Polymerization Definition:

Polymerization is the process in which a large number of small molecules combine to form a large chain-like structure called polymerization. The small molecules are called Monomer. The monomer is the basic unit of the polymer.

Monomer→Polymerization→Polymer 

Examples of some polymerization changes

Amino Acid→Protein
Glucose→starch and glycogen
Ethylene/ ethene→polythene

Natural polymers and synthetic or man-made polymers:

1. Natural polymers: Polymers which are obtained from plants and animals are naturally called natural polymers. These are water-based polymers. Examples of natural polymers are cellulose, natural rubber, silk, wool,  wood, skin etc.

2. Synthetic or man-made polymers: Polymers that are produced by chemical reactions in laboratories are called synthetic polymers.  Examples of synthetic polymers are Bakelite, polythene,  Nylons,  Teflon etc.

Thermosetting polymers and Thermoplastic polymers:

1. Thermosetting polymers: polymers that on heating do not soften and cannot be remoulded are called Thermosetting polymers. Examples of thermosetting polymers are Bakelite, urea etc

2. Thermoplastic polymers: Polymers which on heating capable of softening and remoulding are called thermoplastic polymers. Examples of thermoplastic polymers are polythene, Polypropene, PVC (Poly Vinyl Chloride), polystyrene, PET (Poly-Ethylene-Teraphthalate ), Polycarbonate, etc.

The most important synthetic polymers

1. Bakelite: The monomer of Bakelite is (Phenol + Formaldehyde). It is a Thermosetting polymer. The Bakelite is used in making electric appliances, combs, TV cases,  buttons etc

2. Melamine Formaldehyde Resin: It is a Thermosetting polymer. They are used in making non-breakable crockeries.

3. Urea: The first man-made polymer is urea. It is a Thermosetting polymer. The chemical formula for urea is (NH₂-CO-NH₂). where NH₂ represent Carbamide.

4. PVC (Poly Vinyl Chloride): It is a thermoplastic polymer. The monomer for PVC is Vinyl Chloride. PVC is used in making Pipes, raincoats, bags etc

5. PHBV (Poly-Hydrated-Butrate-CoHydroxy-Velerate): A thermoplastic polymer used in making Drug capsules due to its bio-degradable properties.

6. Natural Rubber/ elastomer/ plantation rubber: The monomer for natural rubber is Latex Rubber ( latex is the bark of a tree). Natural rubber is also called Isoprene (2-methyl 1,3-Butadine).

Vulcanisation of rubber: For hardening the natural rubber we add sulphur (5%-10%) in it called vulcanisation of rubber and in condensation of polymerization, loss of water takes place.

Synthetic Fibres/thread:

1. Nylon-6: It is a synthetic fibre, used in making tyre cords and carpets. The monomer of nylon-6 is Caprolactum.

2. Nylons-6,6: It is also a synthetic fibre, used in making toothbrushes. The monomer of Nylon-6,6 is Stupid acid and Hexamethylene Di-amine.

3. Rayon: Rayon is called artificial silk. Used in making sportswear and summer dresses.  The monomer of rayon is cellulose.

4. Polyacrilonitrite: Also called Orlon or artificial wool.

5. Polyester: It is also terelene. The monomers of polyester are Dicarboxylic acid and ethene diol.

6. Buna-N: It is also a synthetic fibre used in making oil seals. The monomer of Buna-N are 1-3 Butadiene and acrolyne.

7. Buna-S: A synthetic fibre used in resolving tyres. The monomers of Buna-S are 1,3-butadiene and Styrene.

8. Teflon: Also a synthetic fibre used in making non-sticking utensils. The monomer of Teflon is Carbon tetrafluoride

9. Glyptol:  It is a thermosetting polymer used in making paints. It is formed by ethylene glycol and phthalic acid.

10. Lexan: used in making bullet proof jackets.

11. Perspex: used in making glass windows of cars and rail.

12. Dacron: A synthetic fibre used in making insulation, food packaging and making plastic bottles. The monomer of dacron is Ethylene glycol and terephthalic acid. Dacron is an example of a thermoplastic polymer.

Note: Bisphenol A (BPA)  is an industrial chemical mixed with plastics and found in various products like bottles, water supply pipes etc. We must buy products BPA-free. BPA affects on brain and behavior of children.