Question

Which of the following polymers can be made by addition polymerisation reaction?
A.Nylon $- 6$
B.Perlon - U
C.HDPE
D.LDPE

Answer 1

Addition polymers are formed by the repeated addition of monomer molecules possessing double or triple bonds without the co – generation of other products.

Complete answer:
Addition polymerisation results in the generation of polymers without any by product. Examples are the generation of polyethene from the repeated addition of ethene monomers.
Out of the above options only HDPE ( High Density Polyethylene ) and LDPE ( Low Density Polyethene ) are examples of addition polymers since they are formed by addition polymerisation of ethene monomers without any by-products being generated in the reaction. The other two options, i.e. Nylon $- 6$ and Perlon - U are not addition polymers. Nylon $- 6$ is prepared by a ring opening polymerisation reaction of Caprolactam monomer and Perlon – U is also formed by a similar mechanism and hence is not considered as an additional polymer due to the same reason.
HDPE ( High Density Polyethylene ) and LDPE ( Low Density Polyethene ) are addition polymers made from ethylene monomers. The basic difference between them is that LDPE is manufactured by heating ethylene monomers to $350 - 570K$ , in the presence of traces of peroxide or oxygen so that free radical addition mechanism can be carried out. On the other hand, HDPE is manufactured by heating ethane monomer under a pressure of around seven atmospheres, at a temperature of around $333 - 343K$ , in the presence of a catalyst consisting of triethyl aluminium and titanium tetrachloride ( this catalyst is also known as Ziegler-Natta catalyst ) .

So, The correct answer is (C).

Note: The ring opening polymerization reaction with which nylon $- 6$ is prepared is not an addition or condensation polymerisation reaction due to the fact that it generates by-products.