Plastic – what is it, types, application

Do you know what year plastic was invented? For over 170 years, various types of plastic have been used daily in various segments of life.

Properties of plastics

Want to know more about what plastic is? First, some interesting information:

• Plastic is lightweight. 22% of the double-decker Airbus A380 is made of lightweight carbon fiber-reinforced plastic, which helps save fuel and reduce operating costs by 15%.
• Plastic is durable. BMW uses composite rear trunk lids and thermoplastic front wings in its 6 Series coupe. This will save 100 kg of weight without compromising the strength of the structure.
• Plastic is resistant to corrosion and water. This is known to engineers who replaced old Victorian pipes with plastic analogues in the London water supply system. Durable and flexible plastic pipes provide a stable supply of water.
• Plastic does not conduct electricity, so PVC is widely used for wiring, switches, light fittings and handles.

It is a flexible material that can be shaped into any shape. Plastics are known for their durability and resistance to wear. They have excellent resistance to chemicals, acids and solvents. And plastics are cheap to produce. The unique ability to combine with other materials, including paper, adhesives and aluminum foil, increases the appeal of plastics in a variety of industries.

How Plastic Products Are Made

How is plastic made? The process of plastic production is complex and multi-stage, involving several methods, technologies and materials. Its essence is the transformation of raw materials into an object. Raw materials used in the production of plastic are petrochemicals such as ethylene and propylene. The raw materials are purified of impurities and processed before they are put into production.

After the raw materials are prepared, they are heated together with a catalyst, which helps link the molecules into chains. The resulting material is a resin. This polymer resin is what plastic is made from.

To give plastic certain properties, additives are added to it. The formula of the plastic determines the properties of the future product. The composition of the plastic, what additives are used, including colorants, stabilizers, plasticizers and other materials, depend on the updated physical and chemical properties of the product.

The next stage is molding, which involves giving the plastics the desired shape. There are several methods of molding.

Extrusion

In the extrusion process, plastic powder or granules are fed into the extrusion machine through a hopper. The polymer is heated inside the barrel at a controlled temperature, and the screw pushes the molten plastic through a metal die, which is then cooled to give the plastic a fixed, continuous shape.

The product can be cut or trimmed to the desired length. This is one of the most common methods of producing plastic products. The plastic extrusion process is well suited for high-volume production of a wide range of products, including pipes, building products such as ventilation, door and window frames and seals. 

Injection Molding

A plastic polymer is fed into a heated barrel and screw. The screw melts the plastic and injects the liquid polymer into a temperature-controlled split mold that forms the shape of the product. Injection molding is used for high-volume production. Many components can be produced in a short period of time, from tiny parts to large items such as bumpers and trash cans for vehicles. Unlike the extrusion process, the molten plastic is forced into a die to form its final shape.

Extrusion and Injection Blow Molding

Very similar to the plastic extrusion and injection molding processes, but air pressure causes the hollow plastic to expand in the mold, leaving the inside of the object hollow. This process is used to mass-produce inexpensive containers such as bottles, cups, and glasses.

Rotational Molding

This method is used to make hollow structures. The plastic polymer is fed into a mold that is tightly closed, heated, and rotated continuously. The plastic polymer coats all the internal surfaces of the mould uniformly in a single layer. This layer exactly replicates the mould cavity. The mould is then cooled while continuing to rotate, which causes the polymer to harden. The rotation is stopped, the mould is opened and the plastic part is removed.

Suitable for short, cost-effective production runs, ideal for making large, complex moulds with uniform wall thickness, such as large water, chemical and fuel storage tanks, crates, refrigeration boxes, waste bins, cabinets, canoes, toys and play equipment.

Vacuum Casting

A method for producing small functional plastic parts suitable for low volume production. Vacuum casting is a versatile technology for elastomers that uses a vacuum to draw liquid raw materials (e.g. polyurethane resins, cast nylon, wax) into a mold. The process is used when air entrapment is a problem, if there are complex details or recessed surfaces, or if the material is reinforced with fiber or wire. The raw materials are poured into a two-part silicone mold and the vacuum is released. The mold is removed from the chamber and the casting is cured in an oven. The mold is then removed to remove the casting. The mold can be reused.

Thermoforming

The process involves heating a pre-extruded plastic sheet to a plastic temperature, which is then formed with a special stencil. Machines can quickly produce thousands of components. Examples of products include disposable cups, containers, lids, trays, blisters, various products for the food, medical and general retail industries. A simplified version of thermoforming is vacuum forming of plastic.

Compression Molding

The raw material is preheated and placed into an open mold cavity. The mold is closed with a lid, and pressure is applied, which forces the material into all areas of the mold. The heat and pressure are maintained until the material hardens. Once hardened, the formed part can be removed. This method of plastic molding is regularly used in the production of automotive parts such as hoods, fenders, spoilers, as well as smaller, more complex parts. It is also widely used to produce sandwich structures such as honeycomb or polymer foam.

Types of Plastic and Their Applications

It no longer matters who invented plastic first. Today, there are a great many types of plastic, each with a different chemical composition. Each type has unique properties that make it suitable for certain applications.

Polyethylene (PE)

PE is part of the polyolefin family of polymers and is one of the most widely produced plastics in the world. Polyethylene is used in the production of packaging, including plastic bags, films, membranes, liquid containers, bottles, trays, caps for food packaging, etc. It is used to make waste containers, water and food storage, household items, toys, ropes, fishing and sports nets, nets for agricultural use, industrial and decorative fabrics.

Polypropylene (PP)

PP is used to make films, reusable boxes, lids, water bottles, food containers, bottles, furniture, suitcases, garden accessories and kitchen utensils. In the automotive segment, polypropylene is used for the interior trim of cars. Some surgical instruments are made from it.

Polyvinyl chloride (PVC)

PVC is used for a wide range of products in many industries. It is used to make building profiles, drainage and water pipes, wire and cable coils, flooring, roofing membranes, medical products, automotive parts, sports equipment, textiles, footwear, packaging materials.

It is a flexible polymer whose properties can be altered by the additives used. PVC has a number of advantages, such as good chemical and corrosion resistance, excellent abrasion and wear resistance, and flexibility.

Polystyrene (PS)

PS is a lightweight, rigid plastic widely used in food packaging, disposable tableware, insulation, and consumer electronics.

Polyethylene terephthalate (PET)

PET is a clear, lightweight plastic used to make beverage bottles, food containers, and synthetic fibers such as polyester.

Acrylonitrile butadiene styrene (ABS)

ABS is a relatively inexpensive engineering plastic that is not typically used in high-temperature environments due to its low melting point. It is flexible and lightweight, and can be used to make many everyday items, including keys on computer keyboards, power tool housings, phone cases, plastic shields on wall outlets, and children’s building blocks. ABS plastic is used in drainage systems (pipes, fittings), in household appliances. ABS plastic is lighter than PVC but heavier than polyethylene, when used in vehicles it can reduce the weight of vehicles by 10%, making them more economical.

ABS sheet plastic is used on dashboards, wheel covers and body parts due to its strength, resistance to low temperatures and a durable surface that is not easy to scratch.

Polyurethane (PU)

PU is a versatile plastic known for its elasticity, strength and insulating properties. It is used in the production of furniture, foam cushions, coatings and adhesives.

Polycarbonate (PC)

Engineering polycarbonates are among the most durable plastics. Due to their transparency and outstanding rigidity, they are used to make impact-resistant glazing, skylights, aquariums, indoor and outdoor signs, trade and exhibition stands, including racks and brochure holders, LED lighting panels, external car headlights, optical lenses, plastic optical fibers. They are also used in the medical and dental industries.

These are not all types of plastic. The classification of plastics includes several dozen more names.

Conclusion

Plastic is a material that continues to surprise. It is impossible to tell everything about plastic in one article. But you can always contact us to learn more about plastic: types, properties, what certain products are made of. After studying your needs, our specialists will tell you which plastic material and manufacturing method will suit you best. We accept orders for plastic products. We practice both mass production and the implementation of individual projects.