A method for determining the sulfur content in sulfonated polyether ether ketone

Abstract

The present invention discloses a method for determining the sulfur content in sulfonated polyether ether ketone, belonging to the field of material analysis. The steps include putting the sample into a porcelain boat crucible and pushing them together into a carbon-sulfur analyzer equipped with an electric resistance furnace to detect the sulfur content by infrared absorption method. In the porcelain boat crucible, the upper surface of the sample is covered with a first promoting release agent powder. The sulfur content of the first promoting release agent is less than 0.0005%, and the first promoting release agent is selected from tungsten trioxide, calcium oxide, silicon dioxide, tin, nickel or iron. The first promoting release agent can cover the sample, which can prevent the loose sulfonated polyether ether ketone from being blown away by the carrier gas and avoid incomplete combustion of the sample. Moreover, the promoting release agent can promote the release of sulfur elements in the sulfonated polyether ether ketone, avoid the integration curve from being inaccurate due to the slow release of sulfur in the sulfonated polyether ether ketone, and is beneficial to improving the stability and accuracy of the test.

Description

Technical Field

[0001] The present invention relates to a method for determining the sulfur content in sulfonated polyether ether ketone, belonging to the field of material analysis. Background Art

[0002] Sulfonated polyether ether ketone is a modified polymer material and is a raw material for making proton exchange membranes, dialysis membranes, nanofiltration membranes, ultrafiltration membranes with various functions, and is widely used in fields such as fuel cells, vanadium batteries, and wastewater treatment. Sulfonated polyether ether ketone is a sulfonic acid compound obtained by reacting polyether ether ketone with sulfonating agents such as sulfuric acid and chlorosulfonic acid, introducing sulfonic acid groups into carbon atoms in polyether ether ketone or connecting with sulfur atoms in the sulfonating agent.

[0003] The sulfonation degree of sulfonated polyether ether ketone has an important influence on the properties of the material, and the sulfur content is the main parameter determining its sulfonation degree. Therefore, it is very important to determine the sulfur content in sulfonated polyether ether ketone. Currently, there are many methods for testing sulfur elements in materials, such as X-ray fluorescence spectrometry, heating method, melting method, combustion method, etc. Among them, the high-frequency combustion infrared absorption method for detecting sulfur content has the characteristics of rapidity and accuracy.

[0004] The high-frequency combustion infrared absorption method is based on infrared absorption spectroscopy technology. The sample is heated in a high-frequency induction furnace (adding a magnetic conductive substance and using a T-shaped crucible), and oxygen is introduced to make the sulfur in it burn to form sulfur dioxide (the carbon in it will burn to form carbon dioxide). These generated gases form a mixed gas with the carrier gas (oxygen). After passing through a dust collection tube, a drying tube, a purification tube, a catalytic tube, etc. to remove dust and water vapor, the mixed gas containing sulfur dioxide enters the infrared absorption cell detection system, and the sulfur content is determined by measuring the change in infrared energy at a specific wavelength. However, due to the small density and relatively loose aggregation state of sulfonated polyether ether ketone, when tested by the high-frequency combustion infrared absorption method, the powder is easily blown away by the carrier gas, making it difficult to burn fully (it cannot be heated by the magnetic conductive substance and remains on the crucible wall, etc.), resulting in problems such as large fluctuations and inaccuracies in the sulfur content analysis data. Especially for samples with low sulfur content, when measuring a relatively large amount of powder, it is more likely to cause incomplete combustion of the powder.

[0005] The resistance furnace combustion infrared absorption method is to push the crucible (boat-shaped crucible) containing the sample to the combustion zone of the resistance furnace, so that the sample in the crucible burns in an oxygen stream; under the action of high temperature and oxygen stream, the sulfur element in the sample is converted into sulfur dioxide gas. The mixed gas is purified by a dust removal tube, a drying tube, a purification tube, a catalytic furnace, etc. to remove dust, water vapor, etc. The mixed gas containing sulfur dioxide is introduced into the infrared absorption cell detection system, and the content of sulfur element in the organic matter is calculated by measuring the change of infrared energy at a specific wavelength. The resistance furnace combustion infrared absorption method can make the powder in the furnace burn completely. However, it is found in the test process that the sulfur atoms in sulfonated polyether ether ketone are released rapidly first and then slowly, which makes the signal intensity of sulfur element maintain at a relatively low level for a long time (showing a tailing phenomenon) during the test process, resulting in a large area integration error and an inaccurate integration curve; in addition, sulfonated polyether ether ketone has a small density and a relatively loose aggregation state, and a very small part of the sample is blown by the carrier gas to the furnace mouth of the resistance furnace when it is pushed into the interior of the resistance furnace, making the sample burn incompletely, thus resulting in a low test result and low test accuracy. Summary of the Invention

[0006] In order to overcome the deficiencies of the prior art, the present invention provides a method for determining the sulfur content in sulfonated polyether ether ketone, which can make the sulfur element burn completely and release concentratedly in the resistance furnace combustion infrared absorption method, and inhibit the tailing phenomenon.

[0007] The technical solution adopted by the present invention to solve its technical problems is as follows:

[0008] A method for determining the sulfur content in sulfonated polyether ether ketone, the steps include spreading the sample flat in a porcelain boat crucible, and pushing them together into a carbon-sulfur analyzer with a resistance furnace, and detecting the sulfur content by infrared absorption method. In the porcelain boat crucible, the upper surface of the sample is covered with a first promoting release agent powder, and the sulfur content of the first promoting release agent is less than 0.0005%, and the first promoting release agent is selected from tungsten trioxide, calcium oxide, silicon dioxide, tin, nickel or iron.

