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Q. How many of the following polymers given, come under the category of condensation polymers? Bakelite, Teflon, Nylon 6, Dacron, Polyisoprene, Melamine, Neoprene

AP EAMCETAP EAMCET 2019

Solution:

The given polymers are formed as follows :

Bakelite These are made by the condensation reaction of formaldehyde and phenol in presence of either an acid or base, as a catalyst. It involves the formation of methylene bridges in ortho/ para position

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On heating with formaldehyde, novolac undergoes cross - linking to form an infusible solid mass, which is known as bakelite.

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It is a condensation polymer.

Teflon It is prepared by heating tetrafluoroethylene at high pressure in the presence of peroxides or ammonium peroxo sulphate $\left[\left( NH _{4}\right)_{2} S _{2} O _{8}\right]$ catalyst.

It is chemically inert and resistant to attack.

$\underset{\text{Tetrafluroethene}}{nCF_2 = CF_2} \ce{->[n(NH_4)_2S_2O_8][\text{High pressure}]} \underset{\text{Teflon}}{-(CF_2 - CF_2)_n-}$

It is an addition polymer.

Nylon-$6$ or Perlon It is also known as perlon and is obtained from the monomer caprolactum. This caprolactum is obtained from cyclohexane.

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Here, in both monomeric species, there are $6$ carbon atoms each.

Dacron or Terylene It is a polymer obtained by condensation reaction between ethylene glycol and terephthalic acid at $425-475 \,K$ in the presence of zinc acetate antimony trioxide catalyst.

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Nylon -$6$ and dacron both are condensation polymers.

Polyisoprene

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It also an addition polymer.

Melamine In this particular reaction, melamine and formaldehyde copolymerise to give another polymer

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Thus, is a condensation polymer.

Neoprene It is also called polychloroprene and formed by the free radial polymerisation of chloroprene and has superior resistance to vegetable and mineral oils.

$\underset{\text{Chloroprene}}{nCH_2 = \overset{\underset{|}{C}l}{C} - CH = CH_2} \ce{->[\text{Polymerisation}]} \underset{\text{Neoprene}}{-\left[CH_2 - \overset{\underset{|}{C}l}{C} = CH_2 - CH_2\right]_n-}$

It is an addition polymer.

Hence, among the given polymers, we have four (4) condensation-polymers