temperature bonding agent, and the ceramic fiber felt is bonded to the outer surface of the pipeline layer. The carbon nanotubes are uniformly and dispersedly grafted on the polyethylene glycol oxalate to form a uniform heat-conducting net, the heat resistance of the polyethylene glycol oxalate is improved by virtue of the high heat resistance of the polyether-ether-ketone, and the heat of a local overheated position is guided to the periphery through the heat-conducting net, so that the decomposition caused by overhigh temperature is avoided. And on the basis of improving the heat resistance of the pipeline, the non-uniform heat resistance of the pipeline is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of high-temperature-resistant pipeline production, in particular to a multi-end-feeding double-screw extrusion pipeline and a preparation method of high-temperature-resistant polyethylene glycol adipate. BACKGROUND

[0002] It is a conventional process method to mix liquid chemical raw materials which can be quickly mixed in a pipeline and then perform subsequent reactions. During the mixing of the chemical raw materials, the temperature of the chemical raw materials is often unevenly distributed. If the pipeline material is selected according to the average temperature, a small amount of liquid at a position higher than the average temperature will exceed the high-temperature resistance temperature of the pipeline, causing small-area burning of the pipeline. However, long-term accumulation of a small amount will cause pipeline leakage. The existing organic material conveying pipelines made of polyethylene glycol adipate as raw materials all have such problems.

[0003] Polyethylene glycol adipate is an organic material and is used in film materials, shell materials and engineering plastics, and has good toughness and plasticity. However, the heat resistance of polyethylene glycol adipate is not very good, and the thermal decomposition temperature is usually only about 250 DEG C. Therefore, the polyethylene glycol adipate cannot be used in a high-temperature environment. Therefore, a high-temperature-resistant material is copolymerized with the polyethylene glycol adipate by grafting, copolymerization and physical combination, so as to improve the heat resistance of the polyethylene glycol adipate.

[0004] However, in actual use, the traditional mixing methods (such as mechanical stirring and ordinary ultrasonic) are difficult to realize the uniform dispersion of nanoscale materials (such as carbon nanotubes), and are easy to cause agglomeration and dead angles, affect the subsequent grafting reaction, and make the heat resistance and thermal conductivity of the product fluctuate greatly, which cannot meet the demand of high-temperature pipeline materials. In addition, the material heating is not uniform in the laboratory, and the material heating is not uniform. For example, the local temperature is higher than the average temperature. In this case, most of the heat of the heating material does not reach the decomposition temperature of the polyethylene glycol adipate, and the polyethylene glycol adipate decomposition also occurs. Even if the decomposition temperature of the polyethylene glycol adipate is improved, the problem of polyethylene glycol adipate decomposition before reaching the decomposition temperature cannot be solved. SUMMARY

[0005] In view of the above problems in the prior art, the application aims to provide a multi-end-feeding double-screw extrusion pipeline which improves the ability of the pipeline to resist uneven heat on the basis of the heat resistance of the pipeline.

[0006] Another object of the present application is to provide a preparation method of high-temperature-resistant polyethylene glycol adipate for multi-end feeding double screw extrusion pipeline, which uses two-step grafting, changes the polarity of carbon nanotubes by using strong acid, and disperses the carbon nanotubes by using a silane coupling agent, processes the polyether ether ketone to make the surface benzene ring break and have polarity, and then the fully dispersed carbon nanotubes perform esterification reaction with the polar groups on the surface of the polyether ether ketone, and are fully dispersed on the polyether ether ketone, so that the performance of the material is greatly improved.

[0007] The multi-end feeding double screw extrusion pipeline provided by the present application comprises a corrosion-resistant layer, a pipeline layer and a heat preservation layer. The corrosion-resistant layer is made of vinyl ester resin, and a surface coating slurry containing glass flake is prepared and sprayed 2-3 times, with a thickness of 80-100 mu m each time and a total thickness of 160-300 mu m, and the coating is cured at room temperature for 24 hours. The pipeline layer is made of high-temperature-resistant polyethylene glycol adipate, and the particles are softened at high temperature to form the pipeline layer; the temperature of the double screw extruder is 240-260 DEG C, and the temperature of the die is 230-250 DEG C; the vacuum sizing method is used, the vacuum degree is -0.05~-0.08 MPa, the cooling water tank temperature is 15-25 DEG C, and the pulling speed is 0.5-1.0 m / min.

[0008] The heat preservation layer is made of ceramic fiber felt, and the surface of the pipeline layer is uniformly coated with a high-temperature adhesive with a thickness of 0.2-0.5 mm to avoid air bubbles. The ceramic fiber felt is pre-cut to have a lap joint amount of 5% of the circumference of the pipeline, and is wound on the pipeline while the high-temperature adhesive is in a hot melt state, and a pressure of 0.1-0.3 MPa is applied to ensure close adhesion. After the adhesion is completed, the coating is cured at room temperature for 24 hours or heated and cured; after curing, the high-temperature adhesive forms a continuous transition layer to fill the interface micropores.

[0009] The preparation method of the high-temperature-resistant polyethylene glycol adipate provided by the present application comprises the following steps: (1) ultrasonic treatment of carbon nanotubes in mixed acid; (2) modification of the ultrasonically treated carbon nanotubes in silane coupling agent; (3) adding the modified carbon nanotubes into an NMP solution containing polyetherimide to mix and disperse into CNTs-PEI-NMP suspension; (4) adding polyether ether ketone powder into the CNTs-PEI-NMP suspension for mixing and dispersing; (5) reacting the ultrasonically treated CNTs-PEI-NMP suspension with polyether ether ketone in hexafluoroisopropanol for 6 hours, and filtering the CNTs / PEEK polymer after the reaction is completed. (6) The CNTs / PEEK polymer is reacted with trifluoromethanesulfonic acid to introduce sulfonic acid group -SO3H on the surface of the polyether ether ketone, forming a CNTs / PEEK copolymer; the sulfonic acid group is a strong acidic group and has high chemical reactivity. In the grafting reaction, the sulfonic acid group can act as an electrophile or a nucleophile to participate in the reaction, providing additional reaction sites for the grafting reaction. In the grafting reaction with polyethylene glycol adipate, the sulfonic acid group can undergo esterification with the hydroxyl or carboxyl group in the polyethylene glycol adipate molecule, thereby promoting the progress of the grafting reaction. The sulfonic acid group (-SO3H) is introduced on the surface of the polyether ether ketone. As a strong polar group, the sulfonic acid group can significantly improve the interfacial compatibility of the CNTs / PEEK copolymer with the polyethylene glycol adipate matrix and can act as an auxiliary reaction site; (7) The CNTs / PEEK copolymer is double-grafted with polyethylene glycol adipate under the catalysis of tetrabutyl titanate; a large number of carboxyl and hydroxyl groups are introduced on the surface of the CNTs through acid treatment, and the use of a specific monomer to polymerize PEEK ensures that the PEEK chain end also has active groups; (8) After the grafting is completed, the high-temperature-resistant polyethylene glycol adipate is obtained by cooling.

