TY - CONF A1 - Wolff, Dietmar A1 - Jaunich, Matthias A1 - Stark, Wolfgang T1 - Investigating the performance of rubber seals at low temperatures N2 - Rubbers are widely 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. The save enclosure of the radioactive container inventory has to be guaranteed according to legislation and appropriate guidelines for long term storage periods as well as down to temperatures of -40 °C for transportation. Therefore the understanding of failure mechanisms that lead to leakage at low temperatures is necessary to ensure a proper material choice which is certainly also influenced by additional factors as e.g. the aging behavior. T2 - 14th International high-level radioactive waste management conference CY - Albuquerque, New Mexico, USA DA - 28.04.2013 KW - Rubber seals KW - Elastomers KW - Compression set KW - Low temperature KW - Leakage rate PY - 2013 SN - 978-1-62748-644-6 SP - 1 EP - 7(Paper # 6888) PB - Omnipress AN - OPUS4-28530 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 U6 - 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 - JOUR 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 fieldsthefunction of seal materials at lowtemperatures is required. Therefore the understanding of faiiure 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 lowtemperatures is measured in a component test Setup in dependence of the material and the degree of compression. KW - Seal KW - O-ring KW - Low temperature KW - Component test KW - Compression set KW - Dichtungen KW - O-Ringe KW - Tiefe Temperatur KW - Bauteilversuche KW - Druckverformungsrest PY - 2013 SN - 0948-3276 SN - 0022-9520 VL - 66 IS - 7-8 SP - 26 EP - 30 PB - Hüthig CY - Heidelberg AN - OPUS4-28894 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 - 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 stress relaxation KW - Compression set KW - IRHD microhardness KW - Modelling PY - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-545910 SN - 1432-0959 SP - 1 EP - 9 PB - Springer CY - Berlin AN - OPUS4-54591 LA - eng 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 U6 - 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 - Wolff, Dietmar T1 - Use of rubber seals at low temperatures 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, due to the glass transition the material changes from rubber-like entropy-elastic behaviour to stiff energy-elastic behaviour, that allows nearly no strain or retraction. Hence, rubbers are normally used above their glass transition. But as the minimum working temperature limit of elastomers cannot be defined globally and precisely, the lower operation temperature limit of rubber seals should be determined in dependence of the application conditions and the most relevant material properties. In this paper, wesummarize results of our temperature dependent investigation of seal material properties by classical thermal analysis as Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA), combined with measurements of standardized tests as compression set and the seal performance determined in component tests. To reduce the test time of compression set tests a faster technique was developed and applied. To study the influence of dynamic events on the seal performance and to enhance the understanding of occurring seal failure, a setup for a fast partial seal release was designed. T2 - RubberCon 2016 CY - Tampere, Finland DA - 08.06.2016 KW - O-Ring KW - Compression set KW - Leakage rate KW - Low temperature PY - 2016 AN - OPUS4-36514 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jaunich, Matthias A1 - Stark, Wolfgang A1 - Wolff, Dietmar T1 - A new method to evaluate the low temperature function of rubber sealing materials N2 - A new method for the evaluation of the low temperature properties of rubber materials is presented. The method emulates the standardized compression set measurement, which is frequently used for sealing materials, but can be performed within a considerably shorter time. The results are compared with the standard test and found to be qualitatively the same. Slight differences are discussed on the basis of the differences in the measurement procedures. Further data evaluation is done by fitting functions to describe the material behaviour. KW - Sealing material KW - Elastomer KW - Compression set KW - Dynamic mechanical analysis KW - Low temperature behaviour PY - 2010 U6 - https://doi.org/10.1016/j.polymertesting.2010.07.006 SN - 0142-9418 VL - 29 IS - 7 SP - 815 EP - 823 PB - Elsevier Science CY - Amsterdam [u.a.] AN - OPUS4-21914 LA - eng 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 - 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 U6 - 