{"id":1208,"date":"2016-05-02T14:53:32","date_gmt":"2016-05-02T14:53:32","guid":{"rendered":"http:\/\/polymers.com.ua\/?p=1208"},"modified":"2016-05-02T14:53:32","modified_gmt":"2016-05-02T14:53:32","slug":"silicone-polymers","status":"publish","type":"post","link":"https:\/\/polymers.com.ua\/en\/silicone-polymers\/","title":{"rendered":"Silicone polymers"},"content":{"rendered":"

\"\"<\/a>Although more silicone polymers used in construction equipment enough, but because some of their high technical properties, they can be found in the coming years for improving the use of heat resistance of building materials impart hydrophobic properties as well as to protect structures against atmospheric agents.
\nAll polymers were divided into the following two classes: organic polymers, the main chain macromolecules are characterized by carbon-carbon bonds to C-C-C-C-C-, -C carbon-oxygen-O-C-O-C- and carbon nitrogen -C-N-C-N-C-; mineral polymers not containing carbon, especially silicates, for which the main chain macromolecules characteristic kremniykislorodnaya (siloxane) bond -Si-O-Si- O-.
\nOrganic polymers are unstable at temperatures above 250-300 \u00b0, since at elevated temperatures the degradation of these polymers, while the polymers are not degraded mineral at a temperature of 400-500 \u00b0.
\nHeat resistance of the polymer, as is known, depends primarily on the quantities of energy of the atoms. High heat silicate polymers due to the higher silicon bond energy with oxygen in the siloxane groups -Si-O-Si-O-Si-O- (89.3 kcal \/ mol) compared with the binding energy between carbon atoms (58.6 kcal \/ mol), or between the carbon and oxygen atoms.
\nThe presence of only the siloxane groups in the silicate polymers causes their hardness and rigidity, while carbon group characteristic for organic polymers capable of forming in many cases, the flexible, highly elastic and plastic material. |
\nTechnically extremely valuable to be considered those materials which, along with a complex of physico-mechanical properties characteristic of the organic polymer materials (elasticity, etc.), Possess high heat and chemical resistance inherent to siloxane polymers. The material is considered good, when in its structure contains the elements typical organic and inorganic polymers.
\nIn one of these structures comprises a siloxane backbone linkages and pendant groups – carbon linkages alkyd or aryl radicals.
\nSuch silicone polymers have recently received, are a new class of polymers which combine the basic structure of organic silicate polymers and their properties.
\nThe leading role in the development of chemistry and technology of organic silicon compounds and, in particular, polymers belongs to Soviet scientists. Basic laws of obtaining high-molecular compounds were first established by Academician. KA Andrianov in the 1935-1937 biennium. They same technical production methods of organosilicon polymers have been developed.
\nThe structure is based on organosilicon polymers, siloxane bonds in the main chain and organic radicals in the side chains. This structure may be linear or cyclic, branched or spatial.
\nThe starting materials for organosilicon polymers are compounds of the general formula RnSiX4-n, where X = Cl or OR. |
\nThese substances are divided into two groups:
\n1) or alkyd arilhlorsilany (RSiCl3; R2SiCl2; R3SiCl);
\n2) an alkyl or aryl substituted orthosilicic acid RSi (OR) 3; R2Si (OR) 2; R2Si (OR).
\nOrganochlorosilane is prepared in an industrial environment of silicon tetrachloride (SiCl4), and alkyl or aryl chlorides. Silicon tetrachloride obtained by direct chlorination of ferrosilicon.
\nSilicone polymers – matter of different state of aggregation. They may be liquid, solid and brittle, and highly elastic, rubbery.
\nThe characteristic difference between silicone polymers – their higher heat resistance compared with organic polymers.
\nNonpolar side groups and symmetry silicone polymer macromolecules determine its greater hydrophobicity, and high dielectric properties. The hydrophobicity of silicone polymers – one of the most important advantages that these polymers can be used in construction.
\nUnlike linear high polymers spatial polymers are hard, brittle material, the harder they are and the higher the concentration of the spatial relationships. |
\nAt high degrees of polycondensation (corresponding to a molecular weight of 100,000 or more) due to entanglement of long chain molecules and create a “felt” structures linear elastomeric polymer becomes a solid with a low glass transition temperature (-60 \u00b0).
\nDue to the hydrophobic properties of silicone polymers are thin in marble and plaster to protect the exterior paint and moldings buildings from being destroyed by moisture. The resulting hydrophobic film is preserved for many years.
\nOn the basis of silicone polymers created many types of enamels and lacquers used as heat-resistant and weatherproof coatings which protect against corrosion of ferrous and nonferrous metals. These varnishes and enamels are indispensable for the color of various electrical heaters, stoves, metal chimneys in boiler plants, parts of internal combustion engines, and so on. N.
\nEnamel dye additive metal (aluminum powder) or inorganic (metal salt) works when heated to a temperature of 500 \u00b0.
\nIn recent years, the Soviet industry produces silicone plastic material with mineral fillers – asbestos, silica flour and fiberglass. Silicone Fiberglass have high mechanical strength, high electrical insulating properties and are stable at temperatures up to 350 \u00b0. |
\nOn the basis of silicone polymers derived foams that can withstand temperatures up to 400 \u00b0. The high heat resistance of these materials, in contrast to conventional plastics because the silicone polymer degradation under the action of high temperature silicon dioxide SiO2 is formed, which insulates the material of the fire.
\nWaterproofing of articles of silicone polymers are well proven in the construction industry. For example, the introduction of 0.02% aqueous emulsion of silicone fluid in peschanovoloknisty slate twice reduces its water absorption and frost resistance increases.
\nSpecific polyorganosiloxanes applied to the surface of building structures as a 50 percent solution that penetrates to a depth of 3-6 mm, and after drying forms a strong hydrophobic surface, continued for 5-10 years.
\nThis way you can handle brick chimneys, and various artistic stone products, architectural details, and so on. E., Enhancing their weatherability. This treatment protects the joints filled with a solution, prevents cracking caused by repeated wetting and freezing.
\nIt follows that the scope of possible application of silicone polymers in the construction equipment is very wide.<\/p>","protected":false},"excerpt":{"rendered":"

Although more silicone polymers used in construction equipment enough, but because some of their high technical properties, they can be found in the coming years for improving the use of heat resistance of building materials impart hydrophobic properties as well as to protect structures against atmospheric agents. All polymers were divided into the following two […]<\/p>\n

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