[0009] The method for determining the sulfur content in sulfonated polyether ether ketone provided by this application spreads a layer of promoting release agent on the surface of the sample, which can prevent the loose sulfonated polyether ether ketone from being blown away by the carrier gas, avoid incomplete combustion of the sample, and the promoting release agent can promote the release of sulfur element in sulfonated polyether ether ketone, avoid inaccurate integration curve caused by slow sulfur release, and is beneficial to improving the stability and accuracy of the test.

[0010] Further, the mass of the first promoting release agent is equivalent to 1.0 times to 9.2 times the mass of the sample.

[0011] Further, when the melting point of the first promoting release agent is lower than or equal to the temperature of the resistance furnace, the mass of the first promoting release agent is equivalent to 2.3 to 3.2 times the mass of the sample; when the melting point of the first promoting release agent is greater than the temperature of the resistance furnace, the mass of the first promoting release agent is equivalent to 1.0 to 9.2 times the mass of the sample. Preferably, the first promoting release agent is porous tungsten trioxide.

[0012] If the melting point of the first promoting release agent is lower than or equal to the temperature of the resistance furnace, after melting, the first promoting release agent changes from a powder state to a dense liquid state (or a coexistence state of solid and liquid), which is not conducive to the overflow of sulfur dioxide gas; or the first promoting release agent has flowed to the bottom of the crucible or outside the crucible during the experiment, which is not conducive to preventing the loose sulfonated polyether ether ketone sample from being blown away by the carrier gas. Therefore, when the melting point of the first promoting release agent is lower than or equal to the temperature of the resistance furnace, the dosage of the first promoting release agent should not be too much or too little.

[0013] Further, in the porcelain boat crucible, a second promoting release agent powder is padded on the lower surface of the sample. The sulfur content of the second promoting release agent is less than 0.0005%, and the second promoting release agent is selected from tungsten trioxide, calcium oxide, silicon dioxide, tin, nickel or iron.

[0014] Further, the mass of the second promoting release agent is equivalent to 0.1 to 1.6 times the mass of the sample.

[0015] Further, the fineness of the second promoting release agent powder is 200 mesh to 300 mesh.

[0016] Further, the fineness of the first promoting release agent powder is 200 mesh to 300 mesh.

[0017] Further, the temperature of the resistance furnace is stabilized at 1280 °C to 1320 °C, and the O2 flow rate is 180 L / h.

[0018] Further, the integral end time of the spectrogram curve is 40 s to 300 s. In the test program, the basis for the computer to judge whether the test ends is: one is that the change of the curve in the spectrogram with time is less than a certain speed and it automatically ends (peak judgment factor); the other is the test time (integral end time). If the test does not meet the automatic end condition after reaching the set shortest test time, it will be forced to end according to the preset test time (longest test time). If the test time is less than the set shortest test time and the test meets the automatic end condition, the test will not end until the test time reaches the set shortest test time.

[0019] Further, the carbon and sulfur analyzer is calibrated with standard substances, and the numerical relationship between the infrared spectrum intensity value and the sulfur content of the standard substances is established. The calibration method can be multi-point calibration or single-point calibration.

[0020] Further, the reference material is a coal reference material.

[0021] The beneficial effects of the present invention are as follows: In the method for determining the sulfur content in sulfonated polyether ether ketone of the present invention, a first release promoter is spread on the surface of the sample, which can cover the sample, avoid the loose sulfonated polyether ether ketone from being blown away by the carrier gas, and prevent incomplete combustion of the sample. Moreover, the release promoter can promote the release of sulfur elements in sulfonated polyether ether ketone, avoid the integration curve from being inaccurate due to the slow release of sulfur in sulfonated polyether ether ketone, and is beneficial to improving the stability and accuracy of the test. Description of the Drawings

[0022] Figure 1 It is a comparison diagram of infrared absorption spectra between Example 2 and Comparative Example 1.

[0023] Figure 2 It is a comparison diagram of infrared absorption spectra between Example 3 and Comparative Example 1.

[0024] Figure 3 It is a comparison diagram of infrared absorption spectra between Example 4 and Comparative Example 1.

[0025] Figure 4 It is a comparison diagram of infrared absorption spectra between Example 5 and Comparative Example 1.

[0026] Figure 5 It is a comparison diagram of infrared absorption spectra between Example 6 and Comparative Example 1.

[0027] Figure 6 It is a comparison diagram of infrared absorption spectra between Example 9 and Comparative Example 1.

[0028] Figure 7 It is a comparison diagram of infrared absorption spectra among Example 11, Example 4 and Comparative Example 1.

[0029] Figure 8 It is a comparison diagram of infrared absorption spectra between Example 13 and Comparative Example 1.

[0030] Figure 9 It is a comparison diagram of infrared absorption spectra between Example 21 and Comparative Example 3.

[0031] Figure 10 It is a comparison diagram of the crucibles after testing the sulfonated polyether ether ketone SP9 of Comparative Example 3, the steel reference material of Comparative Example 3, and the sulfonated polyether ether ketone SP9 of Example 21. Detailed Embodiments

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be described clearly and completely below. Obviously, the described embodiments are some, but not all, of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present disclosure without creative efforts fall within the scope of protection of the present invention.

[0033] Unless otherwise specified, all technical and scientific terms used herein have the standard meanings in the field to which the claimed subject matter belongs. If there are multiple definitions for a certain term, the definition in this document shall prevail.

[0034] The following lists the materials used in the subsequent embodiments and the precautions in the experiments:

[0035] (1) The porcelain boat crucible (length × height: 88 mm × 10 mm, sulfur content less than 0.0005%) is placed in a muffle furnace before use and calcined at 1200 °C for 4 hours. After taking it out and cooling slightly, it is stored in a desiccator.

[0036] (2) Oxygen: The purity is 99.995%.

[0037] (3) Desiccant: Anhydrous magnesium perchlorate, particle size 0.7 mm - 1.2 mm.

