阅读说明：本技术 一种多壁碳纳米管天然橡胶复合材料的制备方法 (Preparation method of multi-walled carbon nanotube natural rubber composite material ) 是由 郭荣鑫 刘兴姚 杨洋 林志伟 颜峰 马倩敏 万夫雄 于 2019-09-26 设计创作，主要内容包括：本发明目的在于提供一种多壁碳纳米管/天然橡胶复合材料的制备方法,属于纳米橡胶复合材料制备技术领域。本发明首先在带冷凝回流管和蒸馏装置的三嘴平底烧瓶中制备多壁碳纳米管/天然橡胶混合液,然后将多壁碳纳米管/天然橡胶混合液快速平铺,烘干,得到薄片状多壁碳纳米管/天然橡胶复合材料,根据所需尺寸进行裁剪,叠层,硫化,得到多壁碳纳米管/天然橡胶复合材料。制备的多壁碳纳米管/天然橡胶复合材料具有三维多壁碳纳米管导电网络结构,导电性优异,电阻-应变响应和回复性好。本发明有效减少有机溶剂的浪费和保障了多壁碳纳米管在基体材料中具有与初始混合液相同的分布状态,有助于解决多壁碳纳米管在橡胶基体中难分散,易团聚的问题,取代了多壁碳纳米管分散剂和开炼机的使用,操作简便,保证了多壁碳纳米管的完整结构。(The invention aims to provide a preparation method of a multi-walled carbon nanotube/natural rubber composite material, belonging to the technical field of preparation of nano rubber composite materials. The preparation method comprises the steps of firstly preparing a multi-walled carbon nanotube/natural rubber mixed solution in a three-mouth flat-bottom flask with a condensing reflux pipe and a distillation device, then quickly tiling the multi-walled carbon nanotube/natural rubber mixed solution, drying to obtain a flaky multi-walled carbon nanotube/natural rubber composite material, and cutting, laminating and vulcanizing according to the required size to obtain the multi-walled carbon nanotube/natural rubber composite material. The prepared multi-walled carbon nanotube/natural rubber composite material has a three-dimensional multi-walled carbon nanotube conductive network structure, excellent conductivity, and good resistance-strain response and recovery. The invention effectively reduces the waste of organic solvent, ensures that the multi-walled carbon nano-tube has the same distribution state as the initial mixed solution in the matrix material, is beneficial to solving the problems that the multi-walled carbon nano-tube is difficult to disperse and easy to agglomerate in the rubber matrix, replaces the multi-walled carbon nano-tube dispersant and the open mill, has simple and convenient operation, and ensures the complete structure of the multi-walled carbon nano-tube.)

1. The invention relates to a preparation method of a multi-wall carbon nano tube/natural rubber composite material, which comprises the following raw materials: the natural rubber latex, the multi-wall carbon nano tube, the zinc oxide, the stearic acid, the anti-aging agent 4010NA, the sulfur and the accelerator NS, and the preparation process comprises the following steps:

1) respectively adding natural rubber latex and multi-wall carbon nano tubes into a separable flat-bottom three-mouth flat-bottom flask to prepare a uniformly dispersed natural rubber/tetrahydrofuran solution and a multi-wall carbon nano tube/tetrahydrofuran suspension;

2) synchronously mixing the two solutions obtained in the step 1) at a constant speed, performing ultrasonic treatment and stirring to obtain a multi-walled carbon nanotube/natural rubber/tetrahydrofuran mixed solution, adjusting the pH value to 8-9, adding zinc oxide, stearic acid and an anti-aging agent 4010NA, performing ultrasonic treatment, after stirring and dispersing uniformly, adding sulfur and an accelerator NS, continuing ultrasonic treatment, and stirring and dispersing uniformly;

3) heating the mixed solution obtained in the step 2) to 45 +/-5 ℃, continuously stirring to evaporate 60-70% of tetrahydrofuran and water in the mixed solution, and stopping heating and ultrasonic treatment;

4) transferring the mixed solution obtained in the step 3) into a flat-bottomed glassware with enough bottom area, flatly paving to form a solution film, and quickly drying to obtain a film-shaped multi-walled carbon nanotube/natural rubber mixture

5) Cutting, laminating and vulcanizing the mixture obtained in the step 4) according to the size of a mould to obtain the multi-wall carbon nano tube/natural rubber composite material.

