Method and device for determining contents of butadiene, isoprene and styrene in vulcanized rubber

Abstract

The invention relates to the technical field of detection methods, in particular to a method and device for determining the content of butadiene, isoprene and styrene in vulcanized rubber. The method comprises the following steps: cracking and analyzing a vulcanized rubber sample by adopting a cracking-gas chromatograph-mass spectrometer, and carrying out peak area integration by extracting characteristic ions of butadiene, isoprene and styrene to obtain more accurate semaphores. The method comprises the following steps: firstly, drawing a standard curve by utilizing a standard sample with known content, then measuring an unknown sample, and carrying out normalization treatment on the obtained percentage contents of styrene, butadiene and isoprene to finally obtain the accurate proportion of each component in a rubber system. The problems that in the prior art, due to poor chromatographic peak separation or baseline drift, integral is inaccurate, and the sum of the contents of three components under different rubber systems is not 100% can be solved, and the accuracy and rationality of a measurement result are remarkably improved.

Description

Technical Field

[0001] This application relates to the field of detection method technology, and more specifically, to a method and apparatus for determining the content of butadiene, isoprene and styrene in vulcanized rubber. Background Technology

[0002] In the formulation of rubber compounds for tires and other rubber products, the three most commonly used rubbers are natural rubber (NR, whose main structural unit is isoprene), styrene-butadiene rubber (SBR, whose synthetic monomers are butadiene and styrene), and cis-butadiene rubber (BR, whose synthetic monomer is butadiene). The selection and determination of the proportions of these three rubbers are the core information of the formulation system, which directly affects the physical and mechanical properties, processing performance, and durability of the rubber compound. Therefore, accurately determining the content of butadiene, isoprene, and styrene in vulcanized rubber is of great significance for product quality control, formulation reverse engineering, and new product development.

[0003] Currently, existing technologies mostly utilize samples with known styrene (ST), butadiene (BD), and isoprene (IP) ratios for analysis using a pyrolysis gas chromatograph, with detection using a flame ionization detector (FID) or thermal conductivity detector (TCD), recording the peak areas of each component using an integrator, plotting calibration curves, and then performing quantitative analysis on unknown samples.

[0004] However, existing FID or TCD detectors have certain limitations. When analyzing the pyrolysis products of vulcanized rubber in complex matrices, chromatographic peaks may be poorly separated or baseline drift may occur. This can lead to inaccurate peak area integrals of target characteristic compounds (butadiene, isoprene, styrene), thus affecting the accuracy of the final quantitative results. Furthermore, directly using the results obtained from the standard curve regression as the final value can lead to problems for unknown samples where the rubber system is inconsistent with the standard used to plot the standard curve (e.g., the standard is a styrene-butadiene rubber / isoprene rubber system, while the sample to be tested is a mixture of natural rubber / styrene-butadiene rubber / cis-butadiene rubber). The sum of the calculated proportions of the three characteristic compounds may exceed 100%, which is unreasonable and illogical for the method of expressing component content as a percentage.

[0005] Therefore, there is an urgent need for a highly accurate and reasonable method for determining the content of butadiene, isoprene, and styrene in vulcanized rubber. Summary of the Invention

[0006] In view of this, in order to solve the above-mentioned problems in the prior art, this application provides a method and apparatus for determining the content of butadiene, isoprene and styrene in vulcanized rubber.

[0007] The embodiments of this application are implemented as follows: In a first aspect, this application provides a method for determining the content of butadiene, isoprene, and styrene in vulcanized rubber, comprising: The calibration procedure involves preparing at least three standard vulcanizate samples with different gradients, wherein the theoretical contents of butadiene, isoprene, and styrene in the standard vulcanizate samples are known and cover the expected range of the sample to be tested. The standard testing procedure involves using a pyrolysis-gas chromatography-mass spectrometry (PCC-MS) instrument to test the standard vulcanizate samples. The characteristic ions of butadiene, isoprene, and styrene are extracted using a mass spectrometer detector, and the characteristic peak areas of the three characteristic compounds in each standard vulcanizate sample are obtained. The standard curve plotting steps involve establishing standard working curves for butadiene, isoprene, and styrene based on the characteristic peak areas. The sample testing procedure involves testing an unknown vulcanizate sample under the same conditions as the standard testing procedure to obtain the characteristic peak areas of butadiene, isoprene, and styrene in the unknown vulcanizate sample. In the preliminary calculation step, the characteristic peak area of ​​the unknown vulcanized rubber sample is substituted into the corresponding standard working curve to calculate the preliminary butadiene percentage B. DB Preliminary isoprene percentage B IP And preliminary styrene percentage B ST ; The normalization step is applied to the preliminary butadiene percentage B. DB Preliminary isoprene percentage B IP And preliminary styrene percentage B ST After normalization, the final butadiene content P is obtained. DB Isoprene content P IP and styrene content P ST And P DB +P IP +P ST =100%.

