Chemical formula of polyvinyl alcohol. Production and use of polyvinyl alcohol

Chercher 08.02.2022

Other

Other is a synthetic water-soluble and at the same time 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.

Polyvinyl alcohol: preparation

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.

Concerning industrial production polyvinyl product, there are several ways. IN 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 method 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.

What properties does the substance have?

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 increasing this indicator 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.

Basic properties

What kind of substance is this - polyvinyl alcohol? Its application is quite wide. So, what you need to know about the product:

Molecular formula - C 2 H 4 O x.
Temperature at which the substance boils: 228°C.
Density - 1.19 - 1.31 g/cm3.
The temperature at which the substance melts is 200°C.

Use of the substance to produce polymers

Most often, polyvinyl alcohol is used to produce other polymers, for example:

Polyvinyl acetal. This substance is formed as a result of the interaction of polyvinyl alcohol with aldehydes.
Polyvinyl nitrate is an ester of polyvinyl alcohol and nitric acid.

What is it used for and where?

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.

In which industries is the substance used?

Polyvinyl alcohol has long been used in completely different areas and industries. It is made from:

Paper covering for liners.
Barrier layer in polyethylene terephthalate containers for carbon dioxide.
Water-soluble film for the production of washing powders in special capsules.
Lubricant for hard contact lenses, it is also added to eye drops.
Fixative required for sample collection.
Fibers for reinforcing elements in concrete mortar.
Embolization agent during medical procedures.
An adhesive agent and thickener in the production of all kinds of shampoos, as well as latex.
Emulsifier in many industries Food Industry.
Embolic agent in treatment oncological diseases without surgical intervention.

Medical and food industry

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.

The chemical formula of polyvinyl alcohol is (C2H4O)x, where x is responsible for the degree of polymerization. This substance is presented in the form of a white or light cream powder.

Polyvinyl alcohol does not have a specific smell or taste. It is considered a thermoplastic polymer, so it dissolves well in various liquids: glycerin, water, urea, dimethyl formaldehyde. PVA boils at a temperature of 228°C, but begins to melt already at 200°C.

Polyvinyl alcohol is not affected by aggressive substances:

. oils,
. petrol,
. alkali solutions,
. kerosene, etc.

In addition, this substance does not release toxins. This powder always contains about 5% water. This component makes alcohol more plastic. Also, to increase the plasticizing properties, the following is added to the composition of polyvinyl alcohol:

. glycerol,
. butylene glycol,
. phosphoric acid.

On an industrial scale, this powder is obtained as a result of polymer-analogous reactions. They involve both simple and complex compounds of polyvinyl ethers. In practice, this process occurs due to the saponification of polyvinyl acetate in an alcoholic environment. PVA can also react with bases and acids that are in water.

There are several brands of polyvinyl alcohol, they are divided into: fully hydrolyzed and partially hydrolyzed. One of the most popular brands in the textile industry is considered to be 16th grade. Polyvinyl alcohol 16 is white in color and produced in the form of granules. It is used during the processing of fabrics and leather.

Properties of PVA

The properties of polyvinyl chloride are quite varied, since it can be greatly influenced by air humidity. With increased humidity, it begins to lose density. Under normal climatic conditions, this substance has high elasticity and strength. This alcohol is capable of imparting adhesive properties to raw materials.

PVA also has film-forming properties, but at the same time, it is not capable of dissolving in acids, alkalis and solvents. If water gets on dry PVA powder, this material will completely dissolve in it.

Polyvinyl alcohol-based adhesive has high density and viscosity. It is used in the production of containers and tailoring. It is resistant to gasoline, oils and acids.

Application of PVA

This powder is involved in the manufacturing process of other polymer compounds. With its help you get:

. polyvinyl nitrate,
. polyvinyl acetal,
. polyvinyl acetate dispersions.

In Asian countries, PVA is involved in the production of textile fibers and fabrics. If we consider this material from the point of view of universality, then it is used in almost all spheres of human activity.

In the agricultural sector, it is added to synthetic fertilizer formulations; they qualitatively improve the composition of the soil.

In the metallurgical field, PVA is used for hardening steel metal.

Polyvinyl alcohol is an indispensable component in the production process building materials. It helps protect the finish of many materials.

This material can be found in the compositions of perfumes and cosmetics.

A solution of polyvinyl alcohol in the adhesive helps to glue various fabrics, leather, paper and other materials. It is used to glue tags and labels.

IN Western countries this substance has even found its use in the field of painting. With its help, the conservation of iconic ancient exhibits is carried out.
The production of polyvinyl alcohol helps doctors perform blood transfusions and make fixations when collecting samples.

Low molecular weight PVA is used in the food production process. It is introduced into product formulations as a glazing agent. They process fish, seafood, and sausages.

It is also worth noting that this powder is added to the following formulations:

. eye drops,
. contact lens removers,
. construction fittings,
. water-soluble packaging materials,
. shampoos, gels and balms.

Some online resources claim that previously polyvinyl alcohol could be found in any pharmacy. At the moment, this polymer is prohibited for use in the food industry in the territory Russian Federation. In the world they can label E1203 as a food additive.

Manufacturers and cost

The main world producers of polyvinyl alcohol are the following countries:

. China,
. Korea,
. USA.
. Japan,
. Spain.

In the Russian Federation, this material is produced by companies:

. OdiHim LLC,
. LLC VitaHim,
. LLC Ekonomichemikal,
. LLC Status.

The average price for polyvinyl alcohol is $2.5-3.5. PVA is packaged in bags weighing from 20 kg. This material must be stored in dry and well-ventilated areas. The air temperature should be room temperature.

In warehouses with PVS it is strictly prohibited high humidity air. Polyvinyl alcohol can be stored in a stacking manner. If all storage requirements for this material are met, it can retain its properties indefinitely.

Polyvinyl alcohol is an artificial polymer that easily dissolves in water. It was obtained in 1924 by two chemists - Gonel and Hermann - using a saponification reaction.

Physical properties

Polyvinyl alcohol is a powder white, having the ability to form a film. This polymer is very strong and flexible, but since these qualities depend on humidity (it absorbs liquid), the tensile strength decreases, and at a certain degree of humidity greater ductility appears. It has hygroscopic properties and easily dissolves (mainly in water). It is not able to dissolve in organic solvents such as fats and oils. When used, this substance does not have a toxic effect, which means it can be considered harmless.

Obtaining alcohol

Polyvinyl alcohol or PVA is obtained from polyvinyl acetate by hydrolysis or alcoholysis and is produced in the form of granules or powder. When producing PVA, a variety of technological methods are used, from simple to rather complex and labor-intensive.

Polyvinyl alcohol - application

PVA is used quite widely today. It can act as a thickener in the manufacture of glue and shampoos, and is used to produce latex material. It is successfully used by restorers to restore artistic paintings. Due to its hygroscopicity, it found wide application in the creation of hygiene products. All kinds of diapers, tampons and pads are made using PVA. Manufacturers have not forgotten polyvinyl alcohol food products. It is used as an emulsifier in the production of mayonnaise, sauces, ketchups and other food products, and is also used as confectionery.

Modern medicine has also adopted some of the properties of PVA. It is used in the production of some medicines, after being thoroughly purified from impurities. Ophthalmologists use polyvinyl alcohol for preparation and as a lubricant for contact lenses. Even oncologists have found the use of PVS in the treatment of cancer. In particular, it is necessary to perform a non-surgical embolization procedure. And this is not the entire range of uses of polyvinyl alcohol in medicine.

In the textile industry, PVA is used for stripping, and in the paper industry - for stripping. In addition, it is an indispensable component in the production of cellulose. Polyvinyl alcohol is necessary for builders and metallurgists, tanners and manufacturers of paint and varnish products. All factories that produce artificial fibers use PVA to make them, which gives them strength through the process of sizing the threads.

Even such a science as microbiology began to use PVA in the process of cells. Polyvinyl alcohol has also found application in printing, in particular in silk-screen printing. In this area, it is used as a polymer layer for the copying process. It can also be used as a packaging or protective material in production for covering parts, due to the fact that the PVA layer is easily removed.

Enterprises that manufacture and use molds also successfully use this polymer. Today, PVA is becoming increasingly widespread in the national economy. It is affordable, easy to transport (usually in plastic bags, packed in paper bags) in closed transport to avoid getting wet. Since polyvinyl alcohol is flammable, care must be taken when storing and handling it.

Polyvinyl alcohol is a synthetic artificial thermoplastic polymer that is soluble in water. The synthesis of the compound is the exchange reaction of alcoholysis or alkaline hydrolysis.

The polymer was first obtained by chemists Gonel and Hermann in 1924 by the saponification reaction of a solution of polyvinyl ether with potassium hydroxide. Today, the synthesis of polyvinyl alcohol is carried out through polymer-analogous transformations using polyvinyl ethers and polyvinyl ethers as starting materials. The main methods of production are various variations of saponification in an aqueous or alcoholic environment with the presence of acids and bases.

In 2002, in Moscow, under the leadership of Kuznetsov, a gel-free method for producing alcohol was discovered, which has a number of advantages over other methods, such as high productivity, low cost, and short-term synthesis.

One of the properties of polyvinyl alcohol is stability against fats, oils, and organic solvents. The polymer is also considered an excellent adhesive, emulsifying and film-forming agent. The next property is a high degree of tensile strength and flexibility, which depend on the level of air humidity. Water acts on the compound as a plasticizer. Under conditions of high humidity, alcohol loses its tensile strength, but its elasticity increases.

Areas of use

Polyvinyl alcohol acts as a raw material for the production of other polymers:

polyvinyl acetal - obtained through the interaction of aldehydes and alcohol;
polyvinyl nitrate - an ester of alcohol and nitric acid.

The product has found its application as a modifier and thickener in polyvinyl acetate adhesives. In China, the compound is used as a protective colloid for the production of polyvinyl acetate dispersions, and also as a stabilizer for emulsion polymerization. In the field textile production the polymer is used during the manufacture of the fiber.

Other applications:

adhesive agent and thickener in adhesives, shampoos, latexes;
component of child care and women's care products;
acts as a barrier layer for carbon dioxide in PET bottles;
as an emulsifier in the food industry;
component for creating a protective layer during the production of artificial fibers;
in water-soluble films during the manufacture of packaging materials;
in the production of polyvinyl butyrals;
in microbiology in the immobilization of enzymes and cells;
as a surfactant for the formation of encapsulated nanoparticles;
in solutions for contact lenses and eye drops as a lubricant;
in paper covering for liners;
as a fiber for reinforcement in concrete;
as an embolization agent in medical applications;
as a fixative for collecting samples;
as a water-soluble film for packaging laundry detergent in dissolving tablets.

In the food industry, the polymer is used as a glazing agent and a component that provides water binding. Alcohol can be found in compounds for glazing seafood and fish, films and coatings for surface treatment of cheeses and sausages.

Impact on humans

It was found that the food additive number E1203 is not capable of causing adverse effects on the human body. The substance is permitted in Ukraine and other countries European Union, however, it is prohibited in Russia.