Gradient directional porous wave-absorbing / sound-insulating rubber as well as preparation method and application thereof

Abstract

The invention discloses gradient directional porous wave-absorbing / sound-insulating rubber and a preparation method and application thereof, and belongs to the technical field of rubber.The rubber is prepared from ethylene propylene diene monomer, gradient directional porous filler, zinc oxide, stearic acid, sulfur, an accelerant and auxiliaries; the gradient directional porous filler is prepared by assembling modified biomass porous carbon and single-crystal ordered bimetallic porous MOF (Metal Organic Framework); the modified biomass porous carbon is prepared by calcining and acidifying biomass. The preparation method of the single-crystal ordered bimetallic porous MOF comprises the following steps: adding a PS template into a mixed solution of dimethylimidazole, a cobalt salt, a nickel salt and an organic solvent, and carrying out vacuum degassing, standing and drying; and adding into a mixed solution of ammonia water and an organic solvent, degassing in vacuum, and drying to obtain the product. The material has the advantages of excellent wave-absorbing / sound-insulating performance and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of rubber, and relates to a kind of rubber, in particular to a kind of gradient directional porous wave-absorbing / sound-insulating rubber and a preparation method and application thereof. BACKGROUND

[0002] With the development of 5G communication, stealth technology and electronic device integration, flexible polymer materials are required to have high mechanical strength and high electromagnetic wave absorption. In view of complex electromagnetic interference and increasingly sophisticated detection methods, aircrafts are increasingly threatened in air command and combat, and it is particularly important to develop tunable material design for different scenarios. Current research on wave-absorbing composites mostly focuses on the research of wave-absorbing agents themselves, and the functions of the materials are relatively single, such as the separation of mechanical and functional research, and there are few researches on dynamic tunable multifunctional composites according to different scenarios. Through the design of micro-nano structures and the combination of the micro-nano structures with the matrix material, the function integration is realized, and the combination of multiple scales of materials is realized. The influence of external dynamic stimulation on micro-nano structures is one of the important means to realize dynamic tuning. Therefore, the design and realization of multi-scale material structure, the dynamic tuning of multi-spectrum and the function integration of composite materials have become an urgent need in the field of aviation and aerospace and the construction of military forces in China.

[0003] With the rapid development of the rubber industry, rubber (such as natural rubber and silicone rubber) forms a cross-linked network through vulcanization, which gives it excellent resilience (deformation recovery rate > 90%) and permanent deformation resistance, and it is more stable to oil and chemical media. With its unique performance advantages, it has broad application prospects in military stealth, electronic compatibility and civilian communication fields. As a high-performance synthetic rubber, ethylene-propylene-diene rubber (EPDM) has excellent aging resistance and other properties, but it still faces the following key challenges in practical application and research. In order to solve the problem of poor mechanical properties caused by too much filler and low electromagnetic wave absorption performance caused by too little filler, and to realize the compatibility of excellent mechanical properties and electromagnetic wave absorption performance, scholars have increased the research on biomass-derived porous carbon. How to make good use of its rich pore size and large specific surface area for adsorption is particularly important, so how to modify biomass and prepare and form a composite of biomass as filler and rubber has broad research background and research value.

[0004] In the prior art, traditional carbon materials or additives are added to enhance the mechanical and wave-absorbing properties, and the dispersion degree between the filler and the rubber matrix is increased by the additives. However, it is a new idea to realize the compatibility of excellent mechanical and wave-absorbing properties of the composite material from the filler itself. How to realize the modification of the filler itself and the multi-spectrum dynamic tuning to meet the scene requirements of the complex electromagnetic field in the field of aviation and aerospace is the focus of current research by scientists. SUMMARY

[0005] The application provides a gradient directional porous wave-absorbing / sound-insulating rubber and a preparation method and application thereof to overcome the defects of the prior art.

[0006] To achieve the above object, the application adopts the following technical scheme:

[0007] In a first aspect, the application provides a gradient directional porous wave-absorbing / sound-insulating rubber, which is prepared from ethylene-propylene-diene rubber, gradient directional porous filler, zinc oxide, stearic acid, sulfur, accelerator and auxiliary agent; the gradient directional porous filler is prepared from modified biomass porous carbon and single-crystal ordered bimetallic porous MOF; the modified biomass porous carbon is prepared from biomass through calcination and acidification; the preparation method of the single-crystal ordered bimetallic porous MOF is as follows: PS template is added into a mixed solution of dimethylimidazole, cobalt salt, nickel salt and organic solvent, vacuum degassing, standing and drying; then a mixed solution of ammonia and organic solvent is added to induce crystal phase generation, vacuum degassing and drying.

[0008] Further, the preparation method of the PS template is as follows: PVP is dissolved in boiling water, styrene is added, and the mixture is stirred at 70-80 DEG C for 20-40 min, preferably 72 DEG C, 240 rpm mechanical stirring for 30 min; K2S2O8 dissolved in boiling water by using a sound wave method is added, and the mixture is reacted for 20-30 h, preferably 24 h; the amount ratio of PVP, styrene and K2S2O8 is 1-3 g: 50-70 mL: 0.5-1.5 g, preferably 2 g: 60 mL: 1 g.

[0009] Further, in the preparation method of the single-crystal ordered bimetallic porous MOF, the organic solvent is methanol; the cobalt salt is cobalt nitrate hexahydrate; the nickel salt is nickel nitrate hexahydrate; the mass ratio of PS template, dimethylimidazole, cobalt nitrate hexahydrate and nickel nitrate hexahydrate is 40-60: 15-25: 10-20: 10-20, preferably 50: 20: 16: 16; the first vacuum degassing time is 15-25 min, preferably 20 min, the standing time is 20-30 h, preferably 24 h, and the first drying temperature is 25-35 DEG C, preferably 30 DEG C; in the mixed solution of ammonia and organic solvent, the volume ratio of ammonia and organic solvent is 0.5-1.5: 0.5-1.5, preferably 1: 1; the second vacuum degassing time is 5-15 min, preferably 10 min, and the second drying temperature is 25-35 DEG C, preferably 30 DEG C.

[0010] Further, the biomass is pinecone; the preparation method of the modified biomass porous carbon is: crushing the pinecone, sieving, heating to 200-300℃ at 1-3℃ / min for 1.5-2.5h to remove impurities, preferably heating to 260℃ at 2℃ / min for 2h; then heating to 750-850℃ at 1-3℃ / min for 1.5-2.5h in nitrogen atmosphere, preferably heating to 800℃ at 2℃ / min for 2h, to obtain the micrometer biomass porous carbon; then soaking in an acidic solution with pH of 1-3 for acidification for 10-14h, preferably in a nitric acid solution with pH of 2 for acidification for 12h, to obtain the modified biomass porous carbon.

[0011] Further, the preparation method of the gradient directional porous filler is: ultrasonic dispersion of the modified biomass porous carbon in water, then adding the single-crystal ordered bimetallic porous MOF, assembling the single-crystal ordered bimetallic MOF and the modified biomass porous carbon together by electrostatic adsorption effect, to obtain the gradient directional porous filler; the mass ratio of the modified biomass porous carbon and the single-crystal ordered bimetallic MOF is 1-3:1, preferably 2:1.

[0012] Further, the accelerant includes accelerant M and accelerant TMTD; the auxiliary agent is silane coupling agent.

[0013] Further, the mass ratio of the EPDM, the gradient directional porous filler, zinc oxide, stearic acid, sulfur, accelerant M, accelerant TMTD and silane coupling agent is 70-130:70-130:3-7:0.5-1.5:1-2:0.2-0.7:1-5:1-3, preferably 100:100:5:1:1.5:0.5:3:2.

[0014] The second aspect provides a preparation method of the above-mentioned gradient directional porous wave-absorbing rubber: adding the EPDM, the gradient directional porous filler, zinc oxide, stearic acid, sulfur, accelerant and auxiliary agent into an open mill, mixing uniformly, cutting, and putting into a flat vulcanizing machine for vulcanization at 150-200℃ for 5-15min, preferably 170℃ for 10min, to obtain the gradient directional porous wave-absorbing rubber.

[0015] The third aspect provides a preparation method of the above-mentioned gradient directional porous sound-insulating rubber: adding the EPDM, the gradient directional porous filler, zinc oxide, stearic acid, sulfur, accelerant and auxiliary agent into an open mill, mixing uniformly, cutting, and putting into a flat vulcanizing machine for vulcanization at 150-200℃ for 5-15min, preferably 170℃ for 10min; inflating the obtained rubber, to obtain the gradient directional porous sound-insulating rubber.

[0016] The fourth aspect provides application of the above-mentioned gradient directional porous wave-absorbing / sound-insulating rubber in wave absorption / sound insulation.

[0017] The present application has the beneficial effect that the present application provides a gradient directional porous wave-absorbing / sound-insulating rubber and a preparation method and application thereof, biomass pore size is controlled through thermodynamics, micron modified biomass porous carbon is obtained, single crystal ordered bimetallic porous MOF is assembled together with the modified biomass porous carbon by using electrostatic adsorption effect, gradient change of macroporous mesoporous microporous is realized, and excellent impedance matching is realized to improve electromagnetic wave absorption efficiency. Among them, the micron modified biomass porous carbon is used as a skeleton, the agglomeration of the single crystal ordered MOF is inhibited through the pore confinement effect, the dispersibility of the filler in the rubber is improved, the modified biomass porous carbon has a high specific surface area to adsorb the vulcanizing agent, slow-release vulcanization is realized, and uneven vulcanization caused by too much filler in the traditional system is avoided. Further, the rubber is inflated after vulcanization, the tension of the rubber-based composite structure changes with the increase of the internal gas, the natural frequency of the rubber composite structure is shifted, the impedance mutation interface is generated in the internal asymmetric pore gradient, the sound wave reflection is enhanced, the high-frequency sound insulation effect is enhanced, and thus the sound-insulating rubber is obtained. The degree of bulging is controlled by air pressure to realize dynamic tunable absorption / sound insulation, that is, the high-frequency sound insulation performance is excellent in the inflated state, the electromagnetic wave absorption is enhanced in the deflated state, and finally the prepared ternary ethylene-propylene composite rubber-based device can realize dynamic tunable absorption / sound insulation according to different scene requirements. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is an SEM image of the modified biomass porous carbon;

[0019] Figure 2 is an SEM image of the modified biomass porous carbon;

[0020] Figure 3 is a schematic diagram of inflating the rubber, a is a base schematic diagram, and b is a base and rubber inflation schematic diagram. DETAILED DESCRIPTION

[0021] The present application is further described below in conjunction with specific embodiments.

[0022] Embodiment 1

[0023] The present embodiment provides a gradient directional porous wave-absorbing / sound-insulating rubber, and a preparation method thereof is as follows:

[0024] S1, the pine cone is crushed with a crusher, then filtered with a screen, to obtain uniform powder, first heated to 260℃ at 2℃ / min in a muffle furnace for 2h to remove impurities, then heated to 800℃ at 2℃ / min in a nitrogen atmosphere for 2h, then soaked in a nitric acid solution with pH=2 for 12h, and dried to obtain modified biomass porous carbon, the SEM images of different scales are shown in Figure 1 and Figure 2 .

[0025] S2, first, the styrene is washed with 10wt% NaOH solution and deionized water in turn to remove the stabilizer. Then, 2g PVP is dissolved in 500mL boiling deionized water and poured into a 1L three-necked flask. Subsequently, 60mL of washed styrene is added and equilibrated at 72℃ with 240rpm mechanical stirring for 30min. Finally, 1g K2S2O8 is dissolved in 50mL boiling water by ultrasonic method, and then poured into the three-necked flask to initiate polymerization. After 24h of reaction, the obtained emulsion is collected as the desired monodisperse polystyrene spheres, and the three-dimensional ordered PS template is obtained by vacuum suction filtration and dried overnight.

[0026] S3, weigh 0.328g dimethylimidazole, 0.263g cobalt nitrate hexahydrate and 0.263g nickel nitrate hexahydrate, pour them into a 20mL methanol solution, and then add 0.82g PS template, vacuum degassing for 20min, standing for 24h, drying in an oven at 30℃, adding 50mL mixed solution of ammonia and methanol with a volume ratio of 1:1, inducing the formation of crystal phase, vacuum degassing for 10min, and then drying in a 30℃ oven to obtain single-crystal ordered bimetallic porous MOF.

[0027] S4, 2 parts of modified biomass porous carbon are ultrasonically dispersed in deionized water, and then 1 part of single-crystal ordered bimetallic porous MOF is added. The single-crystal ordered bimetallic MOF is assembled with the biomass porous carbon by using the electrostatic adsorption effect to obtain a gradient directional porous filler.

[0028] S5, then 100 parts of the gradient directional porous filler, 100 parts of the ternary ethylene-propylene rubber, 5 parts of zinc oxide, 1 part of stearic acid, 1.5 parts of sulfur, 0.5 parts of accelerator M, 3 parts of accelerator TMTD and 2 parts of silane coupling agent are added to an open mill, and mixed until uniform. The mixture is cut into regular strips and placed in a mold, and then placed in a flat plate vulcanizing machine for vulcanization at 170℃ for 10min to obtain the ternary ethylene-propylene rubber.

[0029] S6, as shown in Figure 3 , the ternary ethylene-propylene rubber is fixed on the base, and the inside of the ternary ethylene-propylene rubber is inflated by adjusting the air pump and flow rate controller. The inflation pressure is 0.1MPa to obtain a gradient directional porous wave-absorbing / sound-insulating rubber.

[0030] Example 2

[0031] This example provides a gradient directional porous wave-absorbing / sound-insulating rubber, and the preparation method is basically the same as that of Example 1, except that in S6, the inflation pressure is 0.2MPa.

[0032] Example 3

[0033] This embodiment provides a gradient directional porous wave-absorbing / sound-insulating rubber, and the preparation method is basically the same as that in Embodiment 1, except that in S6, the inflation air pressure is 0.3 MPa.

[0034] Embodiment 4

[0035] This embodiment provides a gradient directional porous wave-absorbing / sound-insulating rubber, and the preparation method is basically the same as that in Embodiment 1, except that in S5, the gradient directional porous filler is 70 parts.

[0036] Embodiment 5

[0037] This embodiment provides a gradient directional porous wave-absorbing / sound-insulating rubber, and the preparation method is basically the same as that in Embodiment 4, except that in S6, the inflation air pressure is 0.2 MPa.

[0038] Embodiment 6

[0039] This embodiment provides a gradient directional porous wave-absorbing / sound-insulating rubber, and the preparation method is basically the same as that in Embodiment 4, except that in S6, the inflation air pressure is 0.3 MPa.

[0040] Embodiment 7

[0041] This embodiment provides a gradient directional porous wave-absorbing / sound-insulating rubber, and the preparation method is basically the same as that in Embodiment 1, except that in S5, the gradient directional porous filler is 130 parts.

[0042] Embodiment 8

[0043] This embodiment provides a gradient directional porous wave-absorbing / sound-insulating rubber, and the preparation method is basically the same as that in Embodiment 7, except that in S6, the inflation air pressure is 0.2 MPa.

[0044] Embodiment 9

[0045] This embodiment provides a gradient directional porous wave-absorbing / sound-insulating rubber, and the preparation method is basically the same as that in Embodiment 7, except that in S6, the inflation air pressure is 0.3 MPa.

[0046] Comparative Example 1

[0047] This comparative example provides a rubber, and the preparation method is basically the same as that in Embodiment 1, except that no gradient directional porous filler is added.

[0048] Comparative Example 2

[0049] This comparative example provides a rubber, and the preparation method is basically the same as that in Comparative Example 1, except that in S6, the inflation air pressure is 0.2 MPa.

[0050] Comparative Example 3

[0051] The comparative example provides a rubber, the preparation method is basically same with comparative example 1, the difference is only in: in S6, the inflation air pressure is 0.3 MPa.

[0052] Comparative example 4

[0053] The comparative example provides a rubber, the preparation method is basically same with comparative example 4, the difference is only in: in S6, the inflation air pressure is 0.2 MPa.

[0054] Comparative example 5

[0055] The comparative example provides a rubber, the preparation method is basically same with comparative example 4, the difference is only in: in S6, the inflation air pressure is 0.2 MPa.

[0056] Comparative example 6

[0057] The comparative example provides a rubber, the preparation method is basically same with comparative example 4, the difference is only in: in S6, the inflation air pressure is 0.3 MPa.

[0058] The rubber of comparative examples 1-9 and comparative examples 1-6 is tested for mechanical properties, wave-absorbing properties and sound-insulating properties, and the results are shown in Table 1. Among them, the mechanical properties are tested by using a universal testing machine, the wave-absorbing properties are tested by using a vector network analyzer, and the sound-insulating properties are tested by using an anechoic chamber (free field) through a reverberation chamber-anechoic chamber method.

[0059] Table 1 Mechanical properties, wave-absorbing properties and sound-insulating properties of rubber

[0060]

[0061]

[0062] It can be seen from comparative examples 1, 4 and 7 that the electromagnetic wave absorption performance of the gradient directional porous wave-absorbing / sound-insulating rubber will not increase with the increase of the filling ratio of the gradient directional porous filler. On the contrary, a higher filling ratio will not only lead to impedance matching of attenuated electromagnetic waves, but also will lead to a decrease in strength due to stress concentration and interface defects, but an appropriate filling ratio can well play a reinforcing role. It can be seen from comparative examples 1 and 4 that after adding the modified biomass porous carbon, the wave-absorbing performance and mechanical properties of the rubber are improved. It can be seen from comparative examples 1-3, 4-6 and 7-9 that with the increase of the internal air pressure, the electromagnetic wave absorption performance of the rubber is weakened to some extent, but the sound-insulating performance is improved to some extent.

[0063] In the present application, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by one of ordinary skill in the art. Also, the reagents, materials and procedural steps used herein are those widely used in the corresponding field and are conventional.

[0064] Finally, it should be noted that the above only describes the preferred embodiments of the present application, and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art will still be able to modify the technical solutions described in the foregoing embodiments, or make equivalent replacements to some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A gradient directional porous wave-absorbing / sound-insulating rubber, characterized in that: it is prepared from ethylene-propylene-diene rubber, gradient directional porous filler, zinc oxide, stearic acid, sulfur, accelerator and auxiliary agent; the gradient directional porous filler is prepared from modified biomass porous carbon and single-crystal ordered bimetallic porous MOF; the modified biomass porous carbon is prepared from biomass through calcination and acidification; the single-crystal ordered bimetallic porous MOF is prepared by adding PS template into a mixed solution of dimethyl imidazole, cobalt salt, nickel salt and organic solvent, vacuum degassing, standing and drying; then adding a mixed solution of ammonia and organic solvent, vacuum degassing and drying. 2.The gradient directional porous wave-absorbing / sound-insulating rubber according to claim 1, characterized in that: the PS template is prepared by dissolving PVP with boiling water, adding styrene, stirring at 70-80 ℃ for 20-40 min, adding K2S2O8 dissolved in boiling water by using the sound wave method, and reacting for 20-30 h; the amount ratio of PVP, styrene and K2S2O8 is 1-3 g: 50-70 mL: 0.5-1.5 g. 3.The gradient directional porous wave-absorbing / sound-insulating rubber according to claim 1, characterized in that: in the preparation method of the single-crystal ordered bimetallic porous MOF, the organic solvents are all methanol; the cobalt salt is cobalt nitrate hexahydrate, and the nickel salt is nickel nitrate hexahydrate; the mass ratio of PS template, dimethyl imidazole, cobalt nitrate hexahydrate and nickel nitrate hexahydrate is 40-60: 15-25: 10-20: 10-20; the first vacuum degassing time is 15-25 min, the standing time is 20-30 h, and the first drying temperature is 25-35 ℃; in the mixed solution of ammonia and organic solvent, the volume ratio of ammonia and organic solvent is 0.5-1.5: 0.5-1.5; the second vacuum degassing time is 5-15 min, and the second drying temperature is 25-35 ℃. 4.The gradient directional porous wave-absorbing / sound-insulating rubber according to claim 1, characterized in that: the biomass is pine cone; the preparation method of the modified biomass porous carbon is: crushing the pine cone, sieving, heating to 200-300 ℃ at 1-3 ℃ / min to remove impurities, then heating to 750-850 ℃ at 1-3 ℃ / min in a nitrogen atmosphere to obtain biomass porous carbon, and then soaking in an acidic solution with pH of 1-3 for acidification for 10-14 h. 5.The gradient directional porous wave-absorbing / sound-insulating rubber according to claim 1, characterized in that: the preparation method of the gradient directional porous filler is: ultrasonic dispersion of the modified biomass porous carbon in water, then adding the single-crystal ordered bimetallic porous MOF, and assembling the single-crystal ordered bimetallic MOF and the modified biomass porous carbon together by using electrostatic adsorption effect; the mass ratio of the modified biomass porous carbon and the single-crystal ordered bimetallic MOF is 1-3:

1. 6.The gradient directional porous wave-absorbing / sound-insulating rubber according to claim 1, wherein: the accelerators comprise an accelerator M and an accelerator TMTD; the auxiliary agent is a silane coupling agent. 7.The gradient directional porous wave-absorbing / sound-insulating rubber according to claim 6, wherein: the mass ratio of the ethylene-propylene-diene rubber, the gradient directional porous filler, the zinc oxide, the stearic acid, the sulfur, the accelerator M, the accelerator TMTD and the silane coupling agent is 70-130:70-130:3-7:0.5-1.5:1-2:0.2-0.7:1-5:1-3. 8.A method for preparing the gradient directional porous wave-absorbing rubber according to any one of claims 1-7, wherein: the ethylene-propylene-diene rubber, the gradient directional porous filler, the zinc oxide, the stearic acid, the sulfur, the accelerator and the auxiliary agent are added into an open mill, mixed uniformly, cut, and placed into a flat vulcanization machine for vulcanization at 150-200℃ for 5-15 min, and the gradient directional porous wave-absorbing rubber is obtained. 9.A method for preparing the gradient directional porous sound-insulating rubber according to any one of claims 1-7, wherein: the ethylene-propylene-diene rubber, the gradient directional porous filler, the zinc oxide, the stearic acid, the sulfur, the accelerator and the auxiliary agent are added into an open mill, mixed uniformly, cut, and placed into a flat vulcanization machine for vulcanization at 150-200℃ for 5-15 min; and the obtained rubber is inflated, and the gradient directional porous sound-insulating rubber is obtained. 10.An application of the gradient directional porous wave-absorbing / sound-insulating rubber according to any one of claims 1-7 in wave-absorbing / sound-insulating.

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