Plastic and composites
Most plastics are made up of polymers. Polymers are very large molecules
which have been created by chemically bonding many small molecules
For example, polythene, also known as poly (ethene), is created by joining
many ethene molecules together. The small units that are joined together are
called monomers and the process of joining them together is called
The reason this can happen is because the monomers have something
called a double bond, which can open up and join to other monomers.
Depending on the different monomers, the polymers created can have
extremely different qualities. For example, polythene is used to create plastic
bags but PVC, another type of polymer, is used to insulate electrical wires.