TY - CONF A1 - von Woedtke, T. A1 - Abel, P. A1 - Schröder, K. A1 - Schwock, A. A1 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - Biosensor-Membranen mit "Analyt-Fenster" T2 - 8. Internationale Messe mit Kongreß für Sensoren, Meßaufnehmer & Systeme ; 8th International Fair with Congress for Sensors, Transducers & Systems CY - Nürnberg, Deutschland DA - 1997-05-13 PY - 1997 VL - 2 SP - 101 EP - 106 PB - ACS Organisations GmbH CY - Wunstorf AN - OPUS4-11959 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meyer-Plath, Asmus A1 - Finke, B. A1 - Schröder, K. A1 - Ohl, A. T1 - Pulsed and cw microwave plasma excitation for surface functionalization in nitrogen-containing gases N2 - Results are presented of polymer surface functionalization processes in pulsed and continuous wave (cw) microwave-excited plasmas in nitrogen-containing gases under admixture of hydrogen. A maximum selectivity of 100% for amino groups with respect to all nitrogen functional groups (NH2/N) was obtained in cw microwave (MW) plasmas either for very short treatment durations below 100 µs in pure NH3, or within approximately 10 s in hydrogen-rich nitrogen-containing plasmas. The amino and overall nitrogen surface densities, NH2/C and N/C, reach up to 3.5% and 35%, respectively. Post plasma processes of functionalized polymers are discussed in the light of monofunctionalization. Down to pulse duration of 1 ms, plasma decomposition rates of NH3, determined by infrared absorption spectroscopy, are found to scale linearly with the duty cycle. In this regime, the main effect of a duty cycle variation in pulsed NH3 plasmas on surface functionalization can be interpreted to result from changes in the concentration of the dominant stable species in the gas phase, NH3, N2 and H2, which are activated by subsequent plasma pulses. With increasing duty cycle, NH3 decomposition to N2 and 3H2 more and more dominates over the supply of fresh NH3. The nitrogen-removing role of hydrogen in the plasma is discussed in detail, whereas the role of the numerous transient nitrogen-containing species remains to be studied in the future. KW - Pulsed microwave plasma KW - Amino group KW - Polymer KW - Ammonia KW - Infrared absorption PY - 2003 DO - https://doi.org/10.1016/S0257-8972(03)00563-2 SN - 0257-8972 VL - 174-175 SP - 877 EP - 881 PB - Elsevier Science CY - Lausanne AN - OPUS4-13512 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meyer-Plath, Asmus A1 - Schröder, K. A1 - Finke, B. A1 - Ohl, A. T1 - Current trends in biomaterial surface functionalization - nitrogen-containing plasma assisted processes with enhanced selectivity N2 - Low-pressure gas-discharge plasmas are widely used for polymer surface functionalization on industrial scale. For biomaterial applications, the density and selectivity of the functionalization are of particular importance, because functional groups control the immobilization of biomolecules. Therefore, surface modification of biomaterials is a challenging task for low-pressure plasma technique. Plasma processes have been successfully applied to various polymer types in order to generate multifunctional surfaces. This paper discusses the present state and the prospects of non-coating plasma processes to generate mono functional surfaces of controlled amino group density. Such surfaces appear most desirable for many applications. The results of various microwave- and radio-frequency- excited plasma processes reported in the literature are reviewed and compared to a sequence of experiments that was conducted in a UHV reaction environment. Non-thermal plasmas are especially well suited for thermally damageable polymers. The effect of hydrogen admixture to discharges in nitrogen and ammonia is discussed in detail. The optimization of process parameters lead to highly selective amino functionalization of high density. The selectivity reached 100% -NH2/N at a surface density of amino groups of 3% -NH2/C. KW - Low pressure plasma KW - Grafting KW - Polymers KW - Amino group KW - Surface analysis PY - 2003 DO - https://doi.org/10.1016/S0042-207X(02)00766-2 SN - 0042-207X VL - 71 IS - 3 SP - 391 EP - 406 PB - Elsevier Science CY - Kidlington AN - OPUS4-13686 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Barbier, J.