TY - JOUR A1 - Zaghdoudi, M. A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Oxidative ageing of elastomers: experiment and modelling N2 - During an extensive test programme at the Bundesanstalt für Materialforschung und prüfung, material property changes of EPDM O-rings were investigated at different ageing times and two ageing temperatures of 125 ◦ C and 150 ◦ C. To exclude possible diffusion-limited oxidation (DLO) effects that can distort the data, IRHD microhardness measurements were taken over the cross section of compressed O-rings. Continuous stress relaxation measurements were taken on samples free of DLO effects. The additional effect of physical processes to irreversible chemical ones during a long-term thermal exposure is quantified by the analysis of compression set measurements under various test conditions. By combining the different experimental methods, characteristic times relative to the degradation processes were determined. On the basis of experimental data, a microphysically motivated model that takes into account reversible and irreversible processes was developed. The parameter identification strategy of the material model is based on our experimental investigations on homogeneously aged elastomer O-rings. The simulated results are in good agreement with the experiments. KW - Compression Set KW - Compression stress relaxation KW - Modelling KW - Ageing KW - Microhardness PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-609332 DO - https://doi.org/10.1007/s00161-022-01093-9 VL - 36 SP - 289 EP - 297 PB - Springer Nature AN - OPUS4-60933 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zaghdoudi, Maha A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Overview of ongoing long-term ageing investigations on elastomer seals N2 - At the Bundesanstalt für Materialforschung und -prüfung (BAM) in Division 3.4 Safety of Storage Containers, one of our tasks is to evaluate the safety of containers designed for disposal of low and intermediate radioactive waste. As such containers might be transported before and stored until disposal, safe enclosure of the radioactive inventory is important for this time span. Elastomer O-rings are widely used as barrier seals in these containers. Thus, as for many other applications, an understanding of the practical effects of ageing degradation on elastomer seals during long-term exposure is mandatory for predicting the lifetime of such components. According to a long-term test programme on three kinds of rubbers (EPDM and FKM (relevant for application), HNBR (for comparison)), over several years we have studied the degradation and the change of mechanical properties (e.g. hardness, strain at break) at four different ageing temperatures (75 °C, 100 °C, 125 °C and 150 °C) as well as the change of sealing properties. Continuous and intermittent compression stress relaxation (CSR) measurements were performed in order to investigate the respective contribution of crosslinking and chain scission to the observed degradation effects. Thus, the degradation kinetics and mechanisms could be resolved more clearly. For assessing the seal performance, compression set (CS) and leakage rate measurements were conducted. The experimental results showed that the O-rings remained leak-tight under purely static conditions even when CSR, CS and mechanical properties already indicated far advanced degradation. For this reason, a modified leakage test involving a small and rapid partial decompression of the seal was developed that enabled determining an end-of-lifetime criterion for O-rings with a safety margin for thermal shrinkage and vibrations. KW - Seal KW - O-Ring KW - Ageing KW - Component tests PY - 2020 SN - 1863-7116 VL - 15 IS - 3 SP - 146 EP - 151 PB - Gupta CY - Ratingen AN - OPUS4-51161 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Influence of Ageing on Sealability of HNBR, EPDM and FKM O-rings N2 - At BAM, which is the 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 for seals (HNBR, EPDM and FKM) which are aged at four different temperatures (75 °C, 100 °C, 125 °C and 150 °C) up to 1 year. 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. Additionally, hardness is measured for information about the change of mechanical properties. The experimental results indicate that while hardness, 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 only available direct seal performance criterion, 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 - Seal KW - Degradation PY - 2016 SN - 978-3-8163-0674-9 VL - 2016 SP - 551 EP - 563 PB - VDMA AN - OPUS4-38014 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Probst, Ulrich A1 - Schulz, Sebastian A1 - Jaunich, Matthias A1 - Wolff, Dietmar A1 - Völzke, Holger ED - Berger, K.-F. ED - Kiefer, S. T1 - Langzeituntersuchungen an Metalldichtungen mit innen liegendem Federkern und doppelter Ummantelung N2 - In Deutschland werden in Transport- und Lagerbehältern (TLB) wärmeentwickelnde radioaktive Abfälle gegenwärtig über einen Zeitraum von bis zu 40 Jahren zwischengelagert. Aufgrund der Situation der noch nicht abgeschlossenen Endlagersuche werden hier möglicherweise Verlängerungen in Betracht zu ziehen sein. Im Deckeldichtsystem der TLB werden in der Regel Metalldichtungen vom Typ Helicoflex® eines französischen Herstellers verwendet, die aus einem innen liegenden Spiralfederkern und zwei Ummantelungen bestehen. Die Ermittlung der Fliess- und Relaxationseigenschaften der Dichtungskomponenten über den vorgesehenen langen Betriebseitraum sind vor dem Hintergrund des Erhalte eines geforderten hohen Dichtniveaus ein wichtiger Untersuchungsgegenstand. KW - Metalldichtung KW - Langzeiteignung KW - Dichtsysteme KW - Transport- und Lagerbehälter für radioaktive Stoffe PY - 2013 SN - 978-3-9811509-7-1 SP - 1 EP - 11 CY - Mannheim AN - OPUS4-28912 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weber, Mike A1 - Zaghdoudi, Maha A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - A numerical approach to correlate compression stress relaxation and compression set of elastomer O-rings with tightness N2 - The excellent mechanical properties of elastomer seals at a wide range of temperatures as well as their high versatility and recovery potential under several load conditions make these materials well suitable for the application in containers designed for transport and disposal of negligible heat generating radioactive waste. While a seal exchange at defined intervals is typical in many conventional applications, it is impossible or at least hard to perform when principles of minimization of radiation exposure have to be considered which prohibit an avoidable cask handling. An extensive knowledge of the change of the elastomer properties during aging and the availability of reliable end-of-lifetime criteria to guarantee the safe enclosure of the radioactive material for the required time are mandatory. As BAM is involved in most of the national cask licensing procedures and in the evaluation of cask-related long-term safety issues, great