Class 12 Chemistry Polymers Preparation of Important Addition Reaction

Preparation of Important Addition Reaction

  1. Polyamides:-
    1. These polymers possessing amide linkages are important examples of synthetic fibres and are termed as nylons. The general method of preparation consists of the condensation polymerisation of diamines with dicarboxylic acids and also of amino acids and their lactams.
    2. Preparation of Nylons
      1. Nylon 6, 6:-
        1. It is prepared by the condensation polymerisation of hexamethylenediamine with adipic acid under high pressure and at high temperature.
        2. Nylon 6, 6 is used in making sheets, bristles for brushes and in textile industry.
    3. Class_12_Polymers_Preparation_Of_PolyAmides 
      1. Nylon 6:-
        1. It is obtained by heating Caprolactum with water at a high temperature.
        2. Nylon 6 is used for the manufacture of tyre cords, fabrics and ropes.
    4. Class_12_Polymers_Structure_of_Polymers_Nylon 6 
      1. Polyesters: - These are the poly condensation products of dicarboxylic acids and diols.
        1. Dacron or Terylene is the best known example of polyesters. It is manufactured by heating a mixture of ethylene glycol and terephthalic acid at 420 to 460 K in the presence of Zinc acetate antimony trioxide catalyst.
        2. Dacron fibre (Terylene) is crease resistant and is used in blending with cotton and wool fibres and also as glass reinforcing materials in safety helmets, etc.
      2. Phenol – formaldehyde polymer (Bakelite and related polymers):-
        1. Phenol - formaldehyde polymers are the oldest synthetic polymers.
        2. These are obtained by the condensation reaction of phenol with formaldehyde in the presence of either an acid or a base catalyst.
        3. The reaction starts with the initial formation of o-and/or p-hydroxymethylphenol derivatives, which further react with phenol to form compounds having rings joined to each other through –CH2
        4. The initial product could be a linear product – Novolac used in paints.
        5. Novolac on heating with formaldehyde undergoes cross linking to form infusible solid mass called Bakelite. It is used for making combs, phonograph records, electrical switches and handles of various utensils.
      3. Melamine- formaldehyde Polymer:-
        1. Melamine formaldehyde polymer is formed by the condensation polymerisation of melamine and formaldehyde.
        2. It is used in the manufacture of unbreakable crockery.
    5. Class_12_Polymers_Structure_of_PhenolNovolac on heating with formaldehyde undergoes cross linking to form infusible solid mass called Bakelite. It is used for making combs, phonograph records, electrical switches and handles of various utensils.
  2. Class_12_Polymers_Bakelite 
    1. Melamine- formaldehyde Polymer:-
      1. Melamine formaldehyde polymer is formed by the condensation polymerisation of melamine and formaldehyde.
      2. It is used in the manufacture of unbreakable crockery.
  3. Class_12_Polymers_Structure_of_Melamine

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