Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-24620 Beitrag zu einem Tagungsband von der Ehe, Kerstin; Jaunich, Matthias; Wolff, Dietmar UHMW-PE - a shielding material with special properties influenced by radiation 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. Deutsches Atomforum e.V. / Kerntechnische Gesellschaft e.V. 2011 Jahrestagung Kerntechnik 2011 (Proceedings) Jahrestagung Kerntechnik 2011 Berlin, Germany 17.05.2011 19.05.2011 1 5 2016-02-19 OPUS4-24971 Beitrag zu einem Tagungsband Jaunich, Matthias; Schulz, Sebastian; Stark, Wolfgang; Wolff, Dietmar Characterization of the low temperature behaviour of rubber sealing materials Rubbers are often used for seal applications due to their special material properties and easy use. In many applications the material is exposed to low temperatures during Operation. Therefore it is important to know the material behavior at low temperatures to determine the temperature ränge that allows a Safe Operation of the seal, e.g. in storage and transport Containers for radioactive materials. The seal function of an elastomer is limited in temperature 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 and therefore needs an in-depth investigation under consideration of the physical properties and the application conditions. In this work different analytical methods are used to characterize the material behavior at low temperature in the ränge of the glass-rubber-transition and are compared with the quality of Operation of a component which is here defined by the detected leakage rate. 2011 Technomer 2011 - 22. Fachtagung über Verarbeitung und Anwendung von Polymeren 978-3-939382-10-2 Technomer 2011 - 22. Fachtagung über Verarbeitung und Anwendung von Polymeren Chemnitz, Deutschland 10.11.2011 12.11.2011 Kap. 3.7 1 4 2016-02-19 OPUS4-23206 Zeitschriftenartikel Stark, Wolfgang; Jaunich, Matthias Investigation of ethylene/vinyl acetate copolymer (EVA) by thermal analysis DSC and DMA Two types of commercially applied Ethylene/Vinyl Acetate Copolymers (EVA) for encapsulation of photovoltaic modules were investigated by the thermal analysis methods of Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) in the temperature range from -150 °C to 200 °C. Glass transition, crystal melting and cross-linking were analyzed. The aims of the investigations were to gain more information for incoming goods control and to get information about the whole temperature dependent material properties in the investigated temperature range, starting at very low temperatures up to the crosslinking temperature region. Amsterdam [u.a.] Elsevier Ltd. 2011 Polymer testing 30 2 236 242 10.1016/j.polymertesting.2010.12.003 2016-02-19 OPUS4-23288 Vortrag Jaunich, Matthias Untersuchung des Tieftemperaturverhaltens von Elastomeren im Dichtungseinsatz 2011 Polymerwissenschaftliches Seminar des Fachgebietes Polymertechnik/-physik der TU-Berlin Polymerwissenschaftliches Seminar des Fachgebietes Polymertechnik/-physik der TU-Berlin Berlin, Germany 2011-02-17 2011-02-17 2016-02-19 OPUS4-24015 Zeitschriftenartikel Jaunich, Matthias; von der Ehe, Kerstin; Wolff, Dietmar; Völzke, Holger; Stark, Wolfgang Understanding low temperature properties of elastomer seals 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. Ashford Ramtrans Publ. 2011 Packaging, transport, storage & security of radioactive materials (RAMTRANS) 22 2 83 88 10.1179/1746510911Y.0000000004 2016-02-19 OPUS4-24168 Zeitschriftenartikel Stark, Wolfgang; Jaunich, Matthias Thermoanalytische Charakterisierung von Ethylen-Vinylacetat-Copolymer (EVA) für Photovoltaikmodule Das Ziel der Untersuchungen war mit Hilfe von DSC und DMA EVA-Folien im Anlieferungszustand hinsichtlich der Lage der Glasübergangstemperatur, des Schmelzverhaltens und der Temperaturabhängigkeit der Vernetzungsreaktion zu charakterisieren. Auf dieser Basis sollte die Lieferstabilität im Sinne einer Wareneingangskontrolle auf eine messtechnische Basis gestellt werden. In einem 2. Schritt sollte die vernetzte Folie dahingehend charakterisiert werden, ob infolge der Vernetzung eine Änderung der Netzsch 2011 OnSet 8 3 5 2016-02-19 OPUS4-23422 Zeitschriftenartikel Jaunich, Matthias; Stark, Wolfgang; Wolff, Dietmar Low temperature properties of rubber seals 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. Heidelberg Hüthig Deutsche Kautschuk-Gesellschaft 2011 Kautschuk, Gummi, Kunststoffe (KGK) 03 52 55 2016-02-19