efforts have already been made and are still ongoing to scientifically support this task. Among other representative types of elastomers, specimen made from ethylene propylene diene rubber (EPDM) were tested before, during and after aging to capture the with respect to application most important of their complex mechanical properties. Exemplary results of these investigations were used to calibrate material models implemented in the commercial finite element software ABAQUS/Standard®. The finite element model already presented in previous works uses a sequential temperature displacement coupling. The calculated compression stress relaxation (CSR) and compression set (CS) values do satisfactorily match the experimental results. In many investigations performed at BAM both values (CSR and CS) were identified as key indicators of elastomer’s long-term performance. However, the possibility to correlate these equivalent indicators with performance values such as tightness and leakage rate, measurable in the mounted state, is an important goal of our future work. In the presented study the ABAQUS® feature of “pressure penetration” is introduced in the suggested finite element model for this purpose. It provides the possibility to simulate the penetration of a gas into a possible gap between flange and O-ring causing an opening of a leakage path. Three dimensional and axis-symmetric finite element models were generated to represent flat and grooved flanges of different dimensions. The sensitivity of the feature to several input parameters is investigated and the observed behavior of the O-ring is correlated with the results of performed leakage tests. T2 - ASME 2021 Pressure Vessels & Piping Conference (PVP2021) CY - Online meeting DA - 13.07.2021 KW - Elastomer KW - Tightness KW - Leakage KW - Compression set KW - Compression stress relaxation PY - 2021 SN - 978-0-7918-8535-2 DO - https://doi.org/10.1115/PVP2021-61976 SP - 1 EP - 8 PB - American Society of Mechanical Engineers (ASME) CY - New York, NY, USA AN - OPUS4-54422 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Grelle, Tobias A1 - Wolff, Dietmar T1 - Low temperature properties of elastomer seals - Comparison between purely static and partially released seals - N2 - Rubber is widely used as sealing material in various applications. In many fields the function of seal materials at low temperatures is necessary. Therefore the understanding of failure mechanisms that lead to leakage at low temperatures is of high importance. It is known that the material properties of rubbers are strongly temperature dependent. At low temperatures this is caused by the rubber-glass transition (abbr. glass transition). During continuous cooling the material changes from rubber-like entropy-elastic behaviour to stiff energy-elastic behaviour, that allows nearly no strain or retraction, due to the glass transition. Hence rubbers are normally used above their glass transition but the minimum working temperature limit is not defined precisely, what can cause problems during application. Therefore the lower operation temperature limit of rubber seals should be determined in dependence of the material properties. In the past we investigated the material properties and sealing behaviour of elastomeric seals at low temperatures. Additionally we started to study the effect of a small partial release of elastomer seals at low temperatures. To study the influence of dynamic events on seal performance and to enhance the understanding of occurring seal failure, a setup for a fast partial seal release was designed. In this contribution we focus on the correlation of material properties and component behaviour under different application conditions. It is desired to widen the understanding of the process of seal failure at low temperature. T2 - 12. Kautschuk-Herbst-Kolloquium CY - Hannover, Germany DA - 22.11.2016 KW - Seal properties KW - Low temperature KW - Partial release KW - Leakage rate PY - 2016 SN - 9783981407648 SP - 34 AN - OPUS4-38501 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zaghdoudi, Maha A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Scission, cross-linking, and physical relaxation during thermal degradation of elastomers N2 - Elastomers are susceptible to chemical ageing, i.e., scission and cross-linking, at high temperatures. This thermally driven ageing process affects their mechanical properties and leads to limited operating time. Continuous and intermittent stress Relaxation measurements were conducted on ethylene propylene diene rubber (EPDM) and hydrogenated nitrile butadiene rubber (HNBR) samples for different ageing times and an ageing temperature of 125 °C. The contributions of chain scission and cross-linking were analysed for both materials at different ageing states, elucidating the respective ageing mechanisms. Furthermore, compression set experiments were performed under various test conditions. Adopting the two-network model, compression set values were calculated and compared to the measured data. The additional effect of physical processes to scission and cross-linking during a long-term thermal exposure is quantified through the compression set analysis. The characteristic times relative to the degradation processes are also determined. KW - Ageing KW - Scission KW - Cross-linking KW - Compression set KW - Physical relaxation PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486091 DO - https://doi.org/10.3390/polym11081280 SN - 2073-4360 VL - 11 IS - 8 SP - 1280, 1 EP - 12 PB - MDPI AN - OPUS4-48609 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kömmling, Anja A1 - Grelle, Tobias A1 - Jaunich, Matthias A1 - Goral, Milan A1 - Wolff, Dietmar T1 - Three-dimensional thermal expansion of neat and irradiated (U)HMWPE materials at elevated temperatures N2 - The thermal expansion of polymeric parts can be an issue in many applications where the available space is limited, or exact dimensions of the part are required. For this study, a device was designed and built that allowed measuring the thermal expansion simultaneously in all three spatial directions on cubic samples with real-scale dimensions (78 mm edge length). The results are shown between 25 °C and 125 °C for two PE materials, one HMWPE and one tempered UHMWPE, for non-irradiated samples as well as cubes that have been irradiated with 100 and 400 kGy. The results measured with the new device were very similar to those measured with conventional thermo-mechanical analysis equipment and to literature data of UHMWPE. The HMWPE material shows a much larger thermal expansion coefficient in one direction compared to the other two directions during the first heating due to frozen stresses from the pressing step during material manufacturing. These stresses are mostly released by the expansion during the first heating, so that the expansion during the second heating is more uniform. The overall volumetric expansion is the same for both heating runs. By contrast, the tempered UHMWPE material shows no significant