The invention relates to the technology of carbon nanomaterials, specifically to the technology of obtaining modified carbon nanotubes.
Carbon nanotubes (CNTs) tend to form agglomerates, which makes it difficult to distribute them in various media. Even if CNTs are uniformly distributed in some medium, for example, by intense action of ultrasound, after a short time they spontaneously form agglomerates. To obtain stable CNT dispersions, various methods of modifying CNTs are used, which are carried out by attaching certain functional groups to the surface of CNTs, which ensure the compatibility of CNTs with the environment, using surfactants, and shortening too long CNTs by various methods.
In the description of this invention, the term "modification" means a change in the nature of the CNT surface and the geometric parameters of individual nanotubes. A particular case of modification is the functionalization of CNTs, which consists in grafting certain functional groups onto the surface of CNTs.
A known method for modifying CNTs, which includes the oxidation of CNTs under the action of various liquid or gaseous oxidizers (nitric acid in the form of liquid or vapor, hydrogen peroxide, solutions of ammonium persulfate at various pH, ozone, nitrogen dioxide, and others). There are many publications on this method. However, since the essence of the various methods of carbon nanotube oxidation is the same, namely, the oxidation of the surface of carbon nanotubes with the formation of surface hydroxyl and carboxyl groups, this gives reason to consider the various described methods as variants of one method. A typical example is the publication of Datsyuk V., Kalyva M., Papagelis K., Parthenios J., Tasis D., Siokou A., Kallitsis I., Galiotis C. Chemical oxidation of multiwalled carbon nanotubes //Carbon, 2008, vol.46, p.833-840, which describes several options (using nitric acid, hydrogen peroxide and ammonium persulfate).
Common essential features of the considered method and the claimed invention is the treatment of carbon nanotubes with an oxidizing agent solution.
The considered method is characterized by insufficient efficiency for splitting CNT agglomerates and achieving good dispersibility of oxidized CNTs in water and polar organic solvents. As a rule, carbon nanotubes oxidized by known methods are well dispersed in water and polar organic solvents (under the action of ultrasound) only at a very low concentration of nanotubes in the liquid (usually on the order of 0.001-0.05% of the mass). When the threshold concentration is exceeded, the nanotubes are collected into large agglomerates (flakes) that precipitate.
In a number of works, for example, Wang Y., Deng W., Liu X., Wang X. Electrochemical hydrogen storage properties of ball-milled multi-wall carbon nanotubes //International journal of hydrogen energy, 2009, vol.34, p. 1437-1443; Lee J., Jeong T., Heo J., Park S.-H., Lee D., Park J.-B., Han H., Kwon Y., Kovalev I., Yoon S.M., Choi J.-Y ., Jin Y., Kirn J.M., An K.H., Lee Y.H., Yu S. Short carbon nanotubes produced by cryogenic crushing //Carbon, 2006, vol.44, p.2984-2989; Konya Z., Zhu J., Niesz K., Mehn D., Kiricsi I. End morphology of ball milled carbon nanotubes //Carbon, 2004, vol.42, p.2001-2008, a method for modifying CNTs by shortening them is described, which is achieved by prolonged mechanical treatment of CNTs in liquids or frozen matrices. Shortened CNTs have better dispersibility in liquids and better electrochemical properties.
Common essential features of the considered and claimed methods is the mechanical processing of CNTs dispersed in any medium.
The disadvantage of the considered method is that it does not provide the functionalization of CNTs by polar groups, as a result of which the CNTs treated in this way are still insufficiently well dispersed in polar media.
Closest to the claimed invention is the method described in Chiang Y.-C., Lin W.-H., Chang Y.-C. The influence of treatment duration on multi-walled carbon nanotubes functionalized by H2SO4/HNO3 oxidation //Applied Surface Science, 2011, vol.257, p.2401-2410 (prototype). According to this method, modification of CNTs is achieved by their deep oxidation during prolonged boiling in an aqueous solution containing sulfuric and nitric acids. In this case, polar functional groups (in particular, carboxyl groups) are first grafted to the surface of CNTs, and nanotubes are shortened at a sufficiently long treatment time. At the same time, a decrease in the thickness of the nanotubes was also observed due to the complete oxidation of the surface carbon layers to carbon dioxide. Variants of this method are also described in other sources, for example, in the mentioned article by Datsyuk V., Kalyva M. et al., as well as Ziegler K.J., Gu Z., Peng H., Flor E.L., Hauge R.H., Smalley R.E. Controlled oxidative cutting of single-walled carbon nanotubes // Journal of American Chemical Society, 2005, vol. 127, issue 5, p. 1541-1547. In published sources, it is noted that shortened oxidized carbon nanotubes have an increased ability to disperse in water and in polar organic solvents.
A common essential feature of the proposed method and the prototype method is the treatment of CNTs with an aqueous solution of an oxidizing agent. The inventive method and the prototype method also coincide in the achieved result, namely, the grafting of polar functional groups to the CNT surface is achieved simultaneously with the shortening of long CNTs.
The disadvantages of the prototype method are the need to use a large excess of acids, which increases the cost of the process and creates environmental problems in waste disposal, as well as the oxidation of carbon nanotubes to carbon dioxide, which reduces the yield of the final product (modified carbon nanotubes) and increases its cost. In addition, this method is difficult to scale. Glass instruments can be used in the laboratory, but stainless steel equipment is preferred for pilot production. Boiling nanotubes in acid solutions creates the problem of equipment corrosion resistance.
The basis of the claimed invention is the task - by choosing an oxidizing reagent and oxidation conditions to eliminate the shortcomings of the known method.
The problem is solved by the fact that according to the method of modifying carbon nanotubes, which includes the treatment of carbon nanotubes with an aqueous solution of an oxidizing agent, the treatment of carbon nanotubes with an aqueous solution of an oxidizing agent is carried out simultaneously with mechanical treatment, and a solution of persulfate or hypochlorite is used as an oxidizing agent at a pH of more than 10.
Mechanical processing is carried out using a bead mill.
The oxidizing agent is taken in an amount equivalent to 0.1 to 1 g active oxygen atom per 1 g carbon atom of the nanotubes.
Excess hypochlorite in the reaction mixture at a pH of more than 10 is removed by adding hydrogen peroxide.
Carrying out the treatment of carbon nanotubes with an aqueous solution of an oxidizing agent simultaneously with mechanical treatment and the use of a persulfate or hypochlorite solution at pH more than 10 as an oxidizing agent eliminates the need to use a large excess of acids, which increases the cost of the process and creates environmental problems in waste disposal, as well as loss of the finished product due to oxidation of part of carbon nanotubes to carbon dioxide.