-P. A1 - Bissolotti, G. A1 - Christian, S. A1 - Cleaver, K. A1 - Heller, D. A1 - Injaian, M. A1 - Schröder, Volkmar A1 - Witte, F. T1 - Safe preparation of compressed oxidant-fuel gas mixtures in cylinders KW - Sicherheitstechnik KW - Biogas KW - Explosionsgrenzen KW - Prozesssicherheit PY - 2007 IS - 139/07/E SP - 1 EP - 36 PB - European Industrial Gases Association (EIGA) CY - Brussels AN - OPUS4-16501 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröder, K. A1 - Meyer-Plath, Asmus A1 - Keller, D. A1 - Ohl, A. T1 - On the Applicability of Plasma Assisted Chemical Micropatterning to Different Polymeric Biomaterials N2 - A plasma process sequence has been developed to prepare chemical micropatterns on polymeric biomaterial surfaces. These patterns induce a guided localized cell layover at microscopic dimension. Two subsequent plasma steps are applied. In the first functionalization step a microwave ammonia plasma introduces amino groups to obtain areas for very good cell adhesion; the second passivation step combines pattern generation and creation of cell repelling areas. This downstream microwave hydrogen plasma process removes functional groups and changes the linkages of polymer chains at the outermost surfaces. Similar results have been obtained on different polymers including polystyrene (PS), polyhydroxyethylmethacrylate (PHEMA), polyetheretherketone (PEEK), polyethyleneterephthalate (PET) and polyethylenenaphthalate (PEN). Such a rather universal chemical structuring process could widen the availability of biomaterials with specific surface preparations. KW - Microwave plasma KW - Ammonia KW - Hydrogen KW - Polymer surface KW - Cell culture KW - XPS KW - Fluorescence PY - 2002 DO - https://doi.org/10.1023/A:1016239302194 SN - 1084-0184 SN - 1572-8978 VL - 7 IS - 2 SP - 103 EP - 125 PB - Plenum Press CY - New York, NY AN - OPUS4-1729 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Müller-Rochholz, J. A1 - Bronstein, Z. A1 - Schröder, Hartmut A1 - Rybak, Thomas A1 - Zeynalov, Eldar A1 - v. Maubeuge, K. P. ED - Delmas, P. T1 - Long-term behaviour of geosynthetic drains - excavations on landfills after up to 12 years service T2 - 7th International Conference on Geosynthetics (ICG) CY - Nice, France DA - 2002-09-22 PY - 2002 SN - 90-5809-525-8 VL - 2 SP - 565 EP - 568 PB - Balkema CY - Lisse AN - OPUS4-1902 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Schießl, P. A1 - Meng, Birgit A1 - Adam, G. A1 - Rößler, G. A1 - Schröder, P. A1 - Schwamborn, B. A1 - Wallner, B. A1 - Wiegrink, K. ED - Zilch, K. ED - Diederichs, C. J. T1 - Baustoffe PY - 2002 SN - 3-540-65760-6 IS - Kap. 3.1 SP - 3-3-3-60 PB - Springer CY - Berlin AN - OPUS4-2070 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Robertson, Daniela A1 - Böhning, Martin A1 - Schröder, Hartmut A1 - Brummermann, K. A1 - Kaudinya, I. A1 - Saathoff, F. T1 - Möglichkeiten der Abschätzung der Langzeitbeständigkeit von Kunststoffdichtungsbahnen (KDB) auf Polyolefinbasis für den Tunnelbau N2 - Im Rahmen eines von der Bundesanstalt für Straßenwesen (BASt) initiierten Forschungsvorhabens (15.449/2007/ERB: „Prüfverfahren zur Beurteilung der Lebensdauer von Kunststoffdichtungsbahnen für Straßentunnel“) wurden anhand von Untersuchungen an