A carbon nanotube composite rubber and its preparation method

Abstract

This invention discloses a carbon nanotube composite rubber and its preparation method. By controlling the amount of carbon nanotubes added, the coagulation method of Bacillus subtilis and Streptomyces actinomycetes, and the latex coagulation time, this invention improves the dispersion of carbon nanotubes and the bonding between the coupling agent and the latex, solving the problem of carbon nanotube agglomeration and improving the dispersion grade of the composite masterbatch. When preparing the composite solution, the pH is controlled between 3.5 and 5, which accelerates the catalytic effect of the coupling agent and strengthens the interfacial interaction with the matrix, overcoming the shortcomings of polymer nanocomposites such as low elongation, high viscosity, poor processing performance, complex processes, and high production costs. High-temperature drying specifically improves dispersibility and controls drying time, increasing production speed.

Description

Technical Field

[0001] This invention relates to the field of composite rubber, and more particularly to a carbon nanotube composite rubber and its preparation method. Background Technology

[0002] Carbon nanotubes are one-dimensional nanomaterials. In the field of engineering materials, carbon nanotubes are ideal fillers for polymer materials due to their excellent physical and mechanical properties. They have excellent mechanical properties, electrical conductivity, and thermal conductivity, and are therefore considered ideal mechanical strengthening and functional modification materials for polymer-based composite materials. Composite materials made with carbon nanotubes exhibit good elasticity and strength. Carbon nanotubes will be gradually used in industries such as rubber products, tires, and plastics. Simply using raw rubber to manufacture rubber products cannot give full play to the advantages of natural rubber. In order to improve the performance of natural rubber, it is necessary to add reinforcing fillers to natural rubber.

[0003] In the rubber industry, incorporating carbon nanotubes into a rubber matrix to improve its properties has become an ideal composite material for researching high-end rubber products. However, the hydrophobic and oleophobic properties of carbon nanotubes result in a relatively poor interface between the rubber and the carbon nanotubes. Carbon nanotubes themselves have high surface free energy, making them prone to aggregation. The interaction between carbon nanotubes and the matrix is ​​another challenge. The lack of reactive functional groups on the carbon nanotube surface and their inertness weaken the chemical interface between them and the polymer matrix, making it difficult to achieve the desired improvement effect on the polymer matrix. This leads to poor stress transfer and low mechanical properties. Nevertheless, the dispersibility of carbon nanotubes and the interfacial interaction between them and rubber can determine the overall performance of rubber / carbon nanotube composites. The comprehensive performance of carbon nanotubes and their composites is necessary to expand their application areas; therefore, this invention is one method to solve the above problems.

[0004] Chinese patent application number 201810661849.1 discloses a method for preparing a carbon nanotube-carbon black-natural rubber composite masterbatch. This method involves ball milling carbon nanotubes into a chopped tube suspension in a dispersion, modifying carbon black with a surfactant, emulsifying the modified carbon black into a carbon black slurry, mixing the chopped tube suspension and carbon black slurry with natural rubber latex to obtain a carbon nanotube-carbon black-natural rubber composite material, and then coagulating and drying the composite material to obtain the carbon nanotube-carbon black-natural rubber composite masterbatch. The composite masterbatch prepared by this patent contains two reinforcing fillers, carbon black and nanotubes, which increases production costs. Furthermore, the use of a water bath coagulation method for preparing the composite rubber is not conducive to improving the agglomeration phenomenon between the carbon nanotubes and the matrix. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing carbon nanotube composite rubber. The composite masterbatch prepared by this invention employs a reinforcing filler and a bio-coagulation method, which to some extent solves the agglomeration phenomenon between nanomaterials and the matrix, improving the dispersion of the composite masterbatch. The addition of a coupling agent, adjustment of the pH of the prepared solution, and high-temperature drying accelerate the catalytic effect of the coupling agent and strengthen the interfacial interaction with the matrix, overcoming the drawbacks of low elongation, high viscosity, poor processing performance, and complex processes in polymer nanocomposites. When applied to rubber compounds, it exhibits high performance and high dispersion, reducing industrial production costs and meeting the demand for higher mechanical properties in rubber composites.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: a method for preparing carbon nanotube composite rubber, wherein the preparation method is operated as follows:

[0007] Step (1) Preparation of carbon nanotube dispersion: Calculate the amount of carbon nanotubes to be added and the ratio of water to carbon nanotubes based on the weight of dry adhesive. After mixing carbon nanotubes with water, add dispersant and coupling agent. Adjust the pH to 3.5-5.5 using formic acid reagent and emulsify evenly for 20-40 minutes to obtain carbon nanotube dispersion.

[0008] Step (2) The carbon nanotube dispersion, latex and biological culture medium are stirred evenly and then poured into a long tank for aging for 14-24 hours; the biological culture medium is a mixture of Bacillus subtilis culture medium and Streptomyces actinomycetes culture medium at a volume ratio of 4-6:4-6.

[0009] Step (3) The lumps in the matured long trough are pressed thin to 3-5 cm, and then placed in an oven to dry at 95-105℃ to prepare carbon nanotube composite rubber.

[0010] Preferably, the dispersant is sodium dodecylbenzenesulfonate; the coupling agent is silane coupling agent SI-69 or phthalate coupling agent 201.

[0011] Preferably, carbon nanotubes account for 3-5% of the dry adhesive content, the mass ratio of carbon nanotubes to water is 1:40-60, the dispersant accounts for 3-6% of the dry adhesive content, and the coupling agent accounts for 0.3-1.2% of the latex content.

[0012] Preferably, the Bacillus subtilis culture medium consists of the following components: 4-6g beef extract, 8-12g peptone, 4-6g sodium chloride, 18-22g agar, and 800-1200mL distilled water. The cultured bacterial solution is added at a ratio of 2kg latex / 20-40g bacterial solution.

[0013] Preferably, the Streptomyces actinomycete culture medium consists of the following components: 18-22g soluble starch, 0.8-1.2g potassium nitrate, 0.4-0.6g sodium chloride, 0.4-0.6g dipotassium hydrogen phosphate, 0.4-0.6g magnesium sulfate, 0.01-0.015g ferrous sulfate, 18-22g agar, and 800-1200mL distilled water, with a pH of 7.2-7.4. The cultured bacterial solution is added at a ratio of 2kg latex / 20-40g bacterial solution.

[0014] Preferably, the viable count of Bacillus subtilis in the culture medium is 1.1-1.3 billion / mL, and the viable count of Streptomyces actinomycetes in the culture medium is 1.1-1.2 billion / mL.

[0015] Preferably, 1-5% alkaline protease is added to the mixed culture medium of Bacillus subtilis and Streptomyces actinomycetes. When alkaline protease treats fresh latex, as an endopeptidase, it promotes the enzymatic hydrolysis of proteins adsorbed around rubber particles, forming short peptides or amino acids, which causes the latex to coagulate.

[0016] In a second aspect, the present invention also provides a carbon nanotube composite rubber prepared by the method.

[0017] Compared with existing technologies, the present invention has the following beneficial effects: By controlling the amount of carbon nanotubes added, the coagulation method of the biological bacteria, and the coagulation time of the latex, the present invention improves the dispersion of carbon nanotubes and the bonding between the coupling agent and the latex, solving the problem of carbon nanotube agglomeration and improving the dispersion grade of the composite masterbatch; when preparing the composite solution, the pH is controlled between 3.5 and 5, which accelerates the catalytic effect of the coupling agent and strengthens the interfacial interaction with the matrix, solving the disadvantages of low elongation, high viscosity, poor processing performance, complex process, and high production cost of polymer nanocomposites; high-temperature drying specifically improves the dispersibility and drying time control, thus increasing the production speed. Attached Figure Description

[0018] Figure 1 This is a flowchart of the formic acid solidification process.

[0019] Figure 2 This is a flowchart of the biological coagulation process;

[0020] Figure 3 This is a scatter plot;

[0021] Figure 4 This is a scatter plot;

[0022] Figure 5 This is a graph showing the dispersion results.

[0023] Figure 6 This is a graph showing the dispersion results.

[0024] Figure 7 This is a graph showing the dispersion results.

[0025] Figure 8 This is a graph showing the dispersion results. Detailed Implementation

[0026] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited to the following technical solutions. The product index requirements and testing methods for the composite rubber prepared by the present invention are shown in Table 1. The Bacillus subtilis and Actinomycetes strains used in the present invention were purchased from the Shanghai Preservation Biotechnology Center. The alkaline protease was purchased from Cangzhou Xiasheng Enzyme Biotechnology Co., Ltd., with an enzyme activity of 200,000 u / g.

[0027] Table 1 Product Specifications and Testing Methods

[0028]

[0029] Compared with ordinary WF indicators, the main differences are in Mooney viscosity, high dispersion and higher tensile strength.

[0030] Composite rubber processing steps:

[0031] 1. Weighing of latex upon arrival at the factory → Filtration → Inspection of appearance quality → Measurement of dry content → Calculation of dry latex quantity;

[0032] 2. Preparation of carbon nanotube dispersion: Calculate carbon nanotubes based on the amount of dry gel → calculate the ratio of water to carbon nanotubes → add dispersant → coupling agent → adjust pH → emulsify for 30 min → carbon nanotube dispersion;

[0033] 3. Dispersion → Latex → The bacteria and latex are stirred evenly and then flowed into a long tank to solidify;

[0034] 4. Mature the lumps in the long tank for 16-24 hours;

[0035] 5. After curing, the lumps in the long tank are pressed into thinner pieces and then dried in an oven at 105℃ → carbon nanotube composite rubber;

[0036] (1) Preparation of carbon nanotube composite slurry:

[0037] a. Carbon nanotubes account for 3% of the dry adhesive content, the ratio of carbon nanotubes to water is 1:50, the dispersant (sodium dodecylbenzenesulfonate) accounts for 5% of the dry adhesive content, the coupling agent accounts for 1% of the latex content, and the pH is 5.

[0038] b. Carbon nanotubes account for 4% of the dry adhesive content, the ratio of carbon nanotubes to water is 1:50, the dispersant (sodium dodecylbenzenesulfonate) accounts for 5% of the dry adhesive content, the coupling agent accounts for 1% of the dry adhesive content, and the pH is 5.

[0039] The dry adhesive contains 5% carbon nanotubes, the ratio of carbon nanotubes to water is 1:50, the dispersant (sodium dodecylbenzenesulfonate) contains 5% dispersant, the coupling agent contains 1% coupling agent, and the pH is 5.

[0040] (2) Biological coagulation:

[0041] Bacillus subtilis, Actinomycetes

[0042] 1) The two microorganisms were enriched and expanded according to the operation method of Example 1;

[0043] 2) Number of parts of microbial culture medium added:

[0044] a. Mix and stir evenly according to the ratio of 6 parts Bacillus subtilis culture medium and 4 parts actinomycete culture medium;

[0045] b. Mix and stir thoroughly according to the ratio of 5 parts Bacillus subtilis culture medium and 5 parts actinomycete culture medium;

[0046] c. Mix and stir thoroughly according to the ratio of 4 parts Bacillus subtilis culture medium and 6 parts actinomycete culture medium;

[0047] 3) Add a certain proportion of alkaline protease to the composite microbial culture medium to prepare a composite microbial coagulation solution.

[0048] 4) The amount of alkaline protease added is 1%-5% of the latex weight:

[0049] a, 1%

[0050] b, 2%

[0051] c. 3%

[0052] d, 4%

[0053] e, 5%

[0054] Experiments have shown that the optimal solution is:

[0055] Microbial culture medium addition ratio: Add 6 parts (5g / part) to 2kg latex, according to the ratio of 6 parts Bacillus subtilis culture medium, 4 parts Actinomycete culture medium, 5g / part, and 3% alkaline protease, and mix well.