For mechanical processing, devices known in the art, such as a bead mill, a vibrating mill, a ball mill, and other similar devices, can be used. In practice, a bead mill is one of the most convenient devices for solving this problem.
Ammonium persulfate, sodium persulfate, potassium persulfate, sodium hypochlorite, potassium hypochlorite can be used as oxidizing agents. The claimed method is most effective when treating carbon nanotubes with an oxidizing agent solution at a pH of more than 10. At a lower pH, equipment corrosion and untargeted decomposition of the oxidizing agent with the release of chlorine (from hypochlorite) or oxygen (from persulfate) are possible. You can set the required pH value by adding known alkaline substances to the solution, for example, ammonia, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, and other alkaline substances that do not react under conditions of treatment with an oxidizing agent. In this case, one should take into account the known data that hypochlorite reacts with ammonia. Thus, ammonia cannot be used in a hypochlorite system. When using persulfate to establish an alkaline pH, all of the listed substances can be used.
For the implementation of the proposed method, the optimal amount of oxidizing agent is equivalent to from 0.1 to 1 g-atom of active oxygen per 1 g-atom of carbon nanotubes. When the amount of oxidizing agent is less than the specified lower limit, the resulting modified carbon nanotubes are less well dispersed in water and polar organic solvents. Exceeding the amount of oxidizing agent in excess of the specified upper limit is inappropriate, because, although it accelerates the process of oxidation of nanotubes, it does not improve the beneficial effect.
To implement the proposed method, the following initial substances and equipment were used:
Carbon nanotubes of Taunit and Taunit-M brands produced by LLC NanoTechCenter, Tambov.
Ammonium persulfate grade CHDA.
Sodium hypochlorite according to GOST 11086-76 in the form of an aqueous solution containing 190 g/l of active chlorine and 12 g/l of free sodium hydroxide.
Ammonia water 25% brand ChDA.
Sodium carbonate anhydrous grade ChDA.
Distilled water.
Dimethylacetamide, pure grade.
Ethyl alcohol 96%.
Horizontal bead mill МШПМ-1/0,05-ВК-04 manufactured by NPO DISPOD. Zirconia balls with a diameter of 1.6 mm were used as grinding media.
Ultrasonic unit IL-10.
1460 ml of distilled water were poured into a 4-liter stainless steel container and 228.4 g of ammonium persulfate were dissolved, after which 460 ml of 25% ammonia were added. 1099 g of an aqueous paste of Taunit-M carbon nanotubes (purified from mineral impurities by treatment with hydrochloric acid) containing 5.46% of dry matter were added to this solution and thoroughly mixed until a homogeneous suspension was formed. The resulting suspension was loaded into a bead mill with balls with a diameter of 1.6 mm from zirconium dioxide and processed for 7 hours. Then the treated suspension was unloaded, filtered from the beads, acidified with hydrochloric acid to an acidic reaction, filtered through a filter made of non-woven polypropylene material and washed with water until the wash water was neutral. The washed precipitate was sucked off in a vacuum and packaged in a sealed plastic container. The mass content of dry matter (nanotubes) in the resulting paste was 8.52% (the rest is water). The resulting product was dried in an oven at 80°C to constant weight.
To test the solubility (dispersibility), a sample of UNTM-1 was dispersed in water or in organic solvents using sonication. Experiments have shown that CNTM-1 are highly soluble in water, preferably at basic pH (created by the addition of ammonia or organic bases). The addition of a base promotes the formation of a stable solution (dispersion) of modified nanotubes, since it leads to the ionization of surface carboxyl groups and the appearance of a negative charge on the nanotubes.
Thus, a stable aqueous solution was obtained (as seen from the transparency of the solution and the absence of flakes) containing 0.5% UNTM-1 in the presence of 0.5% triethanolamine as a pH regulator. The solubility limit of CNTM-1 in this system is approximately 1%; above this concentration, gel inclusions appear.
In dimethylacetamide (without extraneous additives), sonication was used to obtain stable transparent solutions of UNTM-1 with a mass concentration of 1 and 2%. In this case, dimethylacetamide, which itself is a weak base, effectively dissolves CNTM-1 without the addition of extraneous pH regulators. A 1% solution was indefinitely stable during storage, while a 2% solution, after a few days, began to show signs of thixotropy, but without the formation of agglomerates.
2.7 liters of distilled water was poured into a 4-liter stainless steel container, 397.5 g of anhydrous sodium carbonate was added and stirred until complete dissolution. After the sodium carbonate was dissolved, sodium hypochlorite solution (0.280 L) was poured in and the mixture was thoroughly mixed. Then, 60 g of crude Taunit-M (containing about 3 wt. % catalyst impurities, predominantly magnesium oxide) were poured in gradually with stirring and stirred until a homogeneous suspension. This slurry was loaded into a bead mill with 1.6 mm zirconia balls and processed for 7 hours. Then the treated suspension was unloaded, filtered from the balls, acidified with hydrochloric acid to an acidic reaction, and kept for 3 days at room temperature to completely dissolve the catalyst residues and possible impurities of iron compounds (from the body and fingers of the bead mill). Thus, we simultaneously carried out the acid purification of nanotubes from catalyst impurities. The resulting acidic suspension was filtered through a non-woven polypropylene material filter and washed with water until the wash water was neutral. The washed precipitate was sucked off in a vacuum and packaged in a sealed plastic container. The mass content of dry matter (nanotubes) in the resulting paste was 7.33% (the rest is water). The resulting product was dried in an oven at 80°C to constant weight.
If the amount of hypochlorite in the reaction mixture with nanotubes is excessive, this accelerates the oxidation of the nanotube surface, but creates an environmental problem, because when the mixture is acidified, unreacted hypochlorite releases chlorine, according to the reaction equation:
2NaOCl+2HCl→2NaCl+H 2 O+Cl 2
In order to neutralize excess hypochlorite, hydrogen peroxide is added to the reaction mixture at a pH greater than 10. As established by us, the following reaction occurs:
NaOCl+H 2 O 2 →NaCl+H 2 O+O 2
As a result, harmless products are formed.
To test the solubility (dispersibility), a sample of UNTM-1 was dispersed in water or in organic solvents using sonication. Experiments have shown that CNTM-1 are highly soluble in water, preferably at basic pH (created by the addition of ammonia or triethanolamine). The addition of a base promotes the formation of a stable solution (dispersion) of modified nanotubes, since it leads to the ionization of surface carboxyl groups and the appearance of a negative charge on the nanotubes.
Thus, a stable aqueous solution was obtained (as seen from the transparency of the solution and the absence of flakes) containing 0.5% UNTM-1 in the presence of 0.5% triethanolamine as a pH regulator. The solubility limit of CNTM-1 in this system is approximately 1%; above this concentration, gel inclusions appear.