[0038] (4) Purifying agent: Soda asbestos, particle size 0.7 mm - 1.2 mm.

[0039] (5) Promoter: Tungsten trioxide powder (200 - 300 mesh, porous structure), calcium oxide powder (200 - 300 mesh), silicon dioxide powder (200 - 300 mesh), tin powder (200 - 300 mesh), nickel powder (200 - 300 mesh), iron powder (200 - 300 mesh). The sulfur content is less than 0.0005%.

[0040] (6) Standard substance: Coal standard substance (national first-class standard substance).

[0041] (7) Before testing, check the carbon-sulfur analyzer for air leakage, and preheat the resistance furnace and high-frequency induction furnace for more than 3 hours.

[0042] (8) Operate according to the instrument instructions, and the instrument automatically analyzes and obtains the test results.

[0043] (9) Calibration test: Adopt multi-point calibration or single-point calibration.

[0044] ① Multi-point calibration: Select 4 certified coal reference materials to calibrate the instrument. Designate one as the verification reference material and the other three as calibration reference materials. The sulfur content of the verification reference material should be between the sulfur contents of the three calibration reference materials. Conduct 3 to 5 analyses of each calibration reference material on the selected channel to establish a calibration curve, and then verify it with the verification reference material. During the sample testing process, verify with this verification reference material every 10 measurements. If the test results are out of range, recalibrate.

[0045] ② Single-point calibration: Select two coal reference materials or standard samples. The coal reference materials or standard samples should have a sulfur content similar to that of the test sample. Alternatively, control the mass number of the sample in a single test to make the absolute value of the sulfur content in the test material similar to the absolute value of the sulfur content in the reference material. Execute the single-point calibration procedure according to the requirements of the instrument manual. Analyze one of the reference materials / standard samples 3 to 5 times, calculate the average of these results, and perform a system calibration. The average value should match the standard value and not exceed the uncertainty range given in the reference material / sample certificate. Use the other reference material / standard sample as a test sample for analysis to verify the calibration. The analysis results should be within the uncertainty range of the standard value of this reference material / standard sample.

[0046] (10) Before sample testing, conduct a blank value test: During the testing process, except for not adding the sample, use exactly the same analysis steps, reagents, and dosages for testing. The computer will perform blank value deduction, and the computer will automatically deduct the blank value during the subsequent sample testing process. Repeat the test 3 to 5 times, and the computer will conduct the blank value test. If the blank value is greater than 0.002% and the standard deviation is greater than 0.0005%, find the cause and take corresponding measures.

[0047] (11) Testing process (resistance furnace combustion infrared cell absorption method): Place the sample flat in a porcelain boat crucible, and then push it into the resistance furnace (pure oxygen atmosphere) for combustion, converting the sulfur element into a SO2 mixed gas (containing CO, CO2, and other gases). Then the mixed gas passes through a dust collector, a water removal well test tube, a desiccant reagent tube, a purifying agent reagent tube, and a catalyst reagent tube for dust removal, drying, and purification, and finally enters the sulfur infrared absorption cell detection cell to absorb infrared light of a specific wavelength. By measuring the change in the infrared energy of a specific wavelength, information on the S content can be obtained. Each sample is balanced and tested 3 to 5 times, and its relative standard error RSD ≤ 4%. Take the average value.

[0048] The method of the present application can measure sulfonated polyether ether ketone with a minimum sulfur content of 0.0128%. Limited by the limited source of sulfonated polyether ether ketone, there is currently no sample with a concentration higher than 1.06%. The test range of sulfur in the sulfonated polyether ether ketone of the present application is 0.0128% - 1.06%. The lower the sulfur content, the more difficult it is to detect. It can be expected that if there is a sample with a concentration higher than 1.06%, the upper limit of the test range of the present application can be higher.

[0049] Example 1: Covered with silica on top

[0050] The temperature of the resistance furnace is stabilized at 1280 °C - 1320 °C, the integral end time is set to 110 s - 300 s, and the O2 carrier flow rate is 180 L / h. The multi-point calibration method is adopted. The sulfur contents in the coal standard substances are 0.18%, 0.28%, 0.41%, and 0.76%, and the mass numbers are 90 mg - 95 mg, which are weighed accurately to 0.01 mg to determine the calibration coefficient. Among them, the sample with a sulfur content of 0.41% (mass number 90 mg - 95 mg, weighed accurately to 0.01 mg) is used to verify the calibration coefficient. After calibration is completed, the blank value test and the sulfur content test in sulfonated polyether ether ketone are started.

[0051] Weigh 90 mg - 95 mg (accurately to 0.01 mg) of sulfonated polyether ether ketone SP1 and spread it evenly in a porcelain boat crucible. Then cover the sample with the auxiliary agent silica, and the dosage of silica is 3.1 times - 3.2 times that of SP1. Then push the sample into the combustion zone of the resistance furnace for testing according to the equipment instruction manual. The test result is directly calculated by the software after deducting the blank value. Test independently 3 times. The average value of the 3 tests is 0.241%, the RSD is 2.72%, and the average test time is 111 s.

[0052] Example 2: Covered with tin on top

[0053] After calibrating the instrument and measuring the blank value according to the method and steps of Example 1, the sulfur content in sulfonated polyether ether ketone SP1 is detected. The first sustained-release agent is tin powder, and its dosage is 3.1 times - 3.2 times that of SP1. The average value of the 3 tests is 0.221%, and the RSD is 3.34%.

[0054] Comparative Example 1

[0055] After calibrating the instrument and measuring the blank value according to the method and steps of Example 1, the sulfur content in sulfonated polyether ether ketone SP1 is detected without adding a sustained-release agent. The average value of the 3 tests is 0.212%, the RSD is 3.76%, and the average test time is 111 s.

[0056] Compare the infrared absorption spectra of the tests in Example 2 and Comparative Example 1 to obtain Figure 1 . Figure 1In it, the ordinate is the infrared light absorption intensity Intensity at a specific wavelength, with the unit of volt V (the signal intensity is displayed in the form of voltage); the abscissa is the analysis and test time, with the unit of second. From Figure 1 As can be seen from Figure 1 , at the beginning of the tests of Example 2 and Comparative Example 1, sulfur was released quickly, with an obvious intensity peak. Then the sulfur release slowed down, and another intensity peak appeared at 40 - 50 s. This may be because sulfur doping in sulfonated polyether ether ketone SP1 was at different positions, resulting in different release rates. The sulfur release in this part (at 40 - 50 s) was relatively slow. The intensity peak of the test spectrum with the addition of tin release promoter at 40 - 50 s was significantly higher than that of Comparative Example 1, indicating that the sulfur release rate became faster, and the test result was higher than that of Comparative Example 1. This should be that when there was no release promoter added, a part of sulfur in sulfonated polyether ether ketone SP1 was released quickly first, and then the remaining part was released slowly, resulting in the signal intensity of sulfur element being released at a relatively low level for a long time (showing a tailing phenomenon), leading to the inaccuracy of the integral curve and a low test result. In Example 2, the start of sulfur release was 6 - 7 s slower than that of Comparative Example 1. This may be because at the beginning, metallic tin absorbed heat and melted, and then the heat could be conducted to the sample, so the start of sulfur release would be delayed compared to Comparative Example 1.

[0057] Example 3: Covered with calcium oxide on it

[0058] After calibrating the instrument and measuring the blank value according to the method and steps of Example 1, the sulfur content in sulfonated polyether ether ketone SP1 was detected. The first release promoter was calcium oxide, and its dosage was 5.5 - 5.6 times that of SP1. The average value of 3 tests was 0.241%, the RSD was 3.86%, and the average test time was 113 s.

[0059] Comparing the test spectrum line of Example 3 with that of Comparative Example 1, we got Figure 2 , and it was found that the first intensity peak of Example 3 was significantly delayed and shorter than that of Comparative Example 1, and then the second peak was significantly enhanced and delayed. This should be that at the beginning, calcium oxide absorbed heat and caused slow heat transfer, so the first peak was significantly delayed and became shorter. However, the subsequent sulfur signal intensity increased significantly and then decreased rapidly, indicating that sulfur was released relatively quickly subsequently, avoiding the tailing phenomenon.

[0060] Example 4: Covered with nickel on it

[0061] After calibrating the instrument and measuring the blank value according to the method and steps of Example 1, the sulfur content in sulfonated polyether ether ketone SP1 was detected. The first release promoter was nickel powder, and its dosage was 7.4 - 7.5 times that of SP1. The average value of 3 tests was 0.248%, the RSD was 3.66%, and the average test time was 120 s.

[0062] Comparing the test spectrum line of Example 4 with that of Comparative Example 1, we got Figure 3, it was found that the first intensity peak of Example 4 was significantly delayed and lower than that of Comparative Example 1, and then rapidly decreased after the second peak appeared. This should be because the nickel powder first absorbed heat and melted, and then the heat was transferred to the sample. Therefore, the first peak was significantly delayed and became shorter. However, the sulfur signal intensity increased significantly and then rapidly decreased, indicating that sulfur was released relatively quickly subsequently, avoiding the tailing phenomenon. This also shows that the first release promoter cannot be added too much (too thick coverage), otherwise the sulfur release in the sample will become slower.

[0063] Example 5: Covered with tungsten trioxide on top

[0064] After calibrating the instrument and measuring the blank value according to the method and steps of Example 1, the sulfur content in sulfonated polyether ether ketone SP1 was detected. The first release promoter was tungsten trioxide powder, and its dosage was 5.1 - 5.2 times that of SP1. The average value of 3 tests was 0.229%, the RSD was 3.81%, and the average test time was 111 s.

[0065] Comparing the test spectrum of Example 5 with that of Comparative Example 1, it was obtained that Figure 4 , it was found that the first intensity peak of Example 5 was significantly delayed compared with that of Comparative Example 1, and then rapidly decreased after the second peak appeared. This indicates that the sulfur release rate became faster, and the test result was higher than that of Comparative Example 1. This should be because when no release promoter was added, a part of sulfur in sulfonated polyether ether ketone SP1 was released quickly first, and then the remaining part was released slowly, resulting in the signal intensity of sulfur element being released at a relatively low level for a long time (appearing the tailing phenomenon), leading to the inaccuracy of the integral curve and the low test result. In Example 5, the start of sulfur release was 5 - 6 s slower than that of Comparative Example 1. This may be because tungsten trioxide first absorbed heat and then was transferred to the sample, so the start of sulfur release would be delayed compared with Comparative Example 1. The counting intensity of sulfur after the first peak was significantly higher than that of Comparative Example 1, indicating that adding tungsten trioxide can promote the release of sulfur, and the test result was higher than that of Comparative Example 1.

[0066] Example 6: Covered with iron powder on top

[0067] After calibrating the instrument and measuring the blank value according to the method and steps of Example 1, the sulfur content in sulfonated polyether ether ketone SP1 was detected. The first release promoter was iron powder, and its dosage was 4.2 - 4.3 times that of SP1. The average value of 3 tests was 0.223%, the RSD was 3.65%, and the average test time was 111 s.

[0068] Comparing the test spectrum of Example 6 with that of Comparative Example 1, it was obtained that Figure 5 .

[0069] Example 7: Covered with tungsten trioxide on top and paved with tungsten trioxide below

[0070] The temperature of the resistance furnace is stabilized at 1280 °C to 1320 °C, the integral end time is set to 80 s to 300 s, and the O2 flow rate is 180 L / h. First, calibrate the instrument according to the method and steps of Example 1, and then perform blank value testing and sample testing. Weigh 50 - 53 mg of tungsten trioxide and spread it flat on the bottom of the porcelain boat crucible as the second release promoter. Then weigh 54 - 57 mg (accurate to 0.01 mg) of sulfonated polyether ether ketone SP1 and spread it on the upper layer of tungsten trioxide. Then weigh a certain amount of tungsten trioxide and cover it on the sample. The dosage of the first release promoter is 3.2 - 3.4 times that of SP1. Then push the sample into the combustion zone of the resistance furnace for testing according to the equipment instruction manual. The average value of the 3 tests is 0.227%, the average test time is 81 s, and the RSD is 2.68%. After the test, take the powder at the bottom of the crucible, whose color is the same as that of tungsten trioxide and is analyzed as tungsten trioxide.

[0071] Example 8: Tin covered on the top + Tin paved on the bottom

[0072] Calibrate the instrument and measure the blank value according to the method and steps of Example 7, and then detect the sulfur content in sulfonated polyether ether ketone SP1. The dosage of tin powder as the bottom release promoter (the second release promoter) is 60 - 62 mg, and the dosage of tin powder in the topmost layer (the first release promoter) is 2.3 - 2.4 times that of SP1. The average value of the 3 tests is 0.223%, the RSD is 3.65%, and the average test time is 82 s. After the test, there is a layer of solid at the bottom of the crucible.

[0073] Compare the test results of Example 8 with those of Example 2 and Comparative Example 1. The test time of Example 8 is significantly shorter than that of Comparative Example 1 and Example 2. The test results are consistent with those of Example 2, but the second intensity peak is significantly higher than that of Example 2 and Comparative Example 1. This is because although the dosage of the release promoter tin powder (the total dosage of the first release promoter and the second release promoter in Example 8) is the same as that of Example 2 (Example 2 only has the first release promoter), part of it is placed at the bottom and part of it covers the sample. The tin powder covering the sample becomes thinner, the heat required for tin melting becomes less, and the heat transfer is faster. Therefore, the sulfur release time of Example 8 is significantly faster than that of Example 2 and slower than that of Comparative Example 1. At the same time, there is tin powder paved at the bottom, which can increase the contact area between the sample and tin, helping to promote sulfur release. Therefore, the sulfur release speed becomes faster.

[0074] Example 9: Tin paved on the bottom + Tungsten trioxide covered on the top

[0075] Calibrate the instrument and measure the blank value according to the method and steps of Example 7, and then detect the sulfur content in sulfonated polyether ether ketone SP1, where the dosage of the bottom promoter tin powder is 80 - 82 mg, and the dosage of tungsten trioxide in the topmost layer is 2.3 - 2.4 times that of SP1. The average value of 3 tests is 0.224%, the RSD is 3.65%, and the average test time is 82 s. After the test is completed, there is a layer of powder containing tin solid at the bottom of the crucible.

[0076] Compare the test spectrum of Example 9 with Comparative Example 1 to obtain Figure 6 . The test time of Example 9 is significantly shorter than that of Comparative Example 1, and there is no tailing phenomenon. This is because after the bottom tin melts, the contact area with the sample becomes larger, promoting the release of S. At the same time, the surface covered with tungsten trioxide does not melt, which is beneficial to the release of sulfur into the gas. Therefore, the test time is significantly shortened.

[0077] Example 10: Tungsten trioxide is laid at the bottom + tin is covered on the top

[0078] Calibrate the instrument and measure the blank value according to the method and steps of Example 7, and then detect the sulfur content in sulfonated polyether ether ketone SP1, where the dosage of the bottom promoter tungsten trioxide is 80 - 82 mg, and the dosage of the promoter tin in the topmost layer is 6.7 - 6.8 times that of SP1. The average value of 3 tests is 0.233%, the RSD is 2.42%, and the average test time is 92 s. After the test is completed, there is a layer of solid and a small amount of powder at the bottom of the crucible.

[0079] Compare Example 9 with Example 10 and find that the time when sulfur starts to be released in Example 10 is delayed by 3 - 4 s compared with Example 9. This is because the covered tin powder is thicker and the tin powder has a dense structure, resulting in a slightly slower heat transfer to the powder. In addition, after the test is completed, the bottom of the crucible in Example 10 is a layer of solid, which is tin metal containing tungsten trioxide, while the crucible in Example 9 contains a small amount of tungsten trioxide powder with tin. This shows that tungsten trioxide does not melt while tin melts during the test. Therefore, after the sulfur in the sample of Example 10 is released, it needs to pass through the molten tin layer to be released into the gas, which increases the resistance to sulfur release. And tungsten trioxide has a porous structure, which is beneficial to the release of sulfur through it. Therefore, the test time of Example 10 is also longer. A slight tailing phenomenon is observed during the test of Example 10, and the test result is slightly on the high side.

[0080] Compare Example 8 with Example 10. Its test time is shorter than that of Example 10, and there is no tailing phenomenon. This should be because the covered tin layer is thinner, and after the sulfur in the sample is released, it can quickly pass through the molten tin layer and be released into the gas. Therefore, the test time does not become longer.

[0081] Example 11: Nickel is laid at the bottom + tungsten trioxide is covered on the top

[0082] Calibrate the instrument and measure the blank value according to the method and steps of Example 7, and then detect the sulfur content in sulfonated polyether ether ketone SP1, where the dosage of nickel powder as the bottom promoter is 51 - 52 mg, and the dosage of tungsten trioxide in the topmost layer is 9.1 - 9.2 times that of SP1. The average value of 3 tests is 0.226%, the RSD is 1.99%, and the average test time is 92 s.

[0083] Compare the test spectrograms of Example 11 with those of Example 4 and Comparative Example 1 to obtain Figure 7 . The test time of Example 11 is the shortest, and the sulfur starts to be released slower than that of Comparative Example 1 and faster than that of Example 4. This is because tungsten trioxide has a porous structure and does not melt, which can reduce the resistance of sulfur released into the mixed gas. Therefore, the sulfur in Example 11 is released faster than that in Example 4, and the test time becomes shorter.

[0084] Example 12: Tungsten trioxide is laid on the bottom + tungsten trioxide is covered on the top

[0085] Calibrate the instrument and measure the blank value according to the method and steps of Example 7, and then detect the sulfur content in the sample. The integral end time is set to 70 - 300 s. First, weigh 50 - 53 mg of tungsten trioxide and spread it flat at the bottom of the porcelain boat crucible, then weigh 54 - 59 mg (accurate to 0.01 mg) of sulfonated polyether ether ketone SP1 and spread it on the upper layer of tungsten trioxide (the second promoter), and then weigh a certain amount of tungsten trioxide to cover the sample, and its dosage is 7.0 - 7.1 times that of SP1. Then, push the sample into the combustion area of the resistance furnace for testing according to the equipment instruction manual. The average value of 3 tests is 0.225%, the RSD is 1.61%, and the average test time is 83 s.

[0086] Comparative Example 2

[0087] Calibrate the instrument and measure the blank value according to the method and steps of Example 12, and then detect the sulfur content in sulfonated polyether ether ketone SP1 without adding a promoter. The average value of 3 tests is 0.209%, the RSD is 3.67%, and the average test time is 98 s.

[0088] Compare the tests of Example 7, Example 12, Example 5 with those of Comparative Example 2. The test times of Example 7 and Example 12 are basically the same, and their test results are basically consistent with those of Example 5. The test result of Comparative Example 2 is on the low side, and the test time is significantly longer. This is because the release of S is relatively slow, resulting in the system judging the end of the test, while in fact the test has not ended, so the test result is on the low side. This shows that adding tungsten trioxide as a promoter can accelerate the sulfur release and avoid integral inaccuracy.

[0089] Example 13: Silicon dioxide is laid on the bottom + tungsten trioxide is covered on the top

[0090] Calibrate the instrument and measure the blank value according to the method and steps of Example 12, and then detect the sulfur content in sulfonated polyether ether ketone SP1, where the dosage of the bottom promoter silica is 56 - 57 mg, and the dosage of tungsten trioxide in the topmost layer is 7.0 - 7.1 times that of SP1. The average value of 3 tests is 0.222%, the RSD is 2.38%, and the average test time is 81 s.

[0091] Compare the test spectrograms of Example 13 and Comparative Example 1 to obtain Figure 8 . The test time of Example 13 is significantly shorter, and the release of sulfur starts slower than that of Comparative Example 1, but the spectral intensity of S subsequently increases significantly, indicating that the promoter can promote the release of sulfur.

[0092] Example 14: Lay silica at the bottom and cover with tungsten trioxide on the top

[0093] The temperature of the resistance furnace is stabilized at 1280 °C - 1320 °C, the integration end time is set to 40 s - 300 s, and the O2 carrier gas flow rate is 180 L / h. The single-point calibration method is adopted. The sulfur content in the coal standard substance is 0.76%, and the mass number is 40 - 53 mg (accurate to 0.01 mg when weighing and recording). Use a standard substance with a sulfur content of 1.46% for verification and calibration, and its mass number is 21 - 28 mg (accurate to 0.01 mg when weighing and recording). After measuring the blank value, first weigh 26 - 27 mg of silica and spread it flat at the bottom of the porcelain boat crucible, then weigh 29 - 39 mg of sulfonated polyether ether ketone SP2 (accurate to 0.01 mg) and spread it on the upper layer of silica, and then weigh a certain amount of tungsten trioxide and cover it on the sample, and its dosage is 4.0 - 4.1 times that of SP2. Then push the sample into the combustion zone of the resistance furnace for testing according to the equipment instruction manual. When conducting 4 tests, weigh 29.73 mg, 29.15 mg, 31.14 mg, and 38.56 mg of sulfonated polyether ether ketone SP2 respectively. The test results of sulfur content are 1.06%, 1.08%, 1.01%, and 1.03% respectively. The average value is 1.05%, the RSD is 2.57%, and the average test time is 44 s.

[0094] Example 15: Lay tin at the bottom and cover with tungsten trioxide on the top

[0095] The sulfur content in sulfonated polyether ether ketone SP3 was detected according to the method and steps of Example 14. When calibrating the instrument at a single point, the sulfur content in the coal standard was 0.28%, and the mass number was 90 - 120 mg (accurate to 0.01 mg). A standard with a sulfur content of 0.41% was used for verification and calibration, and its mass number was 21 - 30 mg (accurate to 0.01 mg). The dosage of the bottom promoter tin powder was 31 - 32 mg, and the dosage of tungsten trioxide in the topmost layer was 1.1 - 1.2 times that of SP3. When conducting 4 tests, 403.42 mg, 356.33 mg, 432.42 mg, and 501.73 mg of sulfonated polyether ether ketone SP3 were weighed respectively. The sulfur content test results were 0.067%, 0.070%, 0.075%, and 0.066% respectively. The average value was 0.069%, the RSD was 3.34%, and the average test time was 88 s.

[0096] Example 16: Lining with nickel at the bottom + covering with tungsten trioxide on the top

[0097] After calibrating the instrument and measuring the blank value according to the method of Example 1, the sulfur content in sulfonated polyether ether ketone SP4 was detected according to the method and steps of Example 14. The dosage of the bottom promoter nickel powder was 21 - 22 mg, and the dosage of tungsten trioxide in the topmost layer was 2.5 - 2.5 times that of SP4. When conducting 4 tests, 29.05 mg, 30.52 mg, 45.17 mg, and 38.22 mg of sulfonated polyether ether ketone SP4 were weighed respectively. The sulfur content test results were 0.471%, 0.462%, 0.459%, and 0.473% respectively. The average value was 0.466%, the RSD was 1.46%, and the average test time was 53 s.

[0098] Example 17: Lining with silica at the bottom + covering with tungsten trioxide on the top

[0099] The sulfur content in sulfonated polyether ether ketone SP5 was detected according to the method and steps of Example 14. When calibrating at a single point, the sulfur content in the coal standard was 0.18%, and the mass number was 61 - 69 mg (accurate to 0.01 mg). A standard with a sulfur content of 0.28% was used for verification and calibration, and its mass number was 39 - 44 mg (accurate to 0.01 mg). The dosage of the bottom promoter silica was 21 - 22 mg, and the dosage of tungsten trioxide in the topmost layer was 2.1 - 2.2 times that of SP5. When conducting 4 tests, when 98.92 mg, 98.10 mg, 100.26 mg, and 88.73 mg of sulfonated polyether ether ketone SP5 were weighed respectively, the sulfur content test results were 0.130%, 0.123%, 0.125%, and 0.122% respectively. The average value was 0.125%, the RSD was 2.84%, and the average test time was 52 s.

[0100] Example 18: Covering with silica on the top

[0101] The temperature of the resistance furnace is stabilized at 1280 °C to 1320 °C, the integral end time is set to 40 s to 300 s, and the O2 flow rate is 180 L / h. The instrument is calibrated by the multi-point calibration method. The sulfur content in the coal standard is 0.28%, 0.76%, 1.46%, and the mass number is 90 - 100 mg (accurate to 0.01 mg). A standard with a sulfur content of 0.41% is used to verify the calibration, and its mass number is 90 - 100 mg (accurate to 0.01 mg). After the blank value test, 90 - 100 mg (accurate to 0.01 mg) of sulfonated polyether ether ketone SP6 is weighed and evenly spread in a porcelain boat crucible, and then the sample is covered with the release promoter silica. The dosage of silica is 1.5 - 1.6 times that of SP6. Then, according to the equipment instructions, the sample is pushed into the combustion area of the resistance furnace for testing, and the test results are directly calculated by the software. When tested 4 times, the sulfonated polyether ether ketone SP6 is weighed as 95.72 mg, 99.38 mg, 92.33 mg, and 91.59 mg respectively, and the sulfur content test results are 0.618%, 0.616%, 0.625%, and 0.622% respectively. The average value is 0.620%, the RSD is 0.65%, and the average test time is 58 s.

[0102] Example 19: Covered with silica

[0103] The temperature of the resistance furnace is stabilized at 1280 - 1320 °C, the integral end time is set to 40 s to 300 s, and the O2 flow rate is 180 L / h. The instrument is calibrated by the single-point calibration method. The sulfur content in the coal standard is 0.18%, and the mass number is 280 - 290 mg (accurate to 0.01 mg). A standard with a sulfur content of 0.28% is used to verify the calibration, and its mass number is 180 - 190 mg (accurate to 0.01 mg). After the blank value test, 280 - 300 mg (accurate to 0.01 mg) of sulfonated polyether ether ketone SP7 is weighed and evenly spread in a porcelain boat crucible, and then the sample is covered with the release promoter silica. The dosage of silica is 1.0 - 1.1 times that of SP7. Then, according to the equipment instructions, the sample is pushed into the combustion area of the resistance furnace for testing, and the test results are directly calculated by the software. When tested 3 times, the sulfonated polyether ether ketone SP7 is weighed as 283.61 mg, 290.95 mg, and 292.84 mg respectively, and the sulfur content test results are 0.192%, 0.197%, and 0.194% respectively. The average value is 0.194%, the RSD is 1.29%, and the average test time is 50 s.

[0104] Example 20: Lined with tin at the bottom + covered with tungsten trioxide

[0105] Detect the sulfur content in sulfonated polyether ether ketone SP8 according to the method and steps of Example 14. When performing single-point calibration, the sulfur content in the coal standard is 0.18%, and the mass number is 55 - 70 mg (accurate to 0.01 mg). Use a standard with a sulfur content of 0.28% to verify the calibration, and its mass number is 40 - 45 mg (accurate to 0.01 mg). The dosage of the bottom promoting agent tin powder is 31 - 32 mg, and the dosage of tungsten trioxide in the topmost layer is 1.1 - 1.2 times that of SP8. When conducting 4 tests, weigh sulfonated polyether ether ketone SP8 as 812.36 mg, 857.99 mg, 900.54 mg, and 985.30 mg respectively. The sulfur content test results are 0.0131%, 0.0129%, 0.0125%, and 0.0135% respectively. The average value is 0.0128%, the RSD is 2.38%, and the average test time is 88 s.

[0106] Example 21: Tungsten trioxide is laid at the bottom + silicon dioxide is covered on the top

[0107] The temperature of the resistance furnace is stabilized at 1280 °C - 1320 °C, the integral end time is set to 120 s - 300 s, and the O2 flow rate is 180 L / h. Calibrate the instrument using the single-point calibration method. The sulfur content in the coal standard is 0.18%, and the mass number is 110 - 123 mg (accurate to 0.01 mg). Use a standard with a sulfur content of 0.28% to verify the calibration, and its mass number is 80 - 90 mg (accurate to 0.01 mg). The dosage of the bottom promoting agent tungsten trioxide is 30 - 32 mg, and the dosage of silicon dioxide in the topmost layer is 1.0 - 1.1 times that of sulfonated polyether ether ketone SP9. Conduct sample testing after blank value testing. When conducting 4 tests, weigh sulfonated polyether ether ketone SP9 as 180.53 mg, 184.12 mg, 175.19 mg, and 156.32 mg respectively. The sulfur content test results are 0.121%, 0.120%, 0.125%, and 0.118% respectively. The average value is 0.121%, the RSD is 2.98%, and the average test time is 120 s.

[0108] Comparative Example 3: High-frequency induction furnace test: Ferrotungsten additive is laid on top of the sample

[0109] The operating power is 100%, the power duration is 100 s, the integration end time is 100 s to 200 s, and the O2 flow rate is 180 L / h. The instrument is calibrated by the single-point calibration method. The sulfur content in the steel reference material is 0.127%, and the mass number is 110 - 120 mg (accurate to 0.01 mg). A reference material with a sulfur content of 0.097% is used for verification calibration (when testing, 0.60 g of iron and 2.00 g of tungsten particles are covered on the reference material), and its mass number is 140 - 150 mg (accurate to 0.01 mg). After the blank value is tested, first weigh 100 - 160 mg of sulfonated polyether ether ketone SP9 in a crucible, then weigh 0.60 g of iron and 2.00 g of tungsten particles and cover them on the surface of the sample, and then push the sample into the high-frequency induction furnace for combustion testing according to the equipment instruction manual. The test results are directly calculated by the software. When testing 4 times, the sulfonated polyether ether ketone SP9 is weighed as 152.95 mg, 119.76 mg, 100.61 mg, and 105.81 mg respectively, and the sulfur content test results are 0.0096%, 0.0208%, 0.0124%, and 0.0121% respectively, with an average value of 0.0114% and an RSD of 13.52%. The average test time is 100 s.

[0110] Compare Example 21 with Comparative Example 3, as Figure 9 shown. The test of Comparative Example 3 is unstable, and the test results are significantly lower. Compare the crucible after testing the sulfonated polyether ether ketone SP9 of Comparative Example 3, the crucible after detecting the steel reference material of Comparative Example 3, and the crucible for testing the sulfonated polyether ether ketone SP9 of Example 21, as shown in Figure 10 . At a is the porcelain boat crucible after testing Example 21; at c is the crucible after calibrating the instrument with the steel reference material of Comparative Example 3; at b is the crucible after testing Comparative Example 3. As can be seen from Figure 10 , the crucible of Example 21 (the powder in the crucible in the figure is tungsten trioxide and silicon dioxide; if the sulfonated polyether ether ketone is tested without adding a release promoter, the crucible after testing is very clean without any powder) and the crucible wall after detecting the steel reference material of Comparative Example 3 are basically kept clean, and the sample burns or melts completely, while the surface of the crucible wall after testing the sulfonated polyether ether ketone SP9 of Comparative Example 3 is covered with gray powder, and these powders are the incompletely burned sulfonated polyether ether ketone SP9, indicating that when testing with a high-frequency induction furnace, the powder is easily blown away by the carrier gas to various places, making it difficult for the sample to burn fully (remaining on the crucible wall and combustion chamber, etc.), resulting in large fluctuations in the sulfur content analysis data. Especially for samples with low sulfur content, the required amount of powder for testing is relatively large, which is more likely to cause incomplete combustion of the powder, leading to a large test error.

[0111] In the description of this specification, the descriptions referring to terms such as "one embodiment", "certain embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, materials, or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0112] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A method for determining the sulfur content in sulfonated polyetheretherketone, comprising the steps of spreading the sample in a porcelain boat crucible, pushing the sample into a carbon-sulfur analyzer with a resistance furnace, and detecting the sulfur content by infrared absorption method, characterized in that: In the porcelain boat crucible, the upper surface of the sample is covered with a first release promoter powder, the sulfur content in the first release promoter is less than 0.0005%, and the first release promoter is selected from tungsten trioxide, calcium oxide, silicon dioxide, tin, nickel or iron; the temperature of the resistance furnace is stable at 1280°C~1320°C, and the O2 carrying capacity is 180L / h; when the melting point of the first release promoter is greater than the temperature of the resistance furnace, the mass of the first release promoter is equivalent to 1.0 times~9.2 times the mass of the sample; when the melting point of the first release promoter is lower than or equal to the temperature of the resistance furnace, the mass of the first release promoter is equivalent to 2.3 times~3.2 times the mass of the sample.

2. The method for determining the sulfur content in sulfonated polyetheretherketone according to claim 1, characterized in that: In the porcelain boat crucible, the lower surface of the sample is padded with second release promoter powder, the sulfur content in the second release promoter is less than 0.0005%, and the second release promoter is selected from tungsten trioxide, calcium oxide, silicon dioxide, tin, nickel or iron.

3. The method for determining the sulfur content in sulfonated polyetheretherketone according to claim 2, characterized in that: The mass of the second release-promoting agent is equivalent to 0.1 to 1.6 times the mass of the sample.

4. The method for determining the sulfur content in sulfonated polyetheretherketone according to claim 2, characterized in that: The fineness of the second release-promoting agent powder is 200-300 meshes.

5. The method for determining the sulfur content in sulfonated polyetheretherketone according to claim 1, characterized in that: The fineness of the first release-promoting agent powder is 200-300 meshes.

6. The method for determining the sulfur content in sulfonated polyetheretherketone according to claim 1, characterized in that: The end point time of spectrum curve integration is 40s~300s.

7. The method for determining the sulfur content in sulfonated polyetheretherketone according to claim 1, characterized in that: The carbon-sulfur analyzer is calibrated with a standard substance, and a numerical relationship between the infrared spectrum intensity value and the sulfur content of the standard substance is established; the standard substance is a coal standard.

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