difference between first and second heating run, as the stresses from processing could already relax in the tempering step. The irradiation treatment does not affect the values significantly for the given test set-up. KW - Lupolen KW - Ultra high molecular weight polyethylene KW - GUR KW - Coefficient of thermal expansion KW - High temperature PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-563987 DO - https://doi.org/10.1016/j.polymertesting.2022.107841 SN - 0142-9418 VL - 117 SP - 1 EP - 8 PB - Elsevier Ltd. AN - OPUS4-56398 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Wolff, Dietmar A1 - Stark, Wolfgang T1 - Tieftemperaturverhalten von Elastomerdichtungen - Eigenschaftsbestimmung für den Einsatz in Transport- und Lagerbehältern für radioaktive Stoffe N2 - Die Messung des dynamischen Speichermoduls mit der Dynamisch-Mechanischen-Analyse ermöglicht einen schnellen Überblick über das temperaturabhängige Verhalten von elastomeren Dichtungsmaterialien. Ein direkter Rückschluss von der so ermittelten Glasübergangstemperatur Tg auf die Versagenstemperatur einer Dichtung ist aber ohne zusätzliche Messungen bisher nicht möglich. Mit den Ergebnissen des Druckverformungsrestes DVR und des DVRDMA ist eine ge-nauere Beschreibung der Tieftemperatureigenschaften und dadurch der Funktion von elastomeren Dichtungsmaterialien möglich. Messungen ergeben beispielsweise, dass sich das EPDM bei einer Temperatur von -40 °C laut der Dynamisch Mechanischen Analyse noch im gummielastischen Bereich befindet. Die DVRDMA-Werte zeigen eine Rückstellung um mehr als 40 % der Ausgangsdeformation in wenigen Minuten. Mit derart detailliert bestimmten Eigenschaften lassen sich Rückschlüsse auf einsatzspezifische Anforderungen wie z. B. die Dichtwirkung in Abhängigkeit von Betriebstemperatur und mechanischer Belastungsgeschwindigkeit ziehen, so dass je nach Einsatzbedingungen für die Dichtungen eine geeignete Materialauswahl getrof-fen werden kann. T2 - Jahrestagung Kerntechnik 2010 CY - Berlin, Deutschland DA - 2010-05-04 KW - Dichtungen KW - Elastomere KW - Tieftemperaturverhalten PY - 2010 IS - Sektion 5 / 503 SP - 1 EP - 4 CY - Berlin AN - OPUS4-21272 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Grelle, T. A1 - Wolff, Dietmar T1 - Influences on the low temperature sealability of elastomer O-rings N2 - For many sealing applications rubbers are applied due to their special material properties and easy use. In many applications, e.g. in aviation, traffic or process technology the material can be exposed to low temperatures during Operation. Therefore it is important to know the material behaviour at those low temperatures to determine the temperature range that allows a safe Operation of the seal. As rubbers are used as main sealing materials for Containers for low and intermediate level radioactive waste and as additional component to metal seals in spent fuel and high active waste Containers, a comprehensive elastomer investigation program is run at BAM. This program comprises investigations of elastomer overall performance, durability, influence of gamma irradiation and low temperature behaviour. In this paper we focus on the behaviour of elastomer seals at low temperatures with regard to potential decrease of leak-tightness as material properties of rubbers are strongly temperature dependent. But additionally to the investigation presented in the past which considered the material properties of new materials and the seal behaviour under purely static conditions [1, 2] we now focus on irradiated materials and on the sealing performance after a fast partial release of the compressed seal. For the investigations different materials were used, e.g. fluorocarbon (FKM) and ethylenepropylene-diene (EPDM) rubber. To determine the effect of gamma irradiation some samples were irradiated and studied by several thermo-analytical methods and compression set. For the investigation of the seal performance under non static conditions we decided to design a new measurement setup which allows for a small flange deflection and simultaneous leakage rate measurement at low temperatures. T2 - IRC 2015 - International rubber conference CY - Nuremberg, Germany DA - 29.06.2015 KW - O-ring KW - Glass-rubber transition KW - Irradiation KW - Compression set PY - 2015 SP - 1 EP - 7 AN - OPUS4-33784 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Stark, Wolfgang A1 - Wolff, Dietmar T1 - Druckverformungsrest bei tiefen Temperaturen N2 - Für Elastomenwerkstoffe im Allgemeinen und im Bereich der Dichtungstechnik im Besonderen ist der Druckverformungsrest eine wichtige Kenngröße zur Beurteilung der Eignung eines Werkstoffs bzw. der Funktion eines Bauteils. Er ermöglicht eine Einschätzung des zeitabhängigen Rückstellverhaltens eines Werkstoffs nach Deformation. Dieses ist für Dichtungen von besonderer Bedeutung, da der Test deren Einbauzustand nachstellt. Oft wird er, bei der Prüfung unter erhöhten Temperaturen, zur Beurteilung des Alterungsverhaltens verwendet und kann anhand eines definierten Versagenskriteriums zur Lebensdauerabschätzung eingesetzt werden. Bei tiefen Temperaturen dient er dazu, die limitierende Einsatztemperatur zu bestimmen. Dabei spielt eine Alterung im eigentlichen Sinne nur eine untergeordnete Rolle, wohl aber physikalische Effekte wie Tieftemperaturkristallisation und Glasübergang. Diese Effekte sind weit weniger durch lange Lagerzeiten beeinflusst als die eigentliche Alterung. Die Versuchsdurchführung unterscheidet sich je nach angewandter Norm und kann einen deutlichen Einfluss auf den Druckverformungsrest haben. Alle standardisierten Methoden sind aufgrund der langen Lagerzeiten relativ langwierig und erfordern das regelmäßige Eingreifen durch den Prüfer. Zusätzlich sehen einige Methoden nur die Bestimmung eines einzelnen Wertes nach einer definierten Zeit vor. Um die Messungen zu beschleunigen wurde eine Methode entwickelt, die automatisch die erforderlichen Messungen bei mehreren Temperaturen durchführt. Dazu wird ein Prüfgerät der Dynamisch Mechanischen Analyse verwendet, das kontinuierlich die Deformation während eines frei programmierbaren Temperaturzyklus misst, wodurch eine sehr große Datenmenge verfügbar ist. Ein Vergleich der neuen Methode mit den Ergebnissen des nach ISO 815 genormten Messprinzips ergibt eine gute Übereinstimmung. Ergebnisse der neuen Methode werden vorgestellt und die Vorzüge der kontinuierlichen Datenerfassung, z.B. für die Materialauswahl, diskutiert. Die vorgestellten Ergebnisse beziehen sich zum großen Teil auf die in beschriebenen Untersuchungen und Ergebnisse. T2 - Technomer 2013 - 23. Fachtagung über Verarbeitung und Anwendung von Polymeren CY - Chemnitz, Germany DA - 14.11.2013 PY - 2013 SN - 978-3-939382-11-9 IS - Kapitel V 3.4 SP - 1 EP - 8 AN - OPUS4-29616 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zaghdoudi, Maha A1 - Weber, Mike A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Simulation of compression set of epdm o-rings during aging N2 - It is common practice in the application of finite element analysis to model compression set (CS) of elastomers during aging with two different material models according to the two-network theory of Tobolsky. The theory relies on the existence of two networks. The first one represents the original network after vulcanization and is sensitive to chain scission. The second network accounts for the formation of additional crosslinking during aging. Besides the use of user subroutines to describe the two-network model, an element overlay technique is also needed as the full set of both material behaviors did not exist for assignment to a single element. This element overlay technique is valuable for research and developmental purposes but makes extension to industrial usage quite challenging. Our goal is to simulate the CS of elastomers after long-term aging in a commercial finite element software with no need for extra subroutine codes or mesh superposition. Ethylene propylene diene (EPDM) O-rings were aged in a compressed state at 75 °C, 100 °C, 125 °C and 150 °C for up to 183 days. Investigations of the experimental test results were used to identify material models and their parameters to develop a finite element model to simulate CS. The model was implemented in the finite element software ABAQUS/Standard® with a sequential temperature-displacement coupling. Regarding the influence of temperature, the Arrhenius equation is adopted for the time-temperature relationship. The activation energy value that is required for the simulation is firstly determined from shifting the experimental CS results with the time-temperature superposition technique and plotting the shift factors in an Arrhenius diagram. The experiments were compared with the simulation results. Afterwards different activation energies were used in the simulation and discussed. A suitable choice of the activation energy value with regard to the reference temperature and the test temperature is presented. With the chosen activation energies, the match between numerical CS values after long-term aging and the experimental results was improved. T2 - ASME 2022 Pressure Vessels & Piping Conference CY - Las Vegas, USA DA - 17.07.2022 KW - Simulation KW - Compression set KW - EPDM KW - Aging PY - 2022 SP - 1 EP - 9 AN - OPUS4-57370 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Wolff, Dietmar A1 - Stark, Wolfgang ED - Riedl, A. T1 - Was passiert bei tiefen Temperaturen? - Dichtungsverhalten im Bereich des Glasübergangs N2 - Elastomere werden vielfach als Dichtungsmaterial für verschiedene Anwendungen eingesetzt. In vielen Bereichen ist die Funktion der Dichtung auch bei tiefen Temperaturen erforderlich. Daher ist das Verständnis des Versagensmechanismus von großer Bedeutung. Normalerweise werden Elastomere oberhalb ihres Glass-Gummi Umwandlungsbereiches eingesetzt, wobei die minimale Einsatztemperatur nicht exakt definiert ist. Daher ist es sinnvoll, diese untere Temperatureinsatzgrenze in Abhängigkeit von den Materialeigenschaften zu bestimmen. Hierfür werden die Ergebnisse der thermischen Analyse mit den Resultaten des Druckverformungsrests aus einer abgewandelten Messung mit der Dynamisch Mechanischen Analyse (DMA) kombiniert. Weiterhin werden Ergebnisse von Bauteilversuchen vorgestellt und diskutiert. Die vorgestellten Untersuchungen wurden zum großen Teil auf Untersuchungen im Rahmen der Dissertation von M. Jaunich durchgeführt. T2 - XVIII. Dichtungskolloquium - Sichere und zuverlässige Dichtverbindungen CY - Rheine, Germany DA - 25.09.2013 KW - Dichtung KW - Glasübergang KW - Elastomer KW - Druckverformungsrest PY - 2013 SN - 978-3-8027-2216-5 SP - 51 EP - 58 PB - Vulkan AN - OPUS4-29221 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Grelle, Tobias A1 - Wolff, Dietmar A1 - Probst, Ulrich A1 - Jaunich, Matthias A1 - Völzke, Holger T1 - Investigation of the time and temperature dependent behavior of metal seals in radioactive waste containers N2 - The Bundesanstalt für Materialforschung und –Prüfung (BAM) runs an investigation program on the long-term behavior of multi-component metal seals. Such seals are used in a wide area of applications including transport and storage casks for spent nuclear fuel and high level radioactive waste. The seal function is mainly based on the compression of the inner helical spring, which generates the necessary seal force to keep the sealing surfaces in close contact. This in turn leads to a plastic deformation of the outer jacket of the seal, comprised of highly ductile aluminum or silver that adapts to the sealing surfaces of cask body and bolted lid, thus providing high Level leak tightness. In Germany, those casks are licensed for Interim storage periods of up to 40 years or more if extended Interim storage would become necessary before a final repository is available. Thus, the sealing performance has to be evaluated, including factors like elevated temperature due to decay heat or mechanical loads due to transport under normal as well as accident conditions. Long-term investigations at BAM have been running over the last nine years to identify and evaluate the seal performance by measuring the remaining seal force, the useable resilience and the leakage rate after various time intervals at temperatures ranging from room temperature up to 150 °C. It was found that the seal force and useable resilience decrease with time and temperature, caused by creep deformation of the outer jacket. In order to obtain an analytical description for the seal behavior and to achieve more information on the material behavior under application conditions a comprehensive investigation program with Focus on aluminum as outer jacket material was launched. The program includes material investigations such as compression and tension creep tests with representative basic materials. An additional test setup allows for the continuous measurement of the remaining seal force at temperatures of up to 150 °C. Furthermore, seal segments are compressed and stored in heating chambers, thus producing segments at different stages of the aging process. The segments are investigated regarding the development of the contact area width, jacket thickness and microstructural changes. This data will be used to develop material models and an analytical description of the time and temperature dependent long-term sealing behavior. This paper explains the current status of gained test results and modelling approaches and closes with an outlook to the future Project plans. T2 - ASME 2018 Pressure Vessels and Piping Conference CY - Prague, Czech Republic DA - 15.07.2018 KW - Metal seal KW - Creep KW - Long-term behavior PY - 2018 SP - PVP2018-84584, 1 EP - 6 AN - OPUS4-46110 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jaunich, Matthias A1 - Stark, Wolfgang A1 - Wolff, Dietmar T1 - Druckverformungsrest bei tiefen Temperaturen N2 - Der Druckverformungsrest (DVR) stellt insbesondere für Dichtungsanwendungen eine wichtige Kenngröße zur Beurteilung der Eignung eines Elastomers dar. Er ermöglicht die Einschätzung des zeitabhängigen