Question

write about the Phenol - formaldehyde and related

polymers ​

Answer 1

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a. Bakelite :

Bakelite, the thermosetting polymer obtained from reaction of phenol and .formaldehyde is the oldest synthetic polymer. Phenol and formaldehyde react in presence of acid or base catalyst to form thermosetting/ moulding powder (novolac) in two stages. In the third stage, various articles are shaped from novolac by putting it in appropriate moulds and heating at high temperature (1380 C to 1760 C) and at high pressure. The reactions involved are represented in

During the third stage of thermosetting in the moulds, many crosslinks are formed which results in formation of rigid polymeric material, called bakelite which is insoluble and infusible and has high tensile strength. It can also serve as substitute for glass. Bakelite is used for making articles like telephone instrument, kitchenware, electric insulators.

b. Melamine-formaldehyde polymer :

Decorative table tops like formica and plastic dinner-ware are made from heat and moisture resistant themosetting plastic called melamine - formaldehyde resin. The reactions are Melamine and formaldehyde undergo condensation polymerisation to give cross linked melamine formaldehyde.