Preparation method of PPTA nanometer microsphere styrene-butadiene rubber composite material

Abstract

The application discloses a preparation method of PPTA nanometer microsphere styrene butadiene rubber composite material, which comprises the following steps: 1) styrene butadiene rubber is added into a mixed solvent of cyclohexanone and N-methyl pyrrolidone, and heated and stirred until the styrene butadiene rubber is completely dissolved to obtain a transparent solution; 2) part of the transparent solution is taken, p-phenylenediamine and lithium chloride are added, and stirring is uniformly carried out to obtain solution A; p-phenylenediamine chloride is added into the remaining transparent solution, and stirring is uniformly carried out to obtain solution B; under the condition of nitrogen atmosphere and ice water bath, solution B is slowly dropped into solution A, and stirring reaction is carried out at room temperature to obtain a light brown solution; 3) deionized water is added into the light brown solution, and after stirring, filtration and washing, and drying, the PPTA nanometer microsphere styrene butadiene rubber composite material is obtained. The in-situ solution condensation method and the bottom-up method are combined to synthesize the PPTA nanometer particles which are uniformly dispersed in the rubber matrix, and the surface effect, the quantum size effect and the macroscopic quantum tunnel effect endow the composite material with high strength, high toughness, high impact resistance and other performances.

Description

Technical Field

[0001] The invention relates to a fiber composite material, in particular to a preparation method of a PPTA nano-microsphere styrene-butadiene rubber composite material. Background Art

[0002] PPTA is the abbreviation of poly(p-phenylene terephthalamide) molecule. The fiber composed of PPTA is called para-aramid in my country. It is one of the three major high-performance fibers in the world today due to its high strength, high modulus, high temperature resistance and other high performances. It plays an important role in high-tech fields such as aerospace, defense industry, rail transportation, and new energy. It is a key strategic material that is the focus of research and development.

[0003] In recent years, the application of PPTA in the rubber industry has also received increasing attention. It not only improves the high-temperature resistance and impact resistance of traditional rubber products, but also achieves lightweight and energy-saving effects. It is considered an ideal rubber skeleton material. However, due to the influence of the large number of hydrogen bonds between the rigid linear chain molecules of PPTA, the macroscopic fiber surface formed by it is smooth and has strong chemical inertness, and the interfacial adhesion between it and the rubber matrix is ​​low, which greatly limits its application in the rubber industry. To this end, various chemical methods (such as surface etching and surface grafting) and physical methods (such as surface coating and ultrasonic impregnation) are generally used to modify the surface of PPTA fibers to enhance the interfacial bonding between the fibers and the rubber matrix material. However, these processing technologies mostly focus on surface modification of PPTA fibers. While improving the surface bonding properties of PPTA fibers, they also cause varying degrees of damage to the properties of the fibers themselves, reducing the performance of the composite material. Summary of the Invention

[0004] Existing PPTA fiber and rubber composites modify the PPTA fibers to enhance the bond between the PPTA fibers and the rubber, which damages the fibers and thus affects the mechanical properties of the composite. To address this issue, the present invention discloses a method for preparing a PPTA nanosphere styrene-butadiene rubber composite. This method takes a unique approach by shifting the focus to the rubber matrix. Specifically, PPTA is nano-synthesized within a styrene-butadiene rubber (SBR) matrix to produce a PPTA / SBR composite with uniformly dispersed PPTA nanoparticles. Each PPTA nanoparticle acts as an "anchor point," extremely evenly distributed within the rubber matrix. When composited with PPTA macrofibers, these nano-anchor points anchor to the PPTA fiber surface, thereby enhancing the interfacial forces between the PPTA fibers and the rubber matrix.

[0005] Based on the above mechanism, the specific operating steps of the method of the present invention are:

[0006] 1. Add a certain amount of styrene-butadiene rubber (SBR) to a mixed solvent of cyclohexanone (CYC) and N-methylpyrrolidone (NMP), heat and stir until the SBR is completely dissolved to obtain a clear and transparent solution;

[0007] 2. Take part of the solution from step 1, dissolve p-phenylenediamine (PPD) and lithium chloride therein, and stir evenly to obtain solution A. Dissolve terephthaloyl chloride (TPC) in the remaining solution from step 1 to obtain solution B. Under a nitrogen atmosphere and an ice-water bath, slowly add solution B dropwise to solution A. After the addition is complete, continue stirring at room temperature for 2 hours until the solution gradually changes from orange-yellow to light brown.

[0008] 3. After the color of the reaction liquid no longer changes, stop stirring, pour a small amount of deionized water into the reaction liquid, filter, rinse and dry the residue to obtain the product.

[0009] Different from existing aramid composite materials, the method of the present invention does not process para-aramid, but polymerizes it into poly(p-phenylene terephthalamide) microspheres in a transparent solution, which are directly mixed with styrene-butadiene rubber at the microscopic level, thus fundamentally avoiding the problem of poor adhesion between aramid fiber and rubber.

[0010] Furthermore, in the composite material prepared by the method of the present invention, the weight proportion of styrene-butadiene rubber is 78% to 92.5%, and the weight proportion of poly(p-phenylene terephthalamide) is 7.5% to 22%. The composite material is polymerized by p-phenylenediamine and terephthaloyl chloride in a molar ratio of (1 to 1.05):1 in a mixed solvent of cyclohexanone and N-methylpyrrolidone in a volume ratio of 1:(2-4).

[0011] Furthermore, the amount of styrene-butadiene rubber in the mixed solvent is 4% to 8% by weight of the mixed solvent, and the heating temperature of the mixed solvent is 40° C. to 55° C.

[0012] Furthermore, solution A accounts for 35% to 50% by volume of the transparent solution, and solution B accounts for 50% to 65% by volume of the transparent solution.

[0013] The present invention combines an in-situ solution polycondensation method with a "bottom-up" method to synthesize uniformly dispersed PPTA nanoparticles in a rubber matrix, thereby obtaining a PPTA nanosphere / SBR composite material. This composite material can be added to a conventional rubber mixing formula as a special additive that functions as both a reinforcing agent and an interfacial compatibilizer. When the mixed rubber is compounded with macroscopic PPTA fibers, the integrity of the macroscopic PPTA fibers is maintained, allowing their high performance to be fully utilized. Furthermore, the special properties of the PPTA nanoparticles, such as the surface effect, quantum size effect, and macroscopic quantum tunneling effect, impart excellent properties such as high strength, high toughness, and high impact resistance to the rubber composite material. The present invention has a simple process, mild reaction conditions, a short reaction time, easy control, high synthesis efficiency, and is easily industrialized, providing a new method for preparing high-performance PPTA / rubber composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a transmission electron microscope image of para-aramid nanoparticles during the implementation of Example 1.

[0015] Figure 2 The stress-strain curves of the composite materials obtained in Examples 1 and 2 and pure SBR are shown.

[0016] Figure 3 The bar graph shows the interfacial adhesion between the extracted specimens obtained in Examples 3 and 4 and pure SBR. DETAILED DESCRIPTION

[0017] The present invention is described below with reference to examples, which are only used to explain the present invention and are not used to limit the scope of the present invention.

[0018] Example 1

[0019] A method for preparing a PPTA nano-microsphere styrene-butadiene rubber composite material comprises the following steps:

[0020] (1) Dissolving styrene-butadiene rubber to prepare a homogeneous solution: dissolve 4 g of styrene-butadiene rubber in a mixed solvent of 6 g of cyclohexanone and N-methylpyrrolidone in a volume ratio of 1:3, and mechanically stir at 45°C for 144 h until the styrene-butadiene rubber is completely dissolved. When the solution becomes clear and transparent, a mixed solution is obtained;

[0021] (2) A PPTA nanosphere / SBR composite material was prepared by a solution polycondensation method from bottom to top: 0.1081 g of p-phenylenediamine and 0.085 g of lithium chloride were dissolved in half the volume of the mixed solution, which was recorded as solvent A. 0.203 g of terephthaloyl chloride was dissolved in the other half of the mixed solution in step (1), which was recorded as solvent B. Solvent B was added dropwise to solvent A in an ice-water bath under nitrogen protection. After the addition was completed, the mixture was stirred for 2 h at room temperature to obtain a PPTA nanosphere / SBR composite solution.

[0022] (3) Removing impurities and extracting PPTA nanosphere / SBR composite material: Pour 0.5 g of distilled water into the reaction solution obtained in step (2) and stir continuously to remove the by-products produced by the reaction. At the same time, the added distilled water displaces the product in the reaction solution to precipitate, obtaining a brown colloidal solid. After filtration, rinse with distilled water several times until the filtrate is neutral, and then dry under vacuum conditions for 24 h to obtain the PPTA nanosphere / SBR composite material.

[0023] Example 2

[0024] A method for preparing a PPTA nano-microsphere styrene-butadiene rubber composite material comprises the following steps:

[0025] (1) Dissolving styrene-butadiene rubber to prepare a homogeneous solution: dissolve 4 g of styrene-butadiene rubber in a mixed solvent of 5 g of cyclohexanone and N-methylpyrrolidone in a volume ratio of 1:2, and mechanically stir at 50 °C for 120 h until the styrene-butadiene rubber is completely dissolved. When the solution becomes clear and transparent, a mixed solution is obtained;

[0026] (2) A PPTA nanosphere / SBR composite material was prepared by a solution polycondensation method from bottom to top: 0.3243 g of p-phenylenediamine and 0.255 g of lithium chloride were dissolved in a 35% volume mixed solution, which was recorded as solvent A. 0.609 g of terephthaloyl chloride was dissolved in the remaining 65% volume mixed solution of step (1), which was recorded as solvent B. Solvent B was added dropwise to solvent A in an ice-water bath under nitrogen protection. After the addition was completed, the mixture was stirred for 2 h at room temperature to obtain a PPTA nanosphere / SBR composite solution.

[0027] (3) Removing impurities and extracting PPTA nanosphere / SBR composite material: Pour 0.3 g of distilled water into the reaction solution obtained in step (2) and stir continuously to remove the by-products produced by the reaction. At the same time, the added distilled water displaces the product in the reaction solution to precipitate, obtaining a brown colloidal solid. After filtration, rinse with distilled water several times until the filtrate is neutral, and then dry under vacuum conditions for 24 h to obtain the PPTA nanosphere / SBR composite material.

[0028] Example 3

[0029] A method for preparing a PPTA nano-microsphere styrene-butadiene rubber composite material comprises the following steps:

[0030] (1) Dissolving styrene-butadiene rubber to prepare a homogeneous solution: dissolve 4 g of styrene-butadiene rubber in a mixed solvent of 10 g of cyclohexanone and N-methylpyrrolidone in a volume ratio of 1:4, and mechanically stir at 55 °C for 144 h until the styrene-butadiene rubber is completely dissolved. When the solution becomes clear and transparent, a mixed solution is obtained;

[0031] (2) A PPTA nanosphere / SBR composite material was prepared by a solution polycondensation method from bottom to top: 0.1081 g of p-phenylenediamine and 0.085 g of lithium chloride were dissolved in a 40% volume mixed solution, which was recorded as solvent A. 0.203 g of terephthaloyl chloride was dissolved in the remaining 60% volume mixed solution of step (1), which was recorded as solvent B. Solvent B was added dropwise to solvent A in an ice-water bath under nitrogen protection. After the addition was completed, the mixture was stirred for 2 h at room temperature to obtain a PPTA nanosphere / SBR composite solution.

[0032] (3) Removing impurities and extracting PPTA nanosphere / SBR composite material: Pour 0.5 g of distilled water into the reaction solution obtained in step (2) and stir continuously to remove the by-products produced by the reaction. At the same time, the added distilled water displaces the product in the reaction solution to precipitate, obtaining a brown colloidal solid. After filtration, rinse with distilled water several times until the filtrate is neutral, and then dry under vacuum conditions for 24 h to obtain the PPTA nanosphere / SBR composite material.

[0033] Example 4

[0034] A method for preparing a PPTA nano-microsphere styrene-butadiene rubber composite material comprises the following steps:

[0035] (1) Dissolving styrene-butadiene rubber to prepare a homogeneous solution: dissolve 4 g of styrene-butadiene rubber in a mixed solvent of 8 g of cyclohexanone and N-methylpyrrolidone in a volume ratio of 1:3, and mechanically stir at 45 °C for 144 h until the styrene-butadiene rubber is completely dissolved. When the solution becomes clear and transparent, a mixed solution is obtained;

[0036] (2) A PPTA nanosphere / SBR composite material was prepared by a solution polycondensation method from bottom to top: 0.3243 g of p-phenylenediamine and 0.255 g of lithium chloride were dissolved in half of the mixed solution, which was recorded as solvent A. 0.609 g of terephthaloyl chloride was dissolved in the remaining half of the mixed solution in step (1), which was recorded as solvent B. Solvent B was added dropwise to solvent A in an ice-water bath under nitrogen protection. After the addition was completed, the mixture was stirred for 2 h at room temperature to obtain a PPTA nanosphere / SBR composite solution.

[0037] (3) Removing impurities and extracting PPTA nanosphere / SBR composite material: Pour a small amount of distilled water into the reaction solution obtained in step (2) and stir continuously to remove the by-products produced by the reaction. At the same time, the added distilled water displaces the product in the reaction solution to precipitate it, obtaining a brown colloidal solid. After filtration, rinse with distilled water several times until the filtrate is neutral, and then dry under vacuum conditions for 24 hours to obtain the PPTA nanosphere / SBR composite material.

[0038] The PPTA nanosphere / SBR composite materials obtained in Examples 1 and 2 were mixed and vulcanized to prepare a composite rubber according to the following method: 2.4 phr of stearic acid, 2 phr of antioxidant, 2 phr of zinc oxide, 50 phr of carbon black, 2.2 phr of accelerator CZ, and 1.5 phr of sulfur were added to every 100 phr of rubber, and vulcanized at 150°C and 10 MPa for 20 min.

[0039] The PPTA nanosphere / SBR composites obtained in Examples 3 and 4 were mixed and vulcanized to prepare composite rubbers according to the following formulation and process: 2.4 phr of stearic acid, 2 phr of antioxidant, 2 phr of zinc oxide, 50 phr of carbon black, 2.2 phr of accelerator CZ, and 1.5 phr of sulfur were added per 100 phr of rubber. The mixture was vulcanized at 150°C and 10 MPa for 20 min. PPTA bundles were then inserted into the middle of the resulting composite rubbers to form an ABA-type sandwich structure, thereby preparing aramid-composite rubber extraction specimens.

[0040] Figure 1 This is a transmission electron microscope image of para-aramid nanoparticles during the implementation of Example 1 of the present invention. The transmission electron microscope image shows that PPTA is in a granular state, confirming the formation of PPTA nanospheres in the SBR matrix and their uniform distribution.

[0041] The mechanical properties of the composite rubber prepared by using the composite materials of Example 1 and Example 2 and pure SBR were analyzed by a universal tensile testing machine. The mechanical properties of the composite rubber prepared by using pure SBR and the composite materials obtained in Example 1 and Example 2 are shown in Table 1 and Table 2. The tensile stress curve is shown in Figure 2 As shown in the figure, the tensile strength and 200% modulus of the composite rubber are greatly improved compared with pure SBR.

[0042] Table 1. Comparison of mechanical properties of pure SBR and composite rubbers of Example 1 and Example 2

[0043]

[0044] Table 2. Increase rate of mechanical properties of pure SBR and composite rubber of Example 1 and Example 2

[0045]

[0046] The interface adhesion performance of the extraction specimens prepared from the composite materials of Examples 3 and 4 was compared with that of the pure SBR extraction specimens using a universal tensile testing machine. The interface adhesion of the extraction specimens prepared from the composite materials of Examples 3 and 4 is shown in Tables 3 and 4. The interface adhesion bar graph is shown in Table 4. Figure 3 As shown in the figure, it can be seen that the interfacial adhesion of the aramid-composite rubber sample is increased by 75% compared with the pure SBR sample.

[0047] Table 3. Comparison of interfacial adhesion properties between pure SBR and the composite rubbers of Examples 3 and 4

[0048]

[0049] Table 4. Interface adhesion performance increase rate of pure SBR and composite rubber of Example 3 and Example 4

[0050]

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a PPTA nano-microsphere styrene-butadiene rubber composite material, characterized in that: The following steps are involved: 1) Add styrene-butadiene rubber to a mixed solvent of cyclohexanone and N-methylpyrrolidone, heat and stir until the styrene-butadiene rubber is completely dissolved to obtain a transparent solution; 2) Add p-phenylenediamine and lithium chloride to a portion of the transparent solution obtained in step 1), stir thoroughly, and label this solution as Solution A. Add terephthaloyl chloride to the remaining transparent solution, controlling the molar ratio of p-phenylenediamine to terephthaloyl chloride to be (1-1.05):1, stir thoroughly, and label this solution as Solution B. Under a nitrogen atmosphere and an ice-water bath, slowly add Solution B dropwise to Solution A. After the addition is complete, stir the mixture at room temperature to obtain a light brown solution. 3) adding deionized water to the light brown solution obtained in step 2), stirring and filtering, rinsing and drying the filter residue to obtain a PPTA nanosphere styrene-butadiene rubber composite material; In the obtained PPTA nano-microsphere styrene-butadiene rubber composite material, the weight proportion of styrene-butadiene rubber is 78%~92.5%, and the weight proportion of PPTA is 7.5%~22%.

2. The method according to claim 1, characterized in that In step 1), the volume ratio of cyclohexanone to N-methylpyrrolidone in the mixed solvent is 1:(2-4); the amount of styrene-butadiene rubber used is 4%-8% by weight of the mixed solvent; and the heating temperature of the mixed solvent is 40° C.-55° C.

3. The method according to claim 1, characterized in that In step 2), solution A accounts for 35% to 50% by volume of the transparent solution, and solution B accounts for 50% to 65% by volume of the transparent solution.

Images