Rückstellverhaltens eines Werkstoffs nach Deformation. Neben der Prüfung bei erhöhten Temperaturen, zur Beurteilung des Alterungsverhaltens, lässt sich bei der Durchführung bei tiefen Temperaturen die limitierende Einsatztemperatur bestimmen. Die Versuchsdurchführung unterscheidet sich je nach angewandter Norm und kann einen deutlichen Einfluss auf den DVR-Wert haben. Um bei tiefen Temperaturen eine schnelle Aussage zu gestatten, ist eine im Vergleich zu genormten Methoden deutlich schneller durchzuführende, automatisierte Methode entwickelt und mit Standardmethoden verglichen worden. Durch kontinuierliche Messung des Druckverformungsrests kann die Kinetik der Materialrückstellung betrachtet und dadurch ein effizienter Materialvergleich und eine effiziente Materialauswahl ermöglicht werden. Compression set (CS) is especially for sealing applications an important parameter for material selection. It allows an assessment of the time dependent recovery after deformation. In addition to testing at elevated temperatures which aims at the evaluation of the ageing behaviour, testing at low temperatures permits the determination of the low working temperature limit. The test procedure varies depending on the applied standard and can show a significant effect on the CS value. In order to allow a quick statement regarding low temperatures an automated procedure being significantly faster realisable in relation to the standardised methods has been developed and compared with standard procedures. Continuous measurement of the compression set allows evaluating the recovery kinetics and therefore an efficient comparison and selection of materials. KW - Druckverformungsrest KW - Elastomere KW - Dichtung KW - O-Ring PY - 2014 SN - 0176-1625 VL - 67 IS - 8 SP - 487 EP - 491 PB - Gupta CY - Ratingen AN - OPUS4-31572 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wolff, Dietmar A1 - Jaunich, Matthias A1 - Probst, Ulrich A1 - Nagelschmidt, Sven T1 - Understanding the long-term behavior of sealing systems and neutron shielding material for extended dry cask storage N2 - In Germany, the concept of dry interim storage in dual purpose metal casks before disposal is being pursued for spent nuclear fuel (SF) and high active waste (HAW) management. However, since there is no repository available today, the initially planned and established dry interim storage license duration of up to 40 years will be too short and its extension will become necessary. For such a storage license extension it is required to assess the long-term performance of SF and all safety related storage system components in order to confirm the viability of extended storage. The main safety relevant components are the thick-walled dual purpose metal casks. These casks consist of a monolithic cask body with integrated neutron shielding components (polymers, e.g. polyethylene) and a monitored double lid barrier system with metal and elastomeric seals. The metal seals of this bolted closure system guarantee the required leak-tightness whereas the elastomeric seals allow for leakage rate measurement of the metal seals. This paper presents an update on running long-term tests on metal seals at different temperatures under static conditions over longer periods of time. In addition, first results of our approach to understand the aging behavior of different elastomeric seals and neutron radiation shielding material polyethylene are discussed. T2 - PSAM 12 - Probabilistic safety assessment and management CY - Honolulu, Hawaii, USA DA - 22.06.2014 KW - Extended storage KW - Dual purpose casks KW - Metal seals KW - Elastomeric seals KW - Neutron shielding material PY - 2014 SP - 1 EP - 9 AN - OPUS4-32072 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - von der Ehe, Kerstin A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - UHMW-PE - a shielding material with special properties influenced by radiation N2 - Ultra high molecular weight polyethylene (UHMW-PE) - due to its high hydrogen content - is used as neutron shielding material in casks for storage and transport of radioactive materials. Besides this, UHMW-PE - as a high-performance polymer - has been used for several years in medical technology due to its excellent slip and wear properties. Due to the special properties of UHMW-PE which result basically from its extreme chain lengths and its high degree of crystallinity, it is predestinated for the aforementioned applications. In both cases, irradiation and its impact on the molecular structure of polyethylene play an important role. In the first case, irradiation exists as a by-product of inserting the radioactive material in the cask. Hence PE 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. In the second case irradiation is applied deliberately for purposes such as sterilization and crosslinking, leading to partial improvement of the mechanical properties (e.g. fracture toughness, crack propagation resistance, wear resistance) and better Chemical stability. Specifically concerning their use in the field of medical technology, different types of UHMW-PE have been objects of numerous publications. It is generally accepted that two parallel and competitive processes, based on chain scission and reactions of Ccentered radicals and molecular fragments, occur in PE as a consequence of radiation: radical recombination accounts for crosslinking, together with some disproportionation, formation of low molecular weight fragments, and recrystallization. Furthermore, formation of oxygenated structures in the presence of traces of oxygen is an antagonist of the C-centered radicals. Radiation induced scission preferentially takes place in the amorphous phase and noncrystalline surface of the crystals. It is followed by folding of molecular fragments, crystallinity growth and increased perfection in the crystal lamellae [4, 5]. Chain scission results in shorter polymer molecules, fewer entanglements, and consequently, increased molecular mobility. The scope of our investigation comprises an estimation of the radiation and thermal impact on the molecular and supra molecular structure of the two types of PE used for neutron shielding cask components. A further point which is worth to explore is to what extent these changes are detectable by thermo-analytical (TA) methods, such as Differential Scanning Calorimetry (DSC), Thermo Mechanical Analysis (TMA), Dynamic Mechanical Analysis (DMA) and Thermogravimetry (TG). Additionally FT-IR and solubility measurements have been performed. In our studies we focused on the UHMW-PE material GUR 4120 which was y irradiated at RT and compared to the untreated material. T2 - Jahrestagung Kerntechnik 2011 CY - Berlin, Germany DA - 17.05.2011 PY - 2011 SP - 1 EP - 5 AN - OPUS4-24620 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Ageing of elastomeric seals for storage containers N2 - At BAM Federal Institute for Materials Research and Testing in Germany, it is our responsibility to audit the safety of casks designed for transport and/or storage of radioactive material. With regard to the requirements on long-term safety of the containers, it is necessary to evaluate the service lifetime of the elastomeric seals used in the containers. With ageing, the elastomers will gradually lose their elasticity and their ability for recovery, which might result in a leakage above the allowed level or in a release of radioactivity during an incident. It is important to know the rate of degradation and which property can be used as an practical and easily measurable end-of-lifetime criterion. For this reason, we devised ageing experiments on different kinds of elastomers, namely FKM, EPDM and HNBR. The former two are actually used in containers for radioactive wastes – either as auxiliary seal in casks containing high activity waste, or as main seal in casks for medium or low activity waste. The latter is an often used seal material that is tested for comparative reasons. In our ageing program, these three materials are aged at four different temperatures (75 °C, 100 °C, 125 °C and 150 °C) in order to extrapolate the data to service temperature using a suitable model. They are examined at logarithmic time intervals of several days up to 5 years. The samples are aged in their undeformed O-ring state as well as compressed between flanges with a deformation corresponding to the actual compression during service. Thus we can compare the ageing between relaxed and stressed sample. Additionally, we are ageing samples in flanges that allow leakage rate measurements. Other measurements include monitoring of the recovery force of the seal and the compression set. Furthermore, the samples are examined by thermal and dynamic-mechanical analysis for detecting changes in the glass transition temperature due to crosslinking or chain scission in the material. Besides, hardness is measured as a practical macroscopic indicator. Until now, we have analyzed samples aged up to 100 days. At the highest ageing temperature of 150 °C, the compressed EPDM has already reached a compression set of 95 %, while HNBR and FKM have reached 80 % and 30 %, respectively. Furthermore, HNBR has reached a Shore D hardness of 85, which is an immense increase after the initial value of 80 Shore A. However, when looking at the cross-section of the sample, it was obvious that only a layer of about 1 mm thickness has become so hard, while the inner part remained rubbery. This shows that there has been intense crosslinking mostly near the surface of the HNBR which forms a kind of oxygen diffusion barrier, inhibiting the thermooxidation of the inner part of sample which can retain elastic properties. In EPDM, the oxygen permeability is much greater, which leads to a more homogeneous degradation across the whole sample and thus resulted in a higher compression set. The low compression set of FKM shows the outstanding high-temperature properties of this material. T2 - Annual Meeting on Nuclear Technology 2015 CY - Berlin, Germany DA - 2015-05-05 KW - Elastomer KW - Rubber KW - Aging KW - Lifetime KW - Seal KW - Cask KW - Compression PY - 2015 SN - 978-3-926956-98-9 SP - 1 EP - 10(?) PB - INFORUM-Verl. u. Verwaltungsges. AN - OPUS4-33782 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Aging of elastomeric seals for storage casks N2 - Elastomeric seals are used in many containers, including casks for radioactive waste. However, like all polymers, elastomers are prone to aging, which leads to a loss of sealing force and the ability for recovery which can ultimately result in leakage. Therefore it is important to be able to define an end-of-lifetime criterion and to judge the lifetime of elastomeric seals. For this reason, we started an aging program on three kinds of rubbers (HNBR, EPDM, FKM), monitoring the change of properties at four different aging temperatures over extended periods up to five years. The measured data is used for lifetime prediction by applying a suitable model. T2 - WM2015 Conference CY - Phoenix, Arizona, USA DA - 15.03.2015 KW - Aging KW - Elastomer KW - Seal KW - Leakage KW - Compression PY - 2015 SN - 978-0-9828171-4-8 SP - 15080, 1 EP - 12 AN - OPUS4-33253 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Jaunich, Matthias A1 - Stark, Wolfgang A1 - Wolff, Dietmar T1 - Low temperature properties of rubber seals T2 - 9th Fall rubber colloquium CY - Hannover, Germany DA - 2010-11-03 KW - Dichtungen KW - Elastomere KW - Tieftemperaturverhalten PY - 2010 SN - 978-3-9814076-0-0 SP - 175 EP - 178 AN - OPUS4-22331 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wolff, Dietmar T1 - Investigating the Performance of Rubber Seals at low Temperatures T2 - 2013 International High-Level Radioactive Waste Management Conference CY - Albuquerque, NM, USA DA - 2013-04-28 PY - 2013 AN - OPUS4-28476 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jaunich, Matthias A1 - Stark, Wolfgang A1 - Wolff, Dietmar T1 - Low temperature properties of rubber seals N2 - Rubber is widely used as sealing material in various applications. In many fields the sealing function at low temperatures is necessary. Therefore the understanding of failure mechanisms is of high importance. Rubbers are normally used above their glass-rubber transition region but the minimum working temperature limit is not defined precisely. Therefore the lower operation temperature limit of rubber seals should be determined in dependence of the material properties. The results of Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) are combined with the results of the standardized compression set according to ISO 815 respectively a modified test using the DMA equipment. N2 - Tiefentemperaturverhalten von Elastomerdichtungen Elastomere werden vielfach als Dichtungsmaterial für verschiedene Anwendungen eingesetzt. In vielen Bereichen ist die Funktion der Dichtung auch bei tiefen Temperaturen erforderlich. Daher ist das Verständnis des Versagensmechanismus von großer Bedeutung. Normalerweise werden Elastomere oberhalb ihres Glass-Gummi Übergangsbereiches eingesetzt aber die minimale Einsatztemperatur ist nicht exakt definiert. Daher ist es sinnvoll diese untere Temperatureinsatzgrenze in Abhängigkeit von den Materialeigenschaften zu bestimmen. Die Ergebnisse der DSC und der DMA werden mit den Ergebnissen des standardisierten Druckverformungsrestes nach ISO 815 und einer abgewandelten Messung mit der DMA kombiniert. KW - Sealing material KW - Elastomer KW - Compression set KW - Dynamic mechanical analysis KW - Low temperature behaviour PY - 2011 SN - 0948-3276 SN - 0022-9520 IS - 03 SP - 52 EP - 55 PB - Hüthig CY - Heidelberg AN - OPUS4-23422 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jaunich, Matthias A1 - Stark, Wolfgang A1 - Wolff, Dietmar T1 - Comparison of low temperature properties of different elastomer materials investigated by a new method for compression set measurement N2 - The method for the determination of compression set values with a Dynamic Mechanical Analysis (DMA) setup at low temperatures, which was presented previously, allows a much faster and readily automated procedure than the standardized compression set test according to ISO 815-2. This method is applied to a series of different elastomeric materials that are commonly used for sealing applications. The results of the compression set test are compared with results from thermal analysis to allow an in depth comparison of the material behaviour at low temperatures. Furthermore, a comparison between two EPDM materials is presented. These materials show very similar properties determined by thermo analytical methods such as Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) but differ clearly in their compression set behaviour. This comparison shows the importance and value of information of the compression set test in addition to thermal analysis to judge the behaviour of sealing materials and confirms the relevance of the new compression set test method for the investigation of low temperature properties of elastomers. KW - Sealing material KW - Elastomer KW - Compression set KW - Dynamic mechanical analysis KW - Low temperature behaviour PY - 2012 DO - https://doi.org/10.1016/j.polymertesting.2012.07.016 SN - 0142-9418 VL - 31 IS - 8 SP - 987 EP - 992 PB - Elsevier Science CY - Amsterdam [u.a.] AN - OPUS4-26538 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Völzke, Holger A1 - Wolff, Dietmar A1 - Barnabas, I. A1 - Ordogh, M. A1 - Shirai, K. A1 - Saegusa, T. A1 - Cho, C.-H. A1 - Kook, D. A1 - Lopez, J. F. A1 - Conde, J. M. A1 - Alejano, C. A1 - Lloret, M. A1 - Quecedo, M. A1 - Shea, J. A1 - Ross, P. J. A1 - White, N. A1 - Rossiter, G. A1 - Hodgson, Z. A1 - Sorenson, K. A1 - McConnell, P. A1 - Hanson, B. ED - Sorenson, K. ED - Shirai, K. ED - Völzke, Holger T1 - Extended storage collaboration program - International subcommittee report - International perspectives on technical data gaps associated with extended storage and transportation of used nuclear fuel N2 - The US Electric Power Research Institute (EPRI) chartered a volunteer committee in November 2009 to share information and data related to extended storage and subsequent transportation of used nuclear fuel. This committee is named the Extended Storage Collaboration Program (ESCP) and was initially comprised of representatives from industry (fuel and cask vendors, utilities, the Nuclear Energy Institute, and EPRI), as well as government (e.g., US Department of Energy) and the US Nuclear Regulatory Commission. The primary motivation for establishing this committee was the recognition that used fuel will need to be stored past the regulatory licensing timeframe. In the US, this is mainly a result of the cessation of licensing activities for the planned Yucca Mountain repository. Recognizing that there is a global interest in extended storage and transportation, the International Subcommittee was established in December 2010 to extend the reach of ESCP internationally in order to fully address extended storage and transportation issues, as they apply to different systems, national policies, and regulations around the world. This Subcommittee serves to deepen the overall understanding of degradation mechanisms associated with storage and transportation systems, expand the access to data and programs related to extended storage and transportation, and strengthen the overall technical basis for programmatic decisions. The International Subcommittee established three basic objectives: 1. Conduct a technical data gap survey 2. Assess opportunities to leverage specific research to benefit the larger international group 3. Integrate our work with relevant International Atomic Energy Agency (IAEA) committee work This report constitutes completion of Objective #1. The International Subcommittee worked to identify and prioritize technical gaps that need to be addressed to support licensing activities within their own countries. Because there are varying types of storage and transportation system designs, national policies and regulations, there are identified commonalities as well as differences that stress the importance of this work on an international scale. Section 5 of this report identifies and prioritizes all of the identified data gaps for each participating organization. However, important data gaps were identified that had a consensus of opinion of being a high priority. These technical gaps, as a function of storage system component are: 1. Fuel – hydride effects on fuel cladding and retrievability of fuel after storage 2. Canister – general canister corrosion and stress corrosion cracking of canister closure welds, particularly in marine environments 3. Closure – degradation of bolts and seals (metallic and organic) 4. Overpack – concrete degradation Dry storage systems were originally designed for limited periods. With extended dry storage, it is generally believed that used fuel can be stored safely and securely past the regulatory time period. However, the technical arguments need to be made to justify extended licensing periods. Addressing the data gaps will provide the necessary arguments to justify license extensions. In the development of this report, the International Subcommittee met five times over a period of 18 months to work through the issues of identifying and prioritizing the data gaps, and discussing of technical issues as they pertain to the safety of used fuel storage and transportation. The meeting locations and dates were: 1. Vienna June 2010 2. London October 2010 3. Charlotte December 2010 4. Berlin June 2011 5. Charlotte December 2011 This report is not meant to be a technical document. Rather, it is an overview of country regulatory policy, a review of in-country operational status and used fuel inventory, followed by a role-up of identification and prioritization of technical data gaps. Technical documents that were used in the data gap assessments are referenced. It is important to note that this document represents only the opinions of the contributors. This document in no way represents any official country position. The organizations providing support to the writing of this report are: Germany: - Bundesanstalt für Materialforschung und -prüfung Hungary: - Radioaktiv Julladekokat Kezelo Kozhasznu - Som System Kft. Japan: - Central Research Institute of Electric Power Industry South Korea: - Korea Atomic Energy Research Institute - Korea Radioactive Waste Management Corporation Spain: - Consejo de Seguridad Nuclear - ENRESA Empresa Nacional de Residuos Radiactivos - ENUSA Industrias Avanzadas United Kingdom: - EDF Energy - National Nuclear Laboratory Ltd. United States: - Pacific Northwest National Laboratory - Sandia National Laboratories KW - Used/spent fuel dry storage KW - Used/spent fuel transportation KW - Extended used/spent nuclear fuel storage KW - High burnup spent fuel storage and transportation KW - Spent fuel storage and transportation KW - Extended Storage Collaboration Program (ESCP) KW - ESCP International Subcommittee PY - 2012 UR - https://www.epri.com/research/products/1026481 N1 - This final report was prepared as part of the volunteer