TY - CONF A1 - Geburtig, Anja A1 - Kömmling, Anja A1 - Wachtendorf, Volker ED - Reichert, T. T1 - UV-LEDs - a new tool to determine the spectral response N2 - To determine a polymer’s spectral response of photo degradation, two main methods have been established. The so-called “filter technique” uses polychromatic radiation, which is filtered by a set of various sharp cut-on filters. This procedure provides separated reading points of an activation spectrum of the investigated material. With the "spectrographic technique” a specimen is irradiated with pectrally dispersed radiation, locally quasi monochromatically, and the local property changes.are related to the radiant exposure at the respective wavelengths. A third method, the irradiation of specimens with quasi monochromatic radiation behind interference filters, is rarely used. These methods have advantages and disadvantages and therefore, there are limits for conclusions from these spectral data. Concerning the quasi monochromatic Irradiation of specimens the development of new UV radiation sources looks promising. With the rapid development of inexpensive UV Light-emitting diodes (LEDs), new : sources of nearly monochromatic radiation in the UV ränge are available, even down to about 250 nm. To determine the spectral response, the use of such UV-LEDs in TO-18 ) and TO-39 metal cases combines the advantages of low cost and energy efficiency, stable spectral irradiance, temperature.and humidity control, larger specimen areas, and an easy and stable analysis. Combinations of different UV LEDs are also discussed as replacement for xenon arc ' radiation sources, see patent application EP01528388A1. T2 - 5th European weathering symposium - Natural and artificial ageing of polymers CY - Lisbon, Portugal DA - 21.09.2011 KW - UV resistance KW - Weathering KW - Spectral sensitivity KW - Action spectrum KW - UV-LEDs PY - 2011 SN - 978-3-9813136-2-8 N1 - Serientitel: CEEES Publication – Series title: CEEES Publication IS - 15 SP - 77 EP - 86 PB - GUS (Gesellschaft für Umweltsimulation) CY - Pfinztal AN - OPUS4-24396 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - von der Ehe, Kerstin A1 - Kömmling, Anja A1 - Wolff, Dietmar T1 - Neutron radiation shielding material polyethylene: consequences of gamma irradiation N2 - High and ultra-high molecular weight polyethylenes are high performance materials, which are predestined for a wide range of applications due to characteristics like high density, low weight, good dimensional stability, high chemical resistance, and high hydrogen content. These polymers are used in two demanding areas: as implant material in medical technology (only ultra-high molecular weight polyethylenes) and as a component for neutron shielding purposes in casks for storage and transport of radioactive waste. In the medical field (joint replacements) as well as during neutron radiation shielding application, high and ultra-high molecular weight polyethylenes are exposed to gamma irradiation: in the first case requested as sterilization process and for surface-crosslinking and in the second case existing as a side effect of inserting the radioactive material in the cask. Given that polyethylene as shielding material has to withstand any type of degradation affecting safety relevant aspects to be applicable for long-term radiation shielding purposes for instance over a period of 40 years, the durability of the material is of special interest. High molecular weight polyethylene (HMW-PE; LUPOLEN 5261Z; Lyondell Basell) and ultra-high molecular weight polyethylene (UHMW-PE; GUR 4120; Ticona) were subjected to gamma radiation and afterwards thermally treated. The gamma doses used are in the range of 50 to 600 kGy and irradiation takes place at RT using a Co-60 source. The planned thermal treatment will take place at a temperature of 125 °C for periods of minimum 30 days and maximum of five years. With the applied conventional analytical techniques it is possible to detect structural changes of both types of polyethylene induced by gamma irradiation and certainly of thermal treatment. Through gamma irradiation melting temperature, crystallinity, and density, respectively increased. Furthermore both polyethylenes get oxidized and cross-linked. With regard to the special application as neutron radiation shielding material in casks for storage and transport of radioactive materials, the impact of irradiation lead to changes of material properties. A consolidated view indicates that the detected changes of the irradiated (U)HMW-PE are not safety relevant for long-term neutron radiation shielding purposes over a period of 40 years in Germany. T2 - WM2015 Conference CY - Phoenix, Arizona, USA DA - 15.03.2015 KW - Gamma radiation KW - Polyehtylene KW - HMW KW - DSC KW - IR KW - Crosslinking PY - 2015 SN - 978-0-9828171-4-8 SP - 15062, 1 EP - 10 AN - OPUS4-33254 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kömmling, Anja T1 - Neutron Radiation Shielding Material Polyethylene - Consequences of Gamma Irradiation T2 - Waste Management Symposia CY - Phoenix, AZ, USA DA - 2015-03-15 PY - 2015 AN - OPUS4-32922 