Question

The commercial name of polyacrylonitrile is
a) Dacron
b) Orlon (acrilian)
c) PVC
d) Bakelite

Answer 1

Polyacrylonitrile is a polymer with monomer acrylonitrile. It is also known as the acrylic glass or acrylics. It is a synthetic resin produced from the polymerisation of acrylonitrile. It appeared as transparent and rigid plastic.

Complete step-by-step answer:
Acrylic polymers are the set of polymers noted for their transparency, resistance to breakage and elasticity. They are very popularly known as acrylics or polyacrylates.
For e.g. Polyacrylic acid, of polymethyl methacrylate (PMMA), polyacrylonitrile (PAN) etc.
Polyacrylonitrile (PAN) is prepared by suspension polymerisation, solution polymerisation and bulk polymerisation.
Generally we use radical initiation method in which an initiator is added which forms radical by reacting with the double bond in monomer, generating another radical which attacks the next monomer and thus the polymerisation continues with n number of monomers.
Also they can be prepared in the aqueous solution of concentrated inorganic salt such as calcium thiocyanate, sodium perchlorate, and zinc chloride.
The monomer can be synthesised by reaction of ethanol with hydrogen cyanide forming cyanohydrin, followed by losing a water molecule ( $C{H_2} = CH - CN$ ).

Polyacrylonitrile in trade is also known Orlon which is an acrylic fibre that can be blended into fabrics.
These polymers are colourless, transparent plastic with an excellent outdoor life period and very good strength. When it is burnt, it becomes very toxic due to release of some very harmful chemicals. It has remarkable resistance to heat up to ${220^\circ }C$ and also exhibits good mechanical properties.
Some commonomers like methyl methacrylate, vinyl acetate are added to increase the dye ability of PAN. It has a high crystalline melting point, so it can be used as fibres in hot gas filtration systems.

Hence the correct option is (b).

Note: The monomer is synthesised by using acetone and hydrogen cyanide. When the formation of cyanohydrin takes place at $150^\circ C$ , sulphuric acid is added and the molecule rearranges to methyl methacrylate.