TY - CONF A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Characterisation of degradation and determination of end-of-lifetime criterion for O-ring seals T2 - RubberCon 2017 N2 - The ageing of polymers, including elastomers, is an undesirable but inevitable process leading to a limited lifetime of rubber products such as seals. Independent of the application, as e.g. in automotive, piping or container applications, a long lifetime or at least a timely exchange of a seal before occurrence of critical failure is desired. In order to investigate the degradation of material properties and to determine the lifetime of elastomers used as seals, an ageing programme was started with hydrogenated acrylonitrile butadiene rubber (HNBR), ethylene propylene diene rubber (EPDM) and fluorocarbon rubber (FKM) [1-3]. Both O-ring seals (uncompressed and compressed by 25 %) with a cord diameter of 10 mm as well as sheets with a thickness of 2 mm were aged at 75 °C, 100 °C, 125 °C and 150 °C for up to two years. The changes of material properties during ageing were characterised for each material using samples from the sheets by means of e.g. Dynamic Mechanical Analysis and tensile tests, while sealing properties such as leakage rate were determined on O-rings. The experimental results indicate that while material properties show considerable degradation effects, the static leakage rate stays constant or even decreases before failure occurs quite suddenly at advanced degradation levels. This reveals that static leakage rate has only limited sensitivity for the degradation of the seal material. Our approach to determine a suitable end of lifetime criterion, which involves a partial decompression of the seal during the leakage test, is presented and discussed. T2 - RubberCon 2017 CY - Prague, Czech Republic DA - 23.05.2017 KW - Life time prediction KW - Ageing KW - Rubber seal KW - Leakage PY - 2017 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/40391 AN - OPUS4-40391 SN - 978-80-906662-0-7 SP - 65 EP - 72 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany