Simplified method for evaluating enhancement effect and enhancement efficiency of filler on natural rubber on basis of particle size of bonded latex particles formed by filler and natural latex

Abstract

A method for evaluating the enhancement effect and enhancement efficiency of a filler on natural rubber on the basis of the particle size of bonded latex particles formed by the filler and natural latex. The method comprises: uniformly mixing natural rubber latex and a filler to obtain a solution to be measured, then using an instrument to measure an average particle size value of latex particles, and on the basis of the ratio of the value to the particle size of pure natural latex particles with the same concentration and without adding the filler, evaluating whether the filler has an enhancement effect on natural rubber or not; and on the basis of an established functional relation, further deducing the stress at definite elongation of the filler / natural rubber vulcanized rubber prepared by various processes, and on the basis of the stress at definite elongation, quantitatively evaluating the enhancement efficiency of the filler on the natural rubber. The method can quickly and accurately evaluate the enhancement effect and enhancement efficiency of a filler on natural rubber, thereby, on one hand, providing a scientific, accurate, rapid and efficient evaluation method for the modification effect of fillers, and on the other hand, laying a foundation for scientific, accurate, rapid and efficient optimization of rubber formulas.

Description

A simplified method for evaluating the reinforcing effect and efficiency of fillers on natural rubber based on the particle size of the combined particles formed by fillers and natural rubber latex

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application number 202410169729.5 filed with the Patent Office of China on February 6, 2024, entitled "A simplified method for evaluating the reinforcing effect and efficiency of natural rubber based on the particle size of combined rubber particles formed by fillers and natural latex", the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present invention relates to the technical field of functional natural rubber composite materials, and in particular to a simplified method for judging the reinforcing effect and efficiency of natural rubber based on the particle size of combined rubber particles formed by fillers and natural rubber latex. Background Art

[0004] Rubber is a polymer elastomer composed of linear or branched macromolecules. It exhibits excellent elasticity, fatigue strength, electrical insulation, wear resistance, and heat resistance. It is widely used in electronics, transportation, aerospace, agriculture, healthcare, and daily life. The development of the rubber industry encompasses not just the growth of a single industry but the collaborative advancement of multiple sectors. Therefore, achieving scientific, rapid, standardized, and diversified rubber quality evaluation can better ensure the safety of rubber in service and is of great significance in practical production and daily life.

[0005] Surface properties directly influence the physical adsorption or chemical bonding between fillers and rubber molecular chains, thus affecting the interfacial bonding strength between the two phases and, in turn, determining the filler's reinforcing efficiency in the rubber matrix. Reinforcement efficiency refers to the degree to which the filler in a composite material improves the mechanical properties of the rubber matrix, often expressed as a percentage of mechanical property improvement. This patent uses the 100% modulus of tensile stress increase to quantify reinforcement efficiency.

[0006] At present, there is still a lack of a convenient, fast, intuitive and scientific evaluation method for the reinforcing efficiency of fillers on rubber. Existing evaluation methods are mainly divided into two categories. One is the evaluation of the interaction between fillers and rubber interfaces, which is obtained by testing the bound rubber content in the vulcanized rubber or the cross-linking density of the vulcanized rubber. This method not only requires the use of toxic reagents such as toluene, but also requires the rubber to be treated for three days of reaction, which is time-consuming and labor-intensive. The second category is obtained by testing the mechanical properties of the vulcanized rubber, such as tensile properties, tear properties and abrasion properties. These tests are generally carried out in reference to national or industry standards. The test objects are rubber samples of specific size specifications that meet the standards and need to be completed under specific test equipment and specific test parameters. The changes in the obtained mechanical performance indicators or structural parameters are used to evaluate the changes in rubber properties with environmental parameters and time. There are problems such as sample processing, testing and data processing that are labor-intensive.

[0007] Patent CN115266350A (application date July 29, 2022, publication date November 1, 2022) provides a test method for the permanent deformation of rubber under compression in a medium environment. The method evaluates the quality of the rubber by placing the compression permanent deformation device in a simulated environment. However, the method has the following limitations: (1) It requires specific means and methods, which is time-consuming and labor-intensive. (2) Calibration experiments are required before quality evaluation, which takes a long time. (3) The specimen size or test conditions may affect the test results.

[0008] Patent CN115855635A (application date November 22, 2022, publication date March 28, 2023) provides a rubber quality evaluation method and system based on tensile fracture morphology analysis. This method is based on the analysis of the fracture morphology of rubber after tensile fracture, divides the morphology into arc surface area and rough area, and associates the area ratio of each characteristic area with the tensile strength and elongation at break of the material to qualitatively and quantitatively evaluate the quality of the rubber. There are the following limitations: (1) The equipment used for evaluation is expensive and complicated to operate. (2) It is well known that morphological analysis based on scanning electron microscopy is performed on selected micro-areas, which easily leads to the problem of generalizing from a single case.

[0009] Patent CN115563803A (application date October 25, 2022, publication date January 3, 2023) provides a method for evaluating the service life of natural rubber. By substituting the torque value into the equivalent aging rate equation and the van't Hoff formula, the service life of the rubber compound is obtained. However, the method has the following limitations: (1) It requires extensive preliminary experimental calibration before use. (2) The test conditions can affect the test results.

[0010] In summary, the current methods for evaluating the efficiency of rubber reinforcement by fillers have the following limitations: ① It requires the use of expensive instruments and equipment or toxic reagents, resulting in high costs or being environmentally unfriendly; ② Using performance parameters as evaluation indicators makes sample processing, testing, and data processing time-consuming and laborious. Therefore, it is very necessary to propose new ideas or methods for evaluating the efficiency of rubber reinforcement by fillers. Based on the theory of filler-reinforced rubber, the present invention proposes a new evaluation method, which is significantly correlated with the results of the current evaluation method. The method of the present invention is applicable to all common reinforcing fillers of natural rubber, and is tested in a latex state without the need for subsequent treatment. Therefore, it is easy to evaluate the performance of rubber products before industrial production, quickly optimize rubber formulas, and efficiently evaluate the effect of filler modification.

[0011] Summary of the Invention

[0012] Addressing the current lack of a convenient, rapid, intuitive, and scientific method for evaluating the reinforcing effect and efficiency of fillers on rubber, the present invention provides a streamlined method for evaluating the reinforcing effect and efficiency of fillers on natural rubber based on the particle size of the combined rubber particles formed by the filler and natural rubber latex. This method can quickly and accurately determine the effect of fillers on the mechanical properties of natural rubber vulcanizates.

[0013] The present invention is achieved through the following technical solution: a simplified method for evaluating the reinforcing effect of fillers on natural rubber based on the particle size of combined rubber particles formed by fillers and natural rubber latex, comprising the following steps:

[0014] ① Mix natural rubber latex and filler at a mass ratio of 100:5-0.1. After the interaction between the two in the aqueous phase causes the particle size of the latex to change, dilute it to a certain concentration of latex test solution;

[0015] ② Using an instrument capable of measuring the particle size of a dispersion, the particle size of the latex test solution obtained in step ① is measured, and the average particle size of the combined particles formed by the filler and the natural rubber latex and the average particle size of the pure natural rubber latex at the same concentration without the filler are obtained, and the particle size ratio x=d / d1 is calculated, where d represents the average particle size of the combined particles formed by the filler and the natural rubber latex, and d1 represents the average particle size of the pure natural rubber latex at the same concentration without the filler;

[0016] ③ When the particle size ratio x≧1.14, the filler has a good reinforcing effect on natural rubber prepared by various processes; when the particle size ratio x=1-1.07, the filler has a poor reinforcing effect on natural rubber prepared by various processes; when 1.14>the particle size ratio x>1.07, the filler has a general reinforcing effect on natural rubber prepared by various processes.

[0017] As a further improvement to the technical solution of the method for judging the enhancement effect of the present invention, in step ①, the concentration range of the prepared latex test solution only needs to meet the test range of the particle size test analyzer used.

[0018] As a further improvement of the technical solution of the method for evaluating the enhancement effect of the present invention, in step ①, the prepared latex test solution should be in a stable state without demulsification.

[0019] The present invention further provides a simplified method for evaluating the reinforcing efficiency of fillers on natural rubber based on the particle size of combined rubber particles formed by fillers and natural rubber latex, comprising the following steps:

[0020] ① Mix natural rubber latex and filler at a mass ratio of 100:5-0.1. After the interaction between the two in the aqueous phase causes the particle size of the latex to change, dilute it to a certain concentration of latex test solution;

[0021] ② Using an instrument capable of measuring the particle size of a dispersion, the particle size of the latex test solution obtained in step ① is measured, thereby obtaining the average particle size of the combined particles formed by the filler and the natural rubber latex and the average particle size of the particles of pure natural rubber latex at the same concentration without the filler, and calculating the particle size ratio x=d / d1, where d represents the average particle size of the combined particles formed by the filler and the natural rubber latex, and d1 represents the average particle size of the particles of pure natural rubber latex at the same concentration without the filler;

[0022] ③ When the particle size ratio x≧1.14, the filler has a good reinforcing effect on natural rubber prepared by various processes; when the particle size ratio x=1-1.07, the filler has a poor reinforcing effect on natural rubber prepared by various processes; when 1.14>particle size ratio x>1.07, the filler has a general reinforcing effect on natural rubber prepared by various processes;

[0023] ④ Test the modulus of tensile stress y of the modified filler / natural rubber vulcanizate obtained by at least two different modification processes, and then substitute the modulus of tensile stress y and the value of the particle size ratio x obtained in step ② into the following functional relationship: y=a+bx

[0024] Where: a, b are constants;

[0025] By calculating the corresponding values ​​of a and b, a specific functional relationship corresponding to the evaluation of the reinforcing efficiency of the filler on natural rubber prepared by various processes based on the particle size of the combined rubber particles formed by the filler and natural rubber latex is obtained;

[0026] ⑤ According to steps ① and ②, the average particle size of the combined particles formed by the modified filler and natural rubber latex obtained by other modification processes is tested, and then the particle size ratio x is obtained. Then, the specific functional relationship obtained in step ④ is used to calculate the modulus of tensile stress y of the modified filler / natural rubber vulcanizate. The modulus of tensile stress y' of the natural rubber vulcanizate prepared by the same process without adding the modified filler is tested, and then R is calculated according to the formula R = [(y-y') / y']·100%. When R ≦ 10%, the reinforcing efficiency of the modified filler on natural rubber is low; when R ≧ 20%, the reinforcing efficiency of the modified filler on natural rubber is high; when 20% > R > 10%, the reinforcing efficiency of the modified filler on natural rubber is average.

[0027] As a further improvement to the technical solution of the method for judging enhancement efficiency of the present invention, in step ①, the concentration range of the prepared latex test solution only needs to meet the test range of the particle size test analyzer used.

[0028] As a further improvement to the technical solution of the method for judging enhancement efficiency of the present invention, in step ①, the prepared latex test liquid should be in a stable state and should not be demulsified.

[0029] As a further improvement to the technical solution of the method for evaluating enhancement efficiency of the present invention, in step ④, the mass ratio of the modified filler to natural rubber in the modified filler / natural rubber vulcanizate used in the tensile stress test is consistent with the mass ratio of the modified filler to natural rubber in the natural rubber latex in step ①.

[0030] The technical solution provided by the present invention has the following advantages compared with the prior art:

[0031] (1) The present invention can quickly and accurately determine the reinforcing effect and efficiency of fillers on natural rubber. On the one hand, it can provide a scientific, accurate, rapid and efficient evaluation method for the modification effect of fillers; on the other hand, it can lay the foundation for the scientific, accurate, rapid and efficient optimization of rubber formulations. It is of great significance for promoting the application of fillers in the field of high-performance natural rubber.

[0032] (2) The present invention is applicable to all reinforcing fillers commonly used in natural rubber, such as graphene oxide, carbon black, silica, etc., and is applicable to natural rubber vulcanizates prepared by different preparation methods, such as mechanical blending and solution blending, and has strong applicability.

[0033] (3) The preparation method of the test sample of the present invention is simple and environmentally friendly, without any stringent requirements. All the equipment involved is conventional and replaceable, so it has the advantages of being simple, green, and fast. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0036] FIG1 is a specific functional relationship obtained in Example 1 and Example 2 for judging the reinforcing efficiency of graphene oxide on natural rubber prepared by various processes based on the particle size of the combined colloid particles formed by modified graphene oxide and natural rubber latex.

[0037] FIG2 is the X-ray diffraction curves (XRD) of three modified graphene oxide / natural rubber compounds of Example 1.

[0038] FIG3 is a schematic diagram of the particle size changes of graphene oxide / natural rubber latex and modified graphene oxide / natural rubber latex according to the embodiment.

[0039] Figure 1 shows the specific functional relationship between the particle size of the bound particles formed by modified graphene oxide and natural rubber latex, as determined in Examples 1 and 2, for evaluating the graphene oxide's reinforcement efficiency for natural rubber prepared using various processes. Example 1 shows the specific functional relationship between the graphene oxide's reinforcement efficiency for natural rubber, obtained using three different modifiers: y = a + bx, where y is the modulus of tensile stress of the graphene oxide / natural rubber vulcanizate, and x is the particle size ratio = (average particle size of the bound particles formed by the modified graphene oxide and natural rubber latex obtained using different modification processes) / (average particle size of pure natural rubber latex at the same concentration without graphene oxide). Constant a = -1.747, constant b = 5.607. Based on this functional relationship, the reinforcing efficiency of different modified graphene oxides on natural rubber, obtained by varying the ratio of the same modifier to graphene oxide, can be calculated using the particle size ratio x = (average particle size of the bound particles formed by the modified graphene oxide and natural rubber latex, obtained by different modification processes) / (average particle size of pure natural rubber latex at the same concentration without the modified graphene oxide) to obtain the corresponding tensile stress value y of the vulcanized rubber, thereby obtaining R. It can be seen that the calculated tensile stress value is consistent with the actual tensile stress value, indicating that the streamlined method for evaluating the reinforcing effect and efficiency of fillers on natural rubber of the present invention is highly accurate. In addition, compared with traditional evaluation methods based on bound rubber content and evaluation methods based on the crosslink density of vulcanized rubber, the method of the present invention is time-saving, labor-saving, and environmentally friendly.

[0040] Figure 2 shows that 9° is the (001) crystal plane peak of graphene oxide (GO), among which GC (hexadecyltrimethylammonium bromide modified graphene oxide / natural rubber) and GT (Tween 20 modified graphene oxide / natural rubber) have smaller 2θ, indicating that the natural rubber (NR) molecular chain is successfully inserted between the GO sheets, and the interlayer spacing becomes larger. 19° is the broad peak of NR itself, which has shifted, indicating that the introduction of GO particles has reduced the lattice parameter of NR, reduced the amorphous part, and increased 2θ. The broad peak shift in the NR / GC spectrum is more significant, indicating that the interaction force between NR and modified GO in this system is the largest among the three mixed rubbers, followed by GT, and the worst is GS. This effectively corresponds to the average particle size of the bound particles formed by them with natural rubber latex, and then corresponds to the performance of the vulcanized rubber, verifying the accuracy of the evaluation method of the present invention.

[0041] Figure 3 shows that under strong interfacial interaction, the particle size of the bound particles formed by modified GO and natural rubber latex is larger than that of the bound particles formed by unmodified GO and natural rubber latex. When the interfacial interaction is weak, the particle size of the bound particles formed by GO and natural rubber latex is closer to the particle size of pure natural rubber latex, so the ratio between the two is closer to 1. When the interfacial interaction is strong, the interfacial interaction between modified GO and natural rubber latex exists, resulting in the adsorption of modified GO on the surface of natural rubber particles. As a result, the average particle size of the bound particles formed by modified GO and natural rubber latex increases, and its ratio to the particle size of pure natural rubber latex particles increases accordingly, reaching a maximum of 1.18, as shown in Figure 1. DETAILED DESCRIPTION

[0042] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0043] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all the embodiments.

[0044] The present invention provides a specific embodiment of a simplified method for evaluating the reinforcing effect of a filler on natural rubber based on the particle size of the combined rubber particles formed by the filler and the natural rubber latex, comprising the following steps:

[0045] ① Mix natural rubber latex and filler at a mass ratio of 100:5-0.1. After the interaction between the two in the aqueous phase causes the particle size of the latex to change, dilute it to a certain concentration of latex test solution;

[0046] ② Using an instrument capable of measuring the particle size of a dispersion, the particle size of the latex test solution obtained in step ① is measured, and the average particle size of the combined particles formed by the filler and the natural rubber latex and the average particle size of the pure natural rubber latex at the same concentration without the filler are obtained, and the particle size ratio x=d / d1 is calculated, where d represents the average particle size of the combined particles formed by the filler and the natural rubber latex, and d1 represents the average particle size of the pure natural rubber latex at the same concentration without the filler;

[0047] ③ When the particle size ratio x≧1.14, the filler has a good reinforcing effect on natural rubber prepared by various processes; when the particle size ratio x=1-1.07, the filler has a poor reinforcing effect on natural rubber prepared by various processes; when 1.14>the particle size ratio x>1.07, the filler has a general reinforcing effect on natural rubber prepared by various processes.

