Saturday, February 17, 2007

What type of materials are plastics?

Plastics are synthetic materials that consist of long chains of molecules called polymers. Whe nthe chains a positioned in a long the plastic is rigid. When the polymer molecules are tangled tpgether, the plastic is soft and flexible. All plastic can be moulded under pressure into complicated shapes. Thermoplastics melt when they are heated, and this means that they can be remelted at any time. There are other forms of plastic, known as thermosetting plastics, which cannot be remelted.

The majority of plastics are made from synthetic resins, which are usually derived from oil. Other types come sources such as coal or wood. As they do not conduct electricity, most plastics are excellent insulators, so are widely used in electrical wiring.

The main disadvantage of plastics is that they are very slow to break down,causing serious environmental problems when discarded.

No comments: