Different types of plastics provide ample opportunity to create certain designs and parts. It is no coincidence that such elements are used in a wide variety of fields: from mechanical engineering and radio engineering to medicine and agriculture. Pipes, components for machines, insulating materials, cases for appliances and household products are just a considerable list of what can be created from plastic.
Main varieties
The types of plastics and their use are based on which polymers are based on - natural or synthetic. They are subjected to heating, pressure, and then perform the molding of products of varying complexity. The main thing is that during these manipulations the shape of the finished product is preserved. All plastics are thermoplastic, that is, reversible, and thermosetting (irreversible).
Reversible become plastic under the influence of heating and further pressure, while radical changes in the composition do not occur. The pressed and already solidified product can always be softened and given a certain shape. Known types of plastics (thermoplastic) such as polyethylene and polystyrene. The first is resistant to corrosion and dielectric properties. On its basis pipes, films, sheets are produced; it is widely used as an insulating material.
From styrene to polystyrene
The polymerization of styrene gives polystyrene. From it, various parts are further created on the basis of casting or pressing. These types of plastics are widely used for the manufacture of large parts and products, for example, elements for refrigerators or bathrooms. Among thermosetting plastics, the most commonly used are powders, laminates, fibers, which can be further processed to obtain various parts.
Plastic is a very convenient material in the work, on the basis of which you can create many products. Depending on the thermal properties, the following types of plastics processing are distinguished:
- Pressing. This is the most popular way to obtain products from thermoactive materials. Molding is carried out in special forms under the influence of high temperatures and pressure.
- Injection molding. This method makes it possible to create products of various shapes. For this, special containers are filled with molten plastic. The process itself is characterized by high productivity and efficiency.
- Extrusion. Through this processing, many types of plastic products are obtained, for example, pipes, threads, cords, films for various purposes.
- Blowing. This method is an ideal opportunity to create products of volumetric form, which will have a seam at the junction of the mold.
- Stamping. This method creates products from sheets of plastic and plates using special forms.
Features of polymerization
Plastic can be obtained by polymerization and polycondensation. In the first case, the monomer molecules bind, forming polymer chains without the release of water and alcohol, in the second case, side substances that are not associated with the polymer are formed. Various methods and types of polymerisation of plastics make it possible to obtain compositions that differ in their initial properties. The correct temperature and heat of reaction play an important role in this process, so that the molding material polymerizes correctly. During polymerization, it is important to pay attention to the residual monomer - the smaller it is, the more reliable and longer the plastic will be in operation.
Porosity
If the polymerization conditions were violated, this can lead to defects in the finished product. They will appear bubbles, stains and increased internal stress. There are various types of porosity of plastics:
- Gas. It appears due to the fact that the polymerization mode is violated, and benzoyl peroxide boils. If gas pores are formed in the thickness of the prosthesis, then it needs to be redone.
- Granular porosity occurs due to an excess of polymer powder, evaporation of the monomer from the surface of the material, or insufficient mixing of the plastic composition.
- Compression porosity. It occurs due to a decrease in the volume of the polymerizable mass under the influence of insufficient pressure or lack of molding material.
What to consider?
You should be aware of what types of porosity of plastics are, and avoid defects in the final product. It is necessary to pay attention to the fine porosity on the surface of the prosthesis. This happens due to too much monomer, and the porosity is not polished. If an internal residual stress is generated during plastic work, the product will crack. This situation arises as a result of a violation of the polymerization regime when the object is in boiling water for too long.
In any case, the deterioration of the mechanical properties of polymeric materials ultimately leads to their aging, and therefore the production technology must be fully and completely observed.
Base plastics - what is it?
The material under consideration is widely used in the manufacture of removable laminar denture bases. The most popular types of base plastics have a synthetic base. 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 cure or self-hardening material is obtained. The base plastics of hot polymerization include:
- ethacryl (AKP-15);
- acrylic;
- fluorox;
- acronyl.
The materials for creating removable dentures are elastic plastics, which are needed as soft cushioning pads for bases. They should be safe for the body, firmly connected to the basis of the prosthesis, maintain elasticity and constant volume. Among these plastics, attention is paid to the edent, which is the lining for the bases of removable dentures, and the orthoxyl, which is obtained on the basis of a siloxane resin.
Construction Materials
The main types of plastics are used in various fields of construction, depending on the composition. The most popular materials include the following:
- Polymer concrete. This is a composite plastic, which is based on thermosetting polymers. The best in terms of physical and mechanical properties are considered to be polymer concrete based on epoxy resins. The fragility of the material is compensated by fibrous fillers - asbestos, fiberglass. Polymer concrete is used to create structures that are resistant to chemicals.
- Fiberglass is a modern type of building 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.
- Floor materials. They are represented by different types of roll coatings and liquid-based compositions based on polymers. In construction linoleum based on polyvinyl chloride is widely used, which has good heat and sound insulation indicators. A seamless mastic floor can be created based on a mixture of raw materials with oligomers.
Plastic and its marking
There are 5 types of plastics that have their own designation:
- Polyethylene terephthalate (labeled PETE or PET). It is characterized by economy and a wide scope: it is used to store various drinks, oils, cosmetics.
- High Density Polyethylene (labeled HDPE or PE HD). The material is economical, lightweight, resistant to temperature extremes. It is used for the manufacture of disposable tableware, containers for storing food products, bags, toys.
- Polyvinyl chloride (labeled as PVC or V). This material creates window profiles, furniture details, film for stretch ceilings, pipes, floor coverings and much more. Due to the content of bisphenol A, vinyl chloride, polyvinyl chloride phthalates, it is not used in the manufacture of products (containers, dishes, etc.) for storing food.
- Polyethylene (marking LDPE or PEBD). This cheap material is used in the manufacture of bags, trash bags, linoleum and CDs.
- Polypropylene (labeled PP). It is distinguished by durability, heat resistance, suitable for the production of food containers, packaging for food, toys, syringes.
Popular types of plastics are polystyrene and polycarbonate. They are widely used in a wide variety of industries.
Fields of application
Various types of plastics are used in a wide variety of industries. At the same time, the requirements for them are approximately the same - ease of use and safety. Let us consider in more detail the types of thermoplastic plastics and their scope.
Plastic | Scope of application |
Polyethylene (high and low pressure) | Production of packaging, unloaded parts of machinery and equipment, cases, coatings, foil. |
Polystyrene | Production of equipment, insulation films, styrofoam. |
Polypropylene | Found wide application in the production of pipes, automobile parts, components for refrigeration equipment. |
Polyvinyl Chloride (PVC) | Production of chemical equipment, pipes, various parts, packaging, floor coverings. |
Polycarbonates | Production of precision parts for machinery, equipment, radio and electrical engineering. |
Thermosetting plastics (table)
Material | Scope of application |
Phenoplasts | They are used to create haberdashery products (buttons, etc.), ashtrays, plugs, sockets, cases for radio and telephone sets. |
Aminoplasts | Used for the manufacture of wood glue, electrical parts, haberdashery, thin coatings for decoration, foam materials. |
Fiberglass | They are used in the manufacture of power electrical parts in mechanical engineering, large-sized products of simple shapes (car bodies, boats, instrument housings and the like). |
Polyester | On the basis of polyesters, lifeboats, car parts, furniture, glider and helicopter hulls, corrugated roof slabs, lamp shades, antenna masts, skis and poles, fishing rods, safety helmets and the like are created. |
Epoxy resin | It is used as an insulating material in electric machines, transformers (as high-voltage insulation) and other devices, in the manufacture of telephone fittings, in radio engineering (for the manufacture of printed circuits). |
Instead of a conclusion
In the presented article, we examined the types of plastics and their application. When using such materials, many factors are taken into account, ranging from physical and mechanical properties to the features of the work. For all its economy, plastic has a sufficient level of security, which significantly expands the scope of its application.