Polymers

Polymers

1. What is it?

   • These materials, which are mostly synthetic, are made up of repeating chains of smaller chemical units.

2. Clasification

   • Based on source
     • Natural
       • Found in plants and animals, for example: protein.
     • Semi-synthetic
       • Cellulose acetate and cellulose nitrate are examples.
     • Synthetic
       • Plastic, synthetic fibers, and synthetic rubbers are examples of man-made polymers.
   • Based on structure of Polymers
     • Linear
       • Long, straight chains make up these polymers. Polyvinyl and chloride, are examples.
     • Branched chain
       • Low-density polythene, for example, contains linear chains with some branching.
     • Cross-linked or network
       • Bi-functional and tri-functional monomers with strong covalent connections between linear polymer chains.

3. Clasification

   • Based on Mode of Polymerisa
     • Addition
       • The production of polythene from ethene and polypropene from propene is accomplished by the repeated addition of monomer.
     • Condensation
       • Repeated condensation reactions between two separate bi-functional or tri-functional monomeric components produce condensation polymers.
   • Based on Molecular Forces
     • Elastomers
       • Rubber-like solids with elastomeric characteristics. The weakest intermolecular forces hold the polymer chains together.
     • Fibres
       • Fibres are solids that form threads and have a high tensile strength and modulus.
     • Thermoplastic
       • These are long chain molecules with a linear or somewhat branched structure that can soften and harden repeatedly when heated.
     • Thermosetting
       • These strongly branched molecules that, when heated in molds, undergo substantial cross-linking and become infusible once more.