[0010] In step (3), the mixing and dispersion of the materials are performed by ultrasonic treatment or through a material mixing and dispersion device. The specific method of the material mixing and dispersion device treatment is as follows: the NMP solution of polyetherimide is used as the main fluid, which is pumped into a Venturi mixer at a flow rate of 8-15 m / s by a circulating pump; the slurry prepared by pre-mixing the modified carbon nanotubes with a small amount of NMP is sucked into the main fluid by the negative pressure generated at the throat of the Venturi tube, and the cycle dispersion treatment is performed for 30-120 min.

[0011] In step (4), the mixing and dispersion of the materials are performed by ultrasonic treatment or through a material mixing and dispersion device. The specific method of the material mixing and dispersion device treatment is as follows: the CNTs-PEI-NMP suspension is used as the main fluid, which is pumped into a Venturi mixer at a flow rate of 8-15 m / s by a circulating pump; the slurry prepared by pre-mixing the polyether ether ketone powder with a small amount of NMP is sucked into the main fluid by the negative pressure generated at the throat of the Venturi tube, and the cycle dispersion treatment is performed for 30-120 min.

[0012] The material mixing and dispersing device comprises a reaction kettle, the reaction kettle is connected with a circulating pump through a pipeline, the circulating pump is connected with the top of the reaction kettle through a circulating pipeline, the circulating pipeline is connected with the bottom of the reaction kettle through a Venturi mixer, a valve is arranged between the Venturi mixer and the reaction kettle, an outer wall of the Venturi mixer is arranged outside the Venturi mixer, the Venturi mixer comprises a converging angle and a diverging angle, a storage tank is connected with the converging angle, a nitrogen pressurized mixing tank is connected with the top of the storage tank through a feeding pipeline, a vacuum pump is connected with the reaction kettle, and a stirrer is arranged in the reaction kettle. The storage tank is always kept in a slight positive pressure by nitrogen, after the raw materials in the storage tank are added, nitrogen can be dispersed into the reaction kettle through the Venturi mixer to enhance the mixing and stirring under the condition that air does not enter, and then the vacuum pump is started to discharge the nitrogen.

[0013] The preparation method of the high-temperature-resistant polyethylene glycol adipate comprises the following steps: 1-3 g of carbon nanotubes are subjected to ultrasonic treatment in a mixed solution of 50-150 mL of sulfuric acid and nitric acid, the volume ratio of the sulfuric acid to the nitric acid is 1:3, and the ultrasonic treatment lasts for 2 h. The carbon nanotubes are subjected to ultrasonic treatment in the strong acid, and the carbon nanotubes are oxidized by the strong acid, that is, CNTs+HNO3 / H2SO4→CNTs-COOH+CNTs-OH+other oxygen-containing groups, so that the carbon nanotubes form polar groups such as carboxyl groups and hydroxyl groups, the polarity is improved, the surface of the carbon nanotubes is treated by the mixed acid, impurities such as amorphous carbon and metal catalyst residues on the surface of the carbon nanotubes are effectively removed, the surface charge of the oxidized carbon nanotubes is increased, and the agglomeration is inhibited by the electrostatic repulsion effect and the steric hindrance effect, thereby promoting the uniform dispersion of the carbon nanotubes in the polyether ether ketone matrix.

[0014] The preparation method of the high-temperature-resistant polyethylene glycol adipate comprises the following steps: 1-3 g of carbon nanotubes are subjected to ultrasonic treatment in a mixed solution of 50-150 mL of sulfuric acid and nitric acid, the volume ratio of the sulfuric acid to the nitric acid is 1:3, and the ultrasonic treatment lasts for 2 h. The carbon nanotubes are subjected to ultrasonic treatment in the strong acid, and the carbon nanotubes are oxidized by the strong acid, that is, CNTs+HNO3 / H2SO4→CNTs-COOH+CNTs-OH+other oxygen-containing groups, so that the carbon nanotubes form polar groups such as carboxyl groups and hydroxyl groups, the polarity is improved, the surface of the carbon nanotubes is treated by the mixed acid, impurities such as amorphous carbon and metal catalyst residues on the surface of the carbon nanotubes are effectively removed, the surface charge of the oxidized carbon nanotubes is increased, and the agglomeration is inhibited by the electrostatic repulsion effect and the steric hindrance effect, thereby promoting the uniform dispersion of the carbon nanotubes in the polyether ether ketone matrix.

[0015] The preparation method of the high-temperature-resistant polyethylene glycol adipate comprises the following steps: 1-3 g of carbon nanotubes are subjected to ultrasonic treatment in a mixed solution of 50-150 mL of sulfuric acid and nitric acid, the volume ratio of the sulfuric acid to the nitric acid is 1:3, and the ultrasonic treatment lasts for 2 h. The carbon nanotubes are subjected to ultrasonic treatment in the strong acid, and the carbon nanotubes are oxidized by the strong acid, that is, CNTs+HNO3 / H2SO4→CNTs-COOH+CNTs-OH+other oxygen-containing groups, so that the carbon nanotubes form polar groups such as carboxyl groups and hydroxyl groups, the polarity is improved, the surface of the carbon nanotubes is treated by the mixed acid, impurities such as amorphous carbon and metal catalyst residues on the surface of the carbon nanotubes are effectively removed, the surface charge of the oxidized carbon nanotubes is increased, and the agglomeration is inhibited by the electrostatic repulsion effect and the steric hindrance effect, thereby promoting the uniform dispersion of the carbon nanotubes in the polyether ether ketone matrix. 2The CNTs-PEI-NMP suspension is obtained by ultrasonic treatment for 30 min.