In dimethylacetamide (without extraneous additives), sonication was used to obtain stable transparent solutions of UNTM-1 with a mass concentration of 1 and 2%. In this case, dimethylacetamide, which itself is a base, effectively dissolves UNTM-1 without the addition of extraneous pH regulators, a 1% solution was indefinitely stable during storage, while a 2% solution began to show signs of thixotropy after a few days, but without the formation agglomerates.
For comparison, the solubility (under the action of ultrasound under the same conditions) in the same solvents of Taunit-M carbon nanotubes, oxidized according to the method given in the prototype method, with a mixture of nitric and sulfuric acids without mechanical treatment, was studied. The experiments performed showed that CNTs oxidized with an excess of nitric acid without mechanical treatment have the same solubility as those obtained according to the claimed invention. However, the inventive method is easy to scale, there are no problems with the corrosion resistance of the equipment and environmental problems with the neutralization of waste. The process of mechanochemical processing according to the claimed method proceeds at room temperature. The prototype method requires the use of such a large excess of nitric and sulfuric acids that scaling it up and ensuring environmental safety is very problematic.
These data confirm the effectiveness of the proposed method for obtaining modified CNTs. This does not apply aggressive solutions of acids, as in the prototype method, and the loss of carbon nanotubes due to oxidation to carbon dioxide (carbonate in an alkaline solution) is practically absent.
Thus, the claimed method makes it possible to obtain modified carbon nanotubes with good dispersibility in water and polar organic solvents, can be easily scaled up, and ensures environmentally friendly production.
1. A method for modifying carbon nanotubes, including the treatment of carbon nanotubes with an aqueous solution of an oxidizing agent, characterized in that the treatment of carbon nanotubes with an aqueous solution of an oxidizing agent is carried out simultaneously with mechanical treatment, and a solution of persulfate or hypochlorite is used as an oxidizing agent at a pH of more than 10, and the oxidizing agent is taken in an amount , equivalent to 0.1 to 1 g-atom of active oxygen per 1 g-atom of carbon nanotubes.
2. The method according to claim 1, characterized in that the mechanical processing is carried out using a bead mill.
3. The method according to claim 1, characterized in that the excess of hypochlorite in the reaction mixture at a pH of more than 10 is removed by the addition of hydrogen peroxide.
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Carbon nanotubes are known for their unique mechanical, electrical and thermal properties suitable for a wide range of applications in polymers. Young's modulus of 1000 GPa and tensile strength of 60 GPa were measured on the individual structure. These figures are several orders of magnitude higher than those of conventional engineering plastics. High electrical and thermal conductivity have also been established experimentally, with their values approaching or exceeding those of metals. This combination of product properties and shape, compatible with modern polymer processing technologies, ensures the creation of new structural materials.
Commercial Application
The use of carbon nanotubes to impart antistatic and conductive properties to polymers is now a commercial practice and is spreading in industries such as electronics and automotive. Figure 1 shows a typical image of the conductivity of a structural thermoplastic. Filling to achieve the transmission of electricity in the case of multi-walled carbon nanotubes can be 5-10 times lower than for conductive carbon black. Similar comparisons are made in thermoset resins such as epoxies, but at a much lower fill. This phenomenon can be explained by the theory of percolation (leakage): a path for the flow of electrons is created when the particles are very close to each other or have reached the percolation threshold. Fiber structures with a high ratio (length/diameter) increase the number of electrical contacts and provide a more uniform path. The geometric ratio of hydrocarbon nanotubes in the final product (e.g. injection molded parts) is typically in excess of 100 compared to short carbon fibers (<30) и техническим углеродом (>one). This explains the lower dosage required for a given resistivity. Percolation behavior may vary depending on resin type, viscosity and polymer processing method.
Rice. 1. Dependences of electrical conductivity on the content of carbon fillers: carbon nanotubes, highly conductive carbon black, standard carbon black.
The reduced filler content can provide several benefits such as improved processability, surface appearance, reduced sag, increased ability to retain the mechanical properties of the original polymer. These advantages have led to the introduction of multi-walled carbon nanotubes into conductive polymer applications, Table 1. In these applications, they can compete with additives such as highly conductive carbon black and carbon fibers on a cost/performance basis or on the basis of unique characteristics that are not possible. reach or pick up for product specifications.
Table 1. Commercial applications of conductive polymers with MWCNTs.
Market | Application | Properties of compositions based on carbon nanotubes |
| Cars | Fuel system parts and fuel lines (connectors, pump parts, o-rings, tubes), external body parts for electric painting (bumpers, mirror housings, fuel tank caps) | Improved balance of properties compared to carbon black, recyclability for large parts, resistance to deformation |
| Electronics | Technological tools and equipment, wafer cassettes, conveyor belts, backplanes, clean room equipment | Improved purity of blends compared to carbon fibers, control of surface resistivity, workability for casting thin parts, resistance to deformation, balance of properties, alternative possibilities of plastic blends compared to carbon fibers |
The incorporation of MWCNTs into plastics or elastomers is based on relatively standard devices used in rubber compounds and thermoplastics, such as fine screw extruders and internal mixers. Nanocyl MWCNTs can be supplied in powder form (Nanocyl® 7000) or thermoplastic concentrates (PlastiCyl™).
The use of composite materials for structural purposes
The exceptional strength of carbon nanotubes is being put to good use in the creation of various types of sporting goods based on composite materials of carbon fibers and epoxy resins. To facilitate incorporation and improve bonding with a bonding phase (eg epoxy or polyurethane), carbon nanotubes are usually chemically modified on the surface. The standard improvement, measured on a fiber reinforced composite material, is 10 to 50% in strength and dynamic load. This level of enhancement can be significant for a given composite, usually limited by the properties of the resin.
New developments
A network of exceptionally thin conductive structures such as carbon nanotubes also provides new opportunities in thin film technology, including permanently conductive antistatic transparent and conductive coatings, improved mechanical properties and increased chemical resistance. Highly conductive transparent film technologies are being developed that will compete with metal oxide technologies in the near future, such as the indium tin oxide sputtering technology used today to make transparent electrodes in flat panel displays and more limited designs such as flexible displays.
A modern technology for the production of paper using multi-walled carbon nanotubes has been developed. Such paper is used to create a more flexible thermal barrier coating to protect car mirrors from icing, underfloor heating and other heating devices.
Research is ongoing into new properties obtained by adding MWCNTs to polymers in small quantities, such as fire resistance and anti-rot, which may lead to the development of new products that are more environmentally friendly and have improved performance compared to existing materials, provided that savings are made.