2. The method of claim 1, wherein the multi-walled carbon nanotube/natural rubber composite is prepared by: a separable flat-bottom three-mouth flat-bottom flask is used, and three mouths of the flask are respectively connected with a stirrer, a condenser tube and a distillation device, and the details are shown in the attached figure 1.

3. The method of claim 1, wherein the multi-walled carbon nanotube/natural rubber composite is prepared by: the device shown in the attached figure 1 is adopted to recover the organic solvent, so that the waste of the organic solvent is reduced.

4. The method of claim 1, wherein the multi-walled carbon nanotube/natural rubber composite is prepared by: the rubber vulcanizing agent and the auxiliary agent are added in sequence of adding zinc oxide, stearic acid and anti-aging agent 4010NA, dispersing uniformly, and then adding sulfur and accelerator NS.

5. The method of claim 1, wherein the multi-walled carbon nanotube/natural rubber composite is prepared by: and (3) transferring the mixed solution into a flat-bottomed glassware with a sufficiently large bottom area, quickly spreading the mixed solution to form a film, preventing the multi-walled carbon nanotubes from reuniting and the insoluble vulcanizing agent from precipitating, keeping the uniform dispersion state of the multi-walled carbon nanotubes and the insoluble vulcanizing agent, and drying the film in situ to obtain the multi-walled carbon nanotube/natural rubber composite film.

6. The method of claim 1, wherein the multi-walled carbon nanotube/natural rubber composite is prepared by: and (3) laminating and vulcanizing, namely mutually overlapping and vulcanizing the unvulcanized multi-wall carbon nano tube/rubber composite material at high temperature and pressure.

7. The method of claim 1, wherein the multi-walled carbon nanotube/natural rubber composite is prepared by: the natural rubber latex is not limited to natural rubber latex, other rubber latex or rubber materials and derivatives can be selected, and the multi-wall carbon nanotube is not limited to multi-wall carbon nanotube, single-wall carbon nanotube, graphene oxide and other nano fillers can be selected.

Technical Field

The invention relates to a method for improving the dispersibility of multi-walled carbon nanotubes in a rubber matrix, in particular to a method for preparing a multi-walled carbon nanotube/natural rubber composite material, belonging to the technical field of intelligent rubber composite material preparation.

Background

The carbon nanotube is a tubular substance with a diameter of nanometer level formed by one or more layers of graphite sheets which are curled according to a certain helical angle. Since its discovery by the japanese electron microscopy Lijima in 1991, carbon nanotubes have received extensive attention and intensive research from a large number of researchers and have shown good potential for applications in many fields, especially in electrical and thermal conductivity. The carbon nano tube has special structures such as large specific surface area, length-diameter ratio and the like, and improves the electric conduction, heat conduction, physical properties and the like of the polymer. However, the carbon nanotubes have high surface free energy, are easy to agglomerate, are difficult to disperse in polymers, and limit the application range of the carbon nanotubes.

The carbon nano tube/rubber composite material combines the advantages of high elasticity and large deformation of rubber, high electric and thermal conductivity of the carbon nano tube, excellent mechanical property, electromagnetic shielding and the like, and becomes a research hotspot in the fields of intelligent composite materials and sensors in recent years, and the dispersibility and the structural integrity of the carbon nano tube in a rubber matrix influence the excellent properties of the rubber composite material, such as electric and thermal conductivity and the like. In the existing methods for preparing carbon nanotube/rubber composite materials, in order to improve the dispersibility of carbon nanotubes in rubber matrix and the properties thereof, mechanical mixing, latex mixing and solution mixing are commonly used. The mechanical mixing method improves the dispersibility of the carbon nano tube in the rubber matrix, but the strong shearing force destroys the self structure of the carbon nano tube and influences the conductivity. Although the latex mixing method ensures the structural integrity of the carbon nanotubes in the rubber matrix, the carbon nanotubes and the vulcanizing agent are difficult to disperse uniformly due to the high viscosity of the latex. In contrast, the solution mixing method can ensure the structural integrity of the carbon nanotubes and improve the dispersibility of the carbon nanotubes, and although an organic solvent is used, the solution mixing method is still the best choice at present in order to improve the characteristics of the composite material, such as conductivity and the like, and fully play the role of the carbon nanotubes in the rubber matrix.

Since carbon nanotubes are difficult to disperse and easily agglomerate, it is difficult to obtain a carbon nanotube/rubber composite material having good dispersion even by a solution mixing method, and thus, a method of modifying carbon nanotubes, such as a dispersant and a surfactant, has attracted attention. The introduction of the dispersing agent and the surfactant has certain improvement effect on the dispersibility of the carbon nano tube, and is more obvious in the aspect of mechanical property, but the carbon nano tube treated by the dispersing agent or other modification methods still has agglomeration and winding phenomena, is more serious, and has obvious limitation on the performances of the product such as conductivity and the like. The dispersant and the like are adopted to treat the carbon nano tube, so that the preparation period and the complexity of the product are increased, and the product performance has stronger dependence on the quality of the dispersant treated carbon nano tube. In addition, even if the carbon nanotube/rubber composite solution is uniformly dispersed, the solvent content is high, so that the carbon nanotube is secondarily agglomerated in the process of evaporating the solvent, and part of insoluble vulcanizing agent is precipitated and aggregated to influence the performance of the composite material.

In order to simplify the preparation process and obtain the carbon nanotube/rubber composite material with excellent conductivity, a preparation method of the carbon nanotube/rubber composite material needs to be developed, and the method can ensure the dispersibility of the carbon nanotube in a rubber matrix and the mixing uniformity of a vulcanizing agent, improve the preparation efficiency of the rubber composite material and reduce the waste of an organic solvent.

Disclosure of Invention

The invention aims to prevent the multi-walled carbon nanotubes from being unevenly distributed in a rubber matrix due to secondary agglomeration and free settling of insoluble vulcanizing agents, improve the dispersion uniformity of the multi-walled carbon nanotubes in a natural rubber matrix, shorten the preparation period, reduce the waste of organic solvents and prepare the multi-walled carbon nanotube/natural rubber composite material with excellent conductivity and sensitive resistance/strain response.

In order to achieve the purpose, the invention provides the following technical scheme:

the invention relates to a preparation method of a multi-wall carbon nano tube/natural rubber composite material, which comprises the following raw materials: the natural rubber latex, the multi-wall carbon nano tube, the zinc oxide, the stearic acid, the anti-aging agent 4010NA, the sulfur and the accelerator NS, and the preparation process comprises the following steps:

1) respectively adding natural rubber latex and multi-wall carbon nano tubes into a separable flat-bottom three-mouth flat-bottom flask to prepare a uniformly dispersed natural rubber/tetrahydrofuran solution and a multi-wall carbon nano tube/tetrahydrofuran suspension;

2) synchronously mixing the two solutions obtained in the step 1) at a constant speed, performing ultrasonic treatment and stirring to obtain a multi-walled carbon nanotube/natural rubber/tetrahydrofuran mixed solution, adjusting the pH value to 8-9, adding zinc oxide, stearic acid and an anti-aging agent 4010NA, performing ultrasonic treatment, after stirring and dispersing uniformly, adding sulfur and an accelerator NS, continuing ultrasonic treatment, and stirring and dispersing uniformly;

3) heating the mixed solution obtained in the step 2) to 45 +/-5 ℃, continuously stirring to evaporate 60-70% of tetrahydrofuran and water in the mixed solution, and stopping heating and ultrasonic treatment;

4) transferring the mixed solution obtained in the step 3) into a flat-bottomed glassware with enough bottom area, flatly paving to form a solution film, and quickly drying to obtain a film-shaped multi-walled carbon nanotube/natural rubber mixture

5) Cutting, laminating and vulcanizing the mixture obtained in the step 4) according to the size of a mould to obtain the multi-wall carbon nano tube/natural rubber composite material.

The method has the beneficial effects that the vulcanizing agent and the auxiliary agent are added at different time intervals, the waste of the organic solvent is reduced by adopting the device shown in the attached drawing 1, the mixed solution is moved into a flat-bottomed glassware with a sufficiently large bottom area, the flat-bottomed glassware is quickly paved to form a film, the re-agglomeration of the multi-walled carbon nanotubes and the precipitation of insoluble vulcanizing agent are prevented, the uniform dispersion state of the multi-walled carbon nanotubes and the insoluble vulcanizing agent is kept, the multi-walled carbon nanotube/natural rubber composite film is obtained by drying in situ, and the multi-walled carbon nanotube/natural rubber composite material which is overlapped and not vulcanized is laminated and vulcanized at high temperature and.

Drawings

FIG. 1 is a schematic view of an ultrasonic agitation dispersion test apparatus.

FIG. 2 is a graph showing the dispersibility of multi-walled carbon nanotubes prepared by the method in a natural rubber matrix.

Detailed Description

Specific embodiments are further illustrated for the present invention:

the invention relates to a preparation method of a multi-walled carbon nanotube/natural rubber composite material, which is characterized in that a vulcanizing agent and an auxiliary agent are added at different time intervals, the waste of an organic solvent is reduced, a mixed solution is moved into a flat-bottomed glassware with a sufficiently large bottom area, the flat-bottomed glassware is quickly paved into a film, the re-agglomeration of the multi-walled carbon nanotube and the precipitation of an insoluble vulcanizing agent are prevented, the uniform dispersion state of the multi-walled carbon nanotube and the insoluble vulcanizing agent is kept, and the multi-walled carbon nanotube and the insoluble vulcanizing agent.

The formula comprises the following raw material components in percentage by weight:

100 parts of natural rubber latex, 8 parts of carbon nano tube, 5 parts of zinc oxide, 2 parts of stearic acid, 4010NA2 parts of anti-aging agent, 3 parts of sulfur and 1.5 parts of accelerator NS.

The preparation process comprises the following steps:

1) adding the natural rubber latex into a separable flat-bottom three-mouth flat-bottom flask according to the formula amount, wherein the weight ratio of the natural rubber latex is 1 g: mixing 50mL of tetrahydrofuran, mechanically stirring for 30min, ultrasonically dispersing for 30min, and alternately performing for 2h to form uniformly dispersed natural rubber emulsion;

2) placing the multi-wall carbon nano-tube into a separable flat-bottom three-mouth flat-bottom flask according to the formula amount, and mixing the following components in a proportion of 1mg of the multi-wall carbon nano-tube: 2mL of tetrahydrofuran is mixed, ultrasonic stripping and dispersion are carried out for 1h, a stable natural rubber/tetrahydrofuran suspension is formed, and mechanical stirring is not carried out in the whole process;

3) synchronously pouring the uniformly dispersed natural rubber emulsion and the multi-walled carbon nanotube suspension into a separable flat-bottom three-mouth flat-bottom flask, mechanically stirring for 30min, ultrasonically dispersing for 30min, dropwise adding ammonia water, adjusting the pH value to 8-9, adding zinc oxide, stearic acid and an anti-aging agent 4010NA into the uniformly dispersed mixed solution according to the formula amount, strictly controlling the water temperature to be 15-25 ℃, and simultaneously carrying out ultrasonic stirring and mechanical stirring for 30 min;

4) adding sulfur and an accelerator NS into the mixed solution obtained in the step 3) according to the formula amount, and performing ultrasonic and mechanical stirring simultaneously for dispersing for 30 min;

5) heating the mixed solution obtained in the step 4) to 45 +/-5 ℃, continuously stirring to evaporate 60-70% of tetrahydrofuran and water in the mixed solution, and stopping heating and ultrasonic treatment;

6) transferring the mixed solution obtained in the step 5) into a flat-bottomed glassware with a sufficiently large bottom area to form a solution film, quickly removing surface bubbles formed by the solvent and water in a forced air drying oven at 50 ℃, taking out the solution and putting the solution into a vacuum drying oven at 35 +/-5 ℃ for vacuum drying for 10 hours to obtain a film-shaped multi-walled carbon nanotube/natural rubber mixture;

7) cutting the mixture obtained in the step 6) according to the size of a mould, laminating, and vulcanizing at 160 ℃ and 5MPa to obtain the multi-walled carbon nanotube/natural rubber composite material.

The adding sequence of the vulcanizing agent and the auxiliary agent is as follows: zinc oxide, stearic acid and anti-aging agent 4010NA are added firstly, and after uniform dispersion, sulfur and accelerator NS are added.

Leveling the uniformly dispersed mixed solution into a film shape, drying in situ, and laminating and vulcanizing.

By using the method, the multi-wall carbon nano tube/natural rubber composite material with excellent conductivity and good resistance/strain response effect can be prepared. In the scanning electron microscope image of fig. 2, white dots are the multi-walled carbon nanotubes with cross sections, and it can be seen that the multi-walled carbon nanotubes are uniformly dispersed in the natural rubber matrix. The resistance/strain response diagram of the material shows that along with repeated strain circulation, the resistance change is synchronous with the strain, the resistance change gradually tends to be stable after 5 cycle periods, the material has better sensitivity, and the shoulder effect still exists, which is caused by competition between the destruction and reconstruction of the multi-walled carbon nanotube conductive network in the stretching process.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.