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 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Low temperature properties of rubber seals - influence of gamma irradiation 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. KW - Compression set KW - Irradiation KW - O-ring KW - Seal PY - 2014 SN - 978-3981407624 SP - 1 EP - 7 AN - OPUS4-32326 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 and lifetime prediction of O-ring seals made of HNBR, EPDM and FKM 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 - 12. Kautschuk Herbst Kolloquium CY - Hanover, Germany DA - 22.11.2016 KW - Rubber KW - Compression set KW - Extrapolation KW - Degradation PY - 2016 SN - 9783981407648 VL - 2016 AN - OPUS4-38483 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias T1 - Low temperature properties of rubber seals N2 - Understanding the failure mechanisms that lead to leakage of rubber seals at low temperatures is important. Rubber properties are highly temperature dependent. Changes in behaviour at low temperatures can result from the rubber-glass transition and for some rubbers by partial crystallisation. Experimental results on the low temperature behaviour of different rubber seals were discussed to help understand seal failure processes. T2 - Rubber in Engineering Group (RIEG) webinar an Elastomers at Low Temperatures CY - Online meeting DA - 11.09.2020 KW - Low temperature KW - Rubber seal KW - Compression set KW - Glass transition PY - 2020 UR - https://www.iom3.org/rubber-engineering-group/event/elastomers-low-temperatures AN - OPUS4-51306 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Goral, Milan A1 - Wolff, Dietmar T1 - Insights for lifetime predictions of O-ring seals from five-year long-term aging tests N2 - O-rings made of HNBR, EPDM and FKM were aged in the compressed and uncompressed state at 150 °C, 125 °C, 100 °C, 75 °C, 60 °C and 23 °C for aging times of up to five years. Hardness was measured and increased with aging time and temperature for HNBR and EPDM, but it remained practically constant for FKM. Indenter modulus measurements were performed on the lateral O-ring surface (that was free of DLO effects) to assess an influence of the compression during aging, but none was detected. The equilibrium compression set (CS) exhibited faster and stronger degradation than hardness and was used for lifetime predictions using the time-temperature superposition (TTS) principle. With an end-of-lifetime criterion of 70 % CS, lifetimes of 4.5 years, 50 years and 526 years at 75 °C were estimated for HNBR, EPDM and FKM, respectively. The activation energies derived from an Arrhenius plot of the shift factors from the TTS were 85 kJ/mol, 99 kJ/mol and 78 kJ/mol for HNBR, EPDM and FKM, respectively, revealing that a higher activation energy does not necessarily mean that the material has a higher lifetime at lower temperatures. Furthermore, the measured lifetime of EPDM O-rings at 100 °C (5 years) was compared to that predicted on the basis of the lifetime at 150 °C as well as 125 °C using the corresponding shift factors. The error of the prediction was only ± 4 %. However, this precise prediction could only be achieved using the five-year long-term aging data. When using only data from aging times up to 0.5 years and 2 years, the lifetime of EPDM O-rings at 100 °C was underestimated by 31 % and 22 %, respectively. KW - HNBR KW - EPDM KW - FKM KW - DLO KW - Hardness KW - Compression set KW - Rubber KW - Elastomer KW - Degradation PY - 2020 U6 - https://doi.org/10.1016/j.polymdegradstab.2020.109278 VL - 179 SP - 109278 PB - Elsevier Ltd. AN - OPUS4-51060 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Influence of gamma irradiation on low temperature properties of rubber seal materials N2 - In many fields the function of seal materials is required at low temperatures. Therefore the understanding of failure mechanisms at low temperatures is of high importance. In some applications elastomeric seals are used in environments with increased irradiation backgrounds, as e.g. in containers for radioactive waste. This paper reports on the influence of gamma irradiation on the low temperature properties of different fluorocarbon rubber (FKM) materials. The samples were irradiated with gamma doses of up to 600 kGy and the induced changes of material properties were tested by methods sensitive to the rubber-glass transition, like DSC and DMA. Additionally, compression set measurements were performed to give information about recovery behaviour at low temperatures. KW - Seal KW - O-ring KW - Low temperature KW - Gamma irradiation KW - Compression set KW - Dichtungen KW - O-Ringe KW - Tiefe Temperatur KW - Gamma-Bestrahlung KW - Druckverformungsrest PY - 2015 SN - 0948-3276 SN - 0022-9520 VL - 68 IS - 6 SP - 85 EP - 89 PB - Hüthig CY - Heidelberg AN - OPUS4-33552 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Grelle, Tobias A1 - Wolff, Dietmar T1 - Investigation of elastomer seal behaviour for transport and storage packages N2 - According to the relevant guidelines and regulations, the safe enclosure of radioactive Container contents has to be guaranteed for long storage periods as well as down to temperatures of -40 °C during transportation. As rubbers are widely used as the 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 eiastomer investigation Programme is in place at BAM. This Programme comprises investigations of overall eiastomer performance, durability, influence of gamma irradiation and low temperature behaviour. In this paper we focus on the behaviour of eiastomer seals at low temperatures with regard to the potential increase in leakage as material properties of rubbers are strongly temperature-dependent. During continuous cooling, the material behaviour of elastomers changes in the rubber-glass transition temperature ränge from rubberlike entropy-elasticity to stiff energy-elasticity, allowing for almost no strain or retraction. Hence rubbers are normally used above their rubber-glass transition but the minimum limit at which they work has not been defined precisely. For the investigations, fluorocarbon (FKM) and ethylene-propylene-diene (EPDM) rubbers were selected, as they are often used in radioactive waste Containers. The elastomers were studied using several thermoanalytical methods and compression set. The results were compared with component tests to determine the temperature at which the sealing function of O-rings made of eiastomer breaks down. In addition to these results, under static conditions we designed a new measurement set-up which allows for a small deflection of the flange and simultaneous leakage rate measurement at low temperatures. T2 - RAMTRANS 2015 - 10th International conference on radioactive materials transport and storage CY - Oxford, UK DA - 19.05.2015 KW - O-ring KW - Glass-rubber transition KW - Irradiation KW - Compression set PY - 2015 SP - 1 EP - 10 AN - OPUS4-33489 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Grelle, Tobias A1 - Wolff, Dietmar T1 - Influence of partial release on sealing performance of elastomer O-rings at low temperatures 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 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 acitve 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 below ambient temperatures after a fast partial release. Despite the primarily static application conditions of many seals their behaviour after partial compression release is of interest with regard to potential decrease of leak-tightness. For this investigation a special setup was designed which allows the partial release of compressed seal systems at different temperatures accompanied by leakage rate measurements. The results for FKM seals are presented and discussed. T2 - Technomer 2015 - 24. Fachtagung über Verarbeitung und Anwendung von Polymeren CY - Chemnitz, Germany DA - 12.11.2015 KW - O-ring KW - Glass-rubber transition KW - Compression set KW - Partial release PY - 2015 SN - 978-3-939382-12-6 SP - P 3.7, 1 EP - 6 CY - Chemnitz AN - OPUS4-35130 LA - eng 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 - Wolff, Dietmar ED - Van Breugel, K. ED - Koenders, E.A.B. T1 - Approach for the investigation of long-term behaviour of elastomeric seals for transport and storage packages N2 - Elastomers are widely used as main sealing materials for Containers for low and intermediate Ievel radioactive waste and as additional component to metal seals in spent fuel and high active waste Containers. According to appropriate guidelines and regulations safe enclosure of the radioactive Container contents has to be guaranteed for long storage periods as well as down to temperatures of -40 °C for transportation. Therefore the understanding of seal behaviour in general is of high importance and ageing of elastomeric seals has to be considered with regard to possible dynamic events taking possibly place during transport after storage. T2 - 1st Ageing of materials & structures 2014 conference CY - Delft, The Netherlands DA - 26.05.2014 KW - O-Ring KW - Seal KW - Ageing KW - Elastomer KW - Compression set PY - 2014 SN - 978-94-6186-313-3 SP - 87 EP - 93 AN - OPUS4-30820 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-486091 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 - CONF A1 - Jaunich, Matthias A1 - Kömmling, Anja A1 - Zaghdoudi, Maha T1 - Ageing under Hydrogen: effects on O-ring seals N2 - In this work we present results for three typical sealing materials (EPDM, HNBR, FKM) after up to 100 days ageing at high temperature under hydrogen. To allow for a better evaluation of the occurring changes the results are compared with effects of ageing in air on the material properties. Despite the common assumption that ageing under hydrogen atmosphere is expected to be less severe for the material in com-parison to air ageing, this is not seen for every material. T2 - Technomer 2023 CY - Chemnitz, Germany DA - 09.11.2023 KW - Hydrogen KW - Ageing KW - Seal KW - Compression set PY - 2023 AN - OPUS4-58818 LA - eng 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 - JOUR A1 - Jaunich, Matthias A1 - von der Ehe, Kerstin A1 - Wolff, Dietmar A1 - Völzke, Holger A1 - Stark, Wolfgang T1 - Understanding low temperature properties of elastomer seals N2 - Elastomers are widely used as the main sealing materials for containers for low and intermediate level radioactive waste and as an additional component to metal seals in spent fuel and high active waste containers. The safe encapsulation of the radioactive container inventory has to be guaranteed according to regulation and appropriate guidelines for long term storage periods as well as for temperatures as low as -40°C during transport. 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 elastomers are strongly temperature dependent. At low temperatures, this is caused by the rubber-glass transition (abbreviated: glass transition). During continuous cooling, the material changes from a rubber-like entropy elastic to a stiff energy elastic behaviour, which allows nearly no strain or retraction. Hence, rubbers are normally used above their glass transition, but the minimum working temperature limit is not defined precisely; this can cause problems during the above noted applications. Therefore, the lower operation temperature limit of elastomer seals must be determined in dependence of the material properties. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) are combined with standardised measurements to determine the compression set according to ISO 815. To reduce the test time of the standard tests, a faster technique than normally used was developed. Additionally, the breakdown temperature of the sealing function of complete O ring seals was measured in a component test set-up to compare it with the results of the other tests. The experimental set-up is capable of measuring the leakage rate at low temperatures by the pressure rise method. A fluorocarbon rubber (FKM) was selected for this investigation as it is often used for radioactive waste containers. The materials (seals and test sheets) were purchased from a commercial seal producer. KW - Sealing material KW - Elastomer KW - Compression set KW - Dynamic mechanical analysis KW - Low temperature behaviour PY - 2011 U6 - https://doi.org/10.1179/1746510911Y.0000000004 SN - 1746-5095 SN - 1746-5109 SN - 0957-476X VL - 22 IS - 2 SP - 83 EP - 88 PB - Ramtrans Publ. CY - Ashford AN - OPUS4-24015 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 - Understanding the recovery behaviour and the degradative processes of EPDM during ageing N2 - Recovery is an important measure for seal applications representing to which extent the elastomer regains its initial shape after deformation and release of an applied force. Compression set (CS) indicates the degree of recovery. Ethylene propylene diene rubber (EPDM) was aged at 75 ◦C, 100 ◦C, 125 ◦C and 150 ◦C for different ageing times up to five years and compression set measurements were performed at different times after disassembly and after additional tempering. Short- and long-term recovery up to one year after release for samples aged at 125 ◦C and 150 ◦C was also studied. To assess the curvature in the Arrhenius diagram that may occur due to non-sufficiently aged specimens, a degradation-rate based model was fitted to the CS data after tempering. For each ageing temperature, two decay fit functions were proposed, each with an activation energy and a corresponding degradative process. The influence of ageing on the leak-tightness after fast small partial release is investigated and estimated through the analysis of the shift factors from time temperature superposition (TTS) of CS measurements at different times after disassembly. Shift factors of CS measurement after 1 s and after additional tempering are in good agreement. KW - Compression set KW - Ageing KW - Recovery KW - Degradative processes KW - Leakage rate PY - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-573699 SN - 0142-9418 VL - 121 SP - 107987 PB - Elsevier Ltd. AN - OPUS4-57369 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -