Vulcanization

It works by forming cross-links between sections of the polymer chain which results in increased rigidity and durability, as well as other changes in the mechanical and electrical properties of the material.

The word was suggested by William Brockedon (a friend of Thomas Hancock who attained the British patent for the process) coming from the god Vulcan who was associated with heat and sulfur in volcanoes.

[3] In ancient Mesoamerican cultures, rubber was used to make balls, sandal soles, elastic bands, and waterproof containers.

One day in 1839, when trying to mix rubber with sulfur, Goodyear accidentally dropped the mixture in a hot frying pan.

Goodyear worked out a consistent system for this hardening, and by 1844 patented the process and was producing the rubber on an industrial scale.

Crosslinks with higher number of sulfur atoms give the rubber good dynamic properties but less heat resistance.

Without good flexing properties these movements rapidly form cracks, and ultimately will make the rubber article fail.

[9] Room-temperature vulcanizing (RTV) silicone is constructed of reactive oil-based polymers combined with strengthening mineral fillers.