[0048] The present invention also provides a specific embodiment of a simplified method for evaluating the reinforcing efficiency of fillers on natural rubber based on the particle size of combined rubber particles formed by fillers and natural rubber latex, comprising the following steps:

[0049] ① Mix natural rubber latex and filler at a mass ratio of 100:5-0.1. After the interaction between the two in the aqueous phase causes the latex particle size to change, dilute it into a certain concentration of latex test solution;

[0050] ② Using an instrument capable of measuring the particle size of a dispersion, the particle size of the latex test solution obtained in step ① is measured, and the average particle size of the combined particles formed by the filler and the natural rubber latex and the average particle size of the pure natural rubber latex at the same concentration without the filler are obtained, and the particle size ratio x=d / d1 is calculated, where d represents the average particle size of the combined particles formed by the filler and the natural rubber latex, and d1 represents the average particle size of the pure natural rubber latex at the same concentration without the filler;

[0051] ③ When the particle size ratio x≧1.14, the filler has a good reinforcing effect on natural rubber prepared by various processes; when the particle size ratio x=1-1.07, the filler has a poor reinforcing effect on natural rubber prepared by various processes; when 1.14>particle size ratio x>1.07, the filler has a general reinforcing effect on natural rubber prepared by various processes;

[0052] ④ Test the modulus of tensile stress y of the modified filler / natural rubber vulcanizate obtained by at least two different modification processes, and then substitute the modulus of tensile stress y and the value of the particle size ratio x obtained in step ② into the following functional relationship: y=a+bx

[0053] Where: a, b are constants;

[0054] By calculating the corresponding values ​​of a and b, a specific functional relationship corresponding to the evaluation of the reinforcing efficiency of the filler on natural rubber prepared by various processes based on the particle size of the combined rubber particles formed by the filler and natural rubber latex is obtained;

[0055] ⑤ According to steps ① and ②, the average particle size of the combined particles formed by the modified filler obtained by other modification processes and the natural rubber latex is tested, and then the particle size ratio x is obtained. Then, the specific functional relationship obtained in step ④ is used to calculate the modulus stress value y of the modified filler / natural rubber vulcanizate; the modulus stress value y' of the natural rubber vulcanizate prepared by the same process without adding the modified filler is tested, and then R is calculated according to the formula R = [(y-y') / y']·100%. When R ≦ 10%, the reinforcing efficiency of the modified filler on natural rubber is low; when R ≧ 20%, the reinforcing efficiency of the modified filler on natural rubber is high; when 20% > R > 10%, the reinforcing efficiency of the modified filler on natural rubber is average.

[0056] In the two simplified methods provided by the present invention for judging the reinforcing effect and efficiency of natural rubber based on the particle size of the combined rubber particles formed by the filler and natural latex, in step ①, the concentration range of the prepared latex test liquid only needs to meet the test range of the particle size test analyzer used.

[0057] Furthermore, in step ①, the prepared latex test solution should be in a stable state without demulsification.

[0058] Furthermore, in step ④, the mass ratio of the modified filler to natural rubber in the modified filler / natural rubber vulcanizate used in the tensile stress test is consistent with the mass ratio of the modified filler to natural rubber in the natural rubber latex in step ①.

[0059] The specific embodiments of the present invention are described in detail below.

[0060] Example 1:

[0061] 1. GO was modified with three surface modifiers: cetyltrimethylammonium bromide, sodium lauryl sulfate, and Tween 20. The resulting modified GOs were named GC, GS, and GT, respectively. Natural rubber latex and the three modified GOs were mixed at a mass ratio of 100:0.5 to prepare a uniformly dispersed latex test solution with a concentration of 2.5 mg / L.

[0062] ② Use a particle size analyzer to measure the particle size of each latex test solution and obtain an average value. In this example, the average particle size of the pure natural rubber latex particles obtained by testing was 369.7 μm. The average particle size and corresponding particle size ratio x of the combined particles formed by the three modified GO and natural rubber latex are shown in Table 1.

[0063] ③ The particle size of the bound particles formed by the three modified GO systems and natural rubber latex increased. Among them, the bound particles of the GC-modified system were the largest, indicating that it has the strongest adsorption effect on natural rubber latex particles in the aqueous phase. In this example, the particle size ratio x of the average particle size of the bound particles of the GC-modified system to the particle size of the pure natural rubber latex is 1.089, indicating that this filler has a significant reinforcing effect on natural rubber vulcanizates prepared by various processes. The measured results show that the 100% modulus of tensile stress y' of the pure natural rubber vulcanizate is 3.866 MPa, while the 100% modulus of tensile stress y of the GC / NR is 4.397 MPa. R = [(4.397-3.866) / 3.866]·100% = 13.7%, which is consistent with the reinforcing effect obtained by the method of the present invention.

[0064] ④ After mixing natural rubber latex and three modified GO materials at a mass ratio of 100:0.5, 10 wt.% flocculant CaCl2 solution was added to break the emulsion and the mixture was dried in an oven at 50°C to constant weight. After mixing in an internal mixer at 110°C and 40 rpm for 4 minutes, 2 g of vulcanization accelerator N-(oxydiethylene)-2-benzothiazolesulfenamide, 2 g of antioxidant N-(1-methylisopentyl)-N'-phenyl-p-phenylenediamine, and 2 g of antioxidant 2,2,4-trimethyl-1,2-dihydroquinoline polymer were added and mixed for 4 minutes. 5 g of activator zinc oxide and 2 g of softener stearic acid were added and mixed for 4 minutes. 60 g of reinforcing filler carbon black was added and mixed for another 4 minutes before discharging the rubber compound. After the rubber compound cools to room temperature, transfer it to an open mill and mix it at 60℃. After it is evenly dispersed, add 2g of sulfur and mix it evenly. Then, pass it through the mill until there are no bubbles in the rubber compound. The total mixing time is 10min. After 24h of mixing, place the mixed rubber in a mold and vulcanize it at 150℃*15MPa for 5min (t c90 ), and three modified GO / natural rubber vulcanizates were obtained, among which t c90 Measured using a rubber process analyzer (RPA). Tensile stress at a specific tensile strength was determined using a universal tensile testing machine (AL-7000-SGD, High Speed ​​Rail Testing Instruments Co., Ltd.). The tensile properties were tested according to ISO 37-2005 at a rate of 500 mm / min.

[0065] Graphene oxide modified with three different modifiers yielded a specific functional relationship for its reinforcement efficiency on natural rubber: y = a + bx, where y is the modulus of tensile stress of the graphene oxide / natural rubber vulcanizate, and x is the particle size ratio = (average particle size of the bound particles formed by the modified graphene oxide and natural rubber latex obtained using different modification processes) / (average particle size of pure natural rubber latex at the same concentration without graphene oxide). Constant a = -1.747, constant b = 5.607. Subsequent Example 2 directly utilized this specific functional relationship to calculate the modulus of tensile stress of the modified graphene oxide / natural rubber vulcanizates obtained using different modification processes, with the results shown in Figure 1. Further analysis revealed that the GC-modified system had the highest amount of filler-restricted rubber in the vulcanizate, resulting in the highest bound rubber content. As shown in Figure 2, the interfacial interaction between GC-modified graphene oxide and natural rubber in the rubber mix is ​​the strongest, indicating that the law of the present invention is clearly reflected in the natural rubber mix. This effectively corresponds to the average particle size of the combined rubber particles formed with natural latex, and then corresponds to the performance of the vulcanized rubber, which also verifies the reliability of the evaluation method of the present invention.

[0066] Table 1 Bound rubber particle size and particle size ratio in the latex of Example 1, as well as 100% modulus of tensile stress, 300% modulus of tensile stress, bound rubber content, and crosslinking density of the vulcanized rubber

[0067] Example 2:

[0068] 1. Graphene oxide was modified with the surface modifier cetyltrimethylammonium bromide at varying mass ratios of GO to graphene oxide (1:1, 2:1, 3:1, 4:1, 5:1, and 6:1). Natural rubber latex and modified graphene oxide obtained by different modification processes were mixed at a mass ratio of 100:0.5 to prepare a uniform latex test solution with a concentration of 2.5 mg / L.

[0069] ② Use a particle size analyzer to measure and obtain the average particle size of each latex sample. In this example, the average particle size of the pure natural rubber latex obtained was 369.7 μm. The size of the combined particles formed by the modified GO and natural rubber latex and the particle size ratio x are shown in Table 2.