[0016] The preparation method of the high-temperature-resistant polyethylene glycol is as follows: 0.5 g of polyether ether ketone powder is added into the CNTs-PEI-NMP suspension.

[0017] The CNTs-PEI-NMP suspension with a volume ratio of (5-6) to (6-7) is mixed with hexafluoroisopropanol, and a sulfonic acid group is introduced for copolymerization.

[0018] The CNTs / PEEK copolymer and the polyethylene glycol are grafted under the catalysis of tetrabutyl titanate, and double grafting is realized through esterification.

[0019] Polyether ether ketone segment: the carboxyl group at the end of the polyether ether ketone reacts with the hydroxyl group of the polyethylene glycol to form an ester bond (-COO-).

[0020] Carbon nanotube surface: the carboxyl group of the carbon nanotube and the hydroxyl group of the polyethylene glycol are condensed to form a covalent bond anchor through esterification.

[0021] The reaction formula is as follows: PEEK-COOH+HO-EGO→PEEK-COO-EGO+H2OnCNTs-COOH+nEGO-OH→[CNTs-COO-EGO] n +nH2O.

[0022] The present application forms a dense protective layer by spraying 2-3 passes of the surface coating slurry containing glass flakes (total thickness of 160-300 mu m), which significantly enhances the corrosion resistance of the pipeline to chemical solvents.

[0023] By introducing polyether ether ketone (PEEK) and carbon nanotubes (CNTs) through double grafting technology, the thermal decomposition temperature of polyethylene glycol adipate is increased from 250℃ to 340-368℃, and the thermal conductivity is increased to 0.68-0.85 W / m·K. This improvement directly solves the core problem of "local temperature exceeding the material decomposition threshold" in the background art, and prevents the decomposition of the inner wall of the pipeline due to the local overheating area of the contact with the high-temperature liquid by rapidly diffusing the heat through the uniform heat conduction network.

[0024] The pre-cut lap joint and hot pressing process is adopted, and the hot pressing pressure is 0.1-0.3 MPa, so as to ensure that the thermal insulation layer and the pipeline layer are tightly bonded. The low thermal conductivity (<0.1 W / m·K) of the ceramic fiber felt combined with the interface filling effect of the high-temperature adhesive not only reduces the external heat loss, but also avoids the excessive accumulation of internal heat, realizing the bidirectional management of heat.

[0025] The preparation of the pipeline layer adopts double screw extrusion, and the process temperature is 240-260℃, which is completely compatible with the processing temperature (130-280℃) of the modified polyethylene glycol adipate material of the application, proving that the material can be directly applied to the existing pipeline production line without additional equipment investment.

[0026] The traditional polyethylene glycol adipate pipeline needs to be frequently replaced due to insufficient heat resistance, while the pipeline of the application significantly reduces the maintenance cost by improving the material life (residual carbon rate from 5.2% to 22.3%) and thermal conductivity, especially suitable for scenes that need to withstand high temperature and corrosive medium for a long time in chemical production. It comprehensively solves the problem of uneven heating.

[0027] The application realizes the synergistic design of "heat conduction network + thermal insulation layer": Heat conduction network: carbon nanotubes form a continuous path in the polyethylene glycol adipate matrix, which quickly conducts the local heat of the inner wall of the pipeline contacting the high-temperature liquid to the low-temperature area (such as the outer wall of the pipeline or the adjacent pipe section), avoiding temperature concentration.

[0028] Thermal insulation layer: when the external environment temperature fluctuates, the ceramic fiber felt can stabilize the internal temperature field of the pipeline, reduce the damage of thermal stress to the material structure, and further prolong the service life.

[0029] Compared with the prior art, the beneficial effects of the application are: (1) The present application does not directly use the high temperature resistance of carbon nanotubes and polyethylene glycol to copolymerize, but uses a very small amount of carbon nanotubes for grafting. Two-step grafting is used, that is, strong acid is used to change the polarity of carbon nanotubes, and silane coupling agent is used for dispersion of carbon nanotubes, and polyether ether ketone is treated to make its surface benzene ring break and have polarity, then the fully dispersed carbon nanotubes are esterified with the polar groups on the surface of polyether ether ketone, and are fully dispersed on the polyether ether ketone. And form the combination between carbon nanotubes and polyether ether ketone.

[0030] (2) The second step grafting, carbon nanotubes and polyether ether ketone are grafted to the carboxyl or hydroxyl at both ends of the converted polyethylene glycol through a catalyst, forming a three-dimensional cross-linked structure. Since the carbon nanotubes are fully dispersed on the surface of the polyether ether ketone, when the sheet-like polyether ether ketone is grafted with polyethylene glycol, the carbon nanotubes will be uniformly dispersed and grafted on the polyethylene glycol, forming a uniform heat conduction network. With the high heat resistance of polyether ether ketone, the heat resistance of polyethylene glycol is improved, and the heat of the local overheated area is guided to the surrounding area through the heat conduction network, avoiding the decomposition caused by high temperature. The heat resistance is truly improved, and the damage caused by local heating is effectively overcome.

[0031] (3) The present application introduces high-heat-resistant PEEK molecular chains and high-thermal-conductivity CNTs network into the polyethylene glycol matrix through chemical grafting. This 'heat-resistant skeleton + thermal conduction network' synergistic structure not only improves the overall thermal decomposition temperature of the material, but more importantly, it solves the problem of local overheating that existing technologies cannot handle. When temperature hotspots occur in the pipeline, the uniformly dispersed CNTs network can quickly conduct heat away, avoiding local degradation, thereby achieving a leap from 'high-temperature resistance' to 'non-uniform high-temperature resistance'.

[0032] (4) The negative pressure and turbulent flow generated by the Venturi mixer at high flow rate, combined with cyclic dispersion, break the agglomeration of carbon nanotubes, form a uniform heat conduction network, and solve the problem of local overheating; enhance the reaction efficiency: the design of the contraction angle and the diffusion angle promotes the full contact of the components, improves the conversion rate of the double grafting reaction, and significantly improves the heat resistance. BRIEF DESCRIPTION OF DRAWINGS

[0033] Fig. 1 The structure diagram of the material mixing and dispersing device of the present application; Fig. 2 The structure diagram of the Venturi mixer of the present application; In the figure: 1, reaction kettle; 2, circulating pump; 3, vacuum pump; 4, Venturi mixer; 5, valve; 6, circulating pipeline; 7, mixer outer wall; 8, contraction angle; 9, diffusion angle; 10, storage tank; 11, nitrogen pressurized mixing tank; 12, feeding pipeline. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme of the present application more clear, further detailed description of the present application is made.

