Detection method of cable degassing by-products

Abstract

The invention provides a cable degassing by-product detection method, the detection method adopts an ultraviolet absorption spectrometer (integrating sphere method) to test the ultraviolet absorption spectrum peak of a cable film sample, the main wavelength range of acetophenone in a liquid solution is 280-290 nm, and the main wavelength range of acetophenone in a solid film is 340-350 nm. The concentration of the degassing by-product acetophenone in the cable is measured by measuring the absorbance of a sample under a specific wavelength and combining an acetophenone mass volume concentration-absorbance standard curve. According to the detection method, determination can be completed only by using an ultraviolet spectrophotometer, a complex pretreatment process is not needed, the determination process only needs several minutes, and the method is suitable for rapid screening and on-site detection. Meanwhile, the ultraviolet spectrophotometer is relatively low in equipment cost, expensive reagents are not needed in the determination process, and the detection cost is remarkably reduced.

Description

Technical Field

[0001] The present application relates to the technical field of cable degassing byproduct detection and characterization, and in particular to a method for detecting cable degassing byproducts. Background Art

[0002] At present, high-voltage cross-linked polyethylene cables are cross-linked with peroxides. The commonly used peroxide cross-linking agent is diisopropylbenzene peroxide (DCP), which has a decomposition temperature of about 132°C. During the cross-linking process, DCP is decomposed by heat to form peroxide free radicals. Due to the high activity of the oxide free radicals, they will move rapidly inside the polyethylene. When they encounter the macromolecular chains of polyethylene, they will seize the H atoms on the macromolecular chains to form macromolecular chain free radicals and cross-linked byproducts. The cross-linked byproducts produced by the decomposition of DCP usually exist in the amorphous region of the cross-linked polyethylene in the form of small molecules of acetophenone, thus affecting the safety and reliability of the cable insulation.

[0003] In the related technology, infrared spectroscopy, thermogravimetric analysis, gas chromatography, high performance liquid chromatography and other methods are commonly used to determine the content of by-products. However, among these methods, infrared spectroscopy and thermogravimetric analysis have low accuracy and too many interference factors, which lead to unstable results and affect the determination of whether degassing is completed. Gas chromatography and high performance liquid chromatography are complex and expensive to operate, and are not suitable for real-time monitoring of cable degassing by-products during the production process. Therefore, it is of great practical significance to develop a simple, fast and low-cost method for detecting acetophenone. Summary of the invention

[0004] Based on this, the present application provides a simple, fast and low-cost method for detecting cable degassing byproducts.

[0005] The present application provides a method for detecting cable degassing byproducts, comprising the following steps:

[0006] Respectively measuring the ultraviolet absorbance of a plurality of degassing byproduct standard solutions with different mass concentrations at a first wavelength, and constructing a degassing byproduct mass volume concentration-absorbance standard curve with the mass volume concentration of the degassing byproduct standard solution as the abscissa and the ultraviolet absorbance as the ordinate;

[0007] Take a sheet-like sample 1 and a sample 2 on a film at a certain position of the cable segment to be tested, respectively, and prepare the sample 2 to be tested into a test solution using the same solvent as the degassing byproduct standard solution;

[0008] After the sheet-like sample 1 is covered with the detection window of the integrating sphere, an ultraviolet spectrum scan is performed within a wavelength range of 200nm-900nm, and the solid ultraviolet absorbance Y1 of the sheet-like sample 1 at the second wavelength is recorded; and the liquid ultraviolet absorbance Y2 of the solution to be tested at the first wavelength is measured;

[0009] Based on the correlation between the solid ultraviolet absorbance Y1 and the liquid ultraviolet absorbance Y2, the degassing by-product mass volume concentration-absorbance standard curve, the mass of the sample 2 to be tested and the volume of the test solution prepared from the sample 2 to be tested, a relationship curve between the solid ultraviolet absorbance of the film of the cable segment to be tested at the second wavelength and the mass percentage concentration of the degassing by-products contained in the film is constructed.

[0010] In some embodiments, the degassing byproduct comprises acetophenone.

[0011] In some embodiments, the solvent used to prepare the degassed byproduct standard solution is a mixed solvent of chloroform and n-hexane in a volume ratio of (1-5):(1-5), or a mixed solvent of dichloromethane and methanol in a volume ratio of (1-5):(1-5).

[0012] In some embodiments, the first wavelength and the second wavelength are the same or different.

[0013] In some embodiments, the first wavelength is 280 nm and the second wavelength is 342 nm.

[0014] In some embodiments, the length and width of the sheet-shaped sample 1 to be tested are independently ≥1 cm, and the thickness is 0.1 mm-1 mm.

[0015] In some embodiments, the mass volume concentration of the plurality of degassing by-product standard solutions is greater than or equal to 0.01 mg / L and less than or equal to 1000 mg / L.

[0016] In some embodiments, the mass volume concentrations of the plurality of degassing by-product standard solutions are 1 mg / L, 5 mg / L, 10 mg / L, 25 mg / L and 50 mg / L, respectively.

[0017] In some embodiments, the degassing byproduct mass volume concentration-absorbance standard curve satisfies: Y=0.0074n+0.0223, where Y represents ultraviolet absorbance, n represents the degassing byproduct mass volume concentration, and the correlation coefficient r 2 =0.9954.

[0018] In some embodiments, the detection method further comprises:

[0019] Taking a sheet-like sample 3 from the film at other positions of the cable segment to be tested, and after covering the detection window of the integrating sphere with the sheet-like sample 3, measuring the solid ultraviolet absorbance of the sheet-like sample 3 at the second wavelength;

[0020] The solid ultraviolet absorbance of the sheet-shaped sample 3 to be tested at the second wavelength is substituted into the relationship curve to obtain the mass percentage concentration of the degassing by-product in the sheet-shaped sample 3 to be tested.

[0021] The above-mentioned detection method of cable degassing byproducts can be completed by using only an ultraviolet spectrophotometer, without complicated pre-treatment process, and the measurement process only takes a few minutes, which is suitable for rapid screening and on-site detection. At the same time, the cost of ultraviolet spectrophotometer equipment is relatively low, and no expensive reagents are required during the measurement process, which significantly reduces the detection cost. DETAILED DESCRIPTION

[0022] For ease of understanding of the present invention, the application will be described more fully below with reference to relevant embodiments. The following provides preferred embodiments of the application. However, the application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the application more thorough and comprehensive.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0024] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0025] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0026] Only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and likewise any upper limit can be combined with any other upper limit to form an unspecified range. In addition, each separately disclosed point or single value can itself be combined as a lower limit or upper limit with any other point or single value or with other lower limits or upper limits to form an unspecified range.

[0027] Herein, the “suitable” mentioned in “suitable combination”, “suitable method”, “any suitable method”, etc., shall be based on the ability to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0028] In the present application, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of the present application.

[0029] In this application, "optionally", "optional", and "optional" mean optional or dispensable, that is, any one of the two parallel schemes of "yes" or "no". If multiple "options" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent.

[0030] In the description of the application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0031] If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution. If there is no special description, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0032] If there is no special explanation, all the steps of the present application can be performed sequentially or randomly, preferably sequentially.

[0033] At present, infrared spectroscopy, thermogravimetric analysis, gas chromatography, and high-performance liquid chromatography are commonly used to determine the content of by-products. However, among these methods, infrared spectroscopy and thermogravimetric analysis have low accuracy and too many interference factors, which lead to unstable results and affect the determination of whether degassing is completed. Gas chromatography and high-performance liquid chromatography are complex and expensive to operate, and are not suitable for real-time monitoring of cable degassing by-products during the production process. Therefore, it is of great practical significance to develop a simple, fast, and low-cost method for detecting acetophenone.

[0034] In the related art, the patent application with publication number CN117665065A provides a non-destructive measurement method for the residual content of by-products in the insulation layer of a high-voltage cable. The method places the high-voltage cable in a degassing chamber, cuts, cleans and connects the high-voltage cable at a constant temperature to test the current of the high-voltage cable insulation layer to obtain the test results, and the test results include multiple groups of test currents and their test time, test voltage and test frequency; three exponential fitting is performed according to the test results, and the value of the polarization parameter in a fixed frequency band is obtained by fitting a continuous function and corresponding test time and test frequency. As the degassing progresses, the polarization parameters at different stages are recorded, and p and q are degassing factors. When p and q are less than 0.3, the by-product content reaches the qualified range. This method can achieve the purpose of non-destructive measurement of the by-products of the cable insulation layer, but the experimental operation steps are many, and the calculation and fitting process is complicated, which is not conducive to the detection of cable degassing by-products in the actual production process.

[0035] Based on the above problems, the present application uses an ultraviolet absorption spectrometer (integrating sphere method) to test the ultraviolet absorption spectrum peak of the cable film sample. Since acetophenone has a characteristic absorption peak in the ultraviolet region, the main wavelength range of acetophenone in liquid solution is between 280nm-290nm, and the main wavelength range of acetophenone in solid film is between 340nm-350nm. By measuring the absorbance of the sample at a specific wavelength, combined with the acetophenone mass volume concentration-absorbance standard curve, the concentration of acetophenone, a degassing byproduct in the cable, is determined.

[0036] One or more embodiments of the present application provide a method for detecting cable degassing byproducts, comprising the following steps:

[0037] The ultraviolet absorbance of a plurality of degassing byproduct standard solutions with different mass concentrations at the first wavelength is measured respectively, and a degassing byproduct mass volume concentration-absorbance standard curve is constructed with the mass volume concentration of the degassing byproduct standard solution as the abscissa and the ultraviolet absorbance as the ordinate; a sheet-like sample 1 and a sample 2 are taken from a film at a certain position of the cable segment to be tested respectively, and the sample 2 is prepared into a test solution by using the same solvent as the degassing byproduct standard solution; after the sheet-like sample 1 covers the detection window of the integrating sphere, the sample 1 is measured at a wavelength range of 200nm-900nm. An ultraviolet spectrum scan is performed within the range to record the solid ultraviolet absorbance Y1 of the sheet-like sample 1 to be tested at the second wavelength; and the liquid ultraviolet absorbance Y2 of the test solution to be tested at the first wavelength is measured; based on the correlation between the solid ultraviolet absorbance Y1 and the liquid ultraviolet absorbance Y2, the mass volume concentration-absorbance standard curve of the degassing by-product, the mass of the sample 2 to be tested and the volume of the test solution prepared from the sample 2 to be tested, a relationship curve between the solid ultraviolet absorbance of the film of the cable segment to be tested at the second wavelength and the mass percentage concentration of the degassing by-products contained in the film is constructed.

[0038] It is understandable that the detection method of cable degassing byproducts provided in the present application can be completed by using an ultraviolet spectrophotometer, without the need for a complicated pre-treatment process, and the determination process only takes a few minutes, which is suitable for rapid screening and on-site detection. At the same time, the cost of ultraviolet spectrophotometer equipment is relatively low, and no expensive reagents are required during the determination process, which significantly reduces the detection cost. In addition, since the molecular structure of polyethylene is simple and the ultraviolet characteristic peak of the degassing byproduct acetophenone is obvious, a high-accuracy detection result can be obtained, which is convenient for large-scale industrial application.

[0039] In some embodiments, the degassed byproduct comprises acetophenone.

[0040] As a possible implementation, the solvent used to prepare the degassing byproduct standard solution is a mixed solvent of chloroform and n-hexane in a volume ratio of (1-5):(1-5), or a mixed solvent of dichloromethane and methanol in a volume ratio of (1-5):(1-5). Thus, the cross-linked polyethylene can be fully swollen and the byproducts in the cross-linked polyethylene can be dissolved.

[0041] As non-limiting examples, the volume ratio of chloroform and n-hexane or the volume ratio of dichloromethane and methanol in the mixed solvent can be but is not limited to (1-5):(1-5), (1-4):(1-4), (1-3):(1-3), (1-2):(1-2), (2-5):(2-5), (3-5):(3-5), (3-5):(3-5), (4-5):(4-5), (1-4):(2-5), (1-3):(3-5), (1-2):(4-5), (2-5):(1-4), (3-5):(1-3) or (4-5):(1-2), etc.

[0042] In some embodiments, the first wavelength and the second wavelength are the same or different.

[0043] It should be noted that the "first wavelength", "second wavelength" and the like mentioned in the context are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second" and the like only serve the purpose of non-exhaustive enumeration and description, and should be understood not to constitute a closed limitation on quantity.

[0044] In some embodiments, the first wavelength is 280 nm.

[0045] As a possible implementation, the second wavelength is 342 nm.

[0046] In some embodiments, the length and width of the sheet-like sample 1 are independently ≥1 cm, and the thickness is 0.1 mm-1 mm. As a non-limiting example, the thickness of the sheet-like sample 1 can be, but is not limited to, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, or a range between any two of the above thicknesses. When the thickness of the sheet-like sample is controlled within this range, the ultraviolet absorption peak of acetophenone can be obtained by an ultraviolet absorption spectrometer (integrating sphere method).

[0047] As a possible implementation, the mass volume concentration of multiple degassing byproduct standard solutions all satisfy the requirement of being greater than or equal to 0.01 mg / L and less than or equal to 1000 mg / L. As a non-limiting example, the mass concentration of the degassing byproduct standard solution can be, but is not limited to, 0.01 mg / L, 0.05 mg / L, 0.1 mg / L, 0.5 mg / L, 1 mg / L, 5 mg / L, 10 mg / L, 25 mg / L, 50 mg / L, 100 mg / L, 200 mg / L, 300 mg / L, 400 mg / L, 500 mg / L, 600 mg / L, 700 mg / L, 800 mg / L, 900 mg / L, 1000 mg / L or the range between any two of the above mass concentrations. Therefore, within this concentration range, the mass volume concentration of the degassing byproduct standard solution is roughly linearly related to the ultraviolet absorbance, and the concentration of the degassing byproduct can be more accurately quantitatively analyzed by ultraviolet absorbance.

[0048] In some optional embodiments, the mass volume concentration of each degassed by-product standard solution is 1 mg / L, 5 mg / L, 10 mg / L, 25 mg / L and 50 mg / L, respectively.

[0049] In some embodiments, when the mass volume concentration of each degassing byproduct standard solution is 1 mg / L, 5 mg / L, 10 mg / L, 25 mg / L and 50 mg / L, the degassing byproduct mass volume concentration-absorbance standard curve satisfies: Y=0.0074n+0.0223, wherein Y represents ultraviolet absorbance, n represents the mass volume concentration of the degassing byproduct, and the correlation coefficient r 2 =0.9954.

[0050] In some optional embodiments, the mass volume concentration of each degassed by-product standard solution is 1 mg / L, 10 mg / L, 20 mg / L, 50 mg / L and 100 mg / L, respectively.

[0051] In some embodiments, when the mass volume concentration of each degassing byproduct standard solution is 1 mg / L, 10 mg / L, 20 mg / L, 50 mg / L and 100 mg / L, the degassing byproduct mass volume concentration-absorbance standard curve satisfies: Y=0.008n+0.0495, where Y represents ultraviolet absorbance, n represents the mass volume concentration of the degassing byproduct, and the correlation coefficient r 2 =0.9856.

[0052] As a possible implementation, the detection method further includes:

[0053] A sheet-like sample 3 is taken from the film at other positions of the cable segment to be tested, and after the sheet-like sample 3 covers the detection window of the integrating sphere, the solid ultraviolet absorbance of the sheet-like sample 3 at the second wavelength is measured; the solid ultraviolet absorbance of the sheet-like sample 3 at the second wavelength is substituted into the relationship curve to obtain the mass percentage concentration of the degassing by-products in the sheet-like sample 3.

[0054] The technical scheme of the present invention is described in detail below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods for which specific conditions are not specified in the following embodiments are preferably referred to the guidance given in the present invention, and can also be carried out according to the experimental manual or conventional conditions in the art, or according to the conditions recommended by the manufacturer, or with reference to experimental methods known in the art.

[0055] In the following specific embodiments, the measured parameters of raw material components may have slight deviations within the range of weighing accuracy unless otherwise specified. For temperature and time parameters, acceptable deviations caused by instrument test accuracy or operation accuracy are allowed.

[0056] Example 1

[0057] Step S1, prepare acetophenone standard solutions with mass volume concentrations of 1 mg / L, 5 mg / L, 10 mg / L, 25 mg / L and 50 mg / L respectively.

[0058] Step S2, using an ultraviolet absorption spectrometer to measure the ultraviolet absorbance of the acetophenone standard solution prepared in step S1 at a wavelength of 280 nm, and using the mass volume concentration n of the acetophenone standard solution as the abscissa and the ultraviolet absorbance Y as the ordinate to obtain an acetophenone mass volume concentration-absorbance standard curve: Y=0.0074n+0.0223, with a correlation coefficient r 2 =0.9954.

[0059] Step S3, take a sheet of sample 1 from the film of the cable segment to be tested, the width and length of the sheet of sample 1 are 1 cm respectively, and the thickness is 1 mm, and ensure that the sample 1 is flat and wrinkle-free. Take 1 g of sample 2 from the same position of the film of the cable segment to be tested, and use 10 mL of a mixed solvent to perform ultrasonic extraction on the sample 2 for 2 hours to obtain a solution to be tested; wherein the mixed solvent is chloroform and n-hexane in a volume ratio of 1:1.

[0060] Step S4, clean the integrating sphere to ensure that the inner wall is free of contamination. At the same time, clean the surface of the sheet sample 1 to prevent dust or stains from affecting the test results. Place the sheet sample 1 on the sample holder of the integrating sphere to ensure that the sheet sample 1 is flat and completely covers the detection window. Start the spectrometer and start ultraviolet spectrum scanning of the sheet sample 1, with a scanning wavelength range of 200nm-900nm, and record the solid ultraviolet absorbance Y1 of the sheet sample 1 at 342nm as 0.9.

[0061] Step S5, using an ultraviolet absorption spectrometer to test the ultraviolet absorption spectrum of the test solution prepared in step S3, and obtaining a liquid ultraviolet absorbance Y2 of the test solution at 280 nm of 0.28.

[0062] Step S6, comparing the solid ultraviolet absorbance Y1 and the liquid ultraviolet absorbance Y2, the correlation between the solid ultraviolet absorbance and the liquid ultraviolet absorbance at the same position of the cable segment film to be tested is in accordance with: Y2=0.31Y1. Further, through the acetophenone mass volume concentration-absorbance standard curve Y=0.0074n+0.0223 and the sampling amount of the sample 2 to be tested and the volume of the solution to be tested, the relationship curve between the solid ultraviolet absorbance Y1 of the cable segment film to be tested at 342nm and the mass percentage concentration of the degassing byproducts contained therein is calculated to be in accordance with:

[0063]

[0064] Wherein, Y1 is the solid ultraviolet absorbance, V is the volume of the extraction solvent used in preparing the test solution, in liters (L); N is the dilution factor (in this embodiment, no dilution, N is 1); m is the mass of the sample 2 to be tested, in grams (g).

[0065] Step S7, taking sheet samples from the film at different positions (cable inner layer, cable middle layer, cable outer layer) of the cable segment to be tested, testing the solid ultraviolet absorbance of each sample to be tested by integrating sphere method, and testing the mass percentage concentration of acetophenone based on the measured solid ultraviolet absorbance and the relationship curve obtained in step S6. The results are shown in Table 1.

[0066] Example 2

[0067] Step S1, prepare acetophenone standard solutions with mass volume concentrations of 1 mg / L, 10 mg / L, 20 mg / L, 50 mg / L and 100 mg / L respectively.

[0068] Step S2, using an ultraviolet absorption spectrometer to measure the ultraviolet absorbance of the acetophenone standard solution prepared in step S1 at a wavelength of 280 nm, and using the mass volume concentration n of the acetophenone standard solution as the abscissa and the ultraviolet absorbance Y as the ordinate to obtain an acetophenone mass volume concentration-absorbance standard curve: Y=0.008n+0.0495, with a correlation coefficient r 2 =0.9856.

[0069] Step S3, take a sheet of sample 1 from the film of the cable segment to be tested, the width and length of the sheet of sample 1 are 1 cm respectively, and the thickness is 1 mm, and ensure that the sample 1 is flat and wrinkle-free. Take 1 g of sample 2 from the same position of the film of the cable segment to be tested, and use 10 mL of a mixed solvent to perform ultrasonic extraction on the sample 2 for 2 hours to obtain a solution to be tested; wherein the mixed solvent is dichloromethane and methanol in a volume ratio of 1:1.

[0070] Step S4, clean the integrating sphere to ensure that the inner wall is free of contamination. At the same time, clean the surface of the sheet sample 1 to prevent dust or stains from affecting the test results. Place the sheet sample 1 on the sample holder of the integrating sphere to ensure that the sheet sample 1 is flat and completely covers the detection window. Start the spectrometer and start ultraviolet spectrum scanning of the sheet sample 1, with a scanning wavelength range of 200nm-900nm, and record the solid ultraviolet absorbance Y1 of the sheet sample 1 at 342nm as 0.95.

[0071] Step S5, using an ultraviolet absorption spectrometer to test the ultraviolet absorption spectrum of the test solution prepared in step S3, and obtaining a liquid ultraviolet absorbance Y2 of the test solution at 280 nm of 0.21.

[0072] Step S6, comparing the solid ultraviolet absorbance Y1 and the liquid ultraviolet absorbance Y2, the correlation between the solid ultraviolet absorbance and the liquid ultraviolet absorbance at the same position of the cable segment film to be tested is in accordance with: Y2=0.22Y1. Further, through the acetophenone mass volume concentration-absorbance standard curve Y=0.008n+0.0495 and the sampling amount of the sample 2 to be tested and the volume of the solution to be tested, the relationship curve between the solid ultraviolet absorbance Y1 of the cable segment film to be tested at 342nm and the mass percentage concentration of the degassing byproducts contained therein is calculated to be in accordance with:

[0073]

[0074] Wherein, Y1 is the solid ultraviolet absorbance, V is the volume of the extraction solvent used in preparing the test solution, in liters (L); N is the dilution factor (in this embodiment, no dilution, N is 1); m is the sample mass, in grams (g).

[0075] Step S7, taking sheet samples from the film at different positions (cable inner layer, cable middle layer, cable outer layer) of the cable segment to be tested, testing the solid ultraviolet absorbance of each sample to be tested by integrating sphere method, and testing the mass percentage concentration of acetophenone based on the measured solid ultraviolet absorbance and the relationship curve obtained in step S6. The results are shown in Table 2.

[0076] Comparative Example 1

[0077] The difference between Comparative Example 1 and Example 1 is that the solid absorbance of the sample to be tested is not tested by the integrating sphere method in Comparative Example 1, which is as follows:

[0078] Step S1, prepare acetophenone standard solutions with mass volume concentrations of 1 mg / L, 5 mg / L, 10 mg / L, 25 mg / L and 50 mg / L respectively.

[0079] Step S2, using an ultraviolet absorption spectrometer to measure the ultraviolet absorbance of the acetophenone standard solution prepared in step S1 at a wavelength of 280 nm, and using the mass volume concentration n of the acetophenone standard solution as the abscissa and the ultraviolet absorbance Y as the ordinate to obtain an acetophenone mass volume concentration-absorbance standard curve: Y=0.0074n+0.0223, with a correlation coefficient r 2 =0.9954.

[0080] Step S3, taking 1 g of the sample to be tested from the film at the same position (cable inner layer, cable middle layer, cable outer layer) of the same cable segment to be tested as in Example 1, and using 10 mL of a mixed solvent to ultrasonically extract the sample to be tested for 2 hours to obtain a solution to be tested; wherein the mixed solvent is chloroform and n-hexane in a volume ratio of 1:1.

[0081] Step S4, using an ultraviolet absorption spectrometer to test the ultraviolet absorption spectrum of the test solution prepared in step S3, to obtain the liquid ultraviolet absorbance of the test solution at 280nm, based on the measured liquid ultraviolet absorbance and the acetophenone mass volume concentration-absorbance standard curve and the sampling amount of the test sample and the volume of the test solution, calculate the mass percentage concentration of acetophenone, the results are shown in Table 1.

[0082] Comparative Example 2

[0083] The difference between Comparative Example 2 and Example 2 is that the solid absorbance of the sample to be tested is not tested by the integrating sphere method in Comparative Example 2, which is as follows:

[0084] Step S1, prepare acetophenone standard solutions with mass volume concentrations of 1 mg / L, 10 mg / L, 20 mg / L, 50 mg / L and 100 mg / L respectively.

[0085] Step S2, using an ultraviolet absorption spectrometer to measure the ultraviolet absorbance of the acetophenone standard solution prepared in step S1 at a wavelength of 280 nm, and using the mass volume concentration n of the acetophenone standard solution as the abscissa and the ultraviolet absorbance Y as the ordinate to obtain an acetophenone mass volume concentration-absorbance standard curve: Y=0.008n+0.0495, with a correlation coefficient r 2 =0.9856.

[0086] Step S3, taking 1 g of the sample to be tested from the film at the same position (cable inner layer, cable middle layer, cable outer layer) of the same cable segment to be tested as in Example 2, and using 10 mL of a mixed solvent to ultrasonically extract the sample to be tested for 2 hours to obtain a solution to be tested; wherein the mixed solvent is dichloromethane and methanol in a volume ratio of 1:1.

[0087] Step S4, using an ultraviolet absorption spectrometer to test the ultraviolet absorption spectrum of the test solution prepared in step S3, to obtain the liquid ultraviolet absorbance of the test solution at 280nm, based on the measured liquid ultraviolet absorbance and the acetophenone mass volume concentration-absorbance standard curve and the sampling amount of the sample to be tested and the volume of the test solution, calculate the mass percentage concentration of acetophenone, the results are shown in Table 2.

[0088] Table 1

[0089]

[0090] Table 2

[0091]

[0092] It should be noted that the calculation method of the "relative error" in Table 1 is: the acetophenone concentration calculated based on the solid absorbance value in Example 1 minus the acetophenone concentration calculated based on the liquid absorbance value in Comparative Example 1 to obtain the concentration difference, and the concentration difference is divided by the acetophenone concentration calculated based on the liquid absorbance value in Comparative Example 1, and the absolute value is taken to obtain.

[0093] The calculation method of the "relative error" in Table 2 is: the acetophenone concentration calculated based on the solid absorbance value in Example 2 minus the acetophenone concentration calculated based on the liquid absorbance value in Comparative Example 2 to obtain the concentration difference, and the concentration difference is divided by the acetophenone concentration calculated based on the liquid absorbance value in Comparative Example 2, and the absolute value is taken to obtain.

[0094] It can be seen from the results in Table 1 and Table 2 that the method for detecting cable degassing byproducts provided in the present application can quickly determine the concentration of the degassing byproduct acetophenone in the cable segment film. The measurement process only takes a few minutes, which greatly shortens the test time. At the same time, the absolute value of the error relative to the liquid method test result is smaller, and the accuracy is higher. It is suitable for rapid screening and on-site detection, and is convenient for large-scale industrial application.

[0095] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0096] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for detecting cable degassing byproducts, characterized in that: The steps include: Respectively measuring the ultraviolet absorbance of a plurality of degassing byproduct standard solutions with different mass concentrations at a first wavelength, and constructing a degassing byproduct mass volume concentration-absorbance standard curve with the mass volume concentration of the degassing byproduct standard solution as the abscissa and the ultraviolet absorbance as the ordinate; Take a sheet-like sample 1 and a sample 2 on a film at a certain position of the cable segment to be tested, respectively, and prepare the sample 2 to be tested into a test solution using the same solvent as the degassing byproduct standard solution; After the sheet-like sample 1 is covered with the detection window of the integrating sphere, an ultraviolet spectrum scan is performed within a wavelength range of 200nm-900nm, and the solid ultraviolet absorbance Y1 of the sheet-like sample 1 at the second wavelength is recorded; and the liquid ultraviolet absorbance Y2 of the solution to be tested at the first wavelength is measured; Based on the correlation between the solid ultraviolet absorbance Y1 and the liquid ultraviolet absorbance Y2, the degassing by-product mass volume concentration-absorbance standard curve, the mass of the sample 2 to be tested and the volume of the test solution prepared from the sample 2 to be tested, a relationship curve between the solid ultraviolet absorbance of the film of the cable segment to be tested at the second wavelength and the mass percentage concentration of the degassing by-products contained in the film is constructed.

2. The method for detecting cable degassing byproducts according to claim 1, characterized in that: The degassing by-products include acetophenone.

3. The method for detecting cable degassing byproducts according to claim 1, characterized in that: The solvent used to prepare the degassing byproduct standard solution is a mixed solvent of chloroform and n-hexane in a volume ratio of (1-5):(1-5), or a mixed solvent of dichloromethane and methanol in a volume ratio of (1-5):(1-5).

4. The method for detecting cable degassing byproducts according to claim 1, characterized in that: The first wavelength and the second wavelength are the same or different.

5. The method for detecting cable degassing byproducts according to claim 4, characterized in that: The first wavelength is 280 nm, and the second wavelength is 342 nm.

6. The method for detecting cable degassing byproducts according to claim 1, characterized in that: The length and width of the sheet-like sample 1 to be tested are independently ≥1 cm, and the thickness is 0.1 mm-1 mm.

7. The method for detecting cable degassing byproducts according to claim 1, characterized in that: The mass volume concentration of the plurality of degassing by-product standard solutions is greater than or equal to 0.01 mg / L and less than or equal to 1000 mg / L.

8. The method for detecting cable degassing byproducts according to claim 7, characterized in that: The mass volume concentrations of the plurality of degassing byproduct standard solutions are 1 mg / L, 5 mg / L, 10 mg / L, 25 mg / L and 50 mg / L respectively.

9. The method for detecting cable degassing byproducts according to any one of claims 1 to 8, characterized in that: The detection method further comprises: Taking a sheet-like sample 3 from the film at other positions of the cable segment to be tested, and after covering the detection window of the integrating sphere with the sheet-like sample 3, measuring the solid ultraviolet absorbance of the sheet-like sample 3 at the second wavelength; The solid ultraviolet absorbance of the sheet-shaped sample 3 to be tested at the second wavelength is substituted into the relationship curve to obtain the mass percentage concentration of the degassing by-product in the sheet-shaped sample 3 to be tested.

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