Reinforced elastomers
Carbon black and other powdered fillers are widely used to reinforce rubber in tires and other industrial rubber. The formulation may contain a high level of filler loading to increase strength and stiffness to the desired level (greater than 50% by weight), but lack flexibility in some applications. Replacing 5-10% filling with multi-walled carbon nanotubes such as Nanocyl® 7000 can provide a similar level of strength and stiffness with improved elasticity in high performance elastomers, presenting a new balance of mechanical properties not comparable to traditional materials.
The use of carbon nanotubes for commercial purposes is now a reality that is attracting more and more attention. This means that they are accepted by the industry as a value added component, competing with other options that are regulated by industry standards. Currently, research is underway on new useful and unpredictable properties of carbon nanotubes that will expand their penetration into the polymer industry.
Energy is an important industry that plays a huge role in human life. The energy state of the country depends on the work of many scientists in this field. To date, they are searching For these purposes, they are ready to use anything, starting with sunlight and water, ending with the energy of air. The equipment that is able to generate energy from the environment is highly valued.
General information
Carbon nanotubes are extended rolled graphite planes having a cylindrical shape. As a rule, their thickness reaches several tens of nanometers, with a length of several centimeters. At the end of the nanotubes, a spherical head is formed, which is one of the parts of the fullerene.
There are two types of carbon nanotubes: metal and semiconductor. Their main difference is the conductivity of the current. The first type can conduct current at a temperature equal to 0ºС, and the second - only at elevated temperatures.
Carbon nanotubes: properties
Most modern areas, such as applied chemistry or nanotechnology, are associated with nanotubes, which have a carbon frame structure. What it is? This structure refers to large molecules linked together only by carbon atoms. Carbon nanotubes, whose properties are based on a closed shell, are highly valued. In addition, these formations have a cylindrical shape. Such tubes can be obtained by folding a graphite sheet, or grow from a certain catalyst. Carbon nanotubes, photos of which are presented below, have an unusual structure.
They come in different shapes and sizes: single-layered and multi-layered, straight and sinuous. Despite the fact that nanotubes look quite fragile, they are a strong material. As a result of many studies, it was found that they have properties such as stretching and bending. Under the action of serious mechanical loads, the elements do not tear or break, that is, they can adapt to different voltages.
Toxicity
As a result of multiple studies, it was found that carbon nanotubes can cause the same problems as asbestos fibers, that is, various malignant tumors occur, as well as lung cancer. The degree of negative impact of asbestos depends on the type and thickness of its fibers. Since carbon nanotubes are small in weight and size, they easily enter the human body with air. Further, they enter the pleura and enter the chest, and over time cause various complications. Scientists conducted an experiment and added particles of nanotubes to the food of mice. Products of small diameter practically did not linger in the body, but larger ones dug into the walls of the stomach and caused various diseases.
Acquisition Methods
To date, there are the following methods for obtaining carbon nanotubes: arc charge, ablation, deposition from the gas phase.
Electric arc discharge. Obtaining (carbon nanotubes are described in this article) in a plasma of electric charge, which burns with the use of helium. Such a process can be carried out using special technical equipment for the production of fullerenes. But with this method, other modes of arc burning are used. For example, it decreases, and cathodes of enormous thicknesses are also used. To create an atmosphere of helium, it is necessary to increase the pressure of this chemical element. Carbon nanotubes are obtained by sputtering. To increase their number, it is necessary to introduce a catalyst into the graphite rod. Most often it is a mixture of different metal groups. Further, there is a change in pressure and method of spraying. Thus, a cathodic deposit is obtained, where carbon nanotubes are formed. Finished products grow perpendicular to the cathode and are collected in bundles. They are 40 µm long.
Ablation. This method was invented by Richard Smalley. Its essence is to evaporate different graphite surfaces in a reactor operating at high temperatures. Carbon nanotubes are formed as a result of evaporation of graphite on the bottom of the reactor.
They are cooled and collected by means of a cooling surface. If in the first case, the number of elements was equal to 60%, then with this method the figure increased by 10%. The cost of the laser absolation method is more expensive than all the others. As a rule, single-walled nanotubes are obtained by changing the reaction temperature.
Deposition from the gas phase. The carbon vapor deposition method was invented in the late 50s. But no one even imagined that carbon nanotubes could be obtained with it. So, first you need to prepare the surface with a catalyst. Small particles of different metals, for example, cobalt, nickel and many others, can serve as it. Nanotubes begin to emerge from the catalyst bed. Their thickness directly depends on the size of the catalyzing metal. The surface is heated to high temperatures, and then a gas containing carbon is supplied. Among them are methane, acetylene, ethanol, etc. Ammonia serves as an additional technical gas. This method of obtaining nanotubes is the most common. The process itself takes place in various industrial enterprises, due to which less financial resources are spent for the manufacture of a large number of tubes. Another advantage of this method is that vertical elements can be obtained from any metal particles that serve as a catalyst. Obtaining (carbon nanotubes are described from all sides) became possible thanks to the research of Suomi Iijima, who observed under a microscope their appearance as a result of carbon synthesis.
Main types
Carbon elements are classified by the number of layers. The simplest type is single-walled carbon nanotubes. Each of them has a thickness of about 1 nm, and their length can be much longer. If we consider the structure, then the product looks like wrapping graphite with a hexagonal grid. At its tops are carbon atoms. Thus, the tube has the shape of a cylinder, which has no seams. The upper part of the devices is closed with covers consisting of fullerene molecules.
The next type is multilayer carbon nanotubes. They consist of several layers of graphite, which are folded into a cylinder shape. A distance of 0.34 nm is maintained between them. A structure of this type is described in two ways. According to the first, multilayer tubes are several single-layer tubes nested in each other, which looks like a nesting doll. According to the second, multilayer nanotubes are a sheet of graphite that wraps around itself several times, which looks like a folded newspaper.
Carbon nanotubes: application
Elements are an absolute new representative of the class of nanomaterials.
As mentioned earlier, they have a frame structure, which differs in properties from graphite or diamond. That is why they are used much more often than other materials.
Due to such characteristics as strength, bending, conductivity, they are used in many areas:
- as additives to polymers;
- catalyst for lighting devices, as well as flat-panel displays and tubes in telecommunication networks;
- as an absorber of electromagnetic waves;
- for energy conversion;
- production of anodes in various types of batteries;
- hydrogen storage;
- manufacture of sensors and capacitors;
- production of composites and strengthening of their structure and properties.
For many years, carbon nanotubes, whose application is not limited to one particular industry, have been used in scientific research. Such material has a weak position in the market, as there are problems with large-scale production. Another important point is the high cost of carbon nanotubes, which is about $120 per gram of such a substance.
They are used as the main element for the production of many composites, which are used in the manufacture of many sporting goods. Another industry is the automotive industry. The functionalization of carbon nanotubes in this area is reduced to endowing polymers with conductive properties.
The thermal conductivity coefficient of nanotubes is high enough, so they can be used as a cooling device for various massive equipment. Tips are also made from them, which are attached to the probe tubes.
The most important branch of application is computer technology. Thanks to nanotubes, especially flat displays are created. With the help of them, you can significantly reduce the overall dimensions of the computer itself, as well as increase its technical performance. The finished equipment will be several times superior to current technologies. Based on these studies, it is possible to create high-voltage kinescopes.
Over time, tubes will be used not only in electronics, but also in the medical and energy fields.
Production
Carbon tubing, whose production is distributed between the two types, is unevenly distributed.
That is, MWNTs make a lot more than SWNTs. The second type is done in case of urgent need. Various companies are constantly producing carbon nanotubes. But they are practically not in demand, as their cost is too high.
Production leaders
Today, the leading place in the production of carbon nanotubes is occupied by Asian countries, which are 3 times higher than in other countries of Europe and America. In particular, Japan is engaged in the manufacture of MWNT. But other countries, such as Korea and China, are in no way inferior in this indicator.
Production in Russia
Domestic production of carbon nanotubes lags far behind other countries. In fact, it all depends on the quality of the research in this area. It does not allocate enough financial resources to create scientific and technological centers in the country. Many people do not accept developments in the field of nanotechnology because they do not know how it can be used in industry. Therefore, the transition of the economy to a new path is quite difficult.
Therefore, the President of Russia issued a decree, which indicates the development of various areas of nanotechnology, including carbon elements. For these purposes, a special development and technology program was created.
In order to fulfill all the points of the order, the Rosnanotech company was created. A significant amount was allocated from the state budget for its functioning. It is she who should control the process of development, production and introduction of carbon nanotubes into the industrial sphere. The allocated amount will be spent on the creation of various research institutes and laboratories, and will also strengthen the existing achievements of domestic scientists. Also, these funds will be used to purchase high-quality equipment for the production of carbon nanotubes. It is also worth taking care of those devices that will protect human health, since this material causes many diseases.
As mentioned earlier, the whole problem is to raise funds. Most investors do not want to invest in research and development, especially for a long time. All businessmen want to see profit, but nanodevelopment can take years. This is what repels representatives of small and medium-sized businesses. In addition, without government investment, it will not be possible to fully launch the production of nanomaterials.
Another problem is the lack of a legal framework, as there is no intermediate link between different stages of business. Therefore, carbon nanotubes, the production of which is not in demand in Russia, require not only financial, but also mental investments. While the Russian Federation is far from the countries of Asia, which are leading in the development of nanotechnology.
Today, developments in this industry are carried out at the chemical departments of various universities in Moscow, Tambov, St. Petersburg, Novosibirsk and Kazan. The leading manufacturers of carbon nanotubes are the Granat company and the Komsomolets plant in Tambov.
Positive and negative sides
Among the advantages, one can single out the special properties of carbon nanotubes. They are a durable material that does not collapse under the influence of mechanical influences. In addition, they work well for bending and stretching. This is made possible by the closed frame structure. Their application is not limited to one industry. Tubes have found application in automotive, electronics, medicine and energy.
A huge disadvantage is the negative impact on human health.
Particles of nanotubes, getting into the human body, lead to the emergence of malignant tumors and cancer.
An essential side is the financing of this industry. Many people do not want to invest in science, because it takes a long time to make a profit. And without the functioning of research laboratories, the development of nanotechnologies is impossible.
Conclusion
Carbon nanotubes play an important role in innovative technologies. Many experts predict the growth of this industry in the coming years. There will be a significant increase in production capabilities, which will lead to a decrease in the cost of goods. With decreasing prices, tubes will be in great demand, and will become an indispensable material for many devices and equipment.
So, we found out what these products are.
Powdered carbon materials (graphites, carbons, carbon blacks, CNTs, graphenes) are widely used as functional fillers for various materials, and the electrical properties of composites with carbon fillers are determined by the structure and properties of carbon, as well as by the technology of their production. CNTs are a powder material made of framework structures of an allotropic form of carbon in the form of hollow multiwalled CNTs with an outer diameter of 10–100 nm (Fig. 1). As is known, the electrical resistivity (ρ, Ohm∙m) of CNTs depends on the method of their synthesis and purification and can range from 5∙10-8 to 0.008 Ohm∙m, which is less than
at graphite.
In the manufacture of conductive composites, highly conductive materials (metal powders, carbon black, graphite, carbon and metal fibers) are added to the dielectric. This makes it possible to vary the electrical conductivity and dielectric characteristics of polymer composites.
The present study was carried out to determine the possibility of changing the electrical resistivity of CNTs by modifying them. This will expand the use of such tubes as a filler for polymer composites with a planned electrical conductivity. Samples of CNT powders manufactured by ALIT-ISM (Zhytomyr, Kyiv) and CNT powders subjected to chemical modification were used in the work. To compare the electrical characteristics of carbon materials, samples of CNT "Taunit" (Tambov), synthesized according to TU 2166-001-02069289-2007, CNT LLC "TMSpetsmash" (Kyiv), manufactured according to TU U 24.1-03291669-009:2009, crucible graphite . CNTs manufactured by ALIT-ISM and Taunit are synthesized by the CVD method on a NiO/MgO catalyst, and CNTs from OOO TMSpetsmash are synthesized on a FeO/NiO catalyst (Fig. 2). In the study, under the same conditions, using the same developed methods, the electrophysical characteristics of samples of carbon materials were determined. The electrical resistivity of the samples was calculated by determining the current-voltage characteristics of a sample of dry powder pressed at a pressure of 50 kG (Table 1).
The modification of CNTs (Nos. 1–4) showed the possibility of changing the electrophysical characteristics of CNTs with the help of physicochemical influences (see Table 1). In particular, the electrical resistivity of the original sample was reduced by 1.5 times (No. 1); and for samples No. 2-4 - increase by 1.5-3 times.
At the same time, the total amount of impurities (the share in the form of non-combustible residue) decreased from
2.21 (original CNTs) up to 1.8% for
sample No. 1 and up to 0.5% - for No. 3. The specific magnetic susceptibility of samples No. 2–4 decreased from 127∙10-8 to 3.9∙10-8 m3/kg. The specific surface area of all samples increased by almost 40%. Among the modified CNTs, the minimum electrical resistivity (574∙10-6 Ohm∙m) was recorded for sample No. 1, which is close to the resistance of crucible graphite (33∙10-6 Ohm∙m). In terms of specific resistance, the samples of CNTs "Taunit" and LLC "TMSpetsmash" are comparable with samples No. 2, 3, and the specific magnetic susceptibility of these samples is an order of magnitude higher than that of modified CNT samples (ALIT-ISM).