[0035] As shown in Figs. 1-2 The material mixing and dispersing device comprises a reaction kettle 1, the reaction kettle 1 is connected with a circulating pump 2 through a pipeline, the circulating pump 2 is connected with the top of the reaction kettle 1 through a circulating pipeline 6, the circulating pipeline 6 is connected with the bottom of the reaction kettle 1 through a Venturi mixer 4, a valve 5 is arranged between the Venturi mixer 4 and the reaction kettle 1, a mixer outer wall 7 is arranged outside the Venturi mixer 4, the Venturi mixer 4 comprises a contraction angle 8 and a diffusion angle 9, a storage tank 10 is connected at the contraction angle 8, a nitrogen pressurized mixing tank 11 is connected with the top of the storage tank 10 through a feeding pipeline 12, a vacuum pump 3 is connected with the reaction kettle 1, and a stirrer is arranged in the reaction kettle 1.

[0036] The preparation method of the high-temperature-resistant polyethylene glycol adipate is further described below in combination with the embodiments of the present application: Test method: Tensile strength: GB / T1040.1-2018; Bending strength: GB / T9341-2008; Impact strength: GB / T1043.1-2008; Heat distortion temperature: GB / T1634.1-2021; Acid and alkali tensile strength retention rate: GB / T11547-2008; Melt flow rate: GB / T3682.1-2018; Extrusion shrinkage: GB / T15585-1995; Thermal stability test: The thermal gravimetric analysis method (TGA) is used for analysis, 10 mg of sample is placed in an alumina crucible, a heating source is used for heating in an air atmosphere, the temperature rising rate is controlled at 10℃ / min, the Td of the tested material is observed, and the corresponding Td is recorded during thermal decomposition for comparison, and the higher the Td is, the better the thermal stability is.

[0037] Residual carbon rate test: Grind 15 mg of sample into powder, pass through an 80 mesh sieve, remove large particles, and place in a thermal gravimetric analyzer. Heat from room temperature to 800℃ in an air atmosphere, control the temperature rising rate at 10℃ / min. Burn at 600℃, extract the residual mass, and calculate the residual carbon rate according to residual carbon rate = residual mass / initial mass of sample x 100. The higher the residual carbon rate is, the better the thermal stability is.

[0038] Thermal conductivity: Test using laser flash method, hot press the product into 1mm film, and double-sided spray graphite coating. Calibrate using a sapphire calibration instrument. Put into Netzsch LFA457 MicroFlash tester, trigger laser pulse to record temperature response curve. Fit the temperature rise curve by instrument software, calculate thermal diffusivity a.

[0039] Density p is determined by Archimedes drainage method, specific heat capacity C p Determined by DSC (Differential Scanning Calorimetry).

[0040] Final thermal conductivity λ = a · p · C p The higher the thermal conductivity, the better the thermal conductivity of the product.

[0041] Pipe mechanical properties: Tensile strength: According to GB / T8804.2-2003 "Determination of tensile properties of thermoplastics pipes Part 2: rigid polyvinyl chloride (PVC-U), chlorinated polyvinyl chloride (PVC-C) and high impact polyvinyl chloride (PVC-HI) pipes".

[0042] Bending strength: According to GB / T9341-2008 "Determination of the bending properties of plastics".

[0043] Impact strength (simply supported beam): According to GB / T1043.1-2008 "Determination of the impact properties of plastics by the simply supported beam method".

[0044] Pipe heat resistance: Heat distortion temperature (HDT): According to GB / T1634.1-2021, directly use material test data.

[0045] Local overheating resistance: The inner wall of the prepared pipe is locally (2cm diameter area) continuously contacted with a heat source of 280℃ for 10 minutes, and whether the inner wall of the pipe appears charring, softening, bulging or decomposition phenomenon is observed. This test aims to simulate the working condition of "local temperature higher than average temperature".

[0046] Pipe chemical corrosion resistance: Acid and alkali tensile strength retention rate: According to GB / T11547-2008, after immersing the pipe sample in 10% H2SO4 and 10% NaOH solution at 60℃ for 72h, test its tensile strength and calculate the retention rate.

[0047] Pipe extrusion molding performance: Extrusion shrinkage: According to GB / T15585-1995, directly use material test data.

[0048] Carbon nanotubes, FT7000, average tube diameter 7-11 nm, length 5-20 pm, Jiangsu Tainai Science and Technology Co., Ltd. Silane coupling agent, KH-550 (gamma-aminopropyl triethoxysilane), Nanjing Shuguang Chemical Group Co., Ltd. Polyetherimide, Ultem® 1000, SABIC; Polyether ether ketone, Victrex® PEEK450G, Victrex PLC, United Kingdom; Polyethylene glycol adipate resin, XK7228, Hubei Xinkang Pharmaceutical Chemical Co., Ltd. High-temperature adhesive binder: HC1015, heat-resistant temperature: 1400°C, Langfang Hengcheng Thermal Insulation Material Co., Ltd.

[0049] Example 1 The preparation method of the high-temperature-resistant polyethylene glycol adipate includes the following steps: (1) 1 g of carbon nanotubes with a diameter of 15 nm and a length of 3 pm and a purity of 97% were ultrasonically treated in a mixture of 50 mL of sulfuric acid and nitric acid, the ratio of 98% concentrated sulfuric acid to 65% concentrated nitric acid was 1:3, the ultrasonic frequency was 30 kHz, the ultrasonic power was 250 W, and the temperature was controlled not to exceed 45°C.

[0050] (2) 0.01 g of KH-550 silane coupling agent was dissolved in 0.5 mL of ethanol solution, the ethanol solution concentration was 95%, and the KH-550 silane coupling agent solution was used to modify the filtered and washed carbon nanotubes, the reaction time was 1 h, and the reaction temperature was 120°C. After the reaction, it was washed to neutral and dried.

[0051] (3) 50 mL of N-methyl pyrrolidone was added as a solvent in a container, 0.5 g of polyetherimide was first added, stirred at a reaction temperature of 60°C for 1 h, and then 1 g of modified carbon nanotubes was added to the solution. The container with the mixed solution was placed in an ultrasonic cleaner, the ultrasonic frequency was set to 20 kHz, the ultrasonic power density was 5 W / cm 2 , and the ultrasonic treatment was 30 min to obtain a CNTs-PEI-NMP suspension.

[0052] (4) 0.5 g of polyether ether ketone powder was added to the CNTs-PEI-NMP suspension. Intermittent ultrasonic was performed, the ultrasonic time was 20 min, the cycle ultrasonic was 3 s of work and 2 s of pause, and the ultrasonic power was 300 W.

[0053] (5) 50 mL of the suspension after ultrasonic treatment was directly poured into 60 mL of hexafluoroisopropanol, and 0.1 g of p-toluenesulfonic acid was added as a catalyst, and stirred at a temperature of 90°C for 30 min, and then the temperature was raised to 120°C, and ultrasonic treatment was performed at a power of 200 W for 10 min. Under the protection of nitrogen, the temperature was raised to 280°C and reacted for 6 h. After the reaction was completed, the product was poured into a large amount of methanol to precipitate, filtered and dried to obtain CNTs / PEEK polymer. After copolymerization of polyether ether ketone with fluorine-containing monomers, the melt viscosity of polyether ether ketone can be reduced, and the interfacial compatibility can be enhanced.

[0054] (6) The CNTs / PEEK polymer was added to 15 mL of dichloromethane solvent, and 2.5 mL of triflic acid with a concentration of 98% was added dropwise to the solution, and stirred at a speed of 300 rpm for 2 h, and the reaction temperature was 60°C. The sulfonic acid group (-SO3H) was introduced on the surface of the polyether ether ketone, and the solution was separated and purified to obtain a CNTs / PEEK polymer with a sulfonic acid group.

[0055] (7) 0.3 g of oxalic acid was esterified with 0.625 mL of ethylene glycol at 130°C for 2 h to obtain a polyethylene glycol oxalate prepolymer.

[0056] (8) 0.3 g of the polyethylene glycol oxalate prepolymer obtained in step (7) was added to 15 mL of methanol solution, and then 1.5 g of CNTs / PEEK polymer powder was uniformly added to the methanol solution within 10 min, and stirring was continued during the addition process, and finally 0.01 g of tetrabutyl titanate was added for catalysis, and stirring was continued for 4 h, and the reaction temperature was 130°C, and a water trap was used to remove the water generated during the reaction.

[0057] (9) After the reaction was completed, it was cooled, filtered, washed with methanol 4 times, and then dried in a vacuum drying oven at 58°C for 16 h. A high-temperature-resistant polyethylene glycol oxalate was obtained.

[0058] A multi-end feeding double-screw extrusion pipe includes a corrosion-resistant layer, a pipe layer and a heat preservation layer. The corrosion-resistant layer is selected from vinyl ester resin (commercially available MFE-2 type), and a surface coating slurry containing glass flakes (particle size 40 μm, thickness 3 μm) is prepared, and 3 coats are sprayed, each with a thickness of 90 μm, and the total thickness is 200 μm, and the temperature is cured at room temperature for 24 h. The pipe layer uses the high-temperature-resistant polyethylene glycol oxalate obtained in Example 1, the particles are softened at high temperature, and the pipe layer is formed by extrusion, and the temperature of the double-screw extruder (feeding port-head) is 240°C, 245°C, 250°C, 255°C, 255°C, 250°C, and the mold temperature is 240°C; a vacuum sizing method is used, the vacuum degree is -0.05 MPa, the cooling water tank temperature is 20°C, and the pulling speed is 0.8 m / min.

[0059] The insulation layer uses ceramic fiber felt, and the surface of the pipe layer is evenly coated with a high-temperature adhesive with a thickness of 0.4mm to avoid bubbles; Ceramic fiber felt (density 128kg / m 3 , thermal conductivity 0.08W / m·K) pre-cut to the pipe circumference + 5% overlap, while the high-temperature adhesive is still in the hot melt state, wrap it around the pipe, and apply 0.2MPa pressure to ensure a tight fit; After pasting is completed, it is cured at room temperature for 24 hours or heated to cure. After curing, the high-temperature adhesive forms a continuous transition layer to fill the interface micropores.

[0060] Example 2 The preparation method of high temperature resistant polyethylene glycol oxalate comprises the following steps: (1) 1.2 g of carbon nanotubes with a diameter of 15 nm, a length of 3 μm, and a purity of 97% were ultrasonically treated in a mixture of 60 mL of sulfuric acid and nitric acid. The ratio of 98% concentrated sulfuric acid to 65% concentrated nitric acid was 1:3. The ultrasonic treatment was carried out for 2 h at a frequency of 30 kHz and a power of 250 W. The temperature was controlled not to exceed 45 °C.

[0061] (2) Dissolve 0.012 g of KH-550 silane coupling agent in 0.6 mL of ethanol solution (95% concentration). Modify the filtered and washed carbon nanotubes with the KH-550 silane coupling agent solution. The reaction time is 1 h and the reaction temperature is 120°C. After the reaction, wash to neutrality and dry.

[0062] (3) Add 60 mL of N-methylpyrrolidone as a solvent to the container, first add 0.5 g of polyetherimide and stir at a reaction temperature of 60 °C for 1 h to form a polyetherimide solution, then add 1.2 g of modified carbon nanotubes to the solution, and place the container containing the mixed solution in an ultrasonic cleaner, set the ultrasonic frequency to 20 kHz, and the ultrasonic power density to 5 W / cm 2 , and ultrasonically treated for 30 min to obtain a CNTs-PEI-NMP suspension.

[0063] (4) Add 0.5 g of polyetheretherketone powder to the CNTs-PEI-NMP suspension. Perform intermittent ultrasound for 20 min, with a 3 s working and 2 s pause cycle, and an ultrasound power of 300 W.

