The change of the raw rubber with temperature (or the change of the external force speed) can take the following three states:
1.Glassy state
2.High elasticity
3.Viscous flow state

For example, NR is in a glassy state below -72 ° C, a viscous flow state above 130 ° C, and a sturdy state between two temperatures. The unvulcanized rubber become softens and even viscous at a temperature, and does not maintain a stable shape and necessary properties; it hardens at a low temperature. Because of this, raw rubber must be processed to have the proper performance, which results in the rubber processing industry.