The ability to vary the electrical resistivity of CNTs from 6∙10-4 to
12∙10-4 Ohm∙m. Specifications have been developed for the use of modified CNTs in the manufacture of composite and polycrystalline materials, coatings, fillers, suspensions, pastes and other similar materials.
TU U 24.1-05417377-231:2011 "Nanopowders of multi-walled CNT grades MWCNT-A (MWCNT-A),
MUNT-V (MWCNT-B), MUNT-S (MWCNT-C)"
(Table 2).
When composites are introduced into the polyethylene base as a filler of modified CNT powders, with an increase in their electrical conductivity, the electrical conductivity of the polymer composite increases. Thus, as a result of directed modification of CNTs, the possibility of varying their characteristics, in particular, electrical resistivity, opens up.
Literature
1. Tkachev A.G., Zolotukhin I.V. Apparatus and methods for the synthesis of solid-state nanostructures. - M .: Mashinostroenie-1, 2007.
2. Bogatyreva G.P., Marinich M.A., Bazaliy G.A., Ilnitskaya G.D., Kozina G.K., Frolova L.A. Study of the effect of chemical treatment on the physicochemical properties of carbon nanotubes. Sat. scientific tr. "Fullerenes and nanostructures in condensed media". / Ed.
P.A. Vityaz. - Minsk: State Scientific Institution "Institute of Heat and Mass Transfer
change them. A.V. Lykov" National Academy of Sciences of Belarus, 2011, pp. 141–146.
3. Novak D.S., Berezenko N.M., Shostak T.S., Pakharenko V.O., Bogatyreva G.P., Oleinik N.A., Bazaliy G.A. Electrically conductive nanocomposites based on polyethylene. Sat. scientific tr. "Rock-cutting and metalworking tools - technique and technology of its manufacture and application". - Kyiv: ISM
them. V.N. Bakulya NAS of Ukraine, 2011, issue 14, pp. 394–398.
Powdered carbon materials (graphite, coals, soot, CNTs, graphene) are widely used as functional fillers of different materials, and the electrical properties of composites with carbon fillers are determined by the structure and properties of carbon and by the production technology. The CNTs are a powder material of frame structures of allotropic form of carbon in the form of hollow multiwalled CNTs with an outside diameter of 10 to 100 nm (Fig.1a,b). It is known that the electrical resistivity (ρ, Ohm∙m) of CNTs depends on the method of their synthesis and purification and can range from 5∙10-8 to 0.008 Ohm∙m, which is by order lower than that of graphite .
Fig.1. a) – CNTs powder, b) – a fragment of CNTs (Power Electronic Microscopy)
At manufacture of conductive composites high conductive materials (metal powders, technical carbon, graphite, carbon and metal fibers) are added to dielectrics. This allows to vary the conductivity and dielectric properties of polymer composites.
The present investigation was conducted to determine the possibility of changing the specific electrical resistance of CNTs through their modification. This will expand the use of such tubes as a filler of polymer composites with planned electrical conductivity. The investigation used samples of initial powders of CNTs made by ALIT-ISM (Zhytomyr, Kiev) and CNTs powders which were subjected to various chemical modifications. To compare the electrophysical characteristics of carbon materials CNTs samples "Taunit" (Tambov, Russia) synthesized under 2166-001-02069289-2007, LLC "TMSpetsmash" (Kiev), made under 24.1-03291669-009:2009, crucible graphite, CNTs made by ALIT-ISM and "Taunit" are synthesized with CVD-method on NiO/MgO catalyst and CNTs made by LLC "TMSpetsmash" – on the FeO/NiO catalyst were used (Fig. 2).
Fig.2 a - CNT (ALIT-ISM), b - CNT "TMSpetsmash" (PEM-images).
Investigations under the same conditions using with the same methods developed in the ISM determined the electrical physical characteristics of the samples of carbon materials were determined. The specific electrical resistance of the samples was calculated by determining the current-voltage characteristic of dry powder element pressed under pressure of 50 kg. (Table 1).
The modification of CNTs (No.1-4) has shown the possibility to change the electrical properties of them porpusfully with the help of physical and chemical effects. In particular, specific electrical resistivity of the initial sample was reduced 1.5 times (No.1) and for No. 2 – 4 it was increased 1.5-3 times.
In this case the total amount of impurities (their shere in the form of non-combustible residues) was decreased from 2.21% (initial CNTs) to 1.8% for No.1 and to 0.5% for No.3. Magnetic susceptibility of samples No.2 – 4 was decreased by order. The specific surface area of all samples was increased almost by 40%. Among the modified CNTs minimum specific electrical resistance (574∙10-6 Ohm∙m) is fixed for the sample No.1 which is close to such resistance of crucible graphite (337∙10-6 Ohm∙m). By specific resistance the samples of CNTs "Taunit" and "TMSpetsmash" can be compared with that of samples No.2 and No.3, and the magnetic susceptibility of these samples is by order higher than that of the modified CNTs samples ("Alit -ISM").
Thus, the possibility of modifying CNTs to vary the specific electrical resistivity value of CNTs in the range 6∙10-4÷12∙10-4Ohm∙m was stated. There have been developed specifications 24.1-05417377-231:2011 "Nanopowders of multiwalled CNTs of grades MWCNTs-A, MWCNTs-B, MWCNTs-C (Table 2) for modified CNTs for production of composite and polycrystalline materials, coatings, fillers, suspensions , pastes and other similar materials.
At introduction into the polyethylene base of composites as a filler of modified powders of CNTs of new grades with increasing electrical conductivity of CNTs electrical conductivity of the polymer composite increases. Thus, as a result of the directed modification of CNTs there are new opportunities to vary of their characteristics, in particular, the value of electric resistivity.
Literature
Carbon nanotubes are the future of innovative technologies. The production and introduction of nanotubulenes will improve the quality of goods and products, significantly reducing their weight and increasing strength, as well as endowing them with new characteristics.
Carbon nanotubes or tubular nanostructure (nanotubulene) are single or multi-walled hollow cylindrical structures artificially created in the laboratory, obtained from carbon atoms and possessing exceptional mechanical, electrical and physical properties.
Carbon nanotubes are made from carbon atoms and are shaped like tubes or cylinders. They are very small (at the nanoscale), with a diameter of one to several tens of nanometers and a length of up to several centimeters. Carbon nanotubes are composed of graphite, but have other characteristics that are not characteristic of graphite. They don't exist in nature. Their origin is artificial. The body of nanotubes is synthetic, created by people independently from beginning to end.
If you look at a nanotube magnified a million times, you can see an elongated cylinder consisting of equilateral hexagons with carbon atoms at their vertices. This is a graphite plane rolled into a tube. The chirality of a nanotube determines its physical characteristics and properties.
Magnified a million times, a nanotube is an elongated cylinder consisting of equilateral hexagons with carbon atoms at their vertices. This is a graphite plane rolled into a tube.
Chirality is the property of a molecule not to coincide in space with its mirror image.
More clearly, chirality is when you fold, for example, a sheet of paper evenly. If obliquely, then this is already akhirality. Nanotubulenes can have single-layer and multilayer structures. A multilayer structure is nothing more than several single-layer nanotubes "dressed" one on one.
Discovery history
The exact date of discovery of nanotubes and their discoverer are unknown. This topic is food for debate and reasoning, as there are many parallel descriptions of these structures by scientists from different countries. The main difficulty in identifying the discoverer lies in the fact that nanotubes and nanofibers, falling into the field of view of scientists, did not attract their close attention for a long time and were not carefully studied. Existing scientific works prove that the possibility of creating nanotubes and fibers from carbon-containing materials was theoretically allowed in the second half of the last century.
The main reason why serious studies of micron carbon compounds were not carried out for a long time is that at that time scientists did not have a sufficiently powerful scientific base for research, namely, there was no equipment capable of enlarging the object of study to the required extent and translucent their structure .
If we arrange the events in the study of nanocarbon compounds in chronological order, then the first evidence falls on 1952, when the Soviet scientists Radushkevich and Lukyanovich drew attention to the nanofibrous structure formed during the thermal decomposition of carbon monoxide (the Russian name is oxide). The structure observed using electron microscope equipment had fibers with a diameter of about 100 nm. Unfortunately, things did not go further than fixing an unusual nanostructure, and no further research followed.
After 25 years of oblivion, since 1974, information about the existence of micron tubular structures made of carbon is beginning to hit the newspapers. So, a group of Japanese scientists (T. Koyama, M. Endo, A. Oberlin) during research in 1974-1975. presented to the general public the results of a number of their studies, which contained a description of thin tubes with a diameter of less than 100 Å, which were obtained from vapors during condensation. Also, the formation of hollow structures with a description of the structure and mechanism of formation obtained in the study of the properties of carbon were described by Soviet scientists of the Institute of Catalysis of the Siberian Branch of the USSR Academy of Sciences in 1977.
Å (Agström) - a unit of measurement of distances, equal to 10−10 m. In the SI system, a unit close in value to the angstrom is a nanometer (1 nm = 10 Å).
Fullerenes are hollow, spherical molecules shaped like a ball or rugby ball.
Fullerenes are the fourth, previously unknown, modification of carbon, discovered by the English chemist and astrophysicist Harold Kroto. And only after using the latest equipment in their scientific research, which allows them to examine in detail and shine through the carbon structure of nanotubes, the Japanese scientist Sumio Iijima conducted the first serious research in 1991, as a result of which carbon nanotubes were experimentally obtained and studied in detail. .
In his research, Professor Ijima exposed sputtered graphite to an electric arc discharge to obtain a prototype. The prototype was carefully measured. Its dimensions showed that the diameter of the filaments (carcass) does not exceed a few nanometers, with a length of one to several microns. Studying the structure of a carbon nanotube, scientists found that the object under study can have from one to several layers, consisting of a graphite hexagonal grid based on hexagons. In this case, the ends of the nanotubes structurally resemble a half of a fullerene molecule cut in two.
At the time of the above studies, there were already works by such well-known scientists in their field as Jones, L.A. Chernozatonsky, M.Yu. Kornilov, predicting the possibility of formation of this allotropic form of carbon, describing its structure, physical, chemical and other properties.
The multilayer structure of a nanotube is nothing more than several single-layer nanotubules, “dressed” one on one according to the principle of Russian nesting dolls Electrophysical properties
The electrophysical properties of carbon nanotubes are under the closest scrutiny by scientific communities around the world. By designing nanotubes in certain geometric ratios, it is possible to give them conductive or semiconductor properties. For example, diamond and graphite are both carbon, but due to differences in molecular structure, they have different and in some cases opposite properties. Such nanotubes are called metallic or semiconductor.
Nanotubes that conduct electricity even at absolute zero temperatures are metallic. The zero conductivity of the electric current at absolute zero, which increases with increasing temperature, indicates the hallmark of a semiconductor nanostructure.
The main classification is distributed according to the method of folding the graphite plane. The folding method is indicated by two numbers: "m" and "n", which set the direction of folding along the vectors of the graphite lattice. The properties of nanotubes depend on the geometry of the graphite plane folding, for example, the twisting angle directly affects their electrophysical properties.
Depending on the parameters (n, m), nanotubes can be: straight (achiral), jagged ("armchair"), zigzag and helical (chiral). For the calculation and planning of electrical conductivity, the formula for the ratio of parameters is used: (n-m) / 3.
An integer obtained in the calculation indicates the conductivity of a metallic type nanotube, and a fractional number indicates a semiconductor type. For example, all tubes of the "chair" type are metal. Carbon nanotubes of the metallic type conduct electric current at absolute zero. Nanotubulenes of the semiconductor type have zero conductivity at absolute zero, which increases with increasing temperature.
Nanotubes with a metallic type of conductivity can approximately transmit a billion amperes per square centimeter. Copper, being one of the best metal conductors, is inferior to nanotubes in these indicators by more than a thousand times. When the conductivity limit is exceeded, heating occurs, which is accompanied by the melting of the material and the destruction of the molecular lattice. This does not happen with nanotubulenes under equal conditions. This is due to their very high thermal conductivity, which is twice that of diamond.
In terms of strength, nanotubulene also leaves other materials far behind. It is 5–10 times stronger than the strongest alloys of steel (1.28–1.8 TPa in Young's modulus) and has an elasticity 100 thousand times higher than rubber. If we compare the tensile strength indicators, then they exceed the similar strength characteristics of high-quality steel by 20–22 times!
How to get UN
Nanotubes are obtained by high-temperature and low-temperature methods.
High-temperature methods include laser ablation, solar technology or electric arc discharge. The low temperature method has incorporated chemical vapor deposition using catalytic hydrocarbon decomposition, gas phase catalytic growth from carbon monoxide, production by electrolysis, polymer heat treatment, local low temperature pyrolysis or local catalysis. All methods are difficult to understand, high-tech and very costly. The production of nanotubes can only be afforded by a large enterprise with a strong scientific base.
Simplified, the process of obtaining nanotubes from carbon by the arc method is as follows:
A plasma in a gaseous state is introduced into a reactor heated to a certain temperature with a closed circuit through an injection apparatus. In the reactor, in the upper and lower parts, magnetic coils are installed, one of which is the anode and the other the cathode. The magnetic coils are supplied with a constant electric current. The plasma in the reactor is affected by an electric arc, which is also rotated by a magnetic field. Under the action of a high-temperature electroplasma arc from the surface of the anode, which consists of a carbon-containing material (graphite), carbon evaporates or “snaps out” and condenses on the cathode in the form of carbon nanotubes contained in the precipitate. In order for carbon atoms to be able to condense on the cathode, the temperature in the reactor is lowered. Even a brief description of this technology makes it possible to assess the complexity and cost of obtaining nanotubulenes. It will be a long time before the process of production and application becomes available to most enterprises.
Photo gallery: Scheme and equipment for obtaining nanotubes from carbon
Installation for the synthesis of single-walled carbon nanotubes by the electric arc method 
Small power scientific installation for obtaining a tubular nanostructure 
Low temperature production method 
Installation for the production of long carbon nanotubes
Are they toxic?
Definitely yes.
In the process of laboratory research, scientists came to the conclusion that carbon nanotubes adversely affect living organisms. This, in turn, confirms the toxicity of nanotubes, and it is less and less necessary for scientists to doubt this important issue.
Studies have shown that direct interaction of carbon nanotubes with living cells leads to their death. Especially single-walled nanotubes have strong antimicrobial activity. Experiments scientists began to carry out on a common culture of the kingdom of bacteria (E. coli) E-Coli. In the process of research, single-layer nanotubes with a diameter of 0.75 to 1.2 nanometers were used. As experiments have shown, as a result of the impact of carbon nanotubes on a living cell, cell walls (membranes) are mechanically damaged.
Nanotubes obtained by other methods contain a large amount of metals and other toxic impurities. Many scientists assume that the very toxicity of carbon nanotubes does not depend on their morphology, but is directly related to the impurities contained in them (nanotubes). However, the work carried out by scientists from Yale in the field of nanotube research has shown an erroneous representation of many communities. Thus, the bacteria of Escherichia coli (E-Coli) in the process of research were subjected to treatment with single-walled carbon nanotubes for one hour. As a result, most of the E-Coli died. These studies in the field of nanomaterials have confirmed their toxicity and negative impact on living organisms.
Scientists have come to the conclusion that single-walled nanotubes are the most dangerous, this is due to the proportional ratio of the length of a carbon nanotube to its diameter.
Various studies on the effect of carbon nanotubes on the human body have led scientists to the conclusion that the effect is identical, as in the case of asbestos fibers entering the body. The degree of negative impact of asbestos fibers directly depends on their size: the smaller, the stronger the negative impact. And in the case of carbon nanotubes, there is no doubt about their negative effect on the body. Entering the body with air, the nanotube settles through the pleura in the chest, thereby causing serious complications, in particular, cancerous tumors. If the penetration of nanotubulens into the body occurs through food, they settle on the walls of the stomach and intestines, causing various diseases and complications.
Currently, scientists are conducting research on the biological compatibility of nanomaterials and the search for new technologies for the safe production of carbon nanotubes.
prospects
Carbon nanotubes occupy a wide range of applications. This is due to the fact that they have a molecular structure in the form of a skeleton, thus allowing them to have properties that differ from those of diamond or graphite. It is precisely because of their distinctive features (strength, conductivity, bending) that carbon nanotubes are used more often than other materials.
This carbon invention is used in electronics, optics, mechanical engineering, etc. Carbon nanotubes are used as additives to various polymers and composites to enhance the strength of molecular compounds. After all, everyone knows that the molecular lattice of carbon compounds has incredible strength, especially in its pure form.
Carbon nanotubes are also used in the production of capacitors and various types of sensors, anodes, which are necessary for the manufacture of batteries, as an absorber of electromagnetic waves. This carbon compound has found wide application in the field of manufacturing telecommunication networks and liquid crystal displays. Also, nanotubes are used as an amplifier of catalytic properties in the production of lighting devices.
Commercial Application
| Market | Application | Properties of compositions based on carbon nanotubes |
| Cars | Fuel system parts and fuel lines (connectors, pump parts, o-rings, tubes), external body parts for electric painting (bumpers, mirror housings, fuel tank caps) | Improved balance of properties compared to carbon black, recyclability for large parts, resistance to deformation |
| Electronics | Technological tools and equipment, wafer cassettes, conveyor belts, backplanes, clean room equipment | Improved purity of blends compared to carbon fibers, control of surface resistivity, workability for casting thin parts, resistance to deformation, balance of properties, alternative possibilities of plastic blends compared to carbon fibers |
Carbon nanotubes are not limited to certain areas of application in various industries. The material was invented relatively recently, and, in this regard, it is currently widely used in scientific development and research in many countries of the world. This is necessary for a more detailed study of the properties and characteristics of carbon nanotubes, as well as for the establishment of large-scale production of the material, since it currently occupies a rather weak position in the market.
Carbon nanotubes are used to cool microprocessors. Due to their good conductive properties, the use of carbon nanotubes in mechanical engineering occupies a wide range. This material is used as devices for cooling aggregates with massive dimensions. This is primarily due to the fact that carbon nanotubes have a high specific thermal conductivity.
The use of nanotubes in the development of computer technology plays an important role in the electronics industry. Thanks to the use of this material, production has been established for the manufacture of fairly flat displays. This contributes to the production of compact-sized computer equipment, but at the same time, the technical characteristics of electronic computers are not lost, but even increase. The use of carbon nanotubes in the development of computer technology and the electronics industry will make it possible to achieve the production of equipment that will be many times superior in terms of technical characteristics to current analogues. Based on these studies, high-voltage kinescopes are already being created.
First carbon nanotube processor Usage issues
One of the problems with the use of nanotubes is the negative impact on living organisms, which casts doubt on the use of this material in medicine. Some of the experts suggest that there may be unappreciated risks in the process of mass production of carbon nanotubes. That is, as a result of expanding the scope of nanotubes, there will be a need for their production on a large scale and, accordingly, there will be a threat to the environment.
Scientists propose to look for ways to solve this problem in the application of more environmentally friendly methods and methods for the production of carbon nanotubes. It was also suggested that the manufacturers of this material take a serious approach to the issue of “cleaning up” the consequences of the CVD process, which, in turn, may affect the increase in the cost of products.
Photo of the negative impact of nanotubes on cells a) cells of Escherichia coli before exposure to nanotubes; b) cells after exposure to nanotubes In the modern world, carbon nanotubes make a significant contribution to the development of innovative technologies. Experts give forecasts for an increase in the production of nanotubes in the coming years and a decrease in prices for these products. This, in turn, will expand the scope of nanotubes and increase consumer demand in the market.