[0064] (5) 60 mL of the suspension after ultrasonic treatment was directly poured into 70 mL of hexafluoroisopropanol, and 0.12 g of p-toluenesulfonic acid was added as a catalyst, and stirred at a temperature of 90°C for 30 min, and then the temperature was raised to 120°C, 200W power, ultrasonic treatment for 10 min. Under the protection of nitrogen, it was reacted at 280°C for 6 h. After the reaction was completed, the product was poured into a large amount of methanol to precipitate, filtered and dried to obtain CNTs / PEEK polymer. After copolymerization of polyether ether ketone with fluorine-containing monomers, the melt viscosity of polyether ether ketone can be reduced and the interfacial compatibility can be enhanced.

[0065] (6) 1.7 g of CNTs / PEEK polymer was added to 18 mL of dichloromethane solvent, and 3 mL of triflic acid with a concentration of 98% was added dropwise to the solution, and stirred at a speed of 300 rpm for 2 h, and the reaction temperature was 60°C. The sulfonic acid group (-SO3H) was introduced on the surface of the polyether ether ketone, and the solution was separated and purified to obtain CNTs / PEEK polymer with sulfonic acid group.

[0066] (7) 0.34 g of oxalic acid was esterified with 0.71 mL of ethylene glycol at 130°C for 2 h to obtain polyethylene glycol oxalate prepolymer.

[0067] (8) 0.34 g of polyethylene glycol oxalate prepolymer obtained in step (7) was added to 18 mL of methanol solution, and then 1.7 g of CNTs / PEEK polymer powder was uniformly added to the methanol solution within 10 min, and stirring was continued during the addition process, and finally 0.01 g of tetrabutyl titanate was added for catalysis, and stirring was continued for 4 h, and the reaction temperature was 130°C, and a water trap was used to remove the water generated during the reaction.

[0068] (9) After the reaction was completed, it was cooled, filtered, washed with methanol 4 times, and then dried in a vacuum drying oven at 58°C for 16 h. A high-temperature-resistant polyethylene glycol oxalate was obtained.

[0069] A multi-end feeding double-screw extrusion pipe was prepared using the high-temperature-resistant polyethylene glycol oxalate obtained in Example 2, and the pulling speed was increased to 0.9 m / min, and the other steps were the same as in Example 1.

[0070] Example 3 A method for preparing a high-temperature-resistant polyethylene glycol oxalate, comprising the following steps: (1) 3 g of carbon nanotubes with a diameter of 15 nm, a length of 3 μm and a purity of 97% were ultrasonically treated in a mixture of 150 mL of sulfuric acid and nitric acid, the ratio of 98% concentrated sulfuric acid and 65% concentrated nitric acid was 1:3, ultrasonic treatment was carried out for 2 h, the ultrasonic frequency was 30 kHz, the ultrasonic power was 250 W, and the temperature was controlled not to exceed 45°C.

[0071] (2) Dissolve 0.03 g of KH-550 silane coupling agent in 1.5 mL of ethanol solution (95% concentration). Modify the filtered and washed carbon nanotubes with the KH-550 silane coupling agent solution. The reaction time is 1 h and the reaction temperature is 120°C. After the reaction, wash to neutrality and dry.

[0072] (3) Add 150 mL of N-methylpyrrolidone as a solvent to the container, add 1.5 g of polyetherimide and stir at a reaction temperature of 60 °C for 1 h to form a polyetherimide solution, then add 3 g of modified carbon nanotubes to the solution, place the container containing the mixed solution in an ultrasonic cleaner, set the ultrasonic frequency to 20 kHz, and the ultrasonic power density to 5 W / cm 2 , and ultrasonically treated for 30 min to obtain a CNTs-PEI-NMP suspension.

[0073] (4) Add 0.5 g of polyetheretherketone powder to the CNTs-PEI-NMP suspension. Perform intermittent ultrasound for 20 min, with a 3 s working and 2 s pause cycle, and an ultrasound power of 300 W.

[0074] (5) Pour 150 mL of the suspension after ultrasound directly into 180 mL of hexafluoroisopropanol and add 0.3 g of p-toluenesulfonic acid as a catalyst. Stir at 90 °C for 30 min, then raise the temperature to 120 °C, ultrasonicate at 200 W for 10 min. Under nitrogen protection, react at 280 °C for 6 h. After the reaction, pour the product into a large amount of methanol for precipitation, filter and dry to obtain CNTs / PEEK polymer. After copolymerizing polyetheretherketone with fluorine-containing monomers, the melt viscosity of polyetheretherketone can be reduced and the interfacial compatibility can be enhanced.

[0075] (6) 3.5 g of CNTs / PEEK polymer was added to 35 mL of dichloromethane solvent, and 7 mL of 98% trifluoromethanesulfonic acid was added dropwise to the solution. The mixture was stirred at 300 rpm for 2 h at 60°C. Sulfonic acid groups (-SO3H) were introduced onto the surface of polyetheretherketone, and the solution was separated and purified to obtain CNTs / PEEK polymer with sulfonic acid groups.

[0076] (7) 0.34 g of oxalic acid was esterified with 0.71 mL of ethylene glycol at 130 °C for 2 h to obtain polyethylene glycol oxalate prepolymer.

[0077] (8) Take 0.5 g of polyethylene glycol adipate prepolymer obtained in step (7) and add it to 18 mL of methanol solution. Then, 3.5 g of CNTs / PEEK polymer powder is uniformly added into the methanol solution within 10 min, and stirring is continuously performed during the addition. Finally, 0.01 g of tetrabutyl titanate is added for catalysis, and stirring is continuously performed for 4 h at a reaction temperature of 130°C. A water trap is used to remove water generated during the reaction.

[0078] (9) After the reaction is completed, cooling is performed, and then filtration is performed. The product is washed with methanol 4 times, and then drying is performed in a vacuum drying oven at 58°C for 16 h. A high-temperature-resistant polyethylene glycol adipate is obtained.

[0079] A multi-end feeding double-screw extrusion pipeline is prepared using the high-temperature-resistant polyethylene glycol adipate obtained in Example 3, and the temperature of the extruder head is 260°C. The other steps are the same as those in Example 1.

[0080] Example 4 A method for preparing a high-temperature-resistant polyethylene glycol adipate includes the following steps: (1) The modified CNTs are prepared according to steps (1)-(2) in Example 1.

[0081] (2) In the reaction kettle of the material mixing and dispersing device, 1.5 L of NMP is added, the stirring and heating system is started, and the temperature is raised to 60°C. 15 g of PEI is added and stirred for 1 h until it is completely dissolved.

