A method for characterizing the compatibility of styrene butadiene rubber with other rubbers

Abstract

The application belongs to the technical field of material characterization, and provides a method for characterizing the compatibility of styrene butadiene rubber and other rubbers. A tetrazine compound is added to a mixture of styrene butadiene rubber and other rubbers. The tetrazine compound is more easily reacted with the styrene butadiene rubber, and the mixture forms a bright yellow color at 135 DEG C. Other rubbers are not easily reacted with the tetrazine compound, and the mixture forms a deep purple color at various temperatures. The mixture is uniformly blended in a mixing mill, then reacted at 135-145 DEG C for 1-2 minutes, cooled to room temperature, and then sliced. The morphology and color are observed under a high-depth-of-field intelligent microscope to determine the compatibility of the styrene butadiene rubber and other rubbers. The method is simple to operate, has low equipment cost, is intuitive and fast, is not limited by the formula, provides a theoretical basis and experimental reference for characterizing the compatibility and performance of the styrene butadiene rubber and other rubber blending systems, and has guiding significance for the development of high-performance rubber materials.

Description

Technical Field

[0001] This invention belongs to the field of materials characterization technology, and specifically relates to a method for characterizing the compatibility of styrene-butadiene rubber with other rubbers. Background Technology

[0002] With the rapid development of the rubber industry, higher requirements have been placed on the performance of rubber materials. Styrene-butadiene rubber (SBR), natural rubber, butadiene rubber, and chloroprene rubber are widely used in tires, shock absorbers, conveyor belts, and other fields. SBR, as a synthetic rubber, has good wear resistance, aging resistance, and wet skid resistance, while natural rubber (NR) is known for its excellent elasticity, mechanical strength, and processing properties. Using a blend of multiple rubber types can effectively improve the overall performance of rubber materials and compensate for the limitations of a single rubber type.

[0003] However, styrene-butadiene rubber (SBR) differs from natural rubber and other rubbers in molecular structure, polarity, and interaction forces, leading to compatibility issues during physical blending. Poor compatibility can cause phase separation, interfacial stress concentration, and decreased mechanical properties, ultimately affecting the service life and safety of the final product. Therefore, accurately characterizing the compatibility of various rubber blends to prepare high-performance blended rubbers has become an important research topic. Although existing studies have used methods such as DMA or DSC testing for compatibility assessment, drawing conclusions by analyzing glass transition temperatures and observing curves, these testing procedures are complex, lack intuitiveness, and require considerable time to complete.

[0004] The inventors focused their research on whether they could overcome the aforementioned technical deficiencies and provide a more intuitive method for characterizing the compatibility of styrene-butadiene rubber with other rubbers. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for characterizing the compatibility of styrene-butadiene rubber (SBR) with other rubbers. A tetrazine compound is added to a mixture of SBR and other rubbers. After homogenization in a mixer, the mixture is reacted at 135-145°C for 1-2 minutes, cooled to room temperature, and then cut into 1mm thick slices. The morphology and color are observed under a high-depth-of-field intelligent microscope to determine the compatibility of SBR with other rubbers. This method is simple to operate and has low equipment costs. It provides a theoretical basis and experimental reference for the compatibility characterization and performance control of SBR blends with other rubbers, and has certain guiding significance for promoting the development of high-performance rubber materials.

[0006] The innovation of this invention lies in utilizing the fact that tetrazine compounds react readily with styrene-butadiene rubber (SBR), forming a bright yellow mixture at 135°C; while other rubber types do not react readily with tetrazine compounds, forming a deep purple mixture at various temperatures. When other rubber types have poor compatibility with SBR, the interfaces between the other rubber types and SBR are clearly defined under a microscope after the rubber mixture reacts above 135°C, exhibiting a yellowish-brown and a deep purple hue. When other rubber types have good compatibility with SBR, the interfaces between the other rubber types and SBR are blurred under a microscope after the mixture reacts above 135°C, with fewer independent phase transitions and a more uniform color. This allows for the determination of compatibility.

[0007] The specific technical solution of the present invention is as follows: A method for characterizing the compatibility of styrene-butadiene rubber (SBR) with other rubbers includes the following steps: a tetrazine-based small molecule compound, SBR, and other rubbers are blended in a mixer, reacted at 135-145°C for 1-2 minutes, cooled to room temperature, and a sample of 0.8-1.5 mm thickness (preferably 1 mm) is cut out. The morphology and color are observed under a high-depth-of-field intelligent microscope to determine the compatibility of SBR with other rubbers.

[0008] The criteria for judgment are as follows: When other rubber types have poor compatibility with styrene-butadiene rubber (SBR), after the rubber mixture reacts at temperatures above 135°C, the interface between the other rubber types and SBR is clearly defined under a microscope, showing a boundary line between yellowish-brown and dark purple. When other rubber types have good compatibility with SBR, after the mixture reacts at temperatures above 135°C, the interface between the other rubber types and SBR is blurred under a microscope, with fewer independent phase transitions and a more uniform color.

[0009] The tetrazine compound is selected from 3,6-diphenyl-1,2,4,5-tetrazine (CAS No. 6830-78-0) or 3,6-bis(pyridin-2-yl)-1,2,4,5-tetrazine (CAS No. 1671-87-0), and can be prepared using existing technology or purchased directly; the amount of the above tetrazine compound added is 1-5% of the total weight of styrene-butadiene rubber and other rubbers.

[0010] The selected internal mixer is preferably a small intelligent internal mixer, such as the BR 1600 intelligent internal mixer, manufactured by Farrel Corporation of the United States; The other rubbers mentioned are selected from one or two of natural rubber, butadiene rubber, ethylene propylene diene monomer (EPDM) rubber, and chloroprene rubber; Observation using a high depth-of-field intelligent microscope (ZEISS ZOOM5 model, Germany), with a magnification of over 500x; The initial temperature of the mixing chamber is 40-60℃, and the rotor speed is 50-70 r / min.

[0011] Compared with the prior art, the beneficial effects of this application are as follows: This method employs a more intuitive characterization approach, allowing for rapid and intuitive assessment of the compatibility of styrene-butadiene rubber (SBR) with other rubber types using a microscope. Furthermore, it is not limited by formulation; the mass ratio of SBR to other rubber types can be blended according to the actual formulation, and the amount of tetrazine compounds is calculated based on the weight of the mixed rubber. This approach is more aligned with practical applications, provides greater guidance for actual formulations, is low-cost, and has strong promotional value. It can effectively improve formulation development efficiency and meet the needs of high-performance rubber materials. Attached Figure Description

[0012] Figure 1 A schematic diagram showing the reaction test results of the mixture of styrene-butadiene rubber, natural rubber, and 3,6-bis(3-hydroxyphenyl)-1,2,4,5-tetraazine in Example 1 at different temperatures; Figure 2 A schematic diagram showing the reaction test results of the mixture of chloroprene rubber, styrene-butadiene rubber and 3,6-bis(pyridin-2-yl)-1,2,4,5-tetraazine in Example 2 at different temperatures; Figure 3 A schematic diagram showing the reaction test results of the mixture of EPDM rubber, styrene-butadiene rubber and 3,6-bis(pyridin-2-yl)-1,2,4,5-tetraazine in Example 3 at different temperatures; Figure 4 A schematic diagram showing the reaction test results of the mixture of EPDM rubber, styrene-butadiene rubber and 3,6-bis(pyridin-2-yl)-1,2,4,5-tetraazine in Example 4 at different temperatures; Figure 5 A schematic diagram showing the reaction test results of natural rubber, cis-butadiene rubber, styrene-butadiene rubber and 3,6-bis(pyridin-2-yl)-1,2,4,5-tetraazine mixture in Example 5 at different temperatures; Figure 6 A schematic diagram showing the reaction test results of natural rubber, cis-butadiene rubber, styrene-butadiene rubber and 3,6-bis(pyridin-2-yl)-1,2,4,5-tetraazine mixture in Example 6 at different temperatures; Figure 7 This is a schematic diagram showing the reaction test results of the mixture of natural rubber, styrene-butadiene rubber and 3,6-diphenyl-1,2,4,5-tetraazine in Example 7 at different temperatures. Detailed Implementation

[0013] The technical solution of the present invention will be further described in detail below with reference to the embodiments. Obviously, the embodiments described herein are only used to explain the present invention, but the present invention is not limited to these embodiments.

[0014] Example 1: A method for characterizing the compatibility of styrene-butadiene rubber with other rubbers The composition of the rubber compound, by weight, is as follows: 50 parts of styrene-butadiene rubber, 50 parts of natural rubber, and 5 parts of 3,6-bis(pyridin-2-yl)-1,2,4,5-tetraazine; Sample preparation method: Natural rubber, styrene-butadiene rubber, and 3,6-bis(pyridin-2-yl)-1,2,4,5-tetraazine were blended using a BR 1600 intelligent internal mixer. The initial temperature of the mixing chamber was 50℃, the rotor speed was 60 r / min, and the mixing was carried out for 2 minutes after the temperature reached 135℃. After cooling to room temperature, 1 mm thick samples were cut with a blade and the morphology and color of the samples were observed under a high depth-of-field intelligent microscope. The 120℃ sample was the same except for the rubber discharge temperature.

[0015] To determine the compatibility of styrene-butadiene rubber (SBR) with natural rubber, the reaction test results of SBR, natural rubber, and 3,6-bis(3-hydroxyphenyl)-1,2,4,5-tetraazine at different temperatures are as follows: Figure 1 As shown, the left image represents the glue removal temperature at 120℃, and the right image represents the glue removal temperature at 135℃. Under a high-depth-of-field intelligent microscope at 500x magnification, it can be clearly seen that at 120℃, NR appears dark purple and SBR appears yellow, and there is DS aggregation in the matrix. At 135℃, the aggregation disappears, and the dark purple NR and yellow SBR are clearly separated, which can intuitively show the poor compatibility between the two rubbers.

[0016] Example 2: A method for characterizing the compatibility of styrene-butadiene rubber with other rubbers The difference from Example 1 is that the mixture composition by weight is: 50 parts chloroprene rubber, 50 parts styrene-butadiene rubber, and 5 parts 3,6-bis(pyridin-2-yl)-1,2,4,5-tetraazine.

[0017] The sample preparation method is the same as in Example 1.

[0018] Test results are as follows Figure 2 As shown, the left figure shows the discharge temperature at 120℃, and the right figure shows the discharge temperature at 135℃. At low temperatures, the sample is basically dark purple, indicating that the reaction was not complete at 120℃. At 135℃, the unevenness of the sample cross-section caused differences in brightness, but the sample basically showed a uniform dark yellow color, which intuitively shows that the compatibility between the two adhesives is good.

[0019] Example 3: A method for characterizing the compatibility of styrene-butadiene rubber with other rubbers The difference from Example 1 is that the mixture composition by weight is: 30 parts of EPDM rubber, 70 parts of styrene-butadiene rubber, and 4 parts of 3,6-bis(pyridin-2-yl)-1,2,4,5-tetraazine.

[0020] The sample preparation method was the same as in Example 1, except that the discharge temperature was 115℃ and 130℃.

[0021] Test results are as follows Figure 3 As shown, the left figure shows the discharge temperature at 115℃, and the right figure shows the discharge temperature at 130℃. At 115℃, there are purple aggregates with a size of about 50 micrometers, indicating that the reaction is basically complete. At 130℃, the purple aggregates disappear, and the colloid shows a uniform bright yellow color, indicating that the two colloids have good compatibility.

[0022] Example 4: A method for characterizing the compatibility of styrene-butadiene rubber with other rubbers The difference from Example 1 is that the mixture composition by weight is: 50 parts of EPDM rubber, 50 parts of styrene-butadiene rubber, and 3 parts of 3,6-bis(pyridin-2-yl)-1,2,4,5-tetraazine.

[0023] The sample preparation method was the same as in Example 1, except that the discharge temperature was 125°C and 140°C.

[0024] Test results are as follows Figure 4 As shown, the left figure shows the discharge temperature at 125℃, and the right figure shows the discharge temperature at 140℃. At 125℃, there are purple aggregates with a size of about 50 micrometers, and the overall color is brownish. At 140℃, the purple aggregates disappear completely. The ring-shaped protrusions in the figure are due to air bubbles generated by styrene-butadiene rubber during the mixing process. After slicing, pores are left but do not affect the overall uniform yellow color, indicating that the compatibility between the two is still good after changing the ratio.

[0025] Example 5: A method for characterizing the compatibility of styrene-butadiene rubber with other rubbers The difference from Example 1 is that the mixture composition by weight is: 40 parts natural rubber, 20 parts butadiene rubber, 40 parts styrene-butadiene rubber, and 5 parts 3,6-bis(pyridin-2-yl)-1,2,4,5-tetraazine.

[0026] The sample preparation method is the same as in Example 1.

[0027] Test results are as follows Figure 5 As shown, the left figure shows the discharge temperature at 120℃, and the right figure shows the discharge temperature at 135℃. At 120℃, the boundary between purple and yellow in the sample is relatively blurred and indistinct. However, at 135℃, the sample shows a uniform state. Due to the uneven cross-section of the sample, there are differences in brightness and darkness, and there is a reflective phenomenon in some areas. However, it can still be said that the addition of butadiene rubber effectively improves the compatibility between natural rubber and styrene-butadiene rubber.

[0028] Example 6: A method for characterizing the compatibility of styrene-butadiene rubber with other rubbers The difference from Example 1 is that the mixture composition by weight is: 20 parts natural rubber, 20 parts butadiene rubber, 60 parts styrene-butadiene rubber, and 5 parts 3,6-bis(pyridin-2-yl)-1,2,4,5-tetraazine.

[0029] The sample preparation method is the same as in Example 1.

[0030] Test results are as follows Figure 6 As shown, the left figure shows the discharge temperature at 120℃, and the right figure shows the discharge temperature at 135℃. At 120℃, after changing the ratio, the sample showed a more obvious purple-yellow boundary. At 135℃, the sample showed a uniform state, indicating that the addition of butadiene rubber effectively improved the compatibility between natural rubber and styrene-butadiene rubber.

[0031] Example 7 A method for characterizing the compatibility of styrene-butadiene rubber with other rubbers The difference from Example 1 is that the mixture composition by weight is: 50 parts natural rubber, 50 parts styrene-butadiene rubber, and 5 parts 3,6-diphenyl-1,2,4,5-tetraazine.

[0032] The sample preparation method is the same as in Example 1.

[0033] Test results are as follows Figure 7 As shown, the left figure shows the debinding temperature at 120℃, and the right figure shows the debinding temperature at 135℃. At 120℃, the sample shows a relatively obvious purple-yellow boundary, while at 135℃, the sample still shows a phase separation state, indicating poor compatibility.

[0034] As can be seen from the comparison of the above examples and comparative examples, the reaction process of styrene-butadiene rubber (SBR) with other rubbers gradually increases with the increase of temperature and time. The present method allows for a more intuitive and rapid assessment of the compatibility of SBR with other rubber types using a microscope. Furthermore, it is not limited by the formulation; the mass ratio of SBR with other rubber types can be blended according to the actual formulation. The amount of tetrazine compounds is calculated and added based on the weight of the mixed rubber, which is more in line with practical applications and provides more guidance for actual formulations. It is low in cost, has strong promotional value, can effectively improve the efficiency of formulation development, and meet the needs of high-performance rubber materials.

[0035] This invention includes, but is not limited to, the above embodiments. Any equivalent substitutions or partial improvements made under the spirit and principles of this invention shall be considered to be within the scope of protection of this invention.

Claims

1. A method for characterizing the compatibility of styrene-butadiene rubber with other rubbers, characterized in that, The specific steps are to blend tetrazine small molecule compounds, styrene-butadiene rubber, and other rubbers in an internal mixer, react them at 135-145℃ for 1-2 minutes, cool them to room temperature, cut out samples with a thickness of 0.8-1.5 mm, and observe their morphology and color under a high depth-of-field intelligent microscope to determine the compatibility of styrene-butadiene rubber with other rubbers. The tetrazine small molecule compound mentioned therein is selected from one of 3,6-diphenyl-1,2,4,5-tetrazine or 3,6-bis(pyridin-2-yl)-1,2,4,5-tetrazine; The other rubbers are selected from one or two of natural rubber, butadiene rubber, EPDM rubber, and chloroprene rubber.

2. The method for characterizing the compatibility of styrene-butadiene rubber with other rubbers according to claim 1, characterized in that, The criteria for judgment are as follows: when other rubbers have poor compatibility with styrene-butadiene rubber, after the rubber mixture reacts at a temperature above 135°C, the interface between other rubbers and styrene-butadiene rubber is distinct under a microscope, showing a boundary line between yellowish-brown and dark purple; when other rubbers have good compatibility with styrene-butadiene rubber, after the mixture reacts at a temperature above 135°C, the interface between other rubbers and styrene-butadiene rubber is blurred under a microscope, with fewer independent phase changes and a more uniform color.

3. The method for characterizing the compatibility of styrene-butadiene rubber with other rubbers according to claim 1 or 2, characterized in that, The amount of tetrazine compounds added is 1-5% of the total weight of styrene-butadiene rubber and other rubbers.

4. The method for characterizing the compatibility of styrene-butadiene rubber with other rubbers according to claim 1 or 2, characterized in that, The selected internal mixer is a small intelligent internal mixer.

5. The method for characterizing the compatibility of styrene-butadiene rubber with other rubbers according to claim 1, characterized in that, The sample thickness is 1mm.

6. The method for characterizing the compatibility of styrene-butadiene rubber with other rubbers according to claim 4, characterized in that, The initial temperature of the mixing chamber is 40-60℃, and the rotor speed is 50-70 r / min.

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