What is ageing?

Ageing, i.e. the change (usually deterioration) of physical and chemical properties over a long period of time, occurs in all rubber. As rubber is an organic product, it is very reactive under certain influences, which can cause cracks or embrittlement. Typical triggers of ageing are heat, oxygen, ozone, moisture, mechanical stress and high-energy radiation. These influences can either attack the surface or affect the entire rubber volume. Hot air ageing is a common method for testing heat resistance. The sample is stored in heating cabinets for a certain period of time in order to accelerate ageing processes. The material properties are then compared with the untreated sample. Different rubbers have different strengths in terms of resistance and therefore ageing resistance to certain external influences. Nevertheless, for all types of rubber a storage in a cool, dry place away from light is recommended for all types of rubber in order to minimize ageing processes. Fluoro rubbers and silicones have particularly good ageing resistance. EPDM, ECO, CSM and butyl rubber also have good resistance.