Vulcanizing
Vulcanizing is a process for hardening rubber. The RuBBER extracted from the tree is sticky and plastic. It is vulcanized by heating with suLpHuR or sulphur compounds.
The MoLEcuLEs in unvulcanized rubber have a long zigzag shape. They straighten when the rubber is stretched and break fairly easily. Vulcanizing causes the long molecules to form chemical BoNDs that join them side to side. This makes the rubber tougher and stronger. It still stretches when pulled, but snaps back to its former shape when the force is removed.
See also ELASTICITY.