Polymers

Polymers

1. Uses

   • Toys
   • Plastic buckets
   • Packing bags
   • Cups
   • Automobile tyres

2. Definition

   • Is defined as very large molecules having high molecular mass
   • These are also referred to as macromolecules, which are formed by joining of repeating structural units on a large scale.

3. Formation

   • The repeating structural units are derived from some simple and reactive molecules known as monomers and are linked to each other by covalent bonds.
   • The process of formation of polymers from respective monomers is called polymerisation.

4. Classification

   • Based on source
     • Natural polymers: Found in plants and animals
     • Semi-synthetic polymers: Cellulose derivatives
     • Synthetic polymers: Man made polymers extensively used in daily life
   • Based on structure
     • Linear polymers: Consist of long and straight chains.
     • Branched chain polymers: Contain linear chains having some branches
     • Cross linked or Network polymers: Are usually formed from bi-functional and tri-functional monomers and contain strong covalent bonds between various linear polymer chains
   • Based on Mode of Polymerisation
     • Condensation polymers: Are formed by repeated condensation reaction between two different bi-functional or tri-functional monomeric units.
     • Addition polymers: Are formed by the repeated addition of monomer molecules possessing double or triple bonds
   • Based on Molecular Forces
     • Elastomers: Solids with elastic properties.
     • Fibres: Are the thread forming solids which possess high tensile strength and high modulus.
     • Thermoplastic polymers: are the linear or slightly branched long chain molecules capable of repeatedly softening on heating and hardening on cooling
     • Thermosetting polymers: are cross linked or heavily branched molecules