Elastomer

An elastomer is a cross-linked polymer material with pronounced elastic properties. Elastomers can be significantly deformed under tension or pressure and largely return to their original shape when the load is removed. This is due to a three-dimensionally cross-linked molecular structure consisting of flexible polymer chains: the chains can move against each other but are permanently connected to each other via cross-linking points.

Elastomers are generally used above their glass transition point – they behave like rubber, remain dimensionally stable and flexible at the same time. At very low temperatures, they approach the glassy range and harden; at high temperatures, their elasticity initially increases before excessive heat causes damage to the cross-linking. Unlike thermoplastics, elastomers cannot be remelted.

Typical properties of elastomers are:

• High reversible elasticity and compressibility (resilience)
• Adjustable hardness ranges (e.g. Shore A) with elastic behaviour
• Good vibration and noise damping
• Media-dependent resistance to water, oils/greases, chemicals, ozone and UV radiation
• Pronounced temperature dependence with material-specific areas of application, roughly between approx. –40 °C and +200 °C

Important technical elastomers include:

• EPDM – highly resistant to weathering, ozone, UV, hot water and steam, frequently used in plant engineering and building services engineering
• NBR – resistant to many oils, greases and fuels, classic material for hydraulic and pneumatic applications
• CR (chloroprene) – good ageing and weather resistance, moderate oil resistance, universally applicable
• VMQ (silicone) – very wide temperature range and frequently used in food, medical and electrical engineering
• FKM / FFKM – high-performance elastomers for high temperatures and aggressive chemicals

Elastomers are processed into seals, O-rings, profiles, hoses, customised moulded parts, vibration dampers and many other technical components. In sealing technology – for example in O-rings, profile and flat seals or complex elastomer moulded parts made to drawing – they are the standard material wherever elastic behaviour, reliable sealing and permanent shape retention are required.