Based on their structure, all plastics are linear in nature.
Based on the connections between their monomer units, plastics are classified as linear and cross-linked plastics.
∙ Linear plastics: the monomer units are connected in linear fashion.
∙ Cross-linked plastics: cross-links exists between two linear or branched chains, forming a three-dimensional network.
This arrangement of monomer units define the properties of polymers. Linear polymers can be bent easily, whereas bending cross-linked polymers is difficult.