TY - CONF A1 - Robertson, Daniela A1 - Kaundinya, I. ED - Ziegler, M. ED - Bräu, G. ED - Heerten, G. ED - Laackmann, K. T1 - Influence of transition metal ions on the thermo-oxidative degradation of polyethylene geomembranes (GBR-P) used in road tunnels N2 - Geomembranes are used to seal tunnels and similar constructions against mountain water insurgence. Such water contains different transition metal ions in the form of dissolved metal salts. The influence of metal ions on the oxidative degradation process of geomembranes based on polyethylene is examined. The tests were carried out with the autoclave method according to DIN EN ISO 13438, using a test media separately modified by different transition metal ions. Following the accelerated aging tests, tensile tests and FTIR analysis were carried out to assess the change in material properties during the treatment. Tensile strength and elongation at break for a defined failure criterion (e.g. T50, time to 50% drop of the residual tensile strength and strain relative to the initial value) are measured and the results show a decrease of T50 values during the aging with metal ions compared to the aged sample in the Standard test medium. FTIR results exhibited that a carbonyl peak in the region around 1700 to 1780 cm'1 arose during the thermal treatment, as a result of oxidative degradation. The carbonyl index of samples aged in different modified test media was monitored and the results showed metal ion specific differences in the ability to increase the carbonyl index. These results demonstrate that the presence of certain transition metal ions has a significant influence on the oxidative degradation process. The results presented in this paper are part of an R&D project [Report FE 15.461/2008/ERB, 2013] financed by the German Federal Highway Research Institute (BASt). T2 - 10th International conference on geosynthetics CY - Berlin, Germany DA - 21.09.2014 KW - Oxidation KW - Degradation KW - Transition metal ion KW - Acceleration KW - Very low density polyethylene (VLDPE) PY - 2014 SN - 978-3-9813953-9-6 SP - Paper 170, 1 EP - 7 AN - OPUS4-31716 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -