Elastomers are materials that can be highly expanded by exerting relatively little power. Because of their structure, elastomers have high elasticity and resilience, which means the remaining deformation is very small. There are two main groups of elastomers, the chemically cross-linked materials (rubber materials) and thermoplastic elastomers.

The thermoplastic elastomers (e.g. TPU, TPE, …) demonstrate the characteristic properties of elastomers over a wide temperature range. They are physically but chemically cross-linked, therefore they can by melted at higher temperature and can be processed with traditional thermoplastic processing techniques. Thermoplastic elastomers are soluble, generally, they swell less in comparison to their chemically cross-linked equivalents.

The rubber materials or elastomers (e.g. NBR, FPM, EPDM, …) are polymers, which are formed by cross-linked macromolecules with various vulcanization additives. Due to their chemical cross-linking they do not melt and they begin to decompose at high temperatures. In addition the cross-link ensures that rubber materials do not dissolve and, depending on the medium, do suffer more or less intensive swell or shrinkage.