Knowledge Base

What is Plastic

Plastics are polymeric materials, a material built up from long repeating chains of molecules. Polymers such as rubber occur naturally, but it wasn't until the development of synthetic polymers around 1910 that the polymers tailored to the needs of the engineer first started to appear. One of the first commercial plastics developed was Bakelite and was used for the casing of early radios. During the Second World War, plastics such as nylon and polyethylene were used as a replacement material for other materials in short supply. Because the early plastics were not completely chemically stable, they gained a reputation for being cheap and unreliable. However, advances in plastic technology since then, mean that plastics are a very important and reliable class of materials for product design.

The mechanical properties of plastics tend to be inferior to most metals. Because of this, careful consideration must be given to using plastics for structural applications. Fibre reinforced plastics are extensively used where the mechanical properties of the base plastic material are not sufficient. However because of their relatively low weight, the ability to colour the plastics when manufacturing, and the ability to mould complex shapes relatively easily, plastics are extensively used for product casings and other applications where mechanical strength is not at a premium.

Plastics are not cheap materials. The cost of raw plastic materials is typically higher than steel but less than aluminium. However, because processing costs over large production runs are lower, the use of plastics can result in significantly cheaper products.

For applications requiring strength, the plastics can be reinforced by fibres, usually glass, which give the material added strength.