Types of plastics and their use. Types of porosity of plastic

Various types of plastics provide ample opportunities for the creation of certain designs and details. It is no coincidence that these elements are used in a variety of areas: from mechanical engineering and radio engineering to medicine and agriculture. Pipes, components for machines, insulation materials, housings for appliances and household products - just a considerable list of what can be created from plastic.

The main varieties

The types of plastics and their application are based on which polymers are based - natural or synthetic. They are subjected to heating, pressure, and then perform the molding of products of varying complexity. The main thing is that with these manipulations, the shape of the finished product remains. All plastics are thermoplastic, that is, reversible, and thermoset (irreversible).

Reversible become plastic under the influence of heating and further pressure, with no radical changes in the composition. Pressed and already become a solid product can always be softened and give it a certain shape. Such types of plastics (thermoplastic) as polyethylene and polystyrene are known. The first is resistant to corrosion and dielectric properties. It is based on the production of pipes, films, sheets, it is widely used as an insulating material.

From styrene to polystyrene

As a result of the polymerization of styrene, polystyrene is obtained. From it further different parts are created on the basis of casting or pressing. Such types of plastics are widely used for the production of large parts and products, for example, elements for refrigerators or bathrooms. Among thermosetting plastics, press molds, laminates, fibrous materials are most often used, which can be further processed to produce various details.

Plastic is a very user-friendly material, on the basis of which it is possible to create a variety of products. Depending on the thermal properties, the following types of plastic processing are distinguished:

1. Pressing. This is the most popular way of obtaining products from thermoactive materials. Forming is carried out in special forms under the influence of high temperatures and pressure.
2. Injection molding. This method makes it possible to create products of different shapes. For this purpose, special containers are filled with molten plastic. The process itself is characterized by high productivity and economy.
3. Extrusion. Through such processing, many types of plastic products are obtained, for example, pipes, threads, cords, films of different purposes.
4. Blowing. This method is an ideal opportunity to create volume-shaped products that will have a seam in place of the closing of the mold.
5. Punching. In this way, products made of plastic sheets and plates are produced using special shapes.

Peculiarities of polymerization

Plastics can be obtained by polymerization and polycondensation. In the first case, the molecules of monomers bind to form polymer chains without the release of water and alcohol, in the second - the formation of side-matter, not associated with the polymer. Different methods and types of polymerization of plastics allow to obtain compositions that differ in their initial properties. An important role in this process is played by the correct temperature and heat of reaction, so that the molding mass is polymerized correctly. In polymerization it is important to pay attention to the residual monomer - the smaller it is, the more reliable and longer the operation will be the plastic.

Porosity

If polymerization regimes were violated, this could lead to defects in finished products. They will have bubbles, divorces and increased internal tension. There are different types of plastic porosity:

1. The gas. It appears due to the fact that the polymerization regime is disrupted, and benzoyl peroxide boils. If the gas pores are formed in the thickness of the prosthesis, then it needs to be remade.
2. Granular porosity arises from the excess of the polymer powder, the evaporation of the monomer from the surface of the material, or the insufficiently qualitative mixing of the plastic composition.
3. Compression porosity. It occurs because of a decrease in the volume of the polymerized mass due to insufficient pressure or a shortage of the molding mass.

What to consider?

You should be aware of what kinds of plastic porosity there are, and do not allow defects in the final product. It is necessary to pay attention to the fine porosity on the surface of the prosthesis. This happens because of too much monomer, and the porosity is not polished. If an internal residual stress is generated during operation with the plastic, the product will crack. This situation arises from a violation of the polymerization regime, when the object is too long in boiling water.

In any case, the deterioration of the mechanical properties of polymer materials ultimately leads to their aging, and therefore the technology of production must be observed completely and completely.

Basic plastics - what is it?

The material in question is widely used in the manufacture of bases of removable plate prostheses. The most popular types of basic plastics have a synthetic basis. The mass for bases, as a rule, is a combination of powder and liquid. When mixed, a molding mass is created that hardens when heated or spontaneously. Depending on this, a hot curing material or self-hardening material is obtained. The basic hot polymerization plastics include:

• Ethacryl (AKP-15);
• Acryl;
• Fluoroux;
• Acronyl.

The materials for creating removable prostheses are elastic plastics, which are needed as soft cushioning pads for bases. They should be safe for the body, firmly connect with the basis of the prosthesis, maintain elasticity and constant volume. Among such plastics, attention should be paid to the elender, which is the lining for the bases of removable dentures, and orthoxyl, which is based on a siloxane resin.

Construction Materials

The main types of plastics are used in different areas of construction, depending on the composition. The most popular materials include the following:

1. Polymerconcrete. This is a composite plastic, which is created on the basis of thermosetting polymers. The best in terms of physical and mechanical properties are polymer-based epoxy resins. Friability of the material is compensated by fibrous fillers - asbestos, fiberglass. Polymerconcrete is used in creating structures that are resistant to chemicals.
2. Fiberglass is a modern type of construction plastics, which are sheet materials made of glass fibers, polymer-bonded fabrics. Fiberglass is created on the basis of oriented or chopped fibers, as well as fabrics or mats.
3. Floor materials. They are represented by different types of roll coatings and liquid-based compositions based on polymers. Linoleum on the basis of polyvinylchloride, which has good heat and sound insulation, is widely used in construction. A seamless mastic floor can be created on the basis of a mixture of raw materials with oligomers.

Plastic and its marking

There are 5 types of plastics that have their designation:

1. Polyethylene terephthalate (it has the lettering PETE or PET). It is characterized by economy and wide scope of application: it is used for storage of various drinks, oils, cosmetics.
2. Polyethylene of high density (labeled as HDPE or PE HD). The material is economical, light, resistant to temperature changes. It is used for the manufacture of disposable dishes, containers for storing food products, bags, toys.
3. Polyvinyl chloride (labeled as PVC or V). This material creates window profiles, furniture parts, stretch ceiling film, pipes, floor coverings and much more. Because of the content of bisphenol A, vinyl chloride, phthalates, polyvinyl chloride is not used in the production of products (containers, dishes, etc.) for food storage.
4. Polyethylene (labeled LDPE or PEBD). This cheap material is used in the manufacture of bags, garbage bags, linoleum and CDs.
5. Polypropylene (with lettering PP). It features strength, heat resistance, it is suitable for the production of food containers, food packaging, toys, syringes.

Popular types of plastics - polystyrene and polycarbonate. They are widely used in a wide variety of industries.

Applications

Various types of plastics are used in a variety of industries. At the same time, the requirements for them are approximately the same - ease of operation and safety. Let us consider in more detail the types of thermoplastic plastics and the scope of their application.

Thermoset types of plastics (table)

Instead of concluding

In this article, we looked at the types of plastics and their applications. When using such materials, many factors are taken into account, beginning with the physical and mechanical properties and ending with the features of the work. While economical, plastic has a sufficient level of safety, which significantly expands its scope.