Plastics have names such as polypropylene, polyethylene, polyester ...

Let’s see what happens if we disconnect one of those bonds as in picture 2.
Picture 2:
Basically, this will leave us with two connections to which we can add two more molecules of
ethylene. If we keep repeating these additions we can form a long chain as in picture 3.
As the chain gets longer the ethylene changes from a gas to liquid which becomes thicker
and thicker until it reaches a point when the chains are long enough to form a solid, and
becomes the plastic that you and I know.
Picture 3:
Now we could call our chain “many ethylenes” but that is a bit clumsy. So instead of saying
‘many’, we use the term poly (which comes from the Greek ‘polloi’ meaning ‘many’) and finish
up with polyethylene.
© Packaging Council of Australia 2005
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