Natural and synthesis rubbers are not materials in the generally common sense but rather only basic materials to which a number of mixture components must be added before the vulcanization. In addition to the basic material rubber, all elastmers contain numerous additions like fillers (e.g. soot), softeners, processing aids, aging protection means, vulcanization means, vulcanization accelerators, activators, vulcanization retarders, pigments etc. On average an elastomer mixture consists of 10 to 20 components. The total of all of these components is called the elastomer mixture or elastomer compound.
The used rubber determines the basic characteristics of the vulcanizate, above all the ageing resistance and the flexibility at cold tempertures as well as the conduct opposed to differing media like oils, fuels, water and solvents. The level of the mechanical characteristics like elasticity and sturdiness also depends on the polymer basis as well as on the filling with so-called reinforcing soots or light fillers. Using additional materials, certain characteristics can be varied (like the hardness) and improved (e.g. flexibility with coldness, impact elasticity, pressure permanent set, heat and swelling resistance. The mixture of elastomers is very complex and is adapted to the respective application.