Two main processes are used to produce plastics – polymerization and polycondensation – and they both require specific catalysts. In a polymerization reactor, monomers such as ethylene and propylene are linked together to form long polymer chains. Each polymer has its own properties, structure and size depending on the various types of basic monomers used.
In a polymerization reactor, pressure and heat cause ethylene molecules, mixed with other chemicals, to link together. In ethylene the molecules form a colourless inflammable gas. When the same molecules are linked together in big chains called polymers, the plastic polyethylene or polythene is made — one of the world’s most widely used plastics. Other chemical combinations can produce polymers of different lengths and structures.
Once the polymers have been formed, the hot liquid plastic is taken from the reactor, cooled, and cut into chips or pellets.
- Each molecule of ethylene is made up of two atoms of carbon and four of hydrogen.
- If another chemical, known as a ‘catalyst’, is added these molecules form a long chain. This is called ‘polymerization’.
- Polythene gets its name from ‘poly’ meaning ‘many’.
Picture Credit : Google