Polymers
Polymerisation is the process in which many small and basic molecules, called monomers, join together to form a larger and more complex molecule called a polymer.
There are two different ways in which polymerisation can take place.
- Addition polymerisation
- Condensation polymerisation
Addition polymerisation is the joining together of many small molecules from a single compound, the monomer, to form a larger compound. This can only take place when the monomer is unsaturated. For example, take the polymerisation of Ethane. Before polymerisation the ethane molecules are individual but afterwards they are joined together, to form one larger molecule, or polymer. Ethane is used in this process to produce polythene (Poly-ethene). Polythene is a thermoplastic, i.e. a plastic with the ability to be softened and moulded repeatedly by applying heat and pressure. (As oppose to Thermosetting Plastics). It is the most widely used polymer and is used in the manufacture of one of man's simplest inventions. The plastic bag!
Other examples of Addition Polymers are:
- Polystyrene (Polyphenylethene)
- Polyvinyl Chloride (P.V.C.)
- Polyacrylonitrile
- Polytetrafluoroethene (P.T.F.E.) (Teflon, used in clothing and strong, adhesive tapes.)
All of the above operate along the same principles of polythene, as all listed are made from unsaturated compounds.
Condensation Polymers
Condensation polymerisation is the joining together of many small molecules from two compounds to form a large polymer. Terylene is one of the best known condensation polymers.
It is produced as a fibre which is used for the manufacture of clothing articles, linens, and seat belts in vehicles. Polyesters are another example, commonplace in clothes.
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