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kömmling, Anja T1 - Experiences and perspectives for the design evaluation of Konrad containers N2 - The former iron ore mine Konrad near Salzgitter is the approved final repository for radioactive waste with negligible heat production in Germany and should go into operation in the 2030s. The waste comes from operation and decommissioning of nuclear power plants, as well as from medicine, research and industry using radiation sources or radioactive materials. These types of waste are comparable to international low- and certain types of intermediate-level waste. The waste includes a large variety of products, materials and properties. The containers for such waste have the primary purpose of enabling handling and storing of the waste by safely enclosing the radioactive inventory and shielding of radiation. Due to the large variety of waste forms to be disposed of in the Konrad repository, different container types are specified to account for the different requirements related to each waste type. Each container design for waste disposal in Konrad has to be approved by BGE on the basis of the “final disposal conditions” (Endlagerungsbedingungen) and the respective “product control” (Produktkontrolle). For demonstrating the container’s compliance with the regulatory framework, the waste producers or container manufacturers have to apply for design approval on the basis of a comprehensive safety assessment including all relevant reports about analytical, numerical and experimental safety demonstrations and quality assurance measures for container manufacturing and operation. Usually, BGE commissions independent experts like BAM to evaluate these documents and the design testing (e.g. drop or fire tests). While the basic assessment principle is to verify the container design and quality to be in line with all regulatory requirements, there are often challenges associated with the container’s safety evaluation. As containers of different types have already been produced in large numbers and partially loaded with waste before the regulatory framework became effective (so-called “old” containers), they are considered in the regulations as well and safety assessments have to be provided in an equivalent way. As the requirements for the documentation of manufacturing quality were not yet known at the time these containers were manufactured, this is often challenging in practice. On the other hand, containers requiring the highest safety level (ABK II, sf) due to their nuclear content sometimes cause significant challenges and very long approval processes concerning safety demonstrations for severe accidental conditions like a 5 m drop without impact limiter onto a nearly unyielding target or a one hour 800 °C fire scenario. Furthermore, as the regulatory framework has not been updated for several decades, some requirements and the respective safety assessment methods have to be interpreted under consideration of the current state of knowledge in science and technology. T2 - safeND conference 2025 CY - Berlin, Germany DA - 17.09.2025 KW - Radioactive waste KW - Final disposal KW - Waste container KW - Design evaluation PY - 2025 AN - OPUS4-64989 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kömmling, Anja T1 - Influence of Ageing on Sealability of HNBR, EPDM and FKM O-rings N2 - At BAM, which is a federal institute for materials research and testing in Germany, it is one of our tasks to evaluate the safety of casks designed for transport and/or storage of radioactive material. This includes assessment of elastomeric seals applied in the containers. Besides examining the low-temperature behaviour and irradiation effects of elastomeric seals, it is our goal to evaluate the service lifetime of the seals with regard to the requirements for long-term safety (40 years and more) of the containers. Therefore, we started an accelerated ageing programme with selected rubbers often used in seals (HNBR, EPDM and FKM) which are aged at four different temperatures (75 °C, 100 °C, 125 °C and 150 °C) up to 1.5 years. In order to assess sealability, O-rings are aged in compression by 25 % (corresponding to the compression during service) between plates as well as in flanges that allow leakage rate measurements. For comparison, uncompressed O-rings are aged as well. Further methods characterising seal performance are compression stress relaxation (CSR) reflecting the loss of sealing force of a compressed seal over time, and compression set (CS) which represents the recovery behaviour of a seal after release from compression. In order to understand the underlying ageing mechanisms in each material, the change in material properties is examined using thermal and mechanical analysis. The experimental results indicate that while material properties, CSR and CS show considerable degradation effects, the leakage rate stays constant or even decreases until shrinkage and the loss of resilience of the aged seal leads to the formation of a leakage path. This indicates that static leakage rate, which is the most relevant criterion for seal performance, has