[0070] ③ In this example, the combined particles of graphene oxide and natural rubber latex modified with cetyltrimethylammonium bromide in a mass ratio of 2:1 exhibited the largest particle size, indicating the strongest adsorption of the modified GO particles to the natural rubber latex in the aqueous phase. The particle size ratio, x, was 1.178, demonstrating the enhanced reinforcing effect of this modified GO on natural rubber. In this example, the 100% modulus of tensile stress, y', for the pure natural rubber vulcanizate was 3.866 MPa, while the 100% modulus of tensile stress, y, for the graphene oxide / NR vulcanizate modified with cetyltrimethylammonium bromide in a mass ratio of 2:1 was 4.453 MPa. The ratio R = [(4.453 - 3.866) / 3.866] · 100% = 24.9%, consistent with the reinforcement results obtained by the present method. Furthermore, the particle size of the GC-modified system showed a positive correlation with the variation in the particle size of the natural rubber latex, as well as the conventional bound rubber content and crosslink density, demonstrating the reliability of the present method. ④ Natural rubber latex and the various modified graphene oxides were uniformly mixed at a mass ratio of 100:0.5, and a 10 wt.% flocculant CaCl2 solution was added to break the emulsion. The mixture was then dried in a 50°C oven to constant weight. In an internal mixer, mix at 110°C and 40 rpm for 4 minutes, then add 2g of vulcanization accelerator N-(diethylene oxide)-2-benzothiazole sulfenamide, 2g of antioxidant N-(1-methylisopentyl)-N'-phenyl-p-phenylenediamine, and 2g of antioxidant 2,2,4-trimethyl-1,2-dihydroquinoline polymer and mix for 4 minutes. Then add 5g of activator zinc oxide and 2g of softener stearic acid and mix for 4 minutes. Add 60g of reinforcing filler carbon black and mix for another 4 minutes, then discharge the rubber. After the rubber cools to room temperature, transfer it to an open mixer and mix at 60°C. After uniform dispersion, add 2g of sulfur and mix well. Then, thinly pass the rubber until there are no bubbles in the rubber. The total mixing time is 10 minutes. After 24 hours of stopping the rubber, place the mixed rubber in a mold and vulcanize it at 150°C*15MPa for 5 minutes (t c90 ), then the modified GO / natural rubber vulcanizate is obtained, where t c90 Measured using a rubber process analyzer (RPA). Tensile stress at a specific tensile strength was determined using a universal tensile testing machine (AL-7000-SGD, High Speed ​​Rail Testing Instruments Co., Ltd.). Tensile properties were tested according to ISO 37-2005 at a rate of 500 mm / min.

[0071] ⑤ Given the functional relationship y = a + bx between the particle size ratio and the 100% modulus of tensile stress of the rubber composite, the modulus of tensile stress y of the modified graphene oxide / natural rubber vulcanizate obtained by this modification process was calculated based on a = -1.747 and b = 5.607 obtained in Example 1, and the particle size ratio x obtained in step ③. Furthermore, R = [(y - y') / y'] · 100% was calculated. The results are shown in Table 2. As can be seen, the calculated modulus of tensile stress is highly consistent with the actual value, indicating that this functional relationship can be used to evaluate the reinforcing efficiency of other fillers in natural rubber composites based on the particle size of the combined particles formed with natural rubber latex. This avoids subsequent processing, facilitates the evaluation of rubber products before industrial production, rapidly optimizes rubber formulations, and efficiently evaluates the effectiveness of filler modification.

[0072] Table 2 Bound rubber particle size and particle size ratio in the latex of Example 2, as well as 100% modulus of tensile stress, 300% modulus of tensile stress, bound rubber content, and crosslinking density of the vulcanized rubber

[0073] The above description is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Although detailed descriptions have been made with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents; and such modifications or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the technical solutions of the embodiments, and they should all be included in the scope of protection of the claims.

Claims

1. A simplified method for evaluating the reinforcing effect of fillers on natural rubber based on the particle size of the combined rubber particles formed by fillers and natural rubber latex, characterized in that: The following steps are involved: ① Mix natural rubber latex and filler at a mass ratio of 100:5-0.

1. After the interaction between the two in the aqueous phase causes the particle size of the latex to change, dilute it to a certain concentration of latex test solution; ② Using an instrument capable of measuring the particle size of a dispersion, the particle size of the latex test solution obtained in step ① is measured, and the average particle size of the combined particles formed by the filler and the natural rubber latex and the average particle size of the pure natural rubber latex at the same concentration without the filler are obtained, and the particle size ratio x=d / d1 is calculated, where d represents the average particle size of the combined particles formed by the filler and the natural rubber latex, and d1 represents the average particle size of the pure natural rubber latex at the same concentration without the filler; ③ When the particle size ratio x≧1.14, the filler has a good reinforcing effect on natural rubber prepared by various processes; when the particle size ratio x=1-1.07, the filler has a poor reinforcing effect on natural rubber prepared by various processes; when 1.14>the particle size ratio x>1.07, the filler has a general reinforcing effect on natural rubber prepared by various processes.

2. The simplified method for judging the reinforcing effect of fillers on natural rubber based on the particle size of the combined rubber particles formed by fillers and natural rubber latex according to claim 1, characterized in that: In step ①, the concentration range of the prepared latex test solution only needs to meet the test range of the particle size test analyzer used.

3. The simplified method for judging the reinforcing effect of fillers on natural rubber based on the particle size of the combined rubber particles formed by fillers and natural rubber latex according to claim 1, characterized in that: In step ①, the prepared latex test solution should be in a stable state without demulsification.

4. A simplified method for evaluating the reinforcing efficiency of fillers on natural rubber based on the particle size of the combined particles formed by fillers and natural rubber latex, characterized in that: The following steps are involved: ① Mix natural rubber latex and filler at a mass ratio of 100:5-0.

1. After the interaction between the two in the aqueous phase causes the particle size of the latex to change, dilute it to a certain concentration of latex test solution; ② Using an instrument capable of measuring the particle size of a dispersion, the particle size of the latex test solution obtained in step ① is measured, and the average particle size of the combined particles formed by the filler and the natural rubber latex and the average particle size of the pure natural rubber latex at the same concentration without the filler are obtained, and the particle size ratio x=d / d1 is calculated, where d represents the average particle size of the combined particles formed by the filler and the natural rubber latex, and d1 represents the average particle size of the pure natural rubber latex at the same concentration without the filler; ③ When the particle size ratio x≧1.14, the filler has a good reinforcing effect on natural rubber prepared by various processes; when the particle size ratio x=1-1.07, the filler has a poor reinforcing effect on natural rubber prepared by various processes; when 1.14>particle size ratio x>1.07, the filler has a general reinforcing effect on natural rubber prepared by various processes; ④ Test the modulus of tensile stress y of the modified filler / natural rubber vulcanizate prepared by a certain process of the modified filler obtained by at least two different modification processes respectively, and then substitute the modulus of tensile stress y and the value of the particle size ratio x obtained in step ② into the following functional relationship: y=a+bx Where: a, b are constants; By calculating the corresponding values of a and b, a specific functional relationship corresponding to the evaluation of the reinforcing efficiency of the filler on natural rubber prepared by various processes based on the particle size of the combined rubber particles formed by the filler and natural rubber latex is obtained; ⑤ According to steps ① and ②, the average particle size of the combined particles formed by the modified filler obtained by other modification processes and the natural rubber latex is tested, and then the particle size ratio x is obtained. Then, the specific functional relationship obtained in step ④ is used to calculate the modulus stress value y of the modified filler / natural rubber vulcanizate; the modulus stress value y' of the natural rubber vulcanizate prepared by the same process without adding the modified filler is tested, and then R is calculated according to the formula R = [(y-y') / y']·100%. When R ≦ 10%, the reinforcing efficiency of the modified filler on natural rubber is low; when R ≧ 20%, the reinforcing efficiency of the modified filler on natural rubber is high; when 20% > R > 10%, the reinforcing efficiency of the modified filler on natural rubber is average.

5. The simplified method for judging the reinforcing efficiency of natural rubber based on the particle size of the combined rubber particles formed by the filler and the natural rubber latex according to claim 4, characterized in that: In step ①, the concentration range of the prepared latex test solution only needs to meet the test range of the particle size test analyzer used.

6. The simplified method for judging the reinforcing efficiency of natural rubber based on the particle size of the combined rubber particles formed by the filler and the natural rubber latex according to claim 4, characterized in that: In step ①, the prepared latex test solution should be in a stable state without demulsification.

7. The simplified method for judging the reinforcing efficiency of natural rubber based on the particle size of the combined rubber particles formed by the filler and the natural rubber latex according to claim 4, characterized in that: In step ④, the mass ratio of the modified filler to natural rubber in the modified filler / natural rubber vulcanizate used in the tensile stress test is consistent with the mass ratio of the modified filler to natural rubber in the natural rubber latex in step ①.

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