On the basis of structure of polymers, these can be classified as:

  1. Linear Polymers
  2. Branched Chain Polymers
  3. Cross-linked Polymers

Linear Polymers

These are polymers in which monomeric units are linked together to form linear chains. These linear polymers are well packed and therefore, have high densities, high tensile (pulling) strength and high melting points. For example, polyethelene, nylons and polyesters are examples of linear polymers.

Branched Chain Polymers

These are polymers in which the monomers are joined to form long chain with side chains or branches of different lengths. These branched chains polymers are irregularly packed and therefore, they have lower tensile strength and melting points than linear polymers. For example, low density polyethene, glycogen, starch, etc.

Cross-linked Polymers

These are polymers in which long polymer chains are cross-linked together to from a three dimensional network. These polymers are hard, rigid and brittle because of the network structure. Bakelite, melamine and formaldehyde resin are some examples of this type.