[0082] (3) 3 g of the modified CNTs obtained in step 1 is pre-mixed with 200 mL of NMP into a slurry, and is added into the storage tank of the material mixing and dispersing device.

[0083] (4) The circulating pump is started, and the PEI-NMP solution is pumped into the Venturi mixer (throat diameter: pipe diameter = 1:4, material: Hastelloy C-276) at a flow rate of 10 m / s. The valve at the inlet of the Venturi is adjusted, and the CNTs slurry is uniformly sucked into the main fluid within 20 min.

[0084] (5) The circulation and dispersion are continuously performed for 60 min, and a CNTs-PEI-NMP suspension with extremely uniform dispersion is obtained.

[0085] (6) 20 g of PEEK powder is pre-mixed with 100 mL of NMP into a slurry, and is sucked into the suspension in step 5 within 30 min in the same way by using the material mixing and dispersing device. The circulation treatment is continuously performed for 40 min, and a CNTs-PEEK-PEI-NMP uniformly mixed material is obtained.

[0086] (7) The subsequent steps are the same as steps (5)-(9) in Example 1, and the copolymerization, sulfonation, and grafting reaction with polyethylene glycol adipate are performed, and a high-temperature-resistant polyethylene glycol adipate is obtained.

[0087] A multi-feed twin-screw extrusion pipe was prepared using the high-temperature resistant polyethylene glycol adipate obtained in Example 4, the extruder head temperature was 250°C, the pulling speed was 1.0 m / min, and the other steps were the same as those in Example 1.

[0088] Comparative Example 1: No carbon nanotubes and polyether ether ketone were grafted compared with Example 1: (1) 0.3 g of polyethylene glycol adipate was added to 15 mL of methanol solution.

[0089] (2) No CNTs / PEEK or catalyst was added.

[0090] (3) The reaction was stirred using a water trap at a reaction temperature of 130°C for 4 h.

[0091] (4) After cooling, filtration, methanol washing 3 times, and vacuum drying at a temperature of 60°C for 12 h.

[0092] A multi-feed twin-screw extrusion pipe was prepared using the polyethylene glycol adipate obtained in Comparative Example 1, the extruder head temperature was 230°C, and the other steps were the same as those in Example 1.

[0093] Comparative Example 2: Only carbon nanotubes were grafted, and no polyether ether ketone was grafted compared with Example 1, and the specific steps were as follows: (1) 1.2 g of carbon nanotubes with a diameter of 15 nm, a length of 3 μm, and a purity of 97% were ultrasonically treated in a mixture of 60 mL of sulfuric acid and nitric acid, the ratio of 98% concentrated sulfuric acid and 65% concentrated nitric acid was 1:3, the ultrasonic treatment was performed for 2 h, the ultrasonic frequency was 30 kHz, the ultrasonic power was 250 W, and the temperature was controlled not to exceed 45°C.

[0094] (2) 0.012 g of KH-550 silane coupling agent was dissolved in 0.6 mL of ethanol solution, the ethanol solution concentration was 95%, and the KH-550 silane coupling agent solution was used to modify the filtered and washed carbon nanotubes, the reaction time was 1 h, and the reaction temperature was 120°C. After the reaction, it was washed to neutral and dried.

[0095] (3) 0.3 g of polyethylene glycol adipate was added to 18 mL of methanol solution, then 1.2 g of CNTs powder was uniformly added into the methanol solution within 10 min, stirring was continuously performed during the addition, finally 0.01 g of tetrabutyl titanate was added for catalysis, the reaction was continuously stirred for 4 h, the reaction temperature was 130°C, and a water trap was used to remove the water generated during the reaction.

[0096] (4) After the reaction was completed, it was cooled, filtered, washed with methanol 4 times, and then dried in a vacuum drying oven at 58°C for 16 h. High-temperature resistant polyethylene glycol adipate was obtained.

[0097] The polyethylene glycol oxalate obtained in Comparative Example 2 was used to prepare a multi-end feeding twin-screw extrusion pipeline, and the other steps were the same as those in Example 1.

[0098] Comparative Example 3: Copolymerization process of polyethylene glycol oxalate and polyetheretherketone. The specific steps are: (1) 0.5 g of polyetheretherketone powder was added to 30 mL of hexafluoroisopropanol and 0.06 g of p-toluenesulfonic acid was added as a catalyst. The mixture was stirred at 90°C for 30 min, and then the temperature was raised to 120°C, the power was 200 W, and ultrasonic treatment was performed for 10 min. Under nitrogen protection, the mixture was reacted at 280°C for 6 h. After the reaction, the product was poured into a large amount of methanol for precipitation, filtered and dried to obtain CNTs / PEEK polymer. After copolymerizing polyetheretherketone with fluorinated monomers, the melt viscosity of polyetheretherketone can be reduced and the interfacial compatibility can be enhanced.

[0099] (2) 0.5 g of PEEK polymer was added to 10 mL of dichloromethane solvent, and 2 mL of 98% trifluoromethanesulfonic acid was added dropwise to the solution. The mixture was stirred at 300 rpm for 2 h at 60°C. Sulfonic acid groups (-SO3H) were introduced onto the surface of polyetheretherketone (PEEK). The solution was separated and purified to obtain CNTs / PEEK polymer with sulfonic acid groups.

[0100] (3) Take 0.3 g of polyethylene glycol ether and add it to 18 mL of methanol solution. Then, add 0.5 g of PEEK polymer powder evenly into the methanol solution within 10 min. Stir continuously during the addition process. Finally, add 0.01 g of tetrabutyl titanate for catalysis. Stir continuously for 4 h. The reaction temperature is 130 °C. Use a water separator to remove the water generated during the reaction.

[0101] (4) After the reaction is completed, the mixture is cooled, filtered, washed with methanol four times, and then dried in a vacuum drying oven at 58°C for 16 hours to obtain high-temperature resistant polyethylene glycol ether.

[0102] The polyethylene glycol oxalate obtained in Comparative Example 3 was used to prepare a multi-end feeding twin-screw extrusion pipeline, and the other steps were the same as those in Example 1.

[0103] The performance test data of the polyethylene glycol oxalate obtained in Examples 1-4 and Comparative Examples 1-3 are shown in Table 1.

[0104] The performance test data of the multi-end feeding twin-screw extrusion pipes obtained in Examples 1-4 and Comparative Examples 1-3 are shown in Table 2.

[0105] Table 1: Performance test data of polyethylene glycol oxalate obtained in Examples 1-4 and Comparative Examples 1-3

[0106] Acid and alkali tensile strength retention rate test conditions: 10% H2SO4 / 10% NaOH, 60℃ soaking for 72h.

[0107] From Table 1, it can be seen that Examples 1-4 are overall superior to Comparative Examples 1-3 in terms of thermal decomposition temperature, carbon residue rate, thermal conductivity, mechanical properties, heat distortion temperature, acid and alkali stability and molding performance. Examples 2 and 4 have the best performance, with thermal decomposition temperatures of 365℃ and 368℃, tensile strengths of 42MPa and 45MPa, acid and alkali tensile strength retention rates of 92 / 89% and 95 / 91%, and extrusion shrinkage rates of 1.3% and 1.2%, respectively, reflecting the synergistic reinforcing effect of double grafting and efficient dispersion. Example 3 has a slight decline in performance due to excessive CNTs and some agglomeration, but it is still better than the comparative examples. Comparative Example 1 has the worst performance, and Comparative Examples 2 and 3 have limited performance improvement, proving that double grafting modification is the key to balancing material heat resistance, mechanical properties, corrosion resistance and molding performance.

[0108] Table 2: Performance test data of multi-feed dual-screw extrusion pipes obtained from Examples 1-4 and Comparative Examples 1-3

[0109] As can be seen from Table 2, the pipes prepared in the examples have much better performance than all the comparative examples. This strongly proves the effectiveness of the "heat-resistant skeleton (PEEK) + thermal conductivity network (CNT)" double grafting synergistic reinforcement strategy proposed in the present application. The introduction of PEEK or CNT alone (such as Comparative Examples 2 and 3) cannot comprehensively solve the problem of high temperature resistance, especially uneven high temperature resistance.

Claims

1. A multi-end feeding twin-screw extrusion pipeline, characterized in that: Including corrosion-resistant layer, pipeline layer and insulation layer; The corrosion-resistant layer is made of vinyl ester resin, which is sprayed on the inner surface of the pipe layer; The pipe layer is made of high-temperature resistant polyethylene glycol ether, which is softened by heating and then extruded through a die to form the pipe layer. The insulation layer uses ceramic fiber felt, the outer surface of the pipe layer is evenly coated with high-temperature adhesive, and the ceramic fiber felt is glued to the outer surface of the pipe layer.

2. A method for preparing high-temperature resistant polyethylene glycol ether for use in the multi-end feeding twin-screw extrusion pipe according to claim 1, characterized in that: The following steps are involved: (1) Ultrasonic treatment of carbon nanotubes in mixed acid; (2) adding the ultrasonically treated carbon nanotubes into a silane coupling agent for modification; (3) adding the modified carbon nanotubes into a NMP solution containing polyetherimide and mixing and dispersing them into a CNTs-PEI-NMP suspension; (4) Adding polyetheretherketone powder to the CNTs-PEI-NMP suspension for mixing and dispersion; (5) reacting the ultrasonicated CNTs-PEI-NMP suspension with polyetheretherketone in hexafluoroisopropanol, and filtering after the reaction to obtain a CNTs / PEEK polymer; (6) reacting the CNTs / PEEK polymer with trifluoromethanesulfonic acid to introduce sulfonic acid groups -SO3H on the surface of polyetheretherketone to form a CNTs / PEEK copolymer; (7) Double grafting of CNTs / PEEK copolymer with polyethylene glycol oxalate under the catalysis of tetrabutyl titanate; (8) After the grafting is completed, the mixture is cooled to obtain high-temperature resistant polyethylene glycol oxalate.

3. The method for preparing high temperature resistant polyethylene glycol oxalate according to claim 2, wherein: The mixing and dispersion of the materials in step (3) is carried out by ultrasonic treatment or by a material mixing and dispersing device. The specific method of the material mixing and dispersing device is as follows: the NMP solution of polyetherimide is used as the main fluid and is pumped into the Venturi mixer at a flow rate of 8-15m / s through a circulation pump; the slurry pre-mixed with the modified carbon nanotubes and a small amount of NMP is sucked into the main fluid by the negative pressure generated by the throat of the Venturi tube, and the circulating dispersion treatment is carried out for 30-120min.

4. The method for preparing high temperature resistant polyethylene glycol oxalate according to claim 2, wherein: The mixing and dispersion of the materials in step (4) is carried out by ultrasonic treatment or by a material mixing and dispersing device. The specific method of the material mixing and dispersing device is as follows: the CNTs-PEI-NMP suspension is used as the main fluid and is pumped into the Venturi mixer at a flow rate of 8-15 m / s through a circulation pump; the slurry premixed with polyetheretherketone powder and a small amount of NMP is sucked into the main fluid by the negative pressure generated by the throat of the Venturi tube, and a circulation dispersion treatment is carried out for 30-120 minutes.

5. The method for preparing high temperature resistant polyethylene glycol oxalate according to claim 2, wherein: The carbon nanotubes were ultrasonically treated in a mixture of sulfuric acid and nitric acid.

6. The method for preparing high temperature resistant polyethylene glycol oxalate according to claim 2, wherein: The carbon nanotubes were modified using a 2 wt.% silane coupling agent ethanol solution.

7. The method for preparing high temperature resistant polyethylene glycol oxalate according to claim 2, wherein: The carbon nanotubes are dissolved in a polyetherimide solution and ultrasonically treated to form a uniform suspension.

8. The method for preparing high temperature resistant polyethylene glycol oxalate according to claim 2, wherein: Polyetheretherketone powder was added to the CNTs-PEI-NMP suspension and subjected to intermittent ultrasound to form a CNTs / PEEK polymer.

9. The method for preparing high temperature resistant polyethylene glycol oxalate according to claim 2, wherein: A CNTs-PEI-NMP suspension with a volume ratio of (5-6):(6-7) was copolymerized with hexafluoroisopropanol.

10. The method for preparing high temperature resistant polyethylene glycol oxalate according to claim 2, wherein: The copolymerized CNTs / PEEK polymer reacts with 98% trifluoromethanesulfonic acid to introduce sulfonic acid groups on the surface of polyetheretherketone.

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