The base rubber, wether natural or synthetic, needs to be mixed with a number of different chemicals/ingredients to actually give a rubber compound that can be processed and made into a finished product.
A recipe for making a rubber compound includes, except for the rubber, approximately 10 -15 different chemicals. The different chemicals are divided into groups, depending on their function, and one of the most important chemicals is the vulcanization agents which crosslinks the rubber molecules into a three dimensional network, giving the rubber its unique properties.
Function in the rubber compound
Ozon and ageing resistance
Crosslinks the rubber molecules