Definition:Process by which the soft weak plastic-like material is converted into a strong elastic product. The long chains of the polymer molecules become crosslinked by reactions with the vulcanization agents to form three-dimensional structures.Polymer loses its tackiness caused by polymer flow and becomes insoluble in solvents and is more resistant to deterioration normally caused by heat, light and ageing processes.Sulfur was the first agent used to vulcanise natural rubber. Cyclic (ring) structure composed of eight atoms of sulfur (S8).