Kunststoffdichtungsbahnen (KDB) auf Basis von Polyolefinwerkstoffen die Möglichkeiten der Beurteilung der oxidativen Langzeitbeständigkeit sondiert. Im Mittelpunkt stand die Erprobung des Autoklaventests in Anlehnung an DIN EN ISO 13438 (Methode C1/C2) an ausgewählten, für den Tunnelbau repräsentativen marktüblichen KDB-Produkten. Die Untersuchungen im Autoklaven bei erhöhten Temperaturen (60 °C, 70 °C und 80 °C) und Sauerstoffdrücken (11, 21 und 51 bar) wurden durch vergleichende Versuche im Wärmeschrank (Ofen) bei erhöhter Temperatur (85 °C) in Anlehnung an DIN EN 14575 ergänzt. Die KDBProdukte wurden außerdem einer eingehenden Materialcharakterisierung (Zugprüfung, DMA, DSC) unterzogen. Weiterhin wurden Bauwerksdaten recherchiert und auf ihre Nutzbarkeit zur Bewertung und Prüfbarkeit der Langzeitbeständigkeit von KDB in Tunneln betrachtet. Ziel war auch, die Anwendbarkeit des bisher vorgeschlagenen Extrapolationsmodells zur Auswertung der Ergebnisse von Autoklaventests an im Tunnelbau marktüblichen Produkten für Nutzungsdauern über 25 Jahre zu überprüfen und zur Entwicklung eines geeigneten Prüfverfahrens beizutragen. Der Beitrag geht auf Ergebnisse des Vorhabens ein und zeigt erste Schlussfolgerungen und weiteren Untersuchungsbedarf auf. Die Ergebnisse werden in den „Empfehlungen zu Dichtungssystemen im Tunnelbau EAG-EDT“ des Arbeitskreises 5.1 „Kunststoffe in der Geotechnik und im Wasserbau“ berücksichtigt, deren 2. Auflage in Vorbereitung ist. Aspekte des thermischen Verhaltens der eingesetzten Werkstoffe sowie mögliche Anpassungen der Prüfrandbedingungen für die Autoklaventests werden ergänzt und Hinweise zur Interpretation von Prüfergebnissen gegeben. Außerdem wurden inzwischen ausgehend von den Ergebnissen des Forschungsvorhabens erste Autoklaven-Ringversuche in drei Prüfinstitutionen initiiert. T2 - 12. Informations- und Vortragstagung über "Kunststoffe in der Geotechnik" CY - Munich, Germany DA - 03.03.2011 KW - Kunststoffdichtungsbahnen auf Polyolefinbasis KW - Oxidative Langzeitbeständigkeit KW - Autoklaventest - beschleunigte Alterung KW - DSC KW - DMA PY - 2011 SN - 978-3-940476-26-5 IS - Geotechnik Sonderheft 2011 SP - 35 EP - 42 AN - OPUS4-24399 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hsuan, Y.G. A1 - Schröder, Hartmut A1 - Rowe, K. A1 - Müller, Werner A1 - Greenwood, J. A1 - Cazzuffi, D. A1 - Koerner, R.M. ED - Neil Dixon, T1 - Long-term performance and lifetime prediction of geosynthetics N2 - To properly understand and assess the long-term behaviour of geosynthetic materials it is necessary to investigate the various types of possible degradation mechanims. This includes both chemical and mechanical behaviour, and sometimes even their interactions with one another. Clearly, chemical degradation of geosynthetics depends on the polymer type. For example, polyolefins are vulnerable to oxidation; polyesters are susceptible to hydrolysis; and plasticizers can leach from polyvinyl chloride. This paper describes the concept of these three types of degradation, but focuses on the oxidation of polyolefins since the majority of the geosynthetics is made from this type of polymer. The methods used to predict the lifetime of antioxidants and service life of the geosynthetic material will be illustrated. Furthermore, the influence of temperature, pressure, and ultraviolet light on the service life are also demonstrated. Finally, the current specifications targeting the longevity of different geosynthetics are presented. Regarding mechanical degradation, the paper mainly focuses upon the creep deformation of geogrids and stress crack resistance (SCR) of polyethylene geomembranes and geopipe. The method to assess stress crack resistance is described, and the microscopic mechanisms that lead to such failure are explained. For creep evaluation, different acceleration tests are presented and their applicability with respect to the different types of polymers is illustrated. In addition, the long-term shear behaviour of geocomposites and geosynthetic clay liners is presented. T2 - 4th European Geosynthetics Conference - EuroGeo4 CY - Edinburgh, Scotland, UK DA - 2008-09-07 KW - Geosynthetic KW - Durability KW - Degradation KW - Antioxidant KW - Weathering PY - 2008 SP - 1 EP - 41 AN - OPUS4-17975 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wasternack, J. A1 - Schröder, H. V. A1 - Witte, J. F. A1 - Ilisson, M. A1 - Hupatz, H. A1 - Hille, J. F. A1 - Gaedke, M. A1 - Valkonen, A. M. A1 - Sobottka, S. A1 - Krappe, A. A1 - Schubert, M. A1 - Paulus, B. A1 - Rissanen, K. A1 - Sarkar, B. A1 - Eigler, S. A1 - Resch-Genger, Ute A1 - Schalley, C. A. T1 - Switchable protection and exposure of a sensitive squaraine dye within a redox active rotaxane N2 - In nature,molecular environments in proteins can sterically protect and stabilize reactive species such as organic radicals through non-covalent interactions.Here, wereport a near-infrared fluorescent rotaxane in which the stabilization of a chemically labile squaraine fluorophore by the coordination of a tetralactam macrocycle can be controlled chemically and electrochemically. The rotaxane can be switched between two co-conformations inwhich thewheel either stabilizes or exposes the fluorophore. Coordination by the wheel affects the squaraine’s stability across four redox states and renders the radical anion significantly more stable—by a factor of 6.7—than without protection by a mechanically bonded wheel. Furthermore, the fluorescence properties can be tuned by the redox reactions in a stepwise manner. Mechanically interlockedmolecules provide an excellent scaffold to stabilize and selectively expose reactive species in a co-conformational switching process controlled by external stimuli. KW - Fluorescence KW - Dye KW - Sensor KW - Quantum yield KW - Spectroscopy KW - Photophysics KW - Synthesis KW - Squaraine KW - Switch KW - Redox-active KW - Rotaxane PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-614959 DO - https://doi.org/10.1038/s42004-024-01312-1 VL - 7 SP - 1 EP - 11 AN - OPUS4-61495 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Robertson, Daniela A1 - Schröder, Hartmut A1 - Böhning, Martin A1 - Brummermann, K. A1 - Kaundinya, I. A1 - Saathoff, F. T1 - Test method for the assessment of the service life of polymeric geosynthetic barriers (GBR-P) for road tunnels N2 - This paper is dealing with a systematic investigation to evaluate the testing method “autoclave test” for the assessment of the oxidative durability of polyolefin-based GBR-P products applied in road tunnel construction. The aim was to derive suitable exposure conditions and criteria for a practical testing procedure with regard to service lifetimes up to 100 years. The screening test (index test) according to DIN EN ISO 13438 developed in the BAM was applied in extended form and amended by a basic characterization, as well as complementary analyses, following autoclave exposure. The time dependency of some of the products and the so called lifetime parameter of one product were investigated and compared with the results of conventional oven tests. Based on the results of the research program some conclusions and practical outlooks were concluded. T2 - Euro GEO 5 - 5th European geosynthetics congress CY - Valencia, Spain DA - 16.09.2012 KW - Durability KW - Oxidation KW - Acceleration ageing KW - GBR-P PY - 2012 SN - 978-0415-64340-5 VL - 1 IS - Topic: Transport SP - 150 EP - 154 AN - OPUS4-27312 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -