Vulcanisation
The treatment of natural rubber with sulfur to form cross-links that greatly improve its properties.
Unit
Dimensionless
In depth
Sulfur bridges form between the polyisoprene chains at their remaining double bonds, preventing the chains from sliding permanently past one another. The rubber becomes stronger, more elastic and far less sensitive to temperature, no longer softening in heat or cracking in cold.
Examples in the real world
Goodyear's 1839 discovery that made durable rubber tyres possible; hard ebonite results from heavy sulfur loading.