British Sign Language Glossaries of Curriculum Terms

BSL Chemistry Glossary - addition polymer - Definition

Let me explain the different parts of the process, but first, what is polymerisation?

Polymerisation is a chemical reaction where molecules come together to create longer and longer chains. You can see this represented on the screen here where the individual molecules combine to make these long chains and form substances like starch, proteins, plastics and fibres.

Each one of these tiny molecules is called a 'monomer' which means it is a small molecule and it's these monomers that join/bond together to create polymers. These monomers can react and produce/create polymers.

Displayed on the screen I have three monomer molecules and I'm going to explain how they join together in a process called addition polymerisation. Each of these three molecules has a double bond which you can see here, here and here.

When you put these in with a catalyst a chemical reaction takes place which causes these bonds to break, as you can now see shown on the lower three diagrams. With their bonds broken these molecules are freed up to move around and they form new bonds (covalent bonding).

What we have now is the 6 carbon atoms in the middle diagram have created 6 new single bonds all in a line (in the bottom diagram) and that's the polymer.

The name of the molecule in this example (top of the screen) is ethene and the name of the polymer that it forms is polyethene. If you started off with propene that will form polypropene. You can recognise the name of the original molecule from the part of the word that comes after poly; in this example it’s ethene.