[0056] (3) Drying: Drying temperature 105℃.

[0057] Example 1: Cultivation of bacterial strains

[0058] 1. Screening of Bacillus subtilis strains

[0059] From the purchased Bacillus subtilis slant, select a small number of colonies and streak them onto a Bacillus spore-forming medium (5g beef extract, 10g peptone, 5g sodium chloride, 20g agar, 1000mL distilled water) on a Petri dish. Incubate at 37℃ for approximately 20 hours. Remove the larger colonies and transfer them to a test tube containing 5mL sterile water. Shake well and heat in a 100℃ water bath for 15 minutes. Then, spread the mixture onto a Petri dish containing the spore-forming medium and incubate repeatedly. Finally, transfer the larger colonies from the Petri dish to a slant of the spore-forming medium in a test tube, incubate at 37℃ for approximately 20 hours, and then store in a 4℃ refrigerator for later use.

[0060] 2. Preparation of Bacillus subtilis bacterial culture

[0061] The preserved bacterial strain was activated, and then 5% of the inoculum was inoculated into 1000 mL of culture medium (5 g beef extract, 10 g peptone, 5 g sodium chloride, and 1000 mL distilled water). The medium was incubated at 37°C and 180 rpm for 18 hours. The cultured bacterial solution was then stored for later use.

[0062] 3. Screening of actinomycete strains

[0063] Select a small number of colonies from the purchased actinomycete slant and streak them onto a culture medium (20g soluble starch + 1g potassium nitrate + 0.5g sodium chloride + 0.5g dipotassium hydrogen phosphate + 0.5g magnesium sulfate + 0.01g ferrous sulfate + 20g agar + 1000mL water). Incubate on a petri dish at 28-30℃ for 3-7 days to allow colonies to form. Repeat this process several times. Finally, select the largest colonies from the petri dish and transfer them to a test tube slant of the actinomycete culture medium. Incubate at 28-30℃ for approximately 3-7 days and then remove and store.

[0064] 4. Preparation of Actinomycete Culture

[0065] Spores were inoculated into shake flasks containing liquid culture medium and cultured at a constant temperature using a shaker to obtain mycelium. The inoculation amount was 5%, and the culture medium consisted of 20g soluble starch + 1g potassium nitrate + 0.5g sodium chloride + 0.5g dipotassium hydrogen phosphate + 0.5g magnesium sulfate + 0.01g ferrous sulfate + 1000mL water. The cultured bacterial solution was stored for later use.

[0066] Example 2

[0067] Preparation of carbon nanotube suspension: 16.8g of 3% carbon nanotubes was mixed with 840g of deionized water (ratio 1:50), then 28g of dispersant (sodium dodecylbenzenesulfonate) was added and ultrasonically dispersed. Then 5.6g of 1% silane coupling agent was added and emulsified uniformly, and the pH was adjusted to 5 to obtain a carbon nanotube suspension with a weight of approximately 890.5g.

[0068] Preparation of mixed bacterial strains: 6 parts of Bacillus subtilis culture medium, 4 parts of Actinomycetes-Streptomyces culture medium, and 4% alkaline protease were mixed and stirred evenly; each part of bacterial solution was 5g.

[0069] Take 2000g of latex with a dry rubber content of 28% and add it to the 890.5g carbon nanotube suspension prepared above. Mix the mixture evenly using parallel stirring blades, add the mixed bacteria to solidify, and after 22h of curing, further process the composite material by pressing, washing and drying to obtain carbon nanotube-natural rubber composite material.

[0070] Example 3

[0071] Preparation of carbon nanotube suspension: 22.4g of 4% carbon nanotubes were mixed with 1120g of water (ratio 1:50), then 28g of dispersant (sodium dodecylbenzenesulfonate) was added and ultrasonically dispersed. Then 5.6g of 1% silane coupling agent was added and emulsified uniformly, and the pH was adjusted to 5 to obtain a carbon nanotube suspension with a weight of approximately 1176g.

[0072] Preparation of mixed bacterial strains: 6 parts of Bacillus subtilis culture medium, 4 parts of Actinomycetes-Streptomyces culture medium, and 3% alkaline protease were mixed and stirred evenly, with each part containing 5g of bacterial solution.

[0073] Take 2000g of latex with a dry rubber content of 28% and add it to the 1176g carbon nanotube suspension prepared above. Mix the mixture evenly using parallel stirring blades. Add the mixed bacteria to solidify the mixture. After 22 hours of curing, further process the composite material by pressing, washing, and drying to obtain a carbon nanotube-natural rubber composite material.

[0074] Example 4

[0075] Preparation of carbon nanotube suspension: 28g of 5% carbon nanotubes were mixed with 1400g of water (ratio 1:50), then 28g of dispersant (sodium dodecylbenzenesulfonate) was added and ultrasonically dispersed for 30min. Then 5.6g of 1% silane coupling agent was added and emulsified uniformly for 30min and the pH was adjusted to 5 to obtain a carbon nanotube suspension with a weight of approximately 14896g.

[0076] Preparation of mixed bacterial cultures: Mix 6 parts of Bacillus subtilis-Bacillus subtilis culture medium, 4 parts of Actinomycetes-Streptomyces culture medium, and 5% alkaline protease in a homogeneous ratio. Each culture medium contains 5g.

[0077] Take 2000g of latex with a dry rubber content of 28% and add it to the 1489g carbon nanotube suspension prepared above. Mix the mixture evenly using parallel stirring blades. Add the mixed bacteria to solidify the mixture. After aging for 22 hours, further process the composite material by pressing, washing, and drying to obtain a carbon nanotube-natural rubber composite material.

[0078] The experimental results are shown in Table 2.

[0079] Table 2 Comparison of Raw Rubber Indicators and Requirements

[0080]

[0081]

[0082] As can be seen from Table 2, the rubbers obtained in Examples 2-4 all meet the requirements, while the rubber prepared in Example 3 has the best performance.

[0083] Example 5: Screening of Experimental Conditions

[0084] The effects of solidification method, maturation time, and different dispersants on performance are as follows.

[0085] The formic acid coagulation process is as follows: preparation of carbon nanotube dispersion → addition of fresh latex and formic acid → coagulation and composite masterbatch, such as... Figure 1 As shown.

[0086] The bio-coagulation process is as follows: preparation of carbon nanotube dispersion → addition of fresh latex and bio-coagulant → coagulated composite latex, such as... Figure 2 As shown.

[0087] Table 3. Effects of different solidification methods on performance.

[0088] Performance / Setting Method Required indicators Formic acid coagulation Water bath solidification Biological coagulation Initial value of plasticity, minimum value 30 48 —— 50 Plasticity retention rate, minimum value 60 70 —— 72 *Mounney viscosity, mL / (1′+4′)100℃ ≥80 86.4 75.1 95.6 Tensile strength, MPa, minimum value 20 18.5 27.2 27.7 *Elongation at break, %, minimum value 730 756 —— 808.6 Nitrogen content, % (m / m), maximum value 0.6 0.346 0.372 0.1347

[0089] Table 3 shows that the performance test data of initial plasticity, plasticity retention rate, Mooney viscosity, tensile strength, elongation at break, and nitrogen content all changed under the three different solidification methods. Therefore, among the five test data, the performance test data of bio-solidification is relatively better.

[0090] Table 4. Effects of different curing times on the performance of bio-coagulation

[0091] Performance / Curing Time Required indicators 16h 18h 20h 22h 24h Initial value of plasticity, minimum value 30 46 47 48 50 51 Plasticity retention rate, minimum value 60 74.6 73.5 73 72 71 *Mounney viscosity, mL / (1′+4′)100℃ ≥80 87.6 89.3 92 95.6 96 Tensile strength, MPa, minimum value 20 22.724 24.289 25.9 27.7 25.4 *Elongation at break, %, minimum value 730 777 756.5 780.8 808.6 791.2 Nitrogen content, % (m / m), maximum value 0.6 0.2971 0.2632 0.1431 0.1347 0.1339

[0092] Table 4 shows that the performance test data of initial plasticity, plasticity retention rate, Mooney viscosity, tensile strength, elongation at break, and nitrogen content all changed with different curing times. Analyzing the curing time from 16h to 18h, the data did not change significantly, but the data from 16h to 22h and 24h showed that all five properties changed. The optimal curing time was 22h, so the curing time for this experiment was 22h.

[0093] Table 5 Effects of different dispersants and coupling agents on the performance of biocoagulation.

[0094]

[0095]

[0096] As shown in Table 5, different dispersants did not show significant changes in initial plasticity, plasticity retention rate, and nitrogen content, but there were obvious differences in Mooney viscosity, tensile strength, and elongation at break. The test data of adding sodium dodecylbenzenesulfonate to the two dispersants were better than those of adding CNF dispersant. The test data of adding silane coupling agent to the two silane coupling agents were significantly better than those of phthalate coupling agent. Therefore, sodium dodecylbenzenesulfonate was selected as the dispersant with better data, and silane coupling agent was selected as the coupling agent.

[0097] Example 6

[0098] The dispersibility of rubber prepared by coagulating 3-5% carbon nanotubes with formic acid is as follows: Figures 3-5 As shown; the dispersibility of rubber prepared with a composite bio-coagulation solution containing 3-5% carbon nanotubes is as follows: Figures 6-8 As shown.

[0099] Figure 3 The preparation of 3% carbon nanotube dispersion was carried out by adding 2 kg of fresh rubber latex, coagulating with formic acid, and then pressing, washing and drying to obtain carbon nanotube-natural rubber composite material. After mixing and vulcanization, the carbon nanotube dispersibility of the vulcanized sample was tested and the dispersibility was measured to be level 3.

[0100] Figure 4 The preparation of 4% carbon nanotube dispersion was followed by the addition of 2 kg of fresh rubber latex, coagulation with formic acid, and the carbon nanotube-natural rubber composite material was obtained by pressing, washing and drying. After mixing and vulcanization, the carbon nanotube dispersibility of the vulcanized sample was tested and the dispersibility was measured to be level 5.

[0101] Figure 5The preparation of 5% carbon nanotube dispersion was followed by the addition of 2 kg of fresh rubber latex, coagulation with formic acid, and the carbon nanotube-natural rubber composite material was obtained by pressing, washing and drying. After mixing and vulcanization, the carbon nanotube dispersibility of the vulcanized sample was tested and the dispersibility was measured to be level 4.

[0102] Figure 6 The preparation of 3% carbon nanotube dispersion was followed by the addition of 2 kg of fresh rubber latex. The mixture was then coagulated using a composite microbial coagulation solution. The carbon nanotube-natural rubber composite material was obtained by pressing, washing, and drying. After mixing and vulcanization, the dispersibility of the vulcanized sample was tested, and the dispersibility was measured to be level 7.

[0103] Figure 7 The preparation of 4% carbon nanotube dispersion was followed by the addition of 2 kg of fresh rubber latex. The mixture was then coagulated using a composite microbial coagulation solution. The carbon nanotube-natural rubber composite material was obtained by pressing, washing, and drying. After mixing and vulcanization, the dispersibility of the vulcanized sample was tested, and the dispersibility was measured to be level 9.

[0104] Figure 8 The preparation of 5% carbon nanotube dispersion was followed by the addition of 2 kg of fresh rubber latex. The mixture was then coagulated using a composite microbial coagulation solution. The carbon nanotube-natural rubber composite material was obtained by pressing, washing, and drying. After mixing and vulcanization, the dispersibility of the vulcanized sample was tested, and the dispersibility was measured to be level 6.

[0105] Rubber dispersion grades can be divided into 1-10. Currently, the standard required by the high-performance tire industry is a dispersion grade of 4 or higher. The microbially coagulated composite masterbatch described in this invention meets the tire industry's requirements, and the highest grade can reach 9.

[0106] In summary, the innovations of this invention are: 4% carbon nanotubes and a biological coagulation method, which control the latex coagulation time, thereby improving the dispersion of carbon nanotubes and the bonding between the coupling agent and the latex; the pH of the composite solution is controlled between 3.5 and 5, which accelerates the catalytic effect of the coupling agent and strengthens the interfacial interaction with the matrix, solving the shortcomings of polymer nanocomposites such as low elongation, high viscosity, poor processing performance, complex process, and high production cost; high-temperature drying specifically improves the dispersibility and drying time control, thus increasing the production speed.

[0107] Experimental verification revealed the optimal solution: based on 2kg of fresh latex, the following ratio was found to yield the best results: 4% carbon nanotubes, a carbon nanotube to water ratio of 1:50, 5% dispersant, 1% coupling agent, pH adjusted to 5, 30g of Bacillus subtilis culture medium, and 20g of actinomycete culture medium.

[0108] The core control points of this invention:

[0109] 1. Biological coagulation method;

[0110] 2. Curing time: 12-24 hours;

[0111] 3. Preparation of carbon nanotube dispersion: When preparing composite solutions, the pH should be controlled between 3.5 and 5.

[0112] The above description is merely an embodiment of the present invention. Any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the present invention should be included within the protection scope of the present invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A method for preparing carbon nanotube composite rubber, characterized in that, The preparation method is as follows: Step (1): Preparation of carbon nanotube dispersion: Calculate the amount of carbon nanotubes to be added and the ratio of water to carbon nanotubes based on the weight of dry adhesive. After mixing carbon nanotubes with water, add dispersant and coupling agent. Adjust the pH to 3.5-5.5 using formic acid reagent and emulsify evenly for 20-40 minutes to obtain carbon nanotube dispersion. The dispersant is sodium dodecylbenzenesulfonate; the coupling agent is silane coupling agent SI-69 or phthalate coupling agent 201. The carbon nanotubes account for 3-5% of the dry adhesive content, the mass ratio of carbon nanotubes to water is 1:40-60, the dispersant accounts for 3-6% of the dry adhesive content, and the coupling agent accounts for 0.3-1.2% of the latex content. Step (2): The carbon nanotube dispersion, latex and biological culture medium are stirred evenly and then poured into a long tank for maturation for 20-24 hours; the biological culture medium is a mixture of Bacillus subtilis culture medium and Streptomyces actinomycete culture medium at a volume ratio of 4-6:4-6. 1-5% alkaline protease was added to the mixed culture medium of Bacillus subtilis and Streptomyces actinomycetes; Step (3): Press the lumps in the cured long trough to a thickness of 3-5 cm, and then dry them in an oven at 95-105℃ to obtain carbon nanotube composite rubber.

2. The method for preparing carbon nanotube composite rubber according to claim 1, characterized in that, The Bacillus subtilis culture medium consists of the following components: 4-6g beef extract, 8-12g peptone, 4-6g sodium chloride, 18-22g agar, and 800-1200mL distilled water. The cultured bacterial solution is added at a ratio of 2kg latex / 20-40g bacterial solution.

3. The method for preparing carbon nanotube composite rubber according to claim 1, characterized in that, The culture medium for the actinomycete *Streptomyces* consists of the following components: 18-22g soluble starch, 0.8-1.2g potassium nitrate, 0.4-0.6g sodium chloride, 0.4-0.6g dipotassium hydrogen phosphate, 0.4-0.6g magnesium sulfate, 0.01-0.015g ferrous sulfate, 18-22g agar, and 800-1200mL distilled water, with a pH of 7.2-7.

4. The cultured bacterial solution is added at a ratio of 2kg latex / 20-40g bacterial solution.

4. The method for preparing carbon nanotube composite rubber according to claim 1, characterized in that, The viable count of Bacillus subtilis in the culture medium is 1.1-1.3 billion / mL, and the viable count of Streptomyces actinomycetes in the culture medium is 1.1-1.2 billion / mL.

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