Polymers

Polymers

1. What is it?

   • Any material composed by very large molecules
     • Uses
       • Is used in multiple indutries
         • Is used in big industries like plastic, elastomers, fibres and paints and vanishes
       • Is also used in manufacturing
         • This are some examples:plastic buckets, cups and saucers, children’s toys, packaging bags, synthetic clothing materials, automobile tyres, gears and seals, electrical insulating materials and machine parts

2. Clasification based on The structures of polymers

   • There are three different types based on the structure of the polymers.
   • Linear polymers
     • These polymers consist of long and straight chains. The examples are high density polythene, polyvinyl chloride, etc. 
   • Branched chain polymers
     • These polymers contain linear chains having some branches, e.g., low density polythene.
   • Cross linked or Network polymers
     • These are usually formed from bi-functional and tri-functional monomers and contain strong covalent bonds between various linear polymer chains, e.g. bakelite, melamine, etc.

3. Clasification based on sourced

   • Under this type of classification, there are three sub categories.
   • Natural polymers
     • These polymers are found in plants and animals. Examples are proteins, cellulose, starch, some resins and rubber.
   • Semi-synthetic polymers
     • Cellulose derivatives as cellulose acetate (rayon) and cellulose nitrate, etc. are the usual examples of this sub category.
   • Synthetic polymers
     • A variety of synthetic polymers as plastic (polythene), synthetic fibres (nylon 6,6) and synthetic rubbers (Buna - S) are examples of man- made polymers extensively used in daily life as well as in industry.

4. Clasification based on mode of polymerisation

   • Polymers can also be classified on the basis of mode of polymerisation into two sub groups.
   • Addition Polymers
     • They are formed by repeated addition of monomer with double or triple bands
   • Condensation Polymers
     • They are formed by repeated condesation reaction between two diferent functional or un= functional monomer units

5. Clasification Based in molecular forces

   • Elastomers
     • These are rubber – like solids with elastic properties. In these elastomeric polymers, the polymer chains are held together by the weakest intermolecular forces. These weak binding forces permit the polymer to be stretched.
   • Fibres
     • Fibres are the thread forming solids which possess high tensile  strength and high modulus. These characteristics can be  attributed to the strong intermolecular forces like hydrogen bonding
   • Thermoplastic polymers
     • These are the linear or slightly branched long chain molecules  capable of repeatedly softening on heating and hardening on cooling.
   • Thermosetting polymers
     • These polymers are cross linked or heavily branched molecules,  which on heating undergo extensive cross linking in moulds and again become infusible.