Polyvinyl alcohol (PVA) is an artificial hard white (less often light yellow or cream) polymer that appears as powder, flakes or grains. The crystalline component of the substance can reach up to 68%. The chemical formula of polyvinyl alcohol is as follows: [- CH 2 – CH(OH) -] n, where n is the degree of polymerization. The value of n can reach 5000, that is, a polyvinyl alcohol molecule can contain up to 5000 identical units.
This heat-resistant artificial polymer was first obtained by German chemists W. Hermann and W. Gonel through the saponification reaction of polyvinyl ether with potassium hydroxide (KOH).
If most known polymeric substances are obtained by polymerization of monomers, then the process of producing polyvinyl alcohol has fundamental difference : to obtain this substance, a complete or partial hydrolysis reaction of polyvinyl acetate is required, as a result of which the ethyl acetate group is removed.
Modern industrial synthesis of PVA occurs through various variants of the saponification reaction of polyvinyl acetate in an aqueous or alcoholic medium, in the presence of acids or alkalis that play the role of catalysts.
In 2002, a significant event occurred that made it possible to speed up and reduce the cost of the synthesis of polyvinyl alcohol. A team of scientists led by A. A. Kuznetsov discovered and developed gel-free method receiving PVA.
Pure polyvinyl alcohol is odorless, tasteless and non-toxic. Its only solvent is water. Polyvinyl alcohol does not dissolve in any organic solvent. Particularly resistant to any oils, gasoline, kerosene and other hydrocarbons, as well as diluted alkalis and acids.
PVA is hygroscopic and always contains approximately 5% water, which plasticizes the substance to some extent. But water evaporates easily and quickly. Therefore, ethylene glycol, butylene glycol, phosphoric acid, and glycerin are used as plasticizers for this polymer. The best plasticizer for PVA is glycerin.
Due to its properties, polyvinyl alcohol is widely used in food and pharmaceutical industry , in medicine, in various industries national economy.
Since the described substance is physiologically neutral, the widespread use of polyvinyl alcohol in the food and medical industries is understandable. PVA is used as a film-forming agent, moisture-retaining and glazing food additive, which is assigned the international designation E1203. Thanks to the use of PVA, it is possible to retain the required amount of moisture in products subjected to various processing methods. Polyvinyl alcohol is also included in the glaze that coats freshly frozen fish and seafood. E1203 is included in most types of casings that cover ready-to-eat and semi-finished products. For example, sausages and sausages.
E1203 is officially approved for use in Ukraine and EEC countries. In Russia, this food additive is not officially prohibited, but there is no official permission for the use of polyvinyl alcohol in the manufacture of food products.
The properties of polyvinyl alcohol allow it to be widely used as a material for the production medical equipment, instruments and apparatus. In the pharmaceutical industry, PVA is used in the manufacture of coatings and fillers for various tablets. In addition, polyvinyl alcohol is sometimes used for blood transfusions as a plasma substitute. There are often cases when, in the treatment of oncological diseases, PVS is used as an embolic agent (in cases where surgery is contraindicated or is not necessary). This heat-resistant polymer is also used to produce special fibers that are used to make internal surgical sutures that dissolve over a certain period of time. PVA is also included as a lubricant in liquids for contact lenses and eye drops. This substance is often used in the manufacture of children's and feminine hygiene products and creams.
The use of PVA for the production of polymer films and fibers is widespread. Plasticized polyvinyl alcohol is used to make hoses that are resistant to aggressive liquids.
Some fabric dyeing technologies also require the use of PVA.
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Polyvinyl alcohol is a synthetic water-soluble and thermoplastic polymer. This substance is synthesized due to the exchange reaction of alcoholysis and alkaline hydrolysis. Polyvinyl alcohol was first discovered in 1924. The substance was created by German chemists Wolfram Gonel and Willy Hermann.
Unlike many vinyl polymers, this substance is not formed as a result of polymerization of the corresponding components. The monomer of this product occurs only as the tautomeric form of acetaldehydes. Polyvinyl alcohol is obtained by complete or partial hydrolysis of a substance such as polyvinyl acetate. This method removes ethyl acetate groups from the final alcohol.
Regarding industrial production polyvinyl product, there are several ways. In this case, saponification of the substance occurs in an alcoholic medium or in an aqueous medium in the presence of bases and acids.
Under the leadership of A. A. Kuznetsov, more effective way receiving the product. In this case, it was produced using a gel-free method. This method has many advantages over the previous ones. First of all, we should highlight the relatively low cost, short-term synthesis and high productivity.
Polyvinyl alcohol is widely used in many fields. This can be explained by its basic properties. This substance has adhesive, emulsifying and film-forming properties.
In addition, PVA (polyvinyl alcohol) perfectly tolerates the effects of solvents, fats and oils. The substance is odorless and completely non-toxic. The polymer has high tensile strength and flexibility. It is worth noting that polyvinyl alcohol contains a lot of oxygen.
However, it is worth considering that these properties of the product directly depend on several factors, including humidity. When this indicator increases, the substance begins to absorb water. It also acts on the polymer as a plasticizer. As a result, polyvinyl alcohol loses its strength. In some cases, the substance disintegrates completely and then dissolves in water.
What kind of substance is this - polyvinyl alcohol? Its application is quite wide. So, what you need to know about the product:
Most often, polyvinyl alcohol is used to produce other polymers, for example:
Due to its properties, polyvinyl alcohol is used as a modifier and thickener in polyvinyl acetate adhesives. In China, this substance is used as a stabilizer for emulsion polymerization, and also as a protective colloid in the production of polyvinyl acetate dispersions.
Often the product is used in textile industry. In North Korea and Japan, polyvinyl alcohol is widely used in the production of fibers.
Polyvinyl alcohol has long been used in completely different areas and industries. It is made from:
Polyvinyl alcohol is a physiologically neutral substance. That is why it is often used not only in the medical, but also in the food industry. Typically, this product is used as a glazing, moisture-retaining and film-forming additive. It was given the international name - E1203.
Thanks to polyvinyl alcohol, after various treatments it is possible to retain moisture in the products in the required amount. It is worth noting that the E1203 additive is often used to make glazes that cover many seafood products.
Polyvinyl alcohol is a water-soluble and thermoplastic man-made polymer. Externally E-1203– it is a white (less often light yellow or cream) fine crystalline powder, odorless and tasteless. It is highly soluble in water, moderately soluble in ethyl alcohol, and resistant to fats, oils, gasoline, alkali and acid solutions. It is hygroscopic, has great elasticity and strength, due to the content of about 5% water in its composition, which plasticizes the substance. Moreover, when moisture is absorbed, its elasticity increases, but its strength decreases. Also Polyvinyl alcohol is resistant to light and microorganisms. Chemical formula: (C2H4O)n, where n is the degree of polymerization. The main method for producing polyvinyl alcohol is the saponification of polyvinyl acetate in water or an alcoholic medium, in the presence of acid bases. It is a good emulsifying, moisture-absorbing and film-forming polymer, properties E-1203 provide protection against moisture and oxidation.
In the food industry, partially hydrolyzed Polyvinyl alcohol. It is used as a moisture-retaining agent in production technology food products, to bind the water remaining in the product after production processes. Additive E-1203 used in glazing solutions in frozen fish production technology, as a glazing agent to create a smooth shiny shell finished products. Polyvinyl alcohol is used in films and coatings for surface treatment of sausages, sausages, cheeses and their shells. In the production of dietary supplements (biologically active additives) to food in an amount of 45 g/kg. Widely used in many industries:
It is non-toxic and does not have a negative effect on the human body, is considered a safe food additive and is widely used in medicines. Maximum permissible daily intake E-1203 not defined. Polyvinyl alcohol is approved for use in food production in the European Union, Ukraine and Russian Federation. But it is prohibited for use as a food additive in Australia and New Zealand.
Polyvinyl alcohol is a synthetic water-soluble and thermoplastic polymer. This substance is synthesized due to the exchange reaction of alcoholysis and alkaline hydrolysis. Polyvinyl alcohol was first discovered in 1924. The substance was created by German chemists Wolfram Gonel and Willy Hermann.
Unlike many vinyl polymers, this substance is not formed as a result of polymerization of the corresponding components. The monomer of this product occurs only as the tautomeric form of acetaldehydes. Polyvinyl alcohol is obtained by complete or partial hydrolysis of a substance such as polyvinyl acetate. This method removes ethyl acetate groups from the final alcohol.
As for the industrial production of polyvinyl products, there are several methods. In this case, saponification of the substance occurs in an alcoholic medium or in an aqueous medium in the presence of bases and acids.
Under the leadership of A. A. Kuznetsov, a more effective method for obtaining the product was developed in 2002. In this case, it was produced using a gel-free method. This method has many advantages over the previous ones. First of all, we should highlight the relatively low cost, short-term synthesis and high productivity.
Polyvinyl alcohol is widely used in many fields. This can be explained by its basic properties. This substance has adhesive, emulsifying and film-forming properties.
In addition, PVA (polyvinyl alcohol) perfectly tolerates the effects of solvents, fats and oils. The substance is odorless and completely non-toxic. The polymer has high tensile strength and flexibility. It is worth noting that polyvinyl alcohol contains a lot of oxygen.
However, it is worth considering that these properties of the product directly depend on several factors, including humidity. When this indicator increases, the substance begins to absorb water. It also acts on the polymer as a plasticizer. As a result, polyvinyl alcohol loses its strength. In some cases, the substance disintegrates completely and then dissolves in water.
What kind of substance is this - polyvinyl alcohol? Its application is quite wide. So, what you need to know about the product:
Most often, polyvinyl alcohol is used to produce other polymers, for example:
Due to its properties, polyvinyl alcohol is used as a modifier and thickener in polyvinyl acetate adhesives. In China, this substance is used as a stabilizer for emulsion polymerization, and also as a protective colloid in the production of polyvinyl acetate dispersions.
The product is often used in the textile industry. In North Korea and Japan, polyvinyl alcohol is widely used in the production of fibers.
Polyvinyl alcohol has long been used in completely different fields and industries. It is made from:
Polyvinyl alcohol is a physiologically neutral substance. That is why it is often used not only in the medical, but also in the food industry. Typically, this product is used as a glazing, moisture-retaining and film-forming additive. It was given the international name - E1203.
Thanks to polyvinyl alcohol, after various treatments it is possible to retain moisture in the products in the required amount. It is worth noting that the E1203 additive is often used to make glazes that cover many seafood products.
