Types of Plastics

Types of Plastics

Plastics can be divided into four basic categories: -

• Thermoplastics such as polyethylene, which soften on heating and harden again on cooling (e.g. Milk bottles).

• Thermosetting plastics or resins are plastics which cannot be melted and re-moulded when heated (e.g. printed circuit boards and fibre glass resin)

• Elastomers or rubbers (e.g. Car tyres, rubber-bands, tennis balls)

• Natural polymers such as cellulose, lignin and protein, which provide the mechanical basis for most plant and animal life (e.g. wood, straw and silk). These now include the recently developed biodegradable plastics.

In plastics recycling, thermoplastics dominate, but thermosets, wood, paper and straw can all be used as fillers and reinforcers.