Polymers

15.5

 Different types of polymers have different intermolecular forces of attraction. Elastomers or rubbers have the weakest while fibres have the strongest intermolecular forces of attraction. Plastics have intermediate intermolecular forces of attraction. Hence, the increasing order of the intermolecular forces of the given polymers is as follows:

Buna? S < polythene < Nylon 6, 6

Neoprene < polyvinyl chloride < Nylon 6

15.4

15.3

 Two monomers Hexamethylenediamine [H₂N- (CH₂)₆-NH₂] and adipic acid [HOOC- (CH₂)₄- COOH] combined to form the polymer and a water molecule is removed in this process. Hydrogen (H) is removed from both sides of Hexamethylenediamine and OH group is removed from both sides of adipic acid to give a water molecule.

The monomer is OC- (CH₂)₅-NH known as Caprolactam. The cyclic structure of the monomer changes to linear to form the polymer, as shown below:

The monomer is Tetrafluroethene (CF₂= CF₂), the double bond breaks to form the polymeric

15.2

Polymers are classified based on structure, into 3 types:

Linear Polymer: They have a long and straight chain of Ex: high-density Polythene, Polyvinyl chloride

Branched-chain Polymers: They have linear molecular chains along with some Ex: less density polythene.

Cross-linked or network Polymers: In these polymers, strong covalent bonds are between the linear chains. Generally, they contain 2 or 3 types of functional groups. Ex: Bakelite, melamine.

15.1

Polymer=Poly + Mer

Poly means “many” and “Mer” means unit or part. A polymer is a large molecule which is formed by linking repeating structural units. The structural units are generally simple molecules and they are linked by a covalent bond to form a polymer.