Extended Storage Collaboration Program (ESCP). VL - 1026481 SP - 1 EP - 132 PB - Electric Power Research Institute (EPRI) CY - Palo Alto, CA, USA AN - OPUS4-27405 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kasparek, Eva Maria A1 - Völzke, Holger A1 - Scheidemann, Robert A1 - Zencker, Uwe A1 - Wolff, Dietmar T1 - Experimental and numerical studies of shock absorbing materials for containers for radioactive waste N2 - Safety assessments of Containers for Transport and storage of radioactive materials involvedrop scenarios prescribed in the regulations of the International Atomic Energy Agency - IAEA or potential accidents that might occur in a specific nuclear facility. Hereby, the design of impact limiters and foundation properties of the handling Region have a major effect on the mechanical loading of the cask and lid System. Reliable numerical simulations, which very often constitute a relevant part of such safety proofs, require systematic information About the energy absorption potential of the respectiye materials and its implementation in FEM (finite element) programs. However, when performing drop tests, BAM (BAM Bundesanstalt für Materialforschung und -prüfung, Federal Institute for Materials Research and Testing) identified significant differences between numerical and experimental results, which most likely result from numerical methods that do not sufficiently reproduce the behaviour of impact limiting structures. Particularly concerned are Container impact limiter made of wood or Polyurethane foam as well as damping concrete bricks, which are embedded in foundations of German interim storages. PY - 2012 SN - 1431-5254 VL - 57 IS - 6 SP - 397 EP - 401 PB - Inforum CY - Berlin AN - OPUS4-26261 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Wolff, Dietmar A1 - Stark, Wolfgang T1 - Low temperature properties of rubber seals - results of component tests N2 - Rubbers are widely used as sealing material in various applications. In many fields the function of seal materials at low temperatures is required. Therefore the understanding of failure mechanisms that lead to leakage at low temperatures is of high importance. Therefore the lower operation temperature limit of rubber seals should be determined in dependence of the material properties. The results of Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) are combined with results of standardized measurements as the compression set according to ISO 815. To reduce the test time of the standard tests a faster and more efficient technique was developed and applied. In addition the breakdown temperature of the sealing function of O-ring seals at low temperatures is measured in a component test setup in dependence of the material and the degree of compression. T2 - 10th Fall rubber colloquium CY - Hannover, Germany DA - 07.11.2012 PY - 2012 SN - 978-3-9814076-1-7 IS - khk2012_jaunich.pdf SP - 1 EP - 8 AN - OPUS4-26995 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Stark, Wolfgang A1 - Wolff, Dietmar T1 - Low temperature - For a seal this depends on the applied material T1 - Tieftemperatur - Bei Dichtungen entscheidet dies der eingesetzte Werkstoff N2 - For many sealing applications rubbers are applied due to their special material properties and easy use. In many applications as e.g. in aviation, traffic or process technology the material can be exposed to low temperatures during Operation. Therefore it is important to know the material behavior at those low temperatures to determine the temperature ränge that allows a safe Operation of the seal. One of our main Interests is to ensure the safe enclosureof dangerous goods under various conditions such as different temperatures and over long periods of time. For low temperatures the seal function of an elastomer is limited by the rubber-glass transition during which the material properties change from rubber-like to stiff and glass-like. For a given application this correlation is not trivial, as the glass-rubber transition covers a broad temperatureregion and is strongly influenced by the applied loading frequency. Therefore the applicability of a seal material has to be assessed by its properties in relation to the application conditions and the necessary level of tightness. To characterize the material and the seal function thermal analysis (Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA)), a modlfied method for the accelerated determination of compression set and component tests were applied to different rubber classes, The results show that the temperature ränge where the compression set values come close to 100 % correlates well with the onset temperature of the storage modulus measured by DMA ata measurement frequency of 1 Hz. An in depth analysis of the compression set data allows an estimation of the expected time- and temperature-dependent recovery behavior. T2 - DKT 2012 - German Rubber Conference CY - Nuremberg, Germany DA - 02.07.2012 PY - 2012 IS - 10-2330_5-L-1530 SP - 1 EP - 4 PB - Deutsche Kautschuk-Gesellschaft CY - Frankfurt am Main AN - OPUS4-26190 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Stark, Wolfgang A1 - Wolff, Dietmar T1 - Material behaviour of static seals at low temperatures N2 - For many sealing applications rubber materials are applied due to their Special material properties and easy use. The crucial advantage of elastomeric seals in comparison to other seal is their high resilience. In many applications as e.g. in aviation, traffic or process technology the material can be exposed to low temperatures during Operation. Therefore it is important to know the material behavior at those low temperatures to determine the temperature ränge that allows a safe Operation of the seal. For low temperatures the seal function of an elastomer is in a way limited by the rubber-glass transition during which the material properties change from rubber-like to stiff and glass-like. This may result in a direct loss of the sealing function but especially for purely static applications a leak tightness well below the rubber-glass transition was observed, For a given application this correlation is not trivial, as the glass-rubber transition covers a broad temperature region and is strongly influenced by the applied load period. Therefore the applicability of a seal material has to be assessed by its properties in relation to the application conditions and the -ecessary level of tightness. T2 - 17th ISC - International sealing conference CY - Stuttgart, Germany DA - 13.09.2012 PY - 2012 SN - 978-3-00-039198-9 IS - A 16 SP - 295 EP - 300 CY - Frankfurt/M. AN - OPUS4-26524 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wolff, Dietmar T1 - Well defined liquid crystalline homo and block copolymerthacrylates synthesized by organolanthanide complexes T2 - Europolymer Conference 1999 (EUPOC '99) Regular Macromolecular Structures Based on the Controlled Polymerization Processes CY - Gargnano, Italy DA - 1999-05-23 PY - 1999 AN - OPUS4-11310 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -