A plastic is a synthetic or artificial solid polymer of practical use. A polymer is a very large molecular compound made up of repeating molecular units called monomers. Starch is a natural polymer made up of many linked glucoses. Protein is another natural polymer made up of many linked amino acids. Plastics are polymers that are easily molded to any desired shape during manufacture and are made of repeating hydrocarbon subunits.

Crude oil is a complex mixture of many hydrocarbons. The different hydrocarbons can be separated by fractional distillation. Many of the hydrocarbons are useful in the making of a variety of plastics. The individual hydrocarbon molecules are called monomers (one part). The monomers of a particular type of hydrocarbon are then linked together to form large polymer molecules - this process is known as polymerisation. If the polymer is an easily molded solid and does not degrade quickly then it may have many practical uses and is commonly classified as a plastic.

Properties of Plastics

Cheap and easy to produce.

Easily molded into any shape.

Low-density solids.

Easily coloured.

Do not degrade quickly – they are non-biodegradeable.

Good heat and electrical insulators

As a result of their properties plastics are used to make many everyday objects like pot handles, electrical insulation around electric wires, coat hangers, wheelie bins, cups, water pipes, ropes, computer bodies, furniture and many more.

Environmental Impact of Non-biodegradable Plastics

Plastics could almost last forever. Micro-organisms such as bacteria and fungi, the great decomposers, cannot break them down. These plastics are a major litter problem and may cause problems when some animals try to eat them due to them looking like a normal food source. Reduce, reuse and recycle is the only way to lessen their impact. Use of biodegradable material for packing would greatly lessen our use of plastic. Unfortunately it is rarely possible to reuse plastic items. Our best answer is to recycle the plastic by melting it and reforming it.

Many plastic items have a symbol indicating the type of plastic it is made so all plastics of that type can be easily separated for recycling.