SS3 First Term Chemistry Lesson Note – Synthetic Polymers

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WEEK 3

TOPIC: SYNTHETIC POLYMERS

CONTENT:

1. Definition of terms
2. Addition and condensation polymerization
3. Classification and preparation
4. Properties and uses of polymers

PERIOD 1: DEFINITION OF TERMS

1. Synthetic polymers: are polymers made in the industry from chemical substances. Through scientific research, scientists are able to copy the structures of natural polymers to produce synthetic polymers. Many of the raw materials for synthetic polymers are obtained from petroleum, after the refining and cracking processes. The types of synthetic polymers include: (a). Plastics (b). Fibre (c). elastomers
2. Elastomer: is a polymer that can regain its original shape after being stretched or pressed. Both natural rubber and synthetic rubber are examples of elastomers. Examples of synthetic rubber are neoprene and styrene-butadiene rubber (SBR).SBR is used to make car tyres.
3. Polymers: are large molecules made up of many smaller and identical repeating units joined together by covalent bonds. These molecules are called monomers.
4. Monomers: are the simple molecules from which the large molecules are built or the small molecule or repeating unit or the building block in the
   structure of polymer is called monomer. To be a monomer, the substance unit should have a functionality of at least two; some compounds have two functionalities other have double or triple bonds in the molecule.
5. Polymerization: is the chemical process by which the monomers are joined together to form a big molecule known as a polymer. A polymer is macromolecules (a very big molecule). Hence, the relative molecular mass of a polymer is large. The properties of a polymer are different from its monomers. The conditions necessary for polymerization are: high temperature, high pressure and the presence of chain-initiating substance (initiator) such as traces of oxygen or organic peroxide catalyst. Polymerization is called homo-polymerization if the monomeric units are all the same molecule. It is, however, called co-polymerization if two or more different molecules serve as monomeric units.

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