[0008] In one possible implementation, the method for plotting the standard working curve in the standard curve plotting step includes: Calculate the ratio A of the characteristic peak area of ​​styrene to the sum of the characteristic peak areas of styrene, butadiene, and isoprene in each standard vulcanizate sample. ST , with A ST Plot the standard working curve of styrene with the theoretical percentage content of styrene in the standard vulcanized rubber sample on the x-axis and the y-axis on the y-axis. Calculate the ratio A of the butadiene characteristic peak area to the sum of the characteristic peak areas of the three samples in each standard vulcanized rubber sample. BD , with A BDPlot the standard working curve of butadiene with the theoretical percentage content of butadiene in the standard vulcanized rubber sample as the ordinate, using π as the x-axis. Calculate the ratio A of the isoprene characteristic peak area to the sum of the characteristic peak areas of the three components in each standard vulcanizate sample. IP , with A IP Plot the standard working curve of isoprene with the theoretical percentage content of isoprene in the standard vulcanizate sample on the x-axis and the y-axis on the y-axis.

[0009] In one possible implementation, the standard working curve is a quadratic function curve that passes through the origin.

[0010] In one possible implementation, the normalization step is calculated using the following formula: P ST (%) = B ST / (B ST +B DB +B IP )*100%(1) P DB (%) = B DB / (B ST +B DB +B IP )*100%(2) P IP (%) = B IP / (B ST +B DB +B IP )*100%(3).

[0011] In one possible implementation, the pyrolysis temperature of the pyrolyzer is 550°C and the injection port temperature of the gas chromatograph is 280°C in the standard test procedure and the sample test procedure.

[0012] In one possible implementation, the gas chromatography temperature procedure in the standard test step and the sample test step includes: Initial temperature 40℃, maintain for 2 minutes; Increase the temperature to 140℃ at a rate of 10℃ / min and hold for 15min; Then, increase the temperature to 290°C at a rate of 20°C / min and hold for 5 minutes.

[0013] In one possible implementation, in the standard test step and the sample test step, the integration of the characteristic peak area is performed using an integration event, the parameters of which include: initial area cutoff of 10, initial peak width of 0.024, shoulder peak detection OFF, and initial threshold of 18.

[0014] In one possible implementation, during the calibration step, the standard vulcanizate sample is extracted with acetone before use, and the test mass of the standard vulcanizate sample and the unknown vulcanizate sample is controlled between 100 μg and 150 μg.

[0015] In one possible implementation, the mass spectrometer detector is in full scan mode with a mass number scan range of 33 to 550.

[0016] Secondly, this application provides an apparatus for determining the content of butadiene, isoprene, and styrene in vulcanized rubber, comprising: A pyrolysis-gas chromatography-mass spectrometry system is configured to perform the standard test procedures and sample test procedures; A data processing unit, which is communicatively connected to the pyrolysis-gas chromatography-mass spectrometry system, is programmed to perform the following operations: The mass spectrometer detector is controlled to extract characteristic ions of butadiene, isoprene, and styrene and to obtain the area of ​​the characteristic peaks. Perform the standard curve plotting steps, preliminary calculation steps, and normalization steps as described above; Output the final butadiene content P DB Isoprene content P IP and styrene content P ST .

[0017] The technical solution provided in this application can achieve at least the following beneficial effects: This application provides a method and apparatus for determining the content of butadiene, isoprene, and styrene in vulcanized rubber. It combines pyrolysis-gas chromatography-mass spectrometry with target ion extraction and normalized data processing methods. By constructing a detection process with high specificity, high accuracy, and high adaptability, it achieves accurate determination of the content of key components (butadiene, isoprene, and styrene) in vulcanized rubber. This solves the problems of inaccurate integration due to detector limitations in the original national standard method, as well as unreasonable results due to differences in rubber systems. It transforms the previous analytical approach of "relying on perfect peak separation" and establishes a unified and universal standard for component content analysis, realizing integrated and comparable characterization of tire rubber formulations at the microscopic component level.

[0018] The testing method and apparatus of this application are designed based on the actual needs of tire rubber compound research and development and quality control. The extraction ion method used can effectively eliminate the interference of complex matrices and meet the testing requirements of different formulation systems (such as the combination of natural rubber / styrene-butadiene rubber / cis-butadiene rubber). It provides a reliable technical means for formulation analysis, quality traceability and process optimization. This method has excellent accuracy and robustness and can quickly and accurately provide analysis results based on newly emerging rubber types or formulation changes. This helps to solve the problems of large data deviation and logical inconsistency in traditional methods, and improves the reliability and decision-making value of the test results.

[0019] Based on standard samples with known formulations and standardized testing procedures, this method completely eliminates the previous crude approach of relying on general-purpose detectors and manual integration adjustments by employing a high-sensitivity mass spectrometer detector and intelligent integration events, thereby improving detection efficiency and data authority. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic flowchart illustrating an exemplary embodiment of the present application of a method for determining the content of butadiene, isoprene and styrene in vulcanized rubber; Figure 2 This is a schematic diagram of an exemplary embodiment of the present application illustrating a device for determining the content of butadiene, isoprene, and styrene in vulcanized rubber.

[0022] Figure label: 1. Pyrolysis-gas chromatography-mass spectrometry system; 2. Data processing unit. Detailed Implementation

[0023] To make the objectives, implementation methods and advantages of this application clearer, the exemplary implementation methods of this application will be clearly and completely described below with reference to the accompanying drawings of the exemplary embodiments of this application. Obviously, the exemplary embodiments described are only some embodiments of this application, and not all embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0024] It should be noted that the brief descriptions of terms in this application are only for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise stated, these terms should be understood in their ordinary and common meaning.

[0025] The terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar or related objects or entities, and do not necessarily imply a specific order or sequence, unless otherwise specified. It should be understood that such terms are interchangeable where appropriate.

[0026] The terms “comprising” and “having”, and any variations thereof, are intended to cover but not exclude inclusion, for example, a product or device that includes a range of components is not necessarily limited to all of the components that are clearly listed, but may include other components that are not clearly listed or that are inherent to such product or device.

[0027] In the formulation of rubber compounds for tires and other rubber products, the three most commonly used rubbers are natural rubber (NR, whose main structural unit is isoprene), styrene-butadiene rubber (SBR, whose synthetic monomers are butadiene and styrene), and cis-butadiene rubber (BR, whose synthetic monomer is butadiene). The selection and determination of the proportions of these three rubbers are the core information of the formulation system, which directly affects the physical and mechanical properties, processing performance, and durability of the rubber compound. Therefore, accurately determining the content of butadiene, isoprene, and styrene in vulcanized rubber is of great significance for product quality control, formulation reverse engineering, and new product development.

[0028] Currently, existing technologies mostly utilize samples with known styrene (ST), butadiene (BD), and isoprene (IP) ratios for analysis using a pyrolysis gas chromatograph, with detection using a flame ionization detector (FID) or thermal conductivity detector (TCD), recording the peak areas of each component using an integrator, plotting calibration curves, and then performing quantitative analysis on unknown samples.

[0029] However, existing FID or TCD detectors have certain limitations. When analyzing the pyrolysis products of vulcanized rubber in complex matrices, chromatographic peaks may be poorly separated or baseline drift may occur. This can lead to inaccurate peak area integrals of target characteristic compounds (butadiene, isoprene, styrene), thus affecting the accuracy of the final quantitative results. Furthermore, directly using the results obtained from the standard curve regression as the final value can lead to problems for unknown samples where the rubber system is inconsistent with the standard used to plot the standard curve (e.g., the standard is a styrene-butadiene rubber / isoprene rubber system, while the sample to be tested is a mixture of natural rubber / styrene-butadiene rubber / cis-butadiene rubber). The sum of the calculated proportions of the three characteristic compounds may exceed 100%, which is unreasonable and illogical for the method of expressing component content as a percentage.

[0030] Therefore, there is an urgent need for a highly accurate and reliable method for determining the content of butadiene, isoprene, and styrene in vulcanized rubber. Next, the technical solutions of this application and how they solve the aforementioned technical problems will be described in detail through embodiments and in conjunction with the accompanying drawings. The embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this application.

[0031] In one exemplary embodiment, such as Figure 1 As shown, a method for determining the content of butadiene, isoprene, and styrene in vulcanized rubber is provided. In this embodiment, the method may include the following steps: Step 100: Calibration step, prepare at least three standard vulcanizate samples with different gradients, wherein the theoretical contents of butadiene, isoprene and styrene in the standard vulcanizate samples are known and cover the expected range of the sample to be tested.

[0032] Step 200: Standard testing procedure. The standard vulcanized rubber samples are tested using a pyrolysis-gas chromatography-mass spectrometry system. Characteristic ions of butadiene, isoprene, and styrene are extracted using a mass spectrometer detector, and the characteristic peak areas of the three characteristic compounds in each standard vulcanized rubber sample are obtained.

[0033] Step 300: Standard curve plotting step, based on the characteristic peak area, establish standard working curves for butadiene, isoprene and styrene respectively.

[0034] Step 400: Sample testing step. Under the same conditions as the standard testing step, the unknown vulcanizate sample is tested to obtain the characteristic peak areas of butadiene, isoprene and styrene in the unknown vulcanizate sample.

[0035] Step 500: Preliminary calculation step, substituting the characteristic peak area of ​​the unknown vulcanized rubber sample into the corresponding standard working curve, to calculate the preliminary butadiene percentage B. DB Preliminary isoprene percentage B IP And preliminary styrene percentage B ST .

[0036] Step 600: Normalization step, for the preliminary butadiene percentage content B DB Preliminary isoprene percentage B IP And preliminary styrene percentage B ST After normalization, the final butadiene content P is obtained. DB Isoprene content P IPand styrene content P ST And P DB +P IP +P ST =100%.

[0037] In one embodiment, the core process of the determination method mainly includes four stages: calibration sample preparation, standard curve establishment, unknown sample testing, and normalization processing.

[0038] 1. Preparation of calibration samples This stage involves preparing a series of standard vulcanized rubber samples with known precise components to establish a standard working curve for quantitative analysis.

[0039] 1.1 Selection of Base Materials: Solution-polymerized styrene-butadiene rubber (such as JSRHP755R, with a styrene content of approximately 25%), isoprene rubber (IR, representing the structural unit of natural rubber), and butadiene rubber (BR) were selected as the base raw rubber to cover the three target components: butadiene, isoprene, and styrene. Compounding agents included N234 carbon black, zinc oxide, stearic acid, antioxidant 4020, accelerator NS, and sulfur, all commonly used raw materials in the rubber industry.

[0040] 1.2 Mixing and vulcanization: Mix the five different formulation ratios shown in Table 1 on an internal mixer and a two-roll mill to ensure uniform dispersion of the compounding agents. After mixing, vulcanize the rubber compound on a flat vulcanizing machine at 150°C according to its positive vulcanization time (T90) to produce standard vulcanized rubber sheets.

[0041]

[0042] 1.3 Sample pretreatment: To eliminate the interference of non-rubber components (such as processing oil, antioxidants, etc.) on pyrolysis and chromatographic analysis, the vulcanized standard samples were extracted with acetone in a Soxhlet extractor for 24 hours according to GB / T3516 Method B. The extracted samples were then dried to constant weight in a vacuum oven at 60℃.

[0043] 1.4 Sample Weighing: Using a precision balance, accurately weigh 100 μg to 150 μg of sample from the dried standard sample. The sample should be sheared into fine, uniform particles to ensure the repeatability and representativeness of the lysis.

[0044] 2. Standard test procedures and standard curve plotting In this stage, a pyrolysis-gas chromatography-mass spectrometry (PCC-MS) instrument was used to analyze the standard samples and establish a quantitative standard curve.

[0045] 2.1 Test Equipment and Conditions: An EGA / PY-3030D pyrolyzer manufactured by FrontialLabs, Japan, and an Agilent 7890B / 5977B gas chromatography-mass spectrometry (GC-MS) system were used. Specific operating conditions are shown in Table 2 below. These parameters were optimized to achieve optimal separation and detection of the three characteristic compounds. Table 2 Equipment Operation Test Conditions

[0046] 2.2 Spectrum Processing and Characteristic Peak Area Acquisition Standard samples STD-1 to STD-5 were tested sequentially to obtain total ion chromatograms. Subsequently, the target compound was precisely quantified and integrated using the instrument's data processing software and the extracted ion method.

[0047] Ion extraction: As shown in Table 3, ion chromatograms were extracted for the characteristic ions of butadiene (m / z=54), isoprene (m / z=67), and styrene (m / z=104). The matching degree was set to ≥90% to eliminate background interference.

[0048] Table 3 Characteristic ions of characteristic compounds

[0049] Integration event parameters: To ensure consistency and accuracy of integration, a uniform integration event parameter is used for integration of all extracted ion chromatograms. The parameter settings are shown in Table 4.

[0050] Table 4 Integral Event Parameters

[0051] 2.3 Drawing Standard Working Curves For each standard sample, record the characteristic peak areas of butadiene, isoprene, and styrene obtained by the above method, and then perform the following calculations: Calculate the ratio A of the styrene characteristic peak area to the total characteristic peak area of ​​the three samples in each sample. ST .

[0052] Calculate the ratio A of the butadiene characteristic peak area to the total characteristic peak area of ​​the three samples in each sample. BD .

[0053] Calculate the ratio A of the isoprene characteristic peak area to the total characteristic peak area of ​​the three samples in each sample. IP .

[0054] Plotting the ratio A on the x-axis (X) and the theoretical percentage content of the corresponding component in the standard sample (from Table 1) on the y-axis (Y), standard working curves for styrene, butadiene, and isoprene were plotted respectively. Experience shows that a model using quadratic function fitting with the curve forced to pass through the origin better describes this quantitative relationship, with a goodness of fit (R²) typically greater than 0.999. Exemplary equations for the three standard curves are as follows: Styrene curve: Y = 0.987X² + 1.011X; Butadiene curve: Y = 1.025X² + 0.974X; Isoprene curve: Y = 0.995X² + 1.008X.

[0055] 3. Analysis of Unknown Samples and Calculation of Results The unknown vulcanized rubber sample to be tested (e.g., tire tread rubber taken from the production line, whose formulation system may be a combination of natural rubber / styrene-butadiene rubber / cis-butadiene rubber) shall be pretreated and weighed in accordance with the same methods in Sections 1.3 and 1.4.

[0056] 3.1 Sample Testing and Preliminary Calculations: Testing was conducted under the exact same instrument conditions as in Section 2.1, and characteristic ions were extracted and integrated using the same methods as in Section 2.2 to obtain the A of the unknown sample. ST A BD and A IP Substituting these three ratios into the corresponding standard working curves established in step 2.3, the preliminary styrene percentage B can be calculated. ST Preliminary butadiene percentage B DB And preliminary isoprene percentage B IP .

[0057] 3.2 Normalization Processing Since the rubber system of an unknown sample may not be completely consistent with the standard system used to plot the standard curve, B obtained directly from the standard curve... ST B DB and B IP The sum of the three components may not equal 100%. Therefore, normalization is required to reflect the true proportions of the three components within the specific sample rubber system. The final content is calculated using the following formula: P ST (%) = B ST / (B ST +B DB +B IP )*100%(1; P DB (%) = B DB / (B ST +B DB +BIP )*100%(2; P IP (%) = B IP / (B ST +B DB +B IP )*100%(3).

[0058] Calculated P ST P DB and P IP This represents the final determination results of styrene, butadiene, and isoprene in the unknown vulcanized rubber sample, and the sum of the three is always 100%.

[0059] 4. Method Validation To verify the accuracy of this method, several validation samples with known precise formulations were tested using the above procedure. The results are shown in Table 5. The relative deviations between the measured values ​​and the theoretical values ​​of all components were within ±5%, demonstrating that the method of this invention has extremely high accuracy.

[0060] Table 4 Validation Data Table

[0061] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially as indicated, these steps are not necessarily executed in the indicated order. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps.

[0062] Corresponding to the aforementioned embodiments of the method for determining the content of butadiene, isoprene and styrene in vulcanized rubber, and employing the same technical concept, this application also provides embodiments of an apparatus for determining the content of butadiene, isoprene and styrene in vulcanized rubber.

[0063] In one exemplary embodiment, such as Figure 2 As shown, the apparatus for determining the content of butadiene, isoprene, and styrene in the vulcanized rubber includes: Pyrolysis-gas chromatography-mass spectrometry 1, which is configured to perform the standard test procedure and the sample test procedure; Data processing unit 2, which is communicatively connected to the pyrolysis-gas chromatography-mass spectrometry system, is programmed to perform the following operations: The mass spectrometer detector is controlled to extract characteristic ions of butadiene, isoprene, and styrene and to obtain the area of ​​the characteristic peaks. Perform the standard curve plotting steps, preliminary calculation steps, and normalization steps as described above; Output the final butadiene content (PDB), isoprene content (PIP), and styrene content (PST).

[0064] In one embodiment, the pyrolysis-gas chromatography-mass spectrometry system 1: This hardware system is configured to perform the aforementioned standard test procedures and sample test procedures, and its core includes: The pyrolyzer is programmed to instantly pyrolyze samples at 550°C under an inert atmosphere.

[0065] Gas chromatograph: Its injection port, column and column oven are configured to operate according to the parameters defined in Table 2 (such as injection port temperature 280°C, specific temperature program) to achieve efficient separation of pyrolysis products.

[0066] Mass spectrometer detector: It is set to operate in full scan mode within the mass number range of 33 to 550 and can respond to instructions from the data processing unit to perform the extraction of characteristic ions (m / z=54, 67, 104).

[0067] Data Processing Unit 2: This unit can be a workstation computer integrated with the coupling instrument, or it can be a standalone server or computer system, which communicates with the coupling instrument via a data cable. This unit stores a computer program that, when executed, enables the device to perform the following functions: Control and Acquisition: Control the mass spectrometer detector to perform characteristic ion extraction and receive and store raw spectral data from the coupled instrument.

[0068] Integration calculation: Based on preset integration event parameters (initial area cutoff of 10, initial peak width of 0.024, etc.), the characteristic peak areas of butadiene, isoprene and styrene are automatically calculated.

[0069] Curve construction and calculation: Perform the standard curve drawing steps (including calculating the area ratio A and fitting a quadratic function through the origin), perform the preliminary calculation steps (substitute the A value of the unknown sample into the curve to obtain the B value), and finally perform the normalization steps to calculate the final P value according to formulas (1)-(3).

[0070] Output results: The final butadiene content P will be displayed on the user interface or printed out. DB Isoprene content P IP and styrene content P ST .

[0071] Specific limitations regarding the apparatus for determining the butadiene, isoprene, and styrene content in vulcanized rubber can be found in the above-mentioned limitations on the method for determining the butadiene, isoprene, and styrene content in vulcanized rubber, and will not be repeated here. Each module in the aforementioned apparatus for determining the butadiene, isoprene, and styrene content in vulcanized rubber can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0072] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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.

[0073] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for determining the content of butadiene, isoprene, and styrene in vulcanized rubber, characterized in that, include: The calibration procedure involves preparing at least three standard vulcanizate samples with different gradients, wherein the theoretical contents of butadiene, isoprene, and styrene in the standard vulcanizate samples are known and cover the expected range of the sample to be tested. The standard testing procedure involves using a pyrolysis-gas chromatography-mass spectrometry (PCC-MS) instrument to test the standard vulcanizate samples. The characteristic ions of butadiene, isoprene, and styrene are extracted using a mass spectrometer detector, and the characteristic peak areas of the three characteristic compounds in each standard vulcanizate sample are obtained. The standard curve plotting steps involve establishing standard working curves for butadiene, isoprene, and styrene based on the characteristic peak areas. The sample testing procedure involves testing an unknown vulcanizate sample under the same conditions as the standard testing procedure to obtain the characteristic peak areas of butadiene, isoprene, and styrene in the unknown vulcanizate sample. In the preliminary calculation step, the characteristic peak area of ​​the unknown vulcanized rubber sample is substituted into the corresponding standard working curve to calculate the preliminary butadiene percentage B. DB Preliminary isoprene percentage B IP And preliminary styrene percentage B ST ; The normalization step is applied to the preliminary butadiene percentage B. DB Preliminary isoprene percentage B IP And preliminary styrene percentage B ST After normalization, the final butadiene content P is obtained. DB Isoprene content P IP and styrene content P ST And P DB +P IP +P ST =100%.

2. The method for determining the content of butadiene, isoprene, and styrene in vulcanized rubber as described in claim 1, characterized in that, The method for plotting the standard working curve in the standard curve plotting step includes: Calculate the ratio A of the characteristic peak area of ​​styrene to the sum of the characteristic peak areas of styrene, butadiene, and isoprene in each standard vulcanizate sample. ST , with A ST Plot the standard working curve of styrene with the theoretical percentage content of styrene in the standard vulcanized rubber sample on the x-axis and the y-axis on the y-axis. Calculate the ratio A of the butadiene characteristic peak area to the sum of the characteristic peak areas of the three samples in each standard vulcanized rubber sample. BD , with A BD Plot the standard working curve of butadiene with the theoretical percentage content of butadiene in the standard vulcanized rubber sample as the ordinate, using π as the x-axis. Calculate the ratio A of the isoprene characteristic peak area to the sum of the characteristic peak areas of the three components in each standard vulcanizate sample. IP , with A IP Plot the standard working curve of isoprene with the theoretical percentage content of isoprene in the standard vulcanizate sample on the x-axis and the y-axis on the y-axis.

3. The method for determining the content of butadiene, isoprene, and styrene in vulcanized rubber as described in claim 2, characterized in that, The standard working curve is a quadratic function curve that passes through the origin.

4. The method for determining the content of butadiene, isoprene, and styrene in vulcanized rubber as described in claim 1, characterized in that, The normalization step is calculated using the following formula: P ST (%)=B ST / (B ST +B DB +B IP )*100%(1) P DB (%)=B DB / (B ST +B DB +B IP )*100%(2) P IP (%)=B IP / (B ST +B DB +B IP )*100%(3)。 5. The method for determining the content of butadiene, isoprene, and styrene in vulcanized rubber as described in claim 1, characterized in that, In the standard test procedure and sample test procedure, the pyrolysis temperature of the pyrolyzer is 550℃, and the injection port temperature of the gas chromatograph is 280℃.

6. The method for determining the content of butadiene, isoprene, and styrene in vulcanized rubber as described in claim 1, characterized in that, The temperature program for gas chromatography in the standard test steps and sample test steps includes: Initial temperature 40℃, maintain for 2 minutes; Increase the temperature to 140℃ at a rate of 10℃ / min and hold for 15min; Then, increase the temperature to 290°C at a rate of 20°C / min and hold for 5 minutes.

7. The method for determining the content of butadiene, isoprene, and styrene in vulcanized rubber as described in claim 1, characterized in that, In the standard test steps and sample test steps, the integration of the characteristic peak area is performed using an integration event. The parameters of the integration event include: initial area cutoff of 10, initial peak width of 0.024, shoulder peak detection OFF, and initial threshold of 18.

8. The method for determining the content of butadiene, isoprene, and styrene in vulcanized rubber as described in claim 1, characterized in that, In the calibration step, the standard vulcanized rubber sample is extracted with acetone before use, and the test mass of the standard vulcanized rubber sample and the unknown vulcanized rubber sample is controlled between 100 μg and 150 μg.

9. The method for determining the content of butadiene, isoprene, and styrene in vulcanized rubber as described in claim 1, characterized in that, The mass spectrometer detector is in full scan mode, with a mass number scan range of 33 to 550.

10. An apparatus for determining the content of butadiene, isoprene, and styrene in vulcanized rubber, characterized in that, include: A pyrolysis-gas chromatography-mass spectrometry system is configured to perform the standard test procedures and sample test procedures; A data processing unit, which is communicatively connected to the pyrolysis-gas chromatography-mass spectrometry system, is programmed to perform the following operations: The mass spectrometer detector is controlled to extract characteristic ions of butadiene, isoprene, and styrene and to obtain the area of ​​the characteristic peaks. Perform the standard curve plotting steps, preliminary calculation steps, and normalization steps as described above; Output the final butadiene content P DB Isoprene content P IP and styrene content P ST .

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