Lesson 3 - Polymers

Polymers are long chain molecules that have been made when lots of short molecules (called monomers) join together in a sort of chain reaction!

There are natural polymers occurring in nature, such as silk, wool and cellulose.

There are also synthetic polymers and these are often made from monomers that have come from fractions of crude oil. These polymers include ones such as polythene, PVC, nylon and lycra.

Properties that most polymers tend to share in common are;

• chemically unreactive
• solids at room temperature
• plastic – they can be moulded into shape
• electrical insulators
• strong and hard-wearing

Polymers can be difficult to dispose of because they are very difficult to break down and do not really biodegrade at all!

Some uses of polymers

Man made (synthetic polymers) tend to fall into one of two categories...

1. Thermosoftening polymers

This type of polymer be be continually heated, softened and remoulded... this is because there are only very weak intermolecular forces between the polymer chains. These are usually flexible polymers, e.g. polythene (plastic bags)

2. Thermosetting polymers.

This type of polymer is very different! When it is first made and hardened, strong cross-links form between the polymer chains. These act like chains, holding the chains together and stopping the polymer from flexing and remelting, e.g. vulcanised rubber for car tyres.