CC BY
12УДК 621.315
Jumaeva D.J.
Doctor of Technical Sciences, Professor, Institute of General and Inorganic Chemistry Laboratory of Colloid Chemistry and Industrial Ecology
(Uzbekistan, Tashkent)
Toirov O.Z.
Doctor of Technical Sciences, Professor, Head of Department "Electrical Machines" Tashkent State Technical University (Uzbekistan, Tashkent)
Uralova F.
Master Student of the Department "Electrical Machines" Tashkent State Technical University (Uzbekistan, Tashkent)
Sulaymonova Z. Master Student of the Department "Electrical Machines" Tashkent State Technical University (Uzbekistan, Tashkent)
PHYSICO-CHEMICAL PROPERTIES OF POLYMER INSULATED MATERIALS FOR APPLICATION IN THE CABLE INDUSTRY
Abstract: this article discusses the physical and chemical properties of materials with polymer insulation for use in the cable industry.
Keywords: polymer, cable, insulation, polystyrene, electric current, properties.
To protect cable products, ordinary paper was used in the 18th century: telegraph wires were wound from it. A little later, in 1894, production was enriched with oil-impregnated paper: it was from it that insulation for electrical cables was made. In the 19th century, when the first underground communications began to be built in Europe, the era of natural rubber began, the layer of which protected electromechanical products from moisture penetration. Then people began to master the technology of rubber vulcanization. Well, protective shells based on polyethylene compositions became known only in the 1950 y [1-5].
An electrical structure consisting of a set of insulating materials used in the cable industry is called electrical insulation. No electrical equipment, instruments or structures can be imagined without insulation materials. Even the simplest electrical circuit cannot be assembled without electrical conductors and insulation materials. Electrical insulation serves to ensure that the electric current flows in the desired direction. Electrical insulation materials are divided into gaseous, liquid and solid types according to the state of aggregation. Among them, solid state materials are the most common. According to the chemical structure, the insulation materials used for the cable are divided into organic and inorganic types. At the same time, organic dielectrics produce a large number of different products from polymers in electrical engineering, radio engineering, electronics and other sectors of the economy. A molecule of high molecular weight compounds formed by the covalent bonding of hundreds, thousands, and more atoms is called a macromolecule. The macromolecules of most natural and synthetic polymers consist of the same group of repetitive atoms - elemental rings. Compounds that have such a macromolecule are called polymers. The low molecular weight compounds used in the synthesis of polymers are called monomers. Among dielectrics, high molecular weight organic materials are of particular importance. Compounds that contain carbon are called organic substances. These molecules form a large number of chemical compounds: according to their molecular structure, they can be chain, branched, circular, and other forms. High-molecular materials include cellulose, silk, rubber, and more. Artificially derived molecular materials can be
divided into two categories. It is possible to cite artificial materials that are prepared by chemical processing of natural high-molecular substances. Cellulose ether is obtained by processing cellulose. The second category includes high molecular weight synthetic materials made from low molecular weight substances, which are of particular importance in electrical insulation. The formation of polymers from monomers as a result of a reaction is called polymerization. As a result of polymerization, the molecular mass, liquefaction and boiling point of the substance increase. During the polymerization process, the substance turns into a gaseous or liquid state, a solid or a solid state. Polymers are mainly divided into linear and spatial polymer groups. The structure of linear polymer molecules is in the form of chains and fibers. Examples of linear polymers are natural rubber, polyethylene, siloxane rubbers. Phase or branched polymer molecules are arranged in repetitive groups with a compact structure, arranged flat on three coordinate axes. Linear and spatial polymers differ drastically from each other in terms of properties. Linear polymers are flexible and elastic, and under the influence of temperature most of them first soften and then melt. Phase polymers, on the other hand, are insoluble solids, which undergo chemical decomposition when exposed to temperature. Polymers come in thermoplastic and thermoreactive types. These results are presented in Table 1.
Table 1. Some properties of synthetic polymers
Title Density, kg/m3 Consistenc y, MPa Heat transfer coefficient p, Ом*м t, Em, МВ/м
Polyethylene 918-968 10-15 0,30-0,40 1013-1014 2,3-2,4 10-20
Polystyrene 1020-1390 35-60 0,10 1014-1013 2,4-2,5 20-35
Polytetrafluoro ethylene 2150-2240 15-30 0,23 1013-1014 1,9-2,1 20-30
Polyvinyl chloride 1350-1450 30-50 0,10 1013-1014 3,0-5,0 15-20
Polymethyl methacrylate 1180-1220 40-70 0,1-0,18 1011-1013 3,5-4,5 20-35
Polyamide 1100-1160 70-90 1012-1013 3,0-4,0 15-20
Epoxide 1100-1250 80-90 0,20 1012-1013 3,0-4,0 20-80
Phenol formaldehyde 1250-1300 50-60 0,13-0,25 1011-1012 5,0-4,0 10-20
Silicon is organic 1600-1750 20-45 0.08 1017-1014 3,5-5,0 15-25
Thermoplastic polymers soften when heated and easily deform, dissolve easily under the influence of solvents, and almost do not change their electrical properties under the influence of temperature. When thermoreactive polymers are heated, they become rigid, ie mechanically stable, and lose their flexibility as well as their solubility. Under the influence of temperature, these materials have a structure similar to spatial polymers. In recent years, heat-resistant thermoplastic materials such as polyacrylamide, polytetrafluoroethylene have been developed, which are polmers capable of operating at high temperatures [6-8].
Polyethylene is a slightly opaque, rigid, thermoplastic material. The mechanical and dielectric properties of polyethylene are given in Table 2. Polyethylene is a flexible material resistant to moisture, aggressive chemical environments.
Table 2. Basic properties of polyethylene
Indicators Unity Characteristics of pressure in different conditions
high past middle
Density kg/m3 918-930 954-960 960-968
Durability: in elongation MPa 10-17
in bending 17-20 18-45 18-40
in compression 14-17 20-40 25-40
Relative elongation % 15-20 10-12 5-8
P Om*m 1015 1015 1015
Ps Om 1015 1015 1015
Sr MGts 2,2-2,3 2,2-2,4 2,3-2,4
tga S (2-3)10-4 (2-4)10-4 (2-4)10-4
Em MV/m 45-55 45-55 45-55
Melt temperature °C 103-110 124-132 128-135
Water absorption (30 daily condition), % 0,02 0,005 0,01
Working temperature °S 90 90 90
Polymethyl methacrylate is resistant to acid and alkaline solutions, almost does not absorb water. It is an easily weldable material. This material is used to extinguish the arc discharge from the high-pressure gas formed by the release of large amounts of gas from itself under the influence of the arc discharge. These properties allow the use of polymethyl methacrylate in high-voltage switches. This material is widely used in the field of electrical and radio engineering as a construction and insulation material.
Polytetraftoretylene is a white thermoplastic polymer that is insoluble in acids or alkalis and does not absorb water. The high operating temperature of this polymer is much higher (+250°C) than other polymers. Of all the dielectrics, polytetrophorethylene (fluoroplast-4) has the best dielectric properties, with virtually no change in these properties between 60°C and 250°C. This material is very resistant to external influences. The density of polytetrafluoroethylene is 2150 - 2240 kg/m3, tensile strength is 14-25 MPa, low operating temperature - 80°C. Its dielectric properties are distinguished by their specificity. Polytetrafluoroethylene is the most chemically resistant polymer among plastics and is widely used in the insulation of radios, cables, capacitors, wire cladding and insulation film.
Polyamide is a hard material, a polymer with a high melting point, with high mechanical properties; differs considerably in its resistance to solvents. Due to the good mechanical properties of polyamide, it allows its use in electrical apparatus, wires and cables. This material is mainly used in the production of protective coatings, in the manufacture of insulation layers, in the application of insulation coatings on the surface of wires, electric machines and electrical equipment, in the manufacture of films. Polyethylene terephthalate, i.e. lavsan, is a thermoplastic polymer and is a complex polyester product. It has a mechanical elongation of 170 MPa, a melting point of265°C and is a temperature-resistant, solvent-resistant material. In electrical enginee ring, it is used to make films, fibers and synthetic materials.
Silicon-organic polymer materials consist of a high molecular weight compound that contains silicon in addition to carbon. According to the structure of macromolecules, silicon organic polymers are divided into linear and spatial categories, and these polymers have the following parameters in terms of application and properties, such as liquefaction, viscosity and thermoreactivity. One of the main properties of these polymers is that they can operate at high temperatures for a long time, i.e. at 180 ° C. Silicon-organic polymers are elastic materials with high dielectric properties, resistant to cold and moisture. Many cellulose materials are used as insulation materials in electrical engineering. They are used to make various insulation materials or construction details for electrical machines and transformers. Cellulose-based paper is used to insulate high-voltage cables, telephone cables, transformers and capacitors. Cellulose acetate is mainly obtained from refined cotton cellulose. Fiber and film are obtained from a solution of this material in methylene chloride. A plasticizer is added to the solution to give them flexibility. Triacetate film is commonly used in steam insulation of electric machines. Because ethylcellulose has unique properties, it is used in the cable industry to coat wire and fiber surfaces. In electrical insulation, the fiber is wrapped or woven over the surface of the wire and cord. Tape and fabric fabrics are also used to protect the main insulation of electrical machines and equipment from external mechanical influences. Since the diameter of the fiber is
not cylindrical, the numbering method is used to determine its thickness. The fiber number is determined by the ratio of the length of the fiber to its mass. This means that the larger the fiber number, the thinner the fiber. If several fibers are woven together, the thickness of the structure is indicated as a fractional number 75/3, the image of which shows the number of fibers, and the denominator shows the number of fibers.
REFERENCES:
https://xn—8sbdqwibq1a0i .xn--p1ai/polimery.html
Konstantinov G.G., Arsentiev O.V. Xlpe-insulated cables// BULLETIN of ISTU №6 (46) 2010.
Diagnostics and monitoring of cable networks of medium voltage classes / Kadomskaya K.P., Kachesov V.E., Lavrov Yu.A., Ovsyannikov A.G., Sakhno V.V. // Electrical engineering. 2000. No. 11. S. 48-51.
Manufacturers of power cables for medium and high voltage with XLPE insulation in Russia and CIS countries // Cable-news. 2007. No. 9.
Cable line systems with XLPE insulation are the optimal solution for reliable power supply of modern industrial and social facilities cities // Cable-info. 2006. No. 9. Golynina N.G., Nekrasov M.L. Power cables with XLPE insulation. Characteristics. Application. Tests // Cable-news. 2008. No. 3.
Toirov O.Z., Shatursunov Sh.Sh., Akberdiev M.A. Increasing the efficiency of the liquid fuel combustion chamber of the wire annealing furnace due to the adjustable electric drive // Международный научный журнал "Вестник науки". 2022. №5 (50). Т. 4. ISSN 2712-8849.
Olimjon Toirov, Kamoliddin Alimkhodjaev, Akhror Pardaboev Analysis and ways of reducing electricity losses in the electric power systems of industrial enterprises, SUSE-2021, E3S Web of Conferences 288, 01085 (2021) https://doi.org/10.1051/e3sconf/202128801085
