Plastics Classification

- Oct 11, 2017-


Elastomers are characterized by wide-meshed crosslinking of the "knotted" molecular chains. This type of crosslinking means that the materials have a high level of dimensional stability but are still elastically malleable. By applying load (for instance tensile load) the chains become disentangled, but after removal of the load they relax again. Like thermoset polymers, elastomers are not meltable.

Structure of elastomers

Thermoset plastics

The individual molecular chains of thermoset polymers are characterized by three-dimensional closely-meshed crosslinking. This property means that they can no longer be shaped after hardening. They also cannot be melted. However, because of their strong crosslinking, thermoset polymers do offer good chemical resistance and a high level of thermal stability, as well as being hard and brittle.

Structure of thermoset plastics


Thermoplastic polymers are plastics in which, unlike elastomers and thermoset plastics, the molecular chains are not crosslinked. They consequently demonstrate plastic elastic behaviour and are thermoformable (meltable, weldable). This formability is reversible, in other words can be repeated as often as required as long as the material is not thermally damaged by overheating.

Strucure of thermoplastics