TY - CONF A1 - Hsuan, Y.G. A1 - Schröder, Hartmut A1 - Rowe, K. A1 - Müller, Werner A1 - Greenwood, J. A1 - Cazzuffi, D. A1 - Koerner, R.M. ED - Neil Dixon, T1 - Long-term performance and lifetime prediction of geosynthetics N2 - To properly understand and assess the long-term behaviour of geosynthetic materials it is necessary to investigate the various types of possible degradation mechanims. This includes both chemical and mechanical behaviour, and sometimes even their interactions with one another. Clearly, chemical degradation of geosynthetics depends on the polymer type. For example, polyolefins are vulnerable to oxidation; polyesters are susceptible to hydrolysis; and plasticizers can leach from polyvinyl chloride. This paper describes the concept of these three types of degradation, but focuses on the oxidation of polyolefins since the majority of the geosynthetics is made from this type of polymer. The methods used to predict the lifetime of antioxidants and service life of the geosynthetic material will be illustrated. Furthermore, the influence of temperature, pressure, and ultraviolet light on the service life are also demonstrated. Finally, the current specifications targeting the longevity of different geosynthetics are presented. Regarding mechanical degradation, the paper mainly focuses upon the creep deformation of geogrids and stress crack resistance (SCR) of polyethylene geomembranes and geopipe. The method to assess stress crack resistance is described, and the microscopic mechanisms that lead to such failure are explained. For creep evaluation, different acceleration tests are presented and their applicability with respect to the different types of polymers is illustrated. In addition, the long-term shear behaviour of geocomposites and geosynthetic clay liners is presented. T2 - 4th European Geosynthetics Conference - EuroGeo4 CY - Edinburgh, Scotland, UK DA - 2008-09-07 KW - Geosynthetic KW - Durability KW - Degradation KW - Antioxidant KW - Weathering PY - 2008 SP - 1 EP - 41 AN - OPUS4-17975 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Robertson, Daniela A1 - Schröder, Hartmut A1 - Böhning, Martin A1 - Brummermann, K. A1 - Kaundinya, I. A1 - Saathoff, F. T1 - Test method for the assessment of the service life of polymeric geosynthetic barriers (GBR-P) for road tunnels N2 - This paper is dealing with a systematic investigation to evaluate the testing method “autoclave test” for the assessment of the oxidative durability of polyolefin-based GBR-P products applied in road tunnel construction. The aim was to derive suitable exposure conditions and criteria for a practical testing procedure with regard to service lifetimes up to 100 years. The screening test (index test) according to DIN EN ISO 13438 developed in the BAM was applied in extended form and amended by a basic characterization, as well as complementary analyses, following autoclave exposure. The time dependency of some of the products and the so called lifetime parameter of one product were investigated and compared with the results of conventional oven tests. Based on the results of the research program some conclusions and practical outlooks were concluded. T2 - Euro GEO 5 - 5th European geosynthetics congress CY - Valencia, Spain DA - 16.09.2012 KW - Durability KW - Oxidation KW - Acceleration ageing KW - GBR-P PY - 2012 SN - 978-0415-64340-5 VL - 1 IS - Topic: Transport SP - 150 EP - 154 AN - OPUS4-27312 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weidner, Steffen A1 - Kühn, Gerhard A1 - Werthmann, Barbara A1 - Schröder, Hartmut A1 - Just, Ulrich A1 - Borowski, Renate A1 - Decker, Renate A1 - Schwarz, Bärbel A1 - Schmücking, I. A1 - Seifert, Ingetraut T1 - A new approach of characterizing the hydrolytic degradation of poly(ethylene terephthalate) by MALDI-MS N2 - The hydrolytic degradation of technical poly(ethylene terephthalate) (PET) was investigated by means of different methods such as size-exclusion chromatography (SEC), viscometry, light-scattering, thin-layer chromatography, end-group titration, and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The long-term degradation was simulated by exposing PET filament yarns to aqueous neutral conditions at 90°C for up to 18 weeks. By means of MALDI-MS and thin-layer chromatography, the formation of different oligomers was obtained during polymer degradation. As expected, an ester scission process was found generating acid terminated oligomers (H-[GT]m-OH) and T-[GT]m-OH and ethylene glycol terminated oligomers (H-[GT]m-G), where G is an ethylene glycol unit and T is a terephthalic acid unit. Additionally, the scission of the ester bonds during the chemical treatment led to a strong decrease in the number of cyclic oligomers ([GT]m). The occurrence of di-acid terminated species demonstrated a high degree of degradation. PY - 1997 DO - https://doi.org/10.1002/(SICI)1099-0518(199708)35:11<2183::AID-POLA9>3.0.CO;2-Z SN - 0360-6376 SN - 0887-624X VL - 35 IS - 11 SP - 2183 EP - 2192 PB - Wiley CY - Hoboken, NJ AN - OPUS4-11357 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -