What is polyvinyl chloride (PVC)

Polyvinyl chloride is a material that is widely in demand in various fields of activity. Thermoplastic polymer is obtained by polymerization. PVC is one of the first polymeric materials that have found wide distribution in the world. Depending on the manufacturing technology and the degree of polymerization, the properties of the finished product vary. Advantages of PVC:

• simple manufacturing and processing process;
• strength and durability;
• chemical inertness;
• resistance to corrosion;
• resistance to impact, weight and other mechanical loads;
• moisture resistance and hygiene;
• the ability to manufacture products of any shape.

An additional advantage is low production costs, which determines affordable prices for PVC products. Products made of polyvinyl chloride are light in weight compared to metal analogues and are almost as strong.

PVC: production technology

The formula of polyvinyl chloride involves the use of liquid dichloroethane – an organochlorine compound that has a pungent odor and increased volatility. Initially, rock salt is used to obtain dichloroethane, which serves as a raw material for the production of chlorine. The oil refining product, ethylene, is combined with chlorine to produce dichloroethane. The next stage of production is the production of vinyl chloride from dichloroethane.

The raw material for the industrial production of polyvinyl chloride is vinyl chloride, which changes its structure as a result of the polymerization reaction. During the chemical reaction, which occurs at a temperature of 65 ° C, homogeneous monomers are transformed into polymers. Vinyl chloride and polyvinyl chloride differ in structure. In the second case, the material consists of large particles, which determines the chemical and physical properties. Polymerization of vinyl chloride occurs with the participation of sodium chloride. Different technologies are used in industrial production, which affects the characteristics of the finished product. To understand what PVC is, it is worth knowing the features of different polymerization technologies:

• In suspension. The process takes place in a special reactor in the presence of water, provided that it is uniformly heated to 65 ° C. During the reaction, particles aggregate to form porous granules measuring 100-300 μm. A decrease in pressure in the reactor leads to the removal of monomers that have not reacted. The resulting granules are filtered, dried and packaged.
• In emulsion. The reaction takes place with the participation of emulsifiers – surfactants. During polymerization, latex is formed, which settles on the bottom of the reactor. Temperature conditions – +60 ° C. The process takes place with periodic stirring of the mixture or without intervention. The advantage of the method is more than 95% of the monomers that have entered into the reaction, which means less waste.
• In bulk. It involves a two-stage polymerization process. At the first stage, the raw materials are mixed at high speed. Then activators and other auxiliary substances are introduced into the composition. At the same time, the mixing speed is reduced. The polymerization process takes place until more than 80% of the monomers are converted. The advantage of the method is that there is no need to dry the granules. As a result, production costs are reduced.

More than 80% of the total volume of the material is obtained by the suspension method. The advantages of the technology include ease of execution and high productivity. The introduction of additives and plasticizers into the composition allows you to adjust the properties. Emulsion technology is used less frequently, which is due to the large number of additives required for the reaction. The presence of impurities affects the cost of production and the properties of the finished product. The method of polymerization in mass is not widely used, which is due to the reduced quality of the finished product due to the uneven structure (molecular weight) of the polymer.

Properties and characteristics

PVC is a substance of low toxicity. Heating to a temperature above 150 ° C is accompanied by the release of substances harmful to health – carbon monoxide and hydrogen chloride. The melting point of the material is 150-220 ° C. The main characteristics of PVC:

• does not dissolve in water;
• does not pass electric current;
• does not deteriorate upon contact with aggressive substances – alkalis, acids, gasoline, mineral oils.

The material spontaneously ignites when heated to a temperature of 1100 ° C. The reaction occurs with the release of hydrogen chloride – a poisonous gas. Long-term interaction with benzene and acetone leads to swelling. The density of polyvinyl chloride is 1.35-1.43 g / cm3. Compared to polypropylene and other plastics, PVC has a higher density, which causes increased hardness and strength.

Scope of application

Polyvinyl chloride has been used to manufacture medical equipment, instruments and consumables for over 50 years. Disposable PVC products have replaced and almost completely displaced analogs made of glass and rubber. What is PVC made of in medicine:

• containers and containers for storing and collecting blood;
• disposable syringes and gloves;
• units and components of medical devices;
• tubes for infusion systems and catheters;
• surgical splints.

Polyvinyl chloride is in demand in the mechanical engineering industry. The material is used to make airbags, interior trim elements, seals, coatings, instrument panels and doors, armrests. Equipping cars with PVC parts helps to reduce the vehicle’s own weight. As a result, dynamic characteristics are improved and fuel consumption is reduced.

The material is used to make children’s toys, dishes, food containers, shoes and clothing, linoleum and other floor coverings, bags and backpacks, sports equipment and gear. Polyvinyl chloride is a popular raw material for the production of credit cards, furniture, and household appliances. Other types of products include suspended ceilings, plastic windows, and insulation for electrical wires. PVC is a raw material for the production of pipes and packaging.

Using PVC for the production of household and industrial containers

Today, the term “PVC” is often encountered in everyday life and industrial production, the decoding of which means “polyvinyl chloride”. The scope of application of polyvinyl chloride covers the transportation and storage of liquids. The material is used to manufacture containers that vary in size and shape. Compared to metal counterparts, plastic containers are not subject to corrosion and weigh little, which determines the advantages:

• Reduction of the load on freight transport and, accordingly, the cost of fuel and equipment repair.
• No need for regular and costly maintenance. Plastic products do not need to be treated with anti-corrosion compounds and painted.
• Preservation of the original properties of stored liquids, including taste and smell. The material does not react with water, milk, wine, vegetable oil and other liquids.

Polyvinyl chloride products are highly durable and easy to maintain. Business representatives choose PVC water tanks to reduce production costs. Affordable price and durability are important characteristics that allow you to rationally use the enterprise budget. Plastic tanks are designed for the transportation and storage of various liquids:

• drinking and industrial water;
• agricultural products – juices, milk, vegetable oil;
• gasoline, diesel fuel and other fuels and lubricants;
• fertilizers for agriculture;
• acids, alkalis and other raw materials for the chemical industry.

To successfully develop a business in the agricultural sector, various PVC containers are used. Fish is grown and transported in plastic tanks. Tanks are used to arrange water supply and sewerage systems, store grain, sugar and other bulk agricultural products.

Use of PVC in construction and industry

PVC is a material that has found wide application in the construction industry. Polyvinyl chloride sheets are used for thermal insulation and sound insulation. PVC tanks are not suitable for storing hot water. To arrange an autonomous sewerage and water supply system, you will need plastic tanks made of polypropylene. The polymer material is resistant to temperature changes, suitable for storing cold and hot water. Collapsible soft containers are made of PVC. Polyvinyl chloride tanks are used to collect wastewater and arrange a garden irrigation system. In winter, they are folded and put away in a utility room.