Question

Which of the following polymers does not involve cross linkages?
(A) Bakelite
(B) Melamine
(C) Polythene
(D) Vulcanized rubber

Answer 1

As we know that cross link refers to a bond which links one polymer chain to another polymer chain. We can say that cross linked polymers are those polymers that are obtained when a cross link bond is formed between the monomeric units. They have strong covalent bonds, so it creates the resultant to be stronger and more stable material.

Complete step by step solution:
Since we know that cross- linked polymers are usually formed from bi functional and tri functional monomers and certain strong covalent bonds between various linear polymer chains.
Here in the question, Bakelite, melamine and vulcanized rubber have strong covalent bonds.
Polythene is a linear polymer of monomer ethane, It can be shown as $nC{H_2} = C{H_2} \to n\left[ { - C{H_2} - C{H_2}} \right] \to {\left[ { - C{H_2} - C{H_2} - } \right]_n}$ .
Hence the correct option is (C) Polythene.

Note:
We should know that cross linked polymers are polymers in which long polymer chains are crossed-linked together to create a three dimensional network. These are utilised in making a large number of materials as they are mechanically strong and even resistant to heat, weak or attack by solvents.