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Autoclave testing: a new approach for the evaluation of oxidative long-term resistance of geosynthetics

  • Oxidative long time resistance is essential for many polyolefin based products, especially if repair or exchange is not possible as encountered in many building and geotechnical applications. Current regulations and recommendations for geosynthetics cover mainly the needs of a maximum lifetime of 25 years, though many applications require longer lifetimes up to 100 years and more. Reliable testing of the long time oxidation resistance is complicated by the complex interplay of physicochemical processes and reactions in combination with the need of relatively short testing durations, usually not exceeding 12 months. Thus for conventional atmospheric oven testing, the use of temperatures higher than 100 °C is inevitable, making conclusive Arrhenius extrapolations often questionable. Practical assessments of oxidative durability consist of exposures under accelerated ageing conditions with subsequent characterization of exposed material samples with respect to their residualOxidative long time resistance is essential for many polyolefin based products, especially if repair or exchange is not possible as encountered in many building and geotechnical applications. Current regulations and recommendations for geosynthetics cover mainly the needs of a maximum lifetime of 25 years, though many applications require longer lifetimes up to 100 years and more. Reliable testing of the long time oxidation resistance is complicated by the complex interplay of physicochemical processes and reactions in combination with the need of relatively short testing durations, usually not exceeding 12 months. Thus for conventional atmospheric oven testing, the use of temperatures higher than 100 °C is inevitable, making conclusive Arrhenius extrapolations often questionable. Practical assessments of oxidative durability consist of exposures under accelerated ageing conditions with subsequent characterization of exposed material samples with respect to their residual stabilization and/or their mechanical properties. The autoclave test combines exposures at elevated temperatures with higher oxygen pressures and is performed with material samples immersed in a well defined aqueous medium representing critical environments in geosynthetic applications and including extraction of additives. Under these conditions meaningful results can be obtained within reasonable testing durations at only moderately elevated temperatures up to 80 °C. Application of different physicochemical methods, such as tensile testing, OIT /HP-OIT and analysis of residual antioxidant content (ICOT), in order to determine the time dependent degradation behaviour, reveal valuable information about mechanisms and effectiveness of the used antioxidants. Corresponding results for exposures at different temperatures and oxygen pressures are the basis for a 3D-extrapolation in order to estimate the expected service life. Different empirical models are presented and discussed with respect to their practical impact.zeige mehrzeige weniger

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Metadaten
Autoren/innen:Martin Böhning, Daniela Robertson, Hartmut Schröder
Dokumenttyp:Beitrag zu einem Tagungsband
Veröffentlichungsform:Graue Literatur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):EuroGeo4, 4th European Geosynthetics Conference, September 7-10, 2008, Edinburgh, UK
Jahr der Erstveröffentlichung:2008
Ausgabe/Heft:Paper 143
Erste Seite:1
Letzte Seite:8
Freie Schlagwörter:Ageing; Degradation; Geotextiles; Lifetime prediction; Oxidative resistance; Polyolefin; Polypropylene
Veranstaltung:EuroGeo4, 4th European Geosynthetics Conference
Veranstaltungsort:Edinburgh, UK
Beginndatum der Veranstaltung:2008-09-07
Enddatum der Veranstaltung:2008-09-10
Verfügbarkeit des Volltexts:Papiergebundenes Belegexemplar in der Bibliothek der BAM vorhanden ("Hard-copy Access")
Bibliotheksstandort:Sonderstandort: Publica-Schrank
Datum der Freischaltung:19.02.2016
Referierte Publikation:Nein