only limited sensitivity for the degradation of the seal material. T2 - International Sealing Conference CY - Stuttgart, Germany DA - 12.10.2016 KW - Rubber KW - Degradation KW - Lifetime prediction PY - 2016 AN - OPUS4-38013 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Raedel, Martina A1 - Feldmann, Ines A1 - Bücker, Michael A1 - Kömmling, Anja ED - Roemich, Hannelore ED - Fair, Lauren T1 - Testing bulked adhesives for the Restoration of Stained-Glass Windows N2 - In this study, bulked adhesives were examined regarding changes in properties for their use in the restoration of stained-glass windows. Two epoxy adhesives commonly used in the restoration of flat glass, Araldite® 2020 and Hxtal NYL-1™, were investigated. The adhesives were mixed with various silica-based micro- and nano-particles as fillers. Different tests were carried out on the adhesives with and without fillers in order to characterise their chemical and mechanical properties. The tests included colorimetry, dynamic-mechanical methods of analysis and tests on bending strength. No property changes could be ascertained in the bulked adhesives that would be negative for the restoration of delicate flat glass. T2 - Recent advances in glass and ceramics - ICOM-CC Glass and Ceramics Working Group Interim Meeting CY - Breslau / Wroclaw, Poland DA - 25.05.2016 KW - bulked epoxy adhesives KW - micro-fillers KW - nano-fillers PY - 2016 SN - 978-83-64419-80-5 SP - 155 EP - 163 AN - OPUS4-36457 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Revealing effects of chain scission during ageing of EPDM rubber using relaxation and recovery experiment N2 - Both chain scission and crosslinking reactions occur during ageing of EPDM rubber. However, with many conventional polymer analysis methods such as hardness and DMA, it is hardly possible to obtain information about the contribution of each reaction type to the measured data. For example, hardness and Tg both increase during ageing of EPDM, indicating crosslinking during ageing, but it is not clear whether this is partly counterbalanced by chain scission reactions which would lower hardness and Tg. An indication that chain scission reactions probably counteract the hardness or Tg increase by crosslinking is given by Compression Set (CS) measurements. CS exhibits a higher change than hardness or Tg, as CS increases additively through both chain scission and crosslinking reactions. In order to elucidate the share of chain scission reactions in the total degradation, a method testing relaxation and recovery behaviour using DMA equipment was applied. The method revealed the strong influence of chain scissions, leading to more pronounced relaxation and higher residual strain after compression. KW - Compression set KW - DMA KW - Nnetwork KW - Crosslinking PY - 2016 DO - https://doi.org/10.1016/j.polymertesting.2016.10.026 SN - 0142-9418 SN - 1873-2348 IS - 56 SP - 261 EP - 268 PB - Elsevier Ltd. AN - OPUS4-38012 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kömmling, Anja T1 - Lifetime Prediction of Elastomeric O-Ring Seals N2 - BAM is the federal institute for materials research and testing in Germany. One of our tasks is to evaluate the safety of casks designed for transport and/or storage of radioactive waste. As elastomeric seals are used in the containers as safety-relevant parts, it is our goal to be able to evaluate the service lifetime of the seals with regard to the requirements for long-term safety (40 years and more) of the containers. For this reason, an accelerated ageing programme with selected rubbers often used for seals (HNBR, EPDM and FKM) was started. Ageing was performed at four different temperatures (75 °C, 100 °C, 125 °C and 150 °C) for up to 2 years. For assessing properties related to the sealability, O-rings were aged in compression by 25 % (corresponding to the compression during service) between plates. For comparison, uncompressed O-rings were aged as well. The aged materials were characterized with conventional polymer analysis methods such as hardness and tensile tests, but also with more seal-specific methods such as compression stress relaxation (CSR, reflecting the loss of sealing force of a compressed seal over time), and compression set (CS, representing the recovery behaviour of a seal after release from compression). CS is chosen as the property for lifetime prediction as it is both sensitive to degradation and related to the seal performance. CS data is extrapolated to 60 °C, which yields lifetimes of approximately 5 years for HNBR and 64 years for EPDM for a criterion of 85 % CS respectively, and approx. 40 years for FKM for a criterion of 65 % CS (the highest value measured so far). T2 - Herbsttagung DKG Bezirksgruppe Süd-Südwest CY - Würzburg, Germany DA - 06.10.2016 KW - Rubber KW - Ageing KW - EPDM KW - HNBR KW - FKM PY - 2016 AN - OPUS4-38010 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kömmling, Anja T1 - Lifetime Prediction of Elastomeric O-Ring Seals N2 - BAM is the federal institute for materials research and testing in Germany. One of our tasks is to evaluate the safety of casks designed for transport and/or storage of radioactive waste. As elastomeric seals are used in the containers as safety-relevant parts, it is our goal to be able to evaluate the service lifetime of the seals with regard to the requirements for long-term safety (40 years and more) of the containers. For this reason, an accelerated ageing programme with selected rubbers often used for seals (HNBR, EPDM and FKM) was started. Ageing was performed at four different temperatures (75 °C, 100 °C, 125 °C and 150 °C) for up to 2 years. For assessing properties related to the sealability, O-rings were aged in compression by 25 % (corresponding to the compression during service) between plates. For comparison, uncompressed O-rings were aged as well. The aged materials were characterized with conventional polymer analysis methods such as hardness and tensile tests, but also with more seal-specific methods such as compression stress relaxation (CSR, reflecting the loss of sealing force of a compressed seal over time), and compression set (CS, representing the recovery behaviour of a seal after release from compression). CS is chosen as the property for lifetime prediction as it is both sensitive to degradation and related to the seal performance. CS data is extrapolated to 60 °C, which yields lifetimes of approximately 5 years for HNBR and 64 years for EPDM for a criterion of 85 % CS respectively, and approx. 40 years for FKM for a criterion of 65 % CS (the highest value measured so far). T2 - Vortrag bei der Uni der Bundeswehr CY - Munich, Germany DA - 06.10.2016 KW - Rubber KW - Ageing KW - EPDM KW - HNBR KW - FKM PY - 2016 AN - OPUS4-38007 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kömmling, Anja T1 - Lifetime Prediction of Elastomeric O-Ring Seals N2 - The ageing of polymers, including elastomers, is an undesirable but inevitable process leading to a limited lifetime of rubber products such as seals. In order to investigate the degradation of material properties 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]. Sheets of 2 mm thickness were aged at four different temperatures (75 °C, 100 °C, 125 °C and 150 °C) for time periods of 1 day up to 1 year. The aged samples were examined using standard analytical methods such as hardness, dynamic-mechanical analysis (DMA), thermogravimetric analysis (TGA), mass loss, density and tensile tests. Additionally, DMA equipment was used to investigate relaxation and recovery behaviour which is more sensitive to degradation effects and can help to correctly interpret data from hardness and DMA measurements. The results show e.g. an increase in hardness and glass transition temperature for HNBR and, less pronounced, for EPDM. This confirms ageing mechanisms described in the literature, e.g. dominant crosslinking reactions in HNBR and both chain scissions and crosslinking for EPDM. FKM, which is very heat resistant, exhibits only minor degradation. Where possible, shift factors for time-temperature data sets were determined. The values obtained from different methods are compared and discussed. T2 - Modification, Degradation and Stabilization of Polymer (MoDeSt) Conference CY - Cracow, Poland DA - 04.09.2016 KW - Rubber KW - Ageing KW - EPDM KW - HNBR KW - FKM PY - 2016 AN - OPUS4-38006 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kömmling, Anja T1 - Discoloration effects of high-dose γ-irradiation and long-term thermal ageing of (U)HMW-PE N2 - Two polyethylene types with ultra high (UHMWPE) and high molecular weight (HMWPE), which are used as neutron radiation shielding materials in storage casks for radioactive waste, were subjected to gamma irradiation doses up to 600 kGy and subsequent thermal ageing at 125 °C for up to one year. One material was a medical grade UHMWPE and the other a HMWPE containing an antioxidant. Degradation effects in the materials were characterized using colorimetry, UV-Vis spectroscopy, MIR and FTIR measurements, DSC and, in the case of HMWPE, insoluble content determination. Both materials exhibited a yellowing upon irradiation. The discoloration of UHMWPE disappeared again after thermal ageing, which is why it was attributed to annealable color centers in the form of free radicals entrapped in the crystalline regions of the polymer that recombine during thermal ageing. Furthermore, oxidation species were observed with MIR and FTIR spectroscopy. For HMWPE, the yellowing occurred during both irradiation and thermal ageing and was correlated to antioxidant decomposition. Additionally, black spots were observed after thermal ageing of HMWPE that were attributed to reaction products of antioxidant derivatives and catalyst residues. While only little evidence of oxidation species was found in the light material parts, oxidation is expected to concentrate in the black spots as the catalyst residue promotes hydroperoxide decomposition and thus radical formation that initiate polymer oxidation T2 - Ionizing Radiation and Polymers Conference CY - Giens, France DA - 25.09.2016 KW - Polyethylene KW - Gamma-irradiation KW - Yellowing KW - Degradation PY - 2016 AN - OPUS4-38001 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -