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 OPUS4-13706 Beitrag zu einem Tagungsband Schröder, Hartmut; Munz, Martin; Böhning, Martin; Lorenz, Edelgard; Kneip, Gisela New method for testing the resistance to oxidation - Application and Evaluation: Polyolefinic Products Maastricht European Federation of Corrosion 2006 EUROCORR 2006 - Manuscripts EUROCORR 2006 Maastricht, The Netherlands 2006-09-25 2006-09-28 280 1 8 2016-02-19 OPUS4-17187 Zeitschriftenartikel Schröder, Hartmut; Munz, Martin; Böhning, Martin A new method for testing and evaluating the long-time resistance to oxidation of polyolefinic products A report is presented on the development of a test for determining the long-term oxidation resistance of polyolefin materials, which is accelerated not only by elevated temperatures but also by increased oxygen pressure and a stirred aqueous medium. The method permits durability tests to be carried out at markedly lower temperatures with reasonable testing durations and significantly reduced diffusion limited oxidation effects and allows for physical and chemical impacts of aqueous media. Oxidative durability can be assessed by autoclave immersion exposures at three different temperatures (60, 70 and 80 degrees C) and 50 bar oxygen pressure and at 80 degrees C and two different oxygen pressures (usually 10 and 20 bar). Accelerated test data are evaluated by modified Arrhenius equations with the application of a three-dimensional regression analysis. The application of the test method to various materials, including PP non-woven materials and geosynthetics is demonstrated. 10 refs. Shrewsbury RAPRA Technology Ltd. 2008 Polymers & Polymer composites 16 1 71 79 2016-02-19 OPUS4-15762 Beitrag zu einem Sammelband Schröder, Hartmut; Munz, Martin; Böhning, Martin A new method for testing and evaluating the long-tIme resistance to oxidation of polyolefinic products Shawbury Smithers Rapra Technology Ltd. 2007 Addcon World 2007 978-1-84735-018-3 13th International Plastics Additives and Compounding Conference "Addcon World 2007" Frankfurt/M. 2007-09-05 2007-09-06 Paper 7 1 10 2016-02-19 OPUS4-2884 Zeitschriftenartikel Böhning, Martin; Goering, Harald; Hao, Ning; Mach, Reinhard; Oleszak, Franz; Schönhals, Andreas Molecular Mobility and Gas Transport Properties of Polycarbonate-Based Nanocomposites St. Petersburg Advanced Study Center 2003 Reviews on advanced materials science 5 155 159 2016-02-19 OPUS4-2044 Beitrag zu einem Tagungsband Schönhals, Andreas; Goering, Harald; Böhning, Martin; Fritz, Andreas; Rübner, J. Structure Analysis of Polymeric Nanomaterials by Relaxation Spectroscopy Berlin-Brandenburgischer Verband für Polymerforschung e.V. 2002 Polydays 2002 Polydays 2002 Berlin, Germany 2002-09-30 2002-10-02 1(?) 2016-02-19 OPUS4-2035 Beitrag zu einem Tagungsband Böhning, Martin; Wald, Oliver; Turky, Gamal; Goering, Harald; Brzezinka, Klaus-Werner; Schartel, Bernhard; Schönhals, Andreas Dielectric Relaxation and Gas Transport Properties in Polypropylene Based Nanocomposites 2002 Proceedings of the ACS 2002 Biennial Symposium "Polymeric Nanomaterials" ACS 2002 Biennial Symposium "Polymeric Nanomaterials" Rohnert Park, CA, USA 2002-11-17 2002-11-20 1(?) 3(?) 2016-02-19 OPUS4-2036 Zeitschriftenartikel Böhning, Martin; Tidjani, Adams; Wald, Oliver; Brzezinka, Klaus-Werner; Turky, Gamal; Goering, Harald; Schartel, Bernhard; Schönhals, Andreas Dielectric and gas transport properties of polypropylene-clay nanocomposites Bad Honnef Deutsche Physikalische Gesellschaft 2002 Verhandlungen der Deutschen Physikalischen Gesellschaft Frühjahrstagung des Arbeitskreises Festkörperphysik bei der DPG Regensburg, Germany 2002-03-11 2002-03-15 CPP 5.4 425 2016-02-19 OPUS4-2037 Beitrag zu einem Tagungsband Böhning, Martin; Turky, Gamal; Goering, Harald; Wald, Oliver; Schartel, Bernhard; Schönhals, Andreas Polypropylene/Clay Nanocomposites - Dielectric Relaxation and Gas Transport Properties 2002 Proceedings of the 2nd International Conference on Broadband Dielectric Spectroscopy and Its Applications 2nd International Conference on Broadband Dielectric Spectroscopy and Its Applications Leipzig, Germany 2002-09-02 2002-09-07 2016-02-19 OPUS4-2038 Beitrag zu einem Tagungsband Böhning, Martin; Tidjani, Adams; Wald, Oliver; Turky, Gamal; Goering, Harald; Brzezinka, Klaus-Werner; Schartel, Bernhard; Schönhals, Andreas Polypropylene/Clay Nanocomposites - Gas Transport Characteristics and Molecular Mobility Berlin-Brandenburgischer Verband für Polymerforschung e.V. 2002 Polydays 2002 Polydays 2002 Berlin, Germany 2002-09-30 2002-10-02 1(?) 2(?) 2016-02-19 OPUS4-2040 Beitrag zu einem Tagungsband Böhning, Martin; Goering, Harald Herstellung und Charakterisierung von Nanopartikel/Polymer Composites 2002 BAM-Seminar der Abteilung VI "Funktion von Polymeren" BAM-Seminar der Abteilung VI "Funktion von Polymeren" Berlin, BAM, Deutschland 2002-09-19 2016-02-19 OPUS4-2054 Beitrag zu einem Tagungsband Böhning, Martin; Goering, Harald; Hao, Ning; Schönhals, Andreas Gas Transport in Polymer based Nanocomposite Systems 2002 Workshop "Glasübergang" im Sonderforschungsbereich "Heterogene Polymersysteme" der Universität Halle Workshop "Glasübergang" Rostock, Germany 2002-12-16 2002-12-18 2016-02-19 OPUS4-2061 Beitrag zu einem Tagungsband Goering, Harald; Böhning, Martin; Turky, Gamal; Hao, Ning; Schönhals, Andreas Molecular Dynamics in Polymer Nanocomposites 2002 Workshop "Glasübergang" im Sonderforschungsbereich "Heterogene Polymersysteme" der Universität Halle Workshop "Glasübergang" Rostock, Germany 2002-12-16 2002-12-18 2016-02-19 OPUS4-3623 Posterpräsentation Böhning, Martin Dielectric and gas transport properties of polypropylene-clay nanocomposites 2002 DPG-Frühjahrstagung (Polymerphysik), Fachverband CPP, Themenkreis 3 DPG-Frühjahrstagung (Polymerphysik), Fachverband CPP, Themenkreis 3 Regensburg, Germany 2002-03-11 2002-03-15 2016-02-19 OPUS4-3622 Vortrag Böhning, Martin Dielectric Relaxation and Gas Transport Properties in Polypropylene Based Nanocomposites 2002 ACS 2002 Biennial Symposium: Polymeric Nanomaterials ACS 2002 Biennial Symposium: Polymeric Nanomaterials Rohnert Park, CA, USA 2002-11-17 2002-11-20 2016-02-19 OPUS4-4197 Vortrag Böhning, Martin Gas Transport Characterisation and Molecular Modelling - Possible Corelations and Methodological Extensions 2003 Workshop Glasübergang Workshop Glasübergang Berlin, Germany 2003-12-14 2003-12-16 2016-02-19 OPUS4-11316 Vortrag Böhning, Martin Investigation of swollen polymer/gas-systems: atomistic packing models based on experimental properties 2006 Frühjahrstagung der Deutschen Physikalischen Ges. / AKF Condensed Matter Frühjahrstagung der Deutschen Physikalischen Ges. / AKF Condensed Matter Dresden, Germany 2006-03-26 2006-03-31 2016-02-19 OPUS4-11214 Vortrag Böhning, Martin Gas transport and molecular mobility in polymer/POSS nanocomposites 2006 Euromembrane 2006 Euromembrane 2006 Taormina, Italy 2006-09-24 2006-09-28 2016-02-19 OPUS4-13730 Zeitschriftenartikel Hölck, Ole; Böhning, Martin; Heuchel, M.; Siegert, M.R. Gas-induced structural changes in polymeric membrane materials combining experiment, phenomenological models and simulation Amsterdam Elsevier 2006 Desalination 200 1-3 166 168 10.1016/j.desal.2006.03.283 2016-02-19 OPUS4-13707 Zeitschriftenartikel Böhning, Martin; Hao, Ning; Schönhals, Andreas Gas transport and molecular mobility in polymer/POSS nanocomposites Amsterdam Elsevier 2006 Desalination 200 1-3 142 143 10.1016/j.desal.2006.03.127 2016-02-19 OPUS4-13708 Zeitschriftenartikel Heuchel, M.; Böhning, Martin; Hölck, Ole; Siegert, M.R.; Hofmann, D. Atomistic packing models for experimentally investigated swelling states induced by CO2 in glassy polymers Amsterdam Elsevier 2006 Desalination 199 1-3 443 444 10.1016/j.desal.2006.03.100 2016-02-19 OPUS4-7281 Zeitschriftenartikel Böhning, Martin; Goering, Harald; Fritz, Andreas; Brzezinka, Klaus-Werner; Turky, Gamal; Schönhals, Andreas; Schartel, Bernhard Dielectric Study of Molecular Mobility in Poly(propylene-graft-maleic anhydride)/Clay Nanocomposites Polymer/clay nanocomposite materials based on poly(propylene-graft-maleic anhydride) (PPgMAH) and two different organophilic modified clays were investigated by dielectric relaxation spectroscopy (DRS). In contrast to ungrafted polypropylene (PP), PPgMAH shows a dielectrically active relaxation process which can be assigned to localized fluctuations of the polar maleic anhydride groups. Its relaxation rate exhibits an unusual temperature dependence, which could be attributed to a redistribution of water molecules in the polymeric matrix. This is confirmed by a combination of Raman spectroscopy and thermogravimetric experiments (TGA) with real-time dielectric measurements under controlled atmospheres. In the nanocomposites this relaxation process is shifted to higher frequencies up to 3 orders of magnitude compared to the unfilled polymer. This indicates a significantly enhanced molecular mobility in the interfacial regions. In the nanocomposite materials a separate high-temperature process due to Maxwell-Wagner-Sillars (MWS) polarization was observed. The time constant of this MWS process can be correlated with characteristic length scales in nanocomposites and therefore provides additional information on dispersion and delamination/exfoliation of clay platelets in these materials. These properties also influence the diffusivity of the water molecules as revealed by real-time dielectric investigations. Washington, DC American Chemical Society 2005 Macromolecules 38 7 2764 2774 10.1021/ma048315c 2016-02-19 OPUS4-7062 Beitrag zu einem Sammelband Böhning, Martin; Goering, Harald; Hao, Ning; Mach, Reinhard; Schönhals, Andreas Cassidy, P. Polycarbonate/SiC nanocomposites - Influence of nanoparticle dispersion on molecular mobility and gas transport Chichester Wiley 2005 7th International Symposium on Polymers for Advanced Technologies 16 7th International Symposium on Polymers for Advanced Technologies Fort Lauderdale, FL, USA 2005-09-21 2005-09-24 2-3 262 268 2016-02-19 OPUS4-10976 Vortrag Böhning, Martin Gas Transport and Molecular Mobility in Polymer Based Nanocomposite Systems 2005 1st International Conference on Advanced Materials and their application, National Research Centre, Physics Division 1st International Conference on Advanced Materials and their application, National Research Centre, Physics Division Cairo, Egypt 2005-12-12 2005-12-14 2016-02-19 OPUS4-25969 Vortrag Böhning, Martin Gas transport in glassy polymers and PNCs - experiment, analysis, modeling of diffusion, sorption and dilation 2012 Workshop: Polymers, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Laboratory for Non-Metals Workshop: Polymers, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Laboratory for Non-Metals Zagreb, Croatia 2012-05-23 2012-05-23 2016-02-19 OPUS4-26176 Beitrag zu einem Tagungsband Wolff, Dietmar; von der Ehe, Kerstin; Jaunich, Matthias; Böhning, Martin Performance of neutron radiation shielding material (U)HMW-PE influenced by gamma radiation 2012 PSAM 11 ESREL 2012 - 11th International probabilistic safety assessment and management conference & The annual european safety and reliability conference (Proceedings) PSAM 11 ESREL 2012 - 11th International probabilistic safety assessment and management conference & The annual european safety and reliability conference Helsinki, Finland 2012-06-25 2012-06-29 1 8(?) 2016-02-19 OPUS4-27931 Beitrag zu einem Sammelband Wolff, Dietmar; von der Ehe, Kerstin; Jaunich, Matthias; Böhning, Martin; Goering, Harald Yamamoto, T. (U)HMWPE as neutron radiation shielding materials: impact of gamma radiation on structure and properties Due to their extreme high hydrogen contents, high molecular weight (HMW-) and ultra-high molecular weight (UHMW-) polyethylene (PE) are a comprehensible choice as neutron radiation shielding material in casks for storage and transport of radioactive materials. But as a direct consequence of inserting radioactive material in such casks, gamma radiation occurs. Hence, the impact of gamma radiation on the molecular structure of polyethylene has to be taken into consideration. Consequently, PE has to withstand any type of gamma radiation induced degradation affecting safety relevant aspects in order to be applicable for long term neutron radiation shielding purposes during the whole storage period (in Germany, for instance, up to 40 years). The scope of our investigation comprises an estimation of the impact of gamma radiation and temperature on the molecular and supra molecular structure of the two types of PE used as neutron radiation shielding cask components. A further point which is worth exploring is to what extent these changes are detectable by conventional analysis methods. Therefore, thermoanalytical measurements were performed such as differential scanning calorimetry (DSC), thermo mechanical analysis (TMA), dynamic mechanical analysis (DMA), and thermo gravimetric analysis (TGA). Additionally optical and weighing methods were applied. With those methods it is possible to detect structural changes in polyethylene induced by exposure to gamma radiation. The observed amounts of changes of the irradiated material are not safety relevant for the application of polyethylene as neutron radiation shielding material; moreover, some properties actually improve via irradiation. ASTM International (American Society for Testing and Materials) 2013 Effects of radiation on nuclear materials 25 978-0-8031-7533-4 STP 1547 211 227 10.1520/STP103980 2016-02-20 OPUS4-24423 Posterpräsentation Böhning, Martin Characterization of structural changes in irradiated UHMWPE 2011 11. Schwarzheider Kunststoffkolloquium 11. Schwarzheider Kunststoffkolloquium Schwarzheide, Germany 2011-09-21 2011-09-22 2016-02-19 OPUS4-24621 Beitrag zu einem Tagungsband von der Ehe, Kerstin; Jaunich, Matthias; Wolff, Dietmar; Böhning, Martin; Goering, Harald Radiation induced structural changes of (U)HMW polyethylene with regard to its application for radiation shielding The special properties of high molecular weight polyethylene (HMW-PE) and ultra high molecular weight polyethylene (UHMW-PE) result basically from their extreme chain lengths and their high degree of crystallinity. As high-performance polymers, they are used for a variety of applications. UHMW-PE in particular is often utilized for endoprothesis (due to its excellent slip and wear properties) and due to its high hydrogen content as a neutron moderator in casks for storage and transport of radioactive materials. To prepare the material for instance for its use as a total joint replacement, it is exposed to radiation for several reasons, 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. To be applicable for long term radiation shielding purposes for instance over a period of 40 years, PE has to withstand any type of degradation affecting safety relevant aspects. The scope of our investigation comprises an estimation of the radiation impact on the molecular and supra molecular structure of two types of PE and 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 Thermo Gravimetric Analysis (TGA). Additionally FT-IR spectroscopy as well as density and gas sorption measurements were carried out. Due to the poor solubility of HMW-PE and UHMW-PE, some classical analytical techniques are not applicable. But TA-methods represent a feasible approach to detect structural and morphological features of these materials as well as changes caused by external influences, such as thermal treatment and/or irradiation. With the combination of the applied TA-techniques it is possible to distinguish between crosslinking and degradation. PATRAM 2010 PATRAM 2010 - 16th International symposium on the packaging and transport of radioactive materials (Proceedings) PATRAM 2010 - 16th International symposium on the packaging and transport of radioactive materials London, UK 2010-10-03 2010-10-08 1 8 (T25/Paper 173) 2016-02-19 OPUS4-24399 Beitrag zu einem Tagungsband Robertson, Daniela; Böhning, Martin; Schröder, Hartmut; Brummermann, K.; Kaudinya, I.; Saathoff, F. Möglichkeiten der Abschätzung der Langzeitbeständigkeit von Kunststoffdichtungsbahnen (KDB) auf Polyolefinbasis für den Tunnelbau 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. Deutsche Gesellschaft für Geotechnik 2011 12. Informations- und Vortragstagung über "Kunststoffe in der Geotechnik" 978-3-940476-26-5 12. Informations- und Vortragstagung über "Kunststoffe in der Geotechnik" Munich, Germany 03.03.2011 03.03.2011 Geotechnik Sonderheft 2011 35 42 2016-02-19 OPUS4-24936 Posterpräsentation Böhning, Martin Curing behavior of EVA-based encapsulants for photovoltaic applications 2011 11. Schwarzheider Kunststoffkolloquium 11. Schwarzheider Kunststoffkolloquium Schwarzheide, Germany 2011-09-21 2011-09-22 2016-02-19 OPUS4-27563 Buchkapitel Schartel, Bernhard; Richter, K. H.; Böhning, Martin Morgan, A. B.; Wilkie, C. A.; Nelson, G. L. Synergistic use of talc in halogen-free flame retarded polycarbonate/Acrylonitrile-butadiene-styrene blends Pyrolysis, flammability, fire behavior, melt viscosity, and gas diffusion of bisphenol A polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) were investigated, with bisphenol A bis(diphenyl phosphate) (BDP), with 10 wt.% talc and with BDP in combination with 5, 10 and 20 wt.% talc, respectively. Compared to PC/ABS, PC/ABS + BDP results in an increased decomposition temperature of PC, a higher char yield, a significantly increased LOI, a V-0 classification in UL 94, a reduced peak heat release rate (pHRR), and a reduced total heat release (THR) in the cone calorimeter. This efficient flame retardancy is due to mechanisms in both the gas and condensed phases. PC/ABS + 10 wt.% talc shows a decrease in the PC decomposition temperature. The fire behavior is improved in part compared to PC/ABS, with an increased LOI and reduced pHRR. PC/ABS + BDP + 10 wt.% talc shows a strong synergism in LOI, a V-0 classification, and a decrease in pHRR, whereas THR is slightly increased compared to PC/ABS + BDP. Talc decreases the gas diffusion and enhances the flow limit for low shear rates, both of which influence the pyrolysis and flammability results. Further, talc improves the protection properties of the fire residues. Nevertheless it also partly suppresses flame inhibition and the charring effect of BDP. The synergism between BDP and talc in LOI is obtained even for low talc loadings in PC/ABS + BDP + talc, whereas for higher loadings saturation is observed. Oxford University Press American Chemical Society 2012 Fire and polymers VI: New advances in flame retardant chemistry and science 1118 978-0-8412-2780-4 Chapter 2 15 36 10.1021/bk-2012-1118.ch002 2016-02-20 OPUS4-27626 Zeitschriftenartikel Gallo, Emanuela; Schartel, Bernhard; Schmaucks, G.; von der Ehe, Kerstin; Böhning, Martin Effect of well dispersed amorphous silicon dioxide in flame retarded styrene butadiene rubber Spherically shaped amorphous silicon dioxide with broad size particle distribution was used in combination with aluminium trihydroxide (ATH) in styrene butadiene rubber composites. The pyrolysis, flammability, fire properties, flame spread and gas diffusion were investigated. The kind and amount of ATH, but in particular the fine silicon dioxide chosen as an additive, influenced the thermal decomposition and fire behaviour of styrene butadiene rubber composites. Gravimetric gas sorption measurements showed that the gas diffusion was systematically lower with silicon dioxide. The initial pyrolysis gas release was hindered, increasing the temperature at which decomposition begins as well as the ignition time in fire tests. During combustion, ATH and silicon dioxide accumulate on the surface of the specimen, forming a residual protective layer. A reduced peak heat release rate and fire spread were observed. The addition of a special kind of silicon dioxide is proposed to play a key role in optimising fire retardancy. London, UK IOM Communications 2013 Plastics rubber and composites 42 1 34 42 10.1179/1743289812Y.0000000012 2016-02-20 OPUS4-27599 Zeitschriftenartikel Hölck, Ole; Böhning, Martin; Heuchel, M.; Siegert, M.R.; Hofmann, D. Gas sorption isotherms in swelling glassy polymers - detailed atomistic simulations Detailed atomistic simulations were carried out for swelling polymer/gas systems related to experimental sorption and dilation data for CO2 and CH4 in three glassy polymers (polysulfone PSU, the polyimide 6FDA-TrMPD, and a polymer of intrinsic microporosity PIM-1) at 308 K (35 °C) and pressures up to 50 bar. Corresponding experiments were performed with a gravimetric sorption balance and a dilatometer based on a capacitance distance sensor. For each polymer/gas system molecular packing models were prepared and equilibrated for two reference states: the pure polymer is taken as reference for the respective 'unswollen' state and similarly the state of the highest penetrant pressure reached in the corresponding experiment is taken to represent the 'swollen' state. Models for the latter were constructed in agreement with experimental data (pressure, temperature, gas concentration and volume dilation). Concentration-pressure isotherms of each polymer/gas system were obtained using Grand Canonical Monte Carlo (GCMC) simulations for both reference states (depleted of gas molecules), which are in good agreement with the experimental data in the respective pressure range. As expected these isotherms - due to the simulation technique used, merely based on hole-filling in a static host matrix - do not represent the sorption behavior over a broader range of gas pressures which may involve significant structural rearrangements as well as swelling and relaxational phenomena. Nevertheless, a linear combination of the two GCMC-isotherms allows the interpolation in order to describe the nonlinear gas sorption in the glassy polymers under investigation covering the penetrant pressure range between the reference states in good agreement with the experimental results. Amsterdam Elsevier B.V. 2013 Journal of membrane science 428 523 532 10.1016/j.memsci.2012.10.023 2016-02-20 OPUS4-11589 Beitrag zu einem Sammelband Böhning, Martin; Goering, Harald; Hao, Ning; Schönhals, Andreas Polymer-based Nanocomposites - Particle Dispersion and Physical Properties Düsseldorf VDI-Verl. 2005 Nanofair 2005 - New Ideas for Industry 3-18-091920-5 Nanofair 2005 Dresden, Germany 2005-11-29 2005-11-30 1920 263 267 2016-02-19 OPUS4-15846 Zeitschriftenartikel Hao, Ning; Böhning, Martin; Schönhals, Andreas Gas Transport Properties of Polymeric Nanocomposites Based on Polyhedral Oligomeric Silsesquioxanes Washington, DC Division of Polymeric Materials Science and Engineering, American Chemical Society 2007 PMSE preprints 97 444 445 2016-02-19 OPUS4-15848 Zeitschriftenartikel Hao, Ning; Böhning, Martin; Schönhals, Andreas Structure Property Relationships of Polymeric Nanocomposites based on Polyhedral Oligomeric Silsesquioxanes Washington, DC Division of Polymeric Materials Science and Engineering, American Chemical Society 2007 PMSE preprints 97 789 790 2016-02-19 OPUS4-17485 Zeitschriftenartikel Böhning, Martin; Hölck, Ole; Heuchel, M.; Hofmann, D. Characterization of gas sorption in glassy polymers combining experimental and molecular modeling techniques Washington, DC Division of Polymeric Materials Science and Engineering, American Chemical Society 2008 PMSE preprints 98 875 876 2016-02-19 OPUS4-18295 Vortrag Böhning, Martin Autoclave testing - a new approach for the evaluation of oxidative long-term resistance of geosynthetics 2008 4th European Geosynthetics Conference 4th European Geosynthetics Conference Edinburgh, Scotland 2008-09-07 2008-09-10 2016-02-19 OPUS4-16492 Zeitschriftenartikel Hao, Ning; Böhning, Martin; Schönhals, Andreas Dielectric Properties of Nanocomposites Based on Polystyrene and Polyhedral Oligomeric Phenethyl-Silsesquioxanes Nanocomposites were prepared by solution blending of polyhedral oligomeric silsesquioxane with phenethyl substituents (PhenethylPOSS) into polystyrene (PS). The prepared materials were investigated by dielectric spectroscopy, differential scanning calorimetry (DSC), and density measurements. Additional FTIR investigations were carried out. Pure polystyrene shows two relaxation processes, an intermediate β*-process at lower and the α-relaxation at higher temperatures, the latter corresponding to segmental dynamics (dynamic glass transition). The molecular assignment of the β*-process needs further investigation. PhenethylPOSS can be incorporated into PS up to about 40 wt % without any indication of phase separation. With increasing PhenethylPOSS content, the α-relaxation of the composites shifts to lower temperatures and the loss peak broadens. Thus, the main effect of the nanofiller in the polystyrene matrix is to enhance the segmental dynamics, i.e., plasticization. The incorporation of approximately 40 wt % (approximately 5 mol %) PhenethylPOSS shifts the glass transition temperature Tg by 50 K to lower temperatures. The obtained results for polystyrene are discussed together with those reported recently for polycarbonate where a phase-separated morphology is observed for higher concentrations of PhenethylPOSS. The different behavior of PhenethylPOSS in polystyrene and polycarbonate is interpreted in terms of the different interaction of the phenyl rings within the POSS substituents with the phenyl rings of the polymers. For polystyrene, the interaction is stronger than for polycarbonate which probably leads to the enhanced miscibility of PhenethylPOSS into polystyrene. A detailed analysis of the temperature dependence of the dielectric relaxation strengths points also to additional interactions in the nanocomposites when compared to pure polystyrene. The broadening of the loss peak with increasing concentration is discussed in the framework of composition fluctuations. Washington, DC American Chemical Society 2007 Macromolecules 40 26 9672 9679 10.1021/ma071777g 2016-02-19 OPUS4-17402 Vortrag Böhning, Martin Characterization of gas sorption in glassy polymers combining experimental and molecular modeling techniques 2008 American Chemical Society (ACS) Spring Meeting American Chemical Society (ACS) Spring Meeting New Orleans, LA, USA 2008-04-06 2008-04-10 2016-02-19 OPUS4-17751 Zeitschriftenartikel Hao, Ning; Böhning, Martin; Wohlrab, Sebastian; Schönhals, Andreas Polymer Based Nanocomposites with PhenethylPOSS as Nanofilter Investigated by Dielectric Spectroscopy and Gas Transport Measurements Polyhedral oligomeric silsesquioxane with phenethyl substituents (PhenethylPOSS) as nanofiller was incorporated within Poly(bisphenol A carbonate) (PBAC) as matrix. Dielectric spectroscopy proved an almost complete miscibility of PhenethylPOSS up to 7 wt. %. At higher concentrations phase separation yields composites with a PBAC-rich matrix and POSS-rich domains which posses well shaped interfaces. The nanocomposites were also investigated with respect to their gas transport behaviour. An increase of the gas permeability was found at higher PhenethylPOSS concentrations, which is due to the phase separated structure. Weinheim Wiley-VCH Verl. 2008 Macromolecular symposia 267 1 69 73 10.1002/masy.200850712 2016-02-19 OPUS4-18423 Beitrag zu einem Tagungsband Retzlaff, J.; Bronstein, Z.; Müller-Rochholz, J.; Böhning, Martin; Robertson, Daniela; Schröder, Hartmut Oxidative resistance of geosynthetics: practical aspects and developments of testing at elevated temperature and oxygen pressure Service life of geosynthetics made of polyolefin materials is mainly limited by oxidative degradation. Durability of polyolefin products depend on formulation, morphology resulting from manufacturing, design and particularly on the antioxidants used. Although the fundamental oxidative reactions are known, the complex effect of geosynthetic characteristics and external influences mean that durability assessments require practical tests. The assessment of oxidative durability involves exposure to accelerating conditions as well as the material characterisation with respect to the state of stabilisation and/or degradation (e.g. by tensile testing and/or oxidation induction time). The autoclave test developed by BAM for durability assessments of polyolefin geosynthetics is based on the simultaneous application of moderately elevated temperatures (up to 80 degrees Celsius) and elevated oxygen pressures (up to 5.0 MPa) in combination with a surrounding aqueous medium. Thus this test method provides several advantages in comparison to conventional oven testing, especially with respect to test duration, impact of surrounding environment and the potential to differentiate and rank oxidative resistance between products of very different dimensions (surface/volume) and stabilisation. In view of the increasing demand for durability assessments of geosynthetic products with lifetimes significantly exceeding 25 years, the contribution is focused on practical aspects concerning implementation and optimisation of test procedures, conditions and evaluation of results. Furthermore, advanced approaches based on multiple exposure conditions will also be included and corresponding calculations of expected service life in typical applications will be evaluated with respect to significance and repeatability. Thereby involved standards and recommendations - such as EN ISO 13438, Part C or EAG-EDT - are considered. 2008 EuroGeo4, 4th European Geosynthetics Conference, September 7-10, 2008, Edinburgh, UK EuroGeo4, 4th European Geosynthetics Conference Edinburgh, UK 2008-09-07 2008-09-10 Paper 178 1 4 2016-02-19 OPUS4-18424 Beitrag zu einem Tagungsband Böhning, Martin; Robertson, Daniela; Schröder, Hartmut Autoclave testing: a new approach for the evaluation of oxidative long-term resistance of geosynthetics Oxidative long time resistance is essential for many polyolefin based products, especially if repair or exchange is not possible as encountered in many building and geotechnical applications. Current regulations and recommendations for geosynthetics cover mainly the needs of a maximum lifetime of 25 years, though many applications require longer lifetimes up to 100 years and more. Reliable testing of the long time oxidation resistance is complicated by the complex interplay of physicochemical processes and reactions in combination with the need of relatively short testing durations, usually not exceeding 12 months. Thus for conventional atmospheric oven testing, the use of temperatures higher than 100 °C is inevitable, making conclusive Arrhenius extrapolations often questionable. Practical assessments of oxidative durability consist of exposures under accelerated ageing conditions with subsequent characterization of exposed material samples with respect to their residual stabilization and/or their mechanical properties. The autoclave test combines exposures at elevated temperatures with higher oxygen pressures and is performed with material samples immersed in a well defined aqueous medium representing critical environments in geosynthetic applications and including extraction of additives. Under these conditions meaningful results can be obtained within reasonable testing durations at only moderately elevated temperatures up to 80 °C. Application of different physicochemical methods, such as tensile testing, OIT /HP-OIT and analysis of residual antioxidant content (ICOT), in order to determine the time dependent degradation behaviour, reveal valuable information about mechanisms and effectiveness of the used antioxidants. Corresponding results for exposures at different temperatures and oxygen pressures are the basis for a 3D-extrapolation in order to estimate the expected service life. Different empirical models are presented and discussed with respect to their practical impact. 2008 EuroGeo4, 4th European Geosynthetics Conference, September 7-10, 2008, Edinburgh, UK EuroGeo4, 4th European Geosynthetics Conference Edinburgh, UK 2008-09-07 2008-09-10 Paper 143 1 8 2016-02-19 OPUS4-18425 Beitrag zu einem Tagungsband Retzlaff, J.; Müller-Rochholz, J.; Klapperich, H.; Böhning, Martin The behaviour of geosynthetics under cyclic load Whenever geosynthetics are used to reinforce or stabilise infrastructural elements such as road- and railways, bridge abutments, run- and taxiways on airports or to protect coastlines of canals and other steep slopes they may be exposed to cyclic loads. Therefore, a reduction factor for dynamic effects on the geosynthetic tensile strength has been included into the calculation of the Long Term Design Strength (LTDS). An approach to assess the behaviour of geosynthetics is to adopt Woehler- or Smith graphs and Haigh-diagrams for polymers. This is because an endurance limit for polymers, which defines an infinite life under a defined cyclic load, has not been seen so far. A huge amount of mechanical testing is needed to predict the behaviour of geosynthetics against this particular background. To reduce these efforts while getting an indication of the cyclic effect on geosynthetics, a combined method of mechanical and chemical analysis has been developed. The pure tensile strength tests to determine the residual strength after cyclic stress has been amended by IR-spectroscopy and Differential Scanning Calorimetry (DSC). In this context the chain change model of PET has been proven as valid for cyclic loads as well, which helps to define the endurance limit of materials made out of PET. For polyolefins such as PP and PE, a limit for the maximum alternating load has been identified at the point of the stress strain graph where the actual and the numerical stress of a material diverge from each other. Cyclic tensile strength tests have been carried out in a hydraulic test frame. The test parameters have been set to simulate the service life of a railway bed trafficked by high speed trains (ICE). 2008 EuroGeo4, 4th European Geosynthetics Conference, September 7-10, 2008, Edinburgh, UK EuroGeo4, 4th European Geosynthetics Conference Edinburgh, UK 2008-09-07 2008-09-10 Paper 179 1 7 2016-02-19 OPUS4-16206 Zeitschriftenartikel Hölck, Ole; Heuchel, M.; Böhning, Martin; Hofmann, D. Simulation of Experimentally Observed Dilation Phenomena During Integral Gas Sorption in Glassy Polymers A molecular modeling investigation of dilation effects induced by sorbed gas molecules in two glassy polymers is presented. As experimental reference, integral sorption of CO2 and CH4 was measured for polysulfone (PSU) and a polyimide (6FDA-TrMPD, PI4) at 308 K and a pressure of 10 bar. Simultaneously, the gas induced swelling effect was measured with a dilatometer based on a capacitive distance sensor recorded. The experimental evidence of the (on the observed time scale and concentration levels) elastic nature of the gas induced dilation is supported by the dilation and contraction behavior observed in molecular dynamics (MD) simulations of respective detailed atomistic packing models. These models were constructed in accordance with gas concentration levels obtained from the experimental sorption results. Quantitative deviations between simulated and measured dilations are discussed as a consequence of an anelastic response of the polymer matrix which is too fast to be resolved in the experiments whose kinetics is dominated by diffusional processes. In the simulation, the initial insertion of penetrant molecules into equilibrated packing models circumvents the slow diffusional process of the experiment and allows a reasonable representation of the dilation process as well as a closer investigation. Our simulation approach reveals a different behavior for PSU and PI4 on the corresponding time scale. Most likely, the different chain mobility of the two polymers is responsible for the respective response to the inserted amount of gas molecules which is discussed in terms of the different chain mobilities of the two polymers. Hoboken, NJ Wiley 2008 Journal of polymer science B, polymer physics 46 1 59 71 10.1002/polb.21342 2016-02-19 OPUS4-14405 Zeitschriftenartikel Hölck, Ole; Siegert, M.R.; Heuchel, M.; Böhning, Martin CO2 Sorption Induced Dilation in Polysulfone: Comparative Analysis of Experimental and Molecular Modeling Results Experimental sorption and dilation data of the polysulfone/CO2 system at 308 K and pressures up to 50 bar were measured utilizing a gravimetric sorption balance and a dilatometer based on a capacitive distance sensor. The data of this glassy polymer/gas system were subjected to a thorough kinetic analysis on the basis of a viscoelastic model, which allows the separation of the diffusive/elastic fraction of the sorption/dilation process from the slower relaxational part. The results were interpreted in terms of the common dual mode sorption model and the site distribution model of Kirchheim. Detailed atomistic packing models of the same polymer/gas system were created for two reference states with regard to concentration and swelling. The CO2 sorption isotherms of the packing models corresponding to these two swelling states, calculated using GCMC simulations, could be combined in order to interpolate the gas uptake over the intermediate pressure range with good agreement to the experimental data. The elastic part of the gas induced dilation is successfully described by MD simulations and derived partial molar volumes are in satisfying agreement with experimental findings. Finally, the free volume of the packing models is probed and the obtained size distribution of the free volume elements is compared to the results of the analysis of experimental data according to the site distribution model. Washington, DC American Chemical Society 2006 Macromolecules 39 26 9590 9604 2016-02-19 OPUS4-14768 Zeitschriftenartikel Hao, Ning; Böhning, Martin; Goering, Harald; Schönhals, Andreas Nanocomposites of Polyhedral Oligomeric Phenethylsilsesquioxanes and Poly(bisphenol A carbonate) as Investigated by Dielectric Spectroscopy Nanocomposites were prepared by solution blending of polyhedral oligomeric silsesquioxane with phenethyl substituents (PhenethylPOSS) into poly(bisphenol A carbonate) (PBAC). The nanocomposites were investigated by dielectric spectroscopy, differential scanning calorimetry (DSC) and density measurements. PhenethylPOSS shows one relaxation process, the α-relaxation, confirmed by DSC investigations. PBAC shows a β-relaxation at lower and an α-relaxation at higher temperatures. With increasing PhenethylPOSS content the α-relaxation of the composites shifts to lower temperatures. Thus, incorporation of PhenethylPOSS leads to a plasticization of PBAC due to a decrease of the packing density which is rationalized by density measurements. For higher concentrations of PhenethylPOSS (>10 wt %) the α-relaxation of the polycarbonate matrix splits into two peaks. Moreover, close to the α-relaxation of PhenethylPOSS a third process is observed. These results indicate a phase separation into a PBAC matrix with a few percents of molecularly solved POSS and POSS-rich domains. These POSS-rich domains are surrounded by an interfacial layer of PBAC having a higher concentration of POSS than the matrix. A phase diagram is deduced providing a miscibility criterion. For the phase separated nanocomposites an interfacial polarization phenomena is observed. Using a simplified model the time constant of this process is correlated with the size of the PhenethylPOSS-rich domains and theire increasing size with the increase of the concentration of POSS. Washington, DC American Chemical Society 2007 Macromolecules 40 8 2955 2964 2016-02-19 OPUS4-7296 Posterpräsentation Böhning, Martin; Goering, Harald Preparation and Characterisation of Nanoscaled Nanostructured Materials 2004 Nanofair 2004 Nanofair 2004 Karlsruhe, Germany 2004-11-22 2004-11-24 2016-02-19 OPUS4-7297 Vortrag Böhning, Martin Small Molecules in Polymers and Polymer based Nanocomposites - Molecular Probes for Material Characterization and Design 2004 Polydays 2004 (Berliner Polymerentage); Universität Potsdam, Campus "Am Neuen Palais" Polydays 2004 (Berliner Polymerentage); Universität Potsdam, Campus "Am Neuen Palais" Potsdam, Germany 2004-10-04 2004-10-06 2016-02-19 OPUS4-12398 Zeitschriftenartikel Heuchel, M.; Böhning, Martin; Hölck, Ole; Siegert, M.R.; Hofmann, D. Atomistic Packing Models for Experimentally Investigated Swelling States Induced by CO2 in Glassy Polysulfone and Poly(ether sulfone) Atomistic packing models have been created, which help to better understand the experimentally observed swelling behavior of glassy polysulfone and poly (ether sulfone), under CO2 gas pressures up to 50 bar at 308 K. The experimental characterization includes the measurement of the time-dependent volume dilation of the polymer samples after a pressure step and the determination of the corresponding gas concentrations by gravimetric gas-sorption measurements. The models obtained by force-field-based molecular mechanics and molecular dynamics methods allow a detailed atomistic analysis of representative swelling states of polymer/gas systems, with respect to the dilation of the matrix. Also, changes of free volume distribution and backbone mobility are accessible. The behavior of gas molecules in unswollen and swollen polymer matrices is characterized in terms of sorption, diffusion, and plasticization. Hoboken, NJ Wiley 2006 Journal of polymer science B, polymer physics 44 13 1874 1897 10.1002/polb.20844 2016-02-19 OPUS4-29284 Zeitschriftenartikel Böhning, Martin; Hao, Ning; Schönhals, Andreas Correlation of activation energies of gas diffusivity and local matrix mobility in polycarbonate/POSS nanocomposites According to basic phenomenological models describing the solution-diffusion based mechanism of penetrant diffusion in dense polymers, a connection between the diffusive transport of gas molecules in a polymeric matrix and the molecular mobility of that matrix on a certain length scale is, in principle, established for a long time. However, experimental data directly showing this correlation are rare. The investigation of a series of nanocomposites based on a polyhedral oligomeric silsesquioxane (POSS) and a polycarbonate matrix allows a systematic change of the molecular mobility on a local length scale (β-relaxation) and of the corresponding activation energy EA, both determined by broadband dielectric spectroscopy. Independently, activation energies of penetrant diffusion (ED) of these nanocomposites were determined for N2, O2, CO2, and CH4 and a clear linear correlation between the two activation energies was established for the first time. Hoboken, NJ Wiley 2013 Journal of polymer science B, polymer physics 51 22 1593 1597 10.1002/polb.23381 2016-02-20 OPUS4-22378 Zeitschriftenartikel Hao, N.; Böhning, Martin; Schönhals, Andreas CO2 gas transport properties of nanocomposites based on polyhedral oligomeric phenethyl-silsesquioxanes and poly(bisphenol A carbonate) Polymer-based nanocomposites were prepared by solution blending of polyhedral oligomeric silsesquioxane with phenethyl substituents (PhenethylPOSS) into poly(bisphenol A carbonate) (PBAC). First investigations focused on structure, morphology and dynamics, addressed mainly by dielectric relaxation spectroscopy are substantially extended in this study by the investigation of the CO2 gas transport behavior of these materials, i.e., permeation experiments using the time-lag technique as well as gravimetric gas sorption measurements. The nanocomposite materials were prepared with nanofiller contents ranging from 0 to about 40 wt % by solution blending and films of about 50-100 µm thickness were cast from this solution and used for the investigation of gas transport properties after drying and annealing. From the time-lag measurements the permeability and an effective diffusion coefficient for CO2 is obtained in dependence of POSS concentration and temperature. As main results, both, the permeability and the diffusivity, increase whereas the solubility decreases with increasing POSS concentration. These findings are discussed in the framework of a microphase separated morphology of the nanocomposite systems for POSS concentrations greater than a value cPOSScrit of ca. 7 wt % consisting of a polycarbonate-rich matrix and POSS-rich domains which are surrounded by an interfacial layer. The experimental solubility data suggest that the POSS-rich domains are more or less impermeable for CO2. On the basis of this assumption a quantitative model is provided to correct the solubility data for the phase separated morphology. Moreover the importance of the interfacial layer between the POSS particles or its domains for the properties of nanocomposites especially for the gas transport behavior is addressed by analyzing the sorption isotherms. Also, for the first time results from gas transport measurements and dielectric spectroscopy were quantitatively related to each other by taking the activation energies of CO2 diffusion and of the dielectric β-relaxation into consideration. The obtained clear correlation indicates that the CO2 gas transport is due to localized molecular fluctuations. As a further result, the diffusion coefficient obtained from time-lag and gas sorption measurements is in good agreement with respect to both their absolute values and in their concentration dependence. Washington, DC American Chemical Society 2010 Macromolecules 43 22 9417 9425 10.1021/ma101463m 2016-02-19 OPUS4-21019 Vortrag Böhning, Martin Möglichkeiten der Abschätzung der Langzeitbeständigkeit von Kunststoffdichtungsbahnen (KDB) auf Polyolefinbasis für den Tunnelbau 2010 Fachtagung der Kompetenzplattformen "Life Cycle Assessment (LCA)" neuer Kunststoffe der FH Münster und "Polymere Materialien" der FH Aachen Fachtagung der Kompetenzplattformen "Life Cycle Assessment (LCA)" neuer Kunststoffe der FH Münster und "Polymere Materialien" der FH Aachen Münster, Germany 2010-02-25 2016-02-19 OPUS4-22103 Vortrag Böhning, Martin Oxidationsbeständigkeit von Geokunststoffen 2010 10. Schwarzheider Kunststoffkolloquium 10. Schwarzheider Kunststoffkolloquium Schwarzheide, Germany 2010-09-08 2010-09-09 2016-02-19 OPUS4-22104 Vortrag Böhning, Martin Charakterization of gas sorption in glassy polymers using experimental and molecular modeling techniques 2010 14th International Conference "Polymeric Materials" 14th International Conference "Polymeric Materials" Halle (Saale), Germany 2010-09-15 2010-09-17 2016-02-19 OPUS4-26630 Posterpräsentation Böhning, Martin Kinetic analysis of gas sorption and gas induced dilation and relaxation behaviour of PIM-1 compared to other glassy polymers 2012 Euromembrane 2012 Euromembrane 2012 London, England 2012-09-23 2012-09-27 2016-02-19 OPUS4-26631 Vortrag Böhning, Martin Gas transport in glassy polymers and PNCs - experiment, analysis, modeling of diffusion, sorption and dilation 2012 Workshop: Nanostructured and Nanocomposite Membranes for Gas und Vapour Separation Workshop: Nanostructured and Nanocomposite Membranes for Gas und Vapour Separation Cetraro, Italy 2012-05-15 2012-05-18 2016-02-19 OPUS4-26629 Posterpräsentation Böhning, Martin Correlation of gas diffusivity and local chain mobility in polycarbonate/POSS nanocomposites as determined by broadband dielectric relaxation spectroscopy 2012 Euromembrane 2012 Euromembrane 2012 London, England 2012-09-23 2012-09-27 2016-02-19 OPUS4-27312 Beitrag zu einem Tagungsband Robertson, Daniela; Schröder, Hartmut; Böhning, Martin; Brummermann, K.; Kaundinya, I.; Saathoff, F. Test method for the assessment of the service life of polymeric geosynthetic barriers (GBR-P) for road tunnels 2012 Euro GEO 5 - 5th European geosynthetics congress (Proceedings) 1 978-0415-64340-5 Euro GEO 5 - 5th European geosynthetics congress Valencia, Spain 2012-09-16 2012-09-19 Topic: Transport 150 154 2016-02-20 OPUS4-30096 Zeitschriftenartikel Böhning, Martin; Niebergall, Ute; Adam, Adeline; Stark, Wolfgang Impact of biodiesel sorption on mechanical properties of polyethylene The time-dependent sorption of biodiesel in a typical polyethylene for container applications is investigated in comparison to conventional diesel fuel at three different temperatures. In this context, the desorption behavior is also addressed. Subsequently, the effects of both penetrants on mechanical properties are characterized in terms of impact strength and dynamic-mechanical analysis. The discussion of property changes is firstly based on the sorption kinetics of biodiesel and diesel, which is determined by immersion experiments allowing for the calculation of respective diffusion coefficients. Changes in impact strength as determined by the Charpy method are further characterised in more detail by analyzing the fracture surfaces, and correlated with results of dynamic-mechanical analysis. Amsterdam [u.a.] Elsevier Science 2014 Polymer Testing 34 17 24 10.1016/j.polymertesting.2013.12.003 2016-02-20 OPUS4-55047 Zeitschriftenartikel Thuy, Maximilian; Pedragosa-Rincon, M.; Niebergall, Ute; Oehler, H.; Alig, I.; Böhning, Martin Environmental Stress Cracking of High-Density Polyethylene Applying Linear Elastic Fracture Mechanics The crack propagation rate of environmental stress cracking was studied on high-density polyethylene compact tension specimens under static loading. Selected environmental liquids are distilled water, 2 wt% aqueous Arkopal N100 solution, and two model liquid mixtures, one based on solvents and one on detergents, representing stress cracking test liquids for commercial crop protection products. The different surface tensions and solubilities, which affect the energetic facilitation of void nucleation and craze development, are studied. Crack growth in surface-active media is strongly accelerated as the solvents induce plasticization, followed by strong blunting significantly retarding both crack initiation and crack propagation. The crack propagation rate for static load as a function of the stress intensity factor within all environments is found to follow the Paris-Erdogan law. Scanning electron micrographs of the fracture surface highlight more pronounced structures with both extensive degrees of plasticization and reduced crack propagation rate, addressing the distinct creep behavior of fibrils. Additionally, the limitations of linear elastic fracture mechanisms for visco-elastic polymers exposed to environmental liquids are discussed. Basel MDPI 2022 Polymers 14 12 1 21 urn:nbn:de:kobv:b43-550476 10.3390/polym14122415 https://creativecommons.org/licenses/by/4.0/deed.de 2022-06-16 OPUS4-54565 Buchkapitel Schönhals, Andreas; Böhning, Martin; Szymoniak, Paulina Schönhals, Andreas; Szymoniak, Paulina (Nano)Composite Materials—An Introduction The chapter gives a brief introduction to (nano)compositecomposite materials having the focus on polymer-based nanocomposites. The different dimensionalities of nanoparticles are introduced, along with their distribution in the matrix. Different application fields of polymer-based nanocomposites, like flame retardancy, filled rubbers, nanofilled thermosets and thermoplastics, separation membranes and nanodielectrics, are considered in greater detail. Cham, Switzerland Springer 2022 Dynamics of Coposite Materials 1 31 10.1007/978-3-030-89723-9_1 2022-03-31 OPUS4-53849 Zeitschriftenartikel Zorn, R.; Szymoniak, Paulina; Kolmangadi, Mohamed Aejaz; Malpass-Evans, R.; McKeown, N.; Tyagi, M.; Böhning, Martin; Schönhals, Andreas Low frequency vibrations and diffusion in disordered polymers bearing an intrinsic microporosity as revealed by neutron scattering The microscopic diffusion and the low frequency density of states (VDOS) of PIM-EATB(CH3) are investigated by inelastic and quasi-elastic neutron scattering where also the demethylated counterpart of PIM-EA-TB(H2) is considered. These intrinsic microporous polymers are characterized by large BET surface area values of several hundred m2/g and pore sizes between 0.5 and 2 nm. Detailed comparison is made to the archetype of polymers of intrinsic microporosity, PIM-1, and polynorbornenes also bearing a microporosity. Due to the wavelength of neutrons, the diffusion and vibrations can be addressed on microscopic length and time scales. From the inelastic neutron scattering experiments the low frequency density of states (VDOS) is estimated which shows excess contributions to the Debye-type VDOS known as Boson peak. It was found that the maximum frequency of the Boson peak decreases with increasing microporosity characterized by the BET surface area. However, besides the BET surface area, additional factors such as the backbone stiffness govern the maximum frequency of the Boson peak. Further the mean squared displacement related to microscopic motions was estimated from elastic fixed window scans. At temperatures above 175 K, the mean squared displacement PIM-EA-TB(CH3) is higher than that for the demethylated counterpart PIM-EA-TB(H2). The additional contribution found for PIM-EATB(CH3) is ascribed to the rotation of the methyl group in this polymer because the only difference between the two structures is that PIM-EA-TB(CH3) has methyl groups where PIM-EA-TB(H2) has none. A detailed comparison of the molecular dynamics is also made to that of PIM-1 and the microporous polynorbornene PTCNSi1. The manuscript focuses on the importance of vibrations and the localized molecular mobility characterized by the microscopic diffusion on the gas Transport in polymeric separation membranes. In the frame of the random gate model localized fluctuations can open or close bottlenecks between pores to enable the diffusion of gas molecules. Basel MDPI 2021 Crystals 11 12 1 16 urn:nbn:de:kobv:b43-538490 10.3390/cryst11121482 https://creativecommons.org/licenses/by/4.0/deed.de 2021-12-01 OPUS4-54708 Zeitschriftenartikel Kolmangadi, Mohamed Aejaz; Szymoniak, Paulina; Zorn, R.; Böhning, Martin; Wolff, M.; Zamponi, M.; Schönhals, Andreas Molecular mobility in high-performance polynorbornenes:A combined broadband dielectric, advanced calorimetry,and neutron scattering investigation The molecular dynamics of two addition type polynorbornenes, exo-PNBSiand PTCNSi1, bearing microporosity has been investigated by broadbanddielectric spectroscopy, fast scanning calorimetry, and neutron scattering. Bothpolymers have the same side groups but different backbones. Due to theirfavorable transport properties, these polymers have potential applications inseparation membranes for gases. It is established in literature that molecularfluctuations are important for the diffusion of small molecules through poly-mers. For exo-PNBSi, two dielectric processes are observed, which are assignedto Maxwell/Wagner/Sillars (MWS) process due to blocking of charge carriersat internal voids or pore walls. For PTCNSi1, one MWS-polarization process isfound. This points to a bimodal pore-size distribution for exo-PNBSi. A glasstransition for exo-PNBSi and for PTCNSi1 could be evidenced for the first timeusing fast scanning calorimetry. For Tgand the corresponding apparent activa-tion energy, higher values were found for PTCNSi1 compared to exo-PNBSi.For both polymers, the neutron scattering data reveal one relaxation process.This process is mainly assigned to methyl group rotation probably overlayedby carbon-carbon torsional fluctuations. Wiley 2022 Polymer Engineering and Science 62 7 2143 2155 urn:nbn:de:kobv:b43-547086 10.1002/pen.25995 https://creativecommons.org/licenses/by/4.0/deed.de 2022-04-28 OPUS4-54330 Zeitschriftenartikel Strommer, Bettina; Battig, Alexander; Frasca, Daniele; Schulze, Dietmar; Huth, Christian; Böhning, Martin; Schartel, Bernhard Multifunctional Property Improvements by Combining Graphene and Conventional Fillers in Chlorosulfonated Polyethylene Rubber Composites The incorporation of nanoparticles like multilayer graphene (MLG) into elastomeric composites boosts their technical performance, such as their mechanical behavior and electrical conductivity. Common filler types (carbon black (CB) and aluminum trihydroxide (ATH)) generally fulfill single, specific purposes and are often used in high loadings. CB typically reinforces rubber mechanically, while ATH increases flame retardancy. Small amounts of MLG reduce these high filler contents and maintain the multifunctional characteristics of rubber composites. In chlorosulfonated polyethylene (CSM) + ATH, an intrinsically flame-retardant rubber was designed to achieve the highest standards such as maximum average of heat emission (MARHE) <90 kW m−2, 3 phrMLG was substituted for 15 phr CB and/or 3 phr ATH via an industrially applicable processing approach. Replacing either CB or ATH resulted in a property profile that was multifunctionally improved in terms of features such as mechanical performance, reduced sorption, and flame retardance. MLG nanocomposites are reported to show promise as an industrially utilizable route to obtain multifunctional high-performance rubbers. Washington, DC ACS Publ. 2022 ACS Applied Polymer Materials 4 2 1021 1034 10.1021/acsapm.1c01469 2022-02-14 OPUS4-54303 Zeitschriftenartikel Kolmangadi, Mohamed Aejaz; Szymoniak, Paulina; Smales, Glen Jacob; Bermeshev, M.; Schönhals, Andreas; Böhning, Martin Molecular mobility of polynorbornenes with trimethylsiloxysilyl side groups: Influence of the polymerization mechanism We report dielectric and calorimetric studies on metathesis and addition-type polytricyclononenes, both based on the same monomer bearing three pendant OSiMe3 groups. For the addition-type polymer, dielectric spectroscopy reveals a β*-process related to the microporosity, whereas for its metathesis counterpart, the segmental dynamics manifests as an α-process related to a glass transition. Besides active dielectric processes, a significant conductivity contribution is detected for both samples which for the microporous additiontype polymer is three orders of magnitude greater than for the metathesis polymer. The broadband dielectric spectroscopy is complemented by detailed calorimetric investigations, comprising DSC, FSC, and TMDSC. The calorimetric methods detected the glass transition for the metathesis polymer in agreement with the observed dielectric α-process. Furthermore, the already reported gas transport properties for both polymers are compared, setting them in correlation with the observed molecular mobility and conductivity behavior. The discussed results reflect significant differences in molecular mobility of the two polymers affecting the appearance of microporosity which strongly determines the gas transport properties. Tehran Membrane Processes Research Laboratory (MPRL) 2022 Journal of membrane science and research 8 3 1 9 10.22079/JMSR.2021.538060.1495 2022-02-11 OPUS4-53508 Zeitschriftenartikel Schönhals, Andreas; Szymoniak, Paulina; Kolmangadi, Mohamed Aejaz; Böhning, Martin; Zamponi, M.; Frick, B.; Appel, M.; Günther, G.; Russina, M.; Alentiev, D.; Bermeshev, M.; Zorn, R. Microscopic dynamics of highly permeable super glassy polynorbornenes revealed by quasielastic neutron scattering The molecular dynamics of addition-type poly(tricyclononenes) with Si-substituted bulky side groups has been investigated by a combination of neutron time-of-flight and neutron backscattering spectroscopy methods on a time scale from 0.1 ps to ca. 3 ns. The investigated poly(tricyclononenes) PTCNSi1 and PTCNSi2g both bear a high microporosity which makes them promising candidates for active separation layers for gas separation membranes. At least for larger gas molecules it is assumed that the pathways for diffusion require an enlargement of pre-existing micropores in terms of an activated zone. A low temperature relaxation process was found for both polymers by the performed neutron scattering experiments. This process was assigned to the methyl group rotation. It was analysed in terms of a jump diffusion in a three-fold potential. The analysis of the dependence of the elastic incoherent structure factor on the scattering vector yields the number of methyl groups which might be immobilized. For PTCNSi1 (3 methyl groups in the monomeric unit) it was found that all methyl groups take part in the methyl group rotation whereas for PTCNSi2g (6 methyl groups in monomeric unit) a considerable number of methyl groups are blocked in their rotation. This immobilization of methyl groups is due to the sterically demanding arrangement of the methyl groups in PTCNSi2g. This conclusion is further supported by the result that the activation energy for the methyl group rotation is three times higher for PTCNSi2g than that of PTCNSi1. Elesevier B.V. 2021 Journal of Membrane Science 642 10.1016/j.memsci.2021.119972 2021-10-13 OPUS4-52101 Zeitschriftenartikel Schilling, Markus; Niebergall, Ute; Marschall, Niklas; Alig, I.; Böhning, Martin A phenomenological criterion for an optical assessment of PE-HD fracture surfaces obtained from FNCT The full-notch creep test (FNCT) is a common test method to evaluate the environmental stress cracking (ESC) behavior of high-density polyethylene (PE-HD), e.g. for container materials. The test procedure as specified in ISO 16770 provides a comparative measure of the resistance against ESC using the time to failure of PE-HD specimens under constant mechanical load in a well-defined liquid test environment. Since the craze-crack damage mechanism underlying the ESC phenomenon is associated with brittle failure, the occurrence of a predominantly brittle fracture surface is a prerequisite to consider an FNCT measurement as representative for ESC, i.e. a time to failure dominated by craze-crack propagation. The craze-crack propagation continuously reduces the effective residual cross-sectional area of the specimen during the test, which results in a corresponding increase of the effective mechanical stress. Thus, a transition to ductile shear deformation is inevitable at later stages of the test, leading usually to a pronounced central ligament. Therefore, an optical evaluation of FNCT fracture surfaces concerning their brittleness is essential. An enhanced imaging analysis of FNCT fracture surfaces enables a detailed assessment of craze-crack Propagation during ESC. In this study, laser scanning microscopy (LSM) was employed to evaluate whether FNCT fracture surfaces are representative with respect to craze-crack propagation and ESC. Based on LSM height data, a phenomenological criterion is proposed to assess the validity of distinct FNCT measurements. This criterion is supposed to facilitate a quick evaluation of FNCT results in practical routine testing. Its applicability is verified on a sample basis for seven different commercial PE-HD container materials. Amsterdam Elsevier Ltd. 2021 Polymer Testing 94 107002 urn:nbn:de:kobv:b43-521012 10.1016/j.polymertesting.2020.107002 https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de 2021-02-11 OPUS4-52686 Zeitschriftenartikel Thuy, Maximilian; Niebergall, Ute; Oehler, H.; Alig, I.; Böhning, Martin Evaluation of the damaging effect of crop protection formulations on high density polyethylene using the Full Notch Creep Test Four typical high-density polyethylene container materials were used to investigate damage or stress cracking behavior in contact with model liquids for crop protection products. These model liquids are established in German regulations for the approval of dangerous goods containers and consist of typical admixtures used for crop protection products but without biological active ingredients. This study is performed with the standardized method of Full Notch Creep Test, adapting the media temperature to 40 °C according to the usual conditions where these test liquids are applied. The two model liquids differ into a water-based solution and a composition based on different organic solvents which are absorbed by the material up to significant levels. Therefore, extensive sorption measurements are performed. The fracture surfaces obtained are analyzed in detail not only by light microscopy, but also by laser scanning microscopy as well as scanning electron microscopy. Influence of pre-saturation and applied stress are addressed by respective systematic series of experiments. Elsevier Ltd. 2021 Polymer 228 123853 10.1016/j.polymer.2021.123853 2021-05-31 OPUS4-55485 Zeitschriftenartikel Emamverdi, Farnaz; Yin, Huajie; Smales, Glen Jacob; Harrison, W. J.; Budd, P. M.; Böhning, Martin; Schönhals, Andreas Polymers of intrinsic microporosity - Molecular mobility and physical aging revisited by dielectric spectroscopy and X‑ray scattering Polymers of intrinsic microporosity (PIMs) are promising candidates for the active layer in gas separation membranes due to their high permeability and reasonable permselectivity. These appealing properties originate from a microporous structure as a result of inefficient segment packing in the condensed state due to a combination of a ladder-like rigid backbone and sites of contortion. However, this class of polymers suffers from a significant decrease in the permeability with time due to physical aging, whereby typically, the permselectivity increases. The initial microporous structures approach a denser state via local rearrangements, leading to the reduction of the permeability. Hence, a detailed characterization of the molecular mobility in such materials can provide valuable information on physical aging. In this work, the dielectric behavior of PIM-1 films and their behavior upon heating (aging) were revisited by isothermal frequency scans during different heating/cooling cycles over a broad temperature range between 133 and 523 K (−140 to 250 °C). In addition, the obtained results were compared with data of samples that were annealed at ambient temperatures over different time scales. Multiple dielectric processes were observed: several relaxation processes due to local fluctuations and a Maxwell−Wagner−Sillars polarization effect related to the microporosity. The temperature dependence of the rates of all processes follows the Arrhenius law where the estimated activation energy depends on the nature of the process. The influence of the thermal history (aging) on the processes is discussed in detail. Washington, DC American Chemical Society 2022 Macromolecules 55 7340 7350 10.1021/acs.macromol.2c00934 2022-08-12 OPUS4-56040 Zeitschriftenartikel Strommer, Bettina; Schulze, Dietmar; Schartel, Bernhard; Böhning, Martin Networking Skills: The Effect of Graphene on the Crosslinking of Natural Rubber Nanocomposites with Sulfur and Peroxide Systems Tailored crosslinking in elastomers is crucial for their technical applications. The incorporation of nanoparticles with high surface-to-volume ratios not only leads to the formation of physical networks and influences the ultimate performance of nanocomposites, but it also affects the chemical crosslinking reactions. The influence of few-layer graphene (FLG) on the crosslinking behavior of natural rubber is investigated. Four different curing systems, two sulfur-based with different accelerator-to-sulfur ratios, and two peroxide-based with different peroxide concentrations, are combined with different FLG contents. Using differential scanning calorimetry (DSC), vulcametry (MDR) and swelling measurements, the results show an accelerating effect of FLG on the kinetics of the sulfur-based curing systems, with an exothermic reaction peak in DSC shifted to lower temperatures and lower scorch and curing times in the MDR. While a higher accelerator-to-sulfur ratio in combination with FLG leads to reduced crosslinking densities, the peroxide crosslinkers are hardly affected by the presence of FLG. The good agreement of crosslink densities obtained from the swelling behavior confirms the suitability of vulcameter measurements for monitoring the complex vulcanization process of such nanocomposite systems in a simple and efficient way. The reinforcing effect of FLG shows the highest relative improvements in weakly crosslinked nanocomposites. MDPI 2022 Polymers 14 20 urn:nbn:de:kobv:b43-560409 10.3390/polym14204363 https://creativecommons.org/licenses/by/4.0/deed.de 2022-10-19 OPUS4-55797 Zeitschriftenartikel Maximilian, Thuy; Spyrantis, Alexander; Böhning, Martin; Niebergall, Ute; Maaß, Robert Spatially resolved roughness exponent in polymer fracture The fracture surface of slow and continuous crack propagation during environmental stress cracking of a semicrystalline polyethylene exhibits isotropic roughness exponents at the local scale but resolved across the macroscopic fracture surface a clear position dependence is found. The spatially resolved roughness exponent admits values in the range between 0.1 and 0.4, demonstrating nontrivial exponents in the small length-scale regime. Instead, they vary across the fracture surface according to the stress-state distribution, which suggests that the exponents are intimately linked to the locally dominating dissipation processes during craze cracking. USA, Maryland American Physical Society 2022 Physical review materials 6 9 1 7 10.1103/PhysRevMaterials.6.L090601 2022-09-22 OPUS4-55463 Zeitschriftenartikel Thuy, Maximilian; Niebergall, Ute; Oehler, H.; Alig, I.; Böhning, Martin Damaging effect of admixtures used in crop protection products on high density polyethylene packaging material The phenomenon of environmental stress cracking is still a major issue in materials engineering as well as from a scientific perspective. Especially in the case of packaging materials made of high-density polyethylene, assessing the potential of premature damage due to environmental stress cracking is complex because of the large number of components in possible liquid filling goods. As a first guideline, the well-known effect of detergents and dispersants is usually considered, but the interplay with other components, such as organic solvents is often unknown. Particularly challenging in this respect are crop protection products, consisting of several different admixtures in addition to the biologically active ingredients. This study is based on two model liquids representing these admixtures that were established for testing in this context. The model liquids as well as their constituting components were used as liquid media in the Full Notch Creep Test to characterize the environmental stress cracking behavior of a typical high-density polyethylene. Complementary to the time-to failure of a notched specimen obtained from these tests, the crack opening was monitored optically, and the fracture surface was analyzed post-failure by laser scanning microscopy as well as scanning electron microscopy. Based on the results, the effect of various surfactants as well as the influence of organic solvents on environmental stress cracking are discussed. Amsterdam Elsevier Ltd. 2022 Polymer Testing 114 1 16 urn:nbn:de:kobv:b43-554631 10.1016/j.polymertesting.2022.107672 https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de 2022-08-10 OPUS4-57152 Zeitschriftenartikel Strommer, Bettina; Schulze, Dietmar; Schartel, Bernhard; Böhning, Martin The quantification of anisotropy in graphene/natural rubber nanocomposites: Evaluation of the aspect ratio, concentration, and crosslinking In the processing of nanocomposites, high shear stresses at elevated tempera-tures orient two-dimensional nanoparticles like graphene. This orientationleads to anisotropic mechanical, thermal or barrier properties of the nanocom-posite. This anisotropy is addressed in this study by comparing graphene (few-layer graphene, FLG) with a nanoscaled carbon black (nCB) at a filler contentof 3 phr, by varying the vulcanization, and by comparing different FLG con-tents. Transmission electron microscopy gives insight into the qualitative ori-entation in the nanocomposite with FLG or nCB. The storage moduli paralleland normal to the orientation reveal the direction dependency of reinforce-ment through dynamic mechanical analysis (DMA). Dimensional swellingmeasurements show a restriction of the expansion parallel to the FLG orienta-tion, and an increased expansion normal to the orientation. The vulcanizationsystem and crosslinking determine the respective level of property values, andhigher crosslinking densities increase the anisotropy in DMA resulting invalues of up to 2.9 for the quantified anisotropy factor. With increasing FLGcontent, the anisotropy increases. A comparison of the results reveals swellingmeasurements as the most suitable method for the determination of anisot-ropy. Compared to recent literature, the presented processing induces higheranisotropy, leading to higher reinforcing effects in the direction of orientation Hoboken, New Jersey (USA) Wiley online library 2023 Journal of Applied Polymer Science 140 16 1 15 urn:nbn:de:kobv:b43-571522 10.1002/app.53753 https://creativecommons.org/licenses/by/4.0/deed.de 2023-03-16 OPUS4-36864 Zeitschriftenartikel Schartel, Bernhard; Frasca, Daniele; Schulze, Dietmar; Wachtendorf, Volker; Krafft, Bernd; Morys, Michael; Böhning, Martin; Rybak, Thomas Multilayer graphene rubber nanocomposites Multilayer Graphene (MLG), a nanoparticle with a specific surface of BET = 250 m²/g and thus made of only approximately 10 graphene sheets, is proposed as a nanofiller for rubbers. When homogenously dispersed, it works at low loadings enabling the replacement of carbon black (CB), increase in efficiency, or reduction in filler concentration. Actually the appropriate preparation yielded nanocomposites in which just 3 phr are sufficient to significantly improve the rheological, curing and mechanical properties of different rubbers, as shown for Chlorine-Isobutylene-Isoprene Rubber (CIIR), Nitrile-Butadiene Rubber (NBR), Natural Rubber (NR), and Styrene-Butadiene Rubber (SBR). A mere 3 phr of MLG tripled the Young's modulus of CIIR, an effect equivalent to 20 phr of carbon black. Similar equivalents are observed for MLG/CB mixtures. MLG reduces gas permeability, increases thermal and electrical conductivities, and retards fire behavior. The later shown by the reduction in heat release rate in the cone calorimeter. The higher the nanofiller concentration is (3 phr, 5 phr, and 10 phr was investigated), the greater the improvement in the properties of the nanocomposites. Moreover, the MLG nanocomposites improve stability of mechanical properties against weathering. An increase in UV-absorption as well as a pronounced radical scavenging are proposed and were proved experimentally. To sum up, MLG is interesting as a multifunctional nanofiller and seems to be quite ready for rubber development. AIP AIP 2016 AIP Conference Proceedings 1736 978-0-7354-1390-0 TOP 2016, VIII International Conference on “Times of Polymers and Composites” Naples, Italy 19.06.2016 23.06.2016 020046, 1 4 10.1063/1.4949621 2016-07-15 OPUS4-37595 Zeitschriftenartikel Frasca, Daniele; Schulze, Dietmar; Böhning, Martin; Krafft, Bernd; Schartel, Bernhard Multilayer graphene chlorine isobutyl isoprene rubber nanocomposites: influence of the multilayer graphene concentration on physical and flame-retardant properties In recent years, different nanoparticles have been proposed and successfully introduced as nanofillers in rubber nanocomposites. In this study, multilayer graphene (MLG) is proposed as a nanoparticle that functions efficiently at low concentrations. MLG consists of just 10 or so graphene sheets. Chlorine isobutyl isoprene rubber (CIIR)/MLG nanocomposites with different MLG loadings were prepared using an ultrasonically assisted solution mixing procedure followed by two-roll milling. The incorporation of MLG provides a clear improvement in the rheological, mechanical, curing, and gas barrier properties of the nanocomposites. Adding only 3 phr ofMLGto CIIR increased the Young's modulus by more than two times and reduced the permeability ofO2 andCO2 by 30%. Higher nanofiller concentrations yielded further improvement in the properties of the nanocomposites. Moreover, CIIR/MLG nanocomposites showed reduced flammability. 2016 Rubber Chemistry and Technology 89 2 316 334 10.5254/rct.15.84838 2016-09-30 OPUS4-31583 Zeitschriftenartikel Böhning, Martin; Niebergall, Ute; Adam, Adeline; Stark, Wolfgang Influence of biodiesel sorption on temperature-dependent impact properties of polyethylene In a previous paper we investigated the influence of sorbed biodiesel or diesel on mechanical properties of a typical polyethylene grade for tank applications. Besides the basic sorption and desorption behavior of these two fuels, the study addressed the concentration-dependent mechanical properties as revealed by a non-instrumented Charpy impact test and dynamic mechanical analysis (DMA). In the present paper we extend this investigation focusing on the temperature-dependent impact fracture behavior. Therefore, an instrumented Charpy impact test was employed, allowing a more detailed analysis of the fracture behavior. Furthermore, from the load-time-diagrams obtained from the instrumented impact test, corresponding fracture times can be calculated, allowing a clear correlation of the fuel sorption induced changes in fracture toughness with the enhanced ß-relaxation observed by DMA. As in the previous study, the fracture surfaces of the impact tested specimens were analyzed in order to confirm the brittle or ductile character of the fracture indicated by impact strength and the corresponding load-deflection diagrams. Amsterdam [u.a.] Elsevier Science 2014 Polymer Testing 40 133 142 10.1016/j.polymertesting.2014.09.001 2016-02-20 OPUS4-21997 Beitrag zu einem Tagungsband von der Ehe, Kerstin; Jaunich, Matthias; Böhning, Martin; Goering, Harald; Wolff, Dietmar Detection of structural changes of (U)HMW-PE induced by gamma irradiation Halle / Saale Druck-Zuck GmbH 2010 14th International conference "Polymeric materials" - P.2010 (Proceedings) 978-3-86829-282-4 14th International conference "Polymeric materials" Halle (Saale), Germany 2010-09-15 2010-09-17 1 6 2016-02-19 OPUS4-20103 Vortrag Böhning, Martin Atomistic simulation of gas sorption isotherms in a polymer of intrinsic microporosity (PIM-1) 2009 EUROMEMBRANE 2009 Conference EUROMEMBRANE 2009 Conference Montpellier, France 2009-09-06 2009-09-10 2016-02-19 OPUS4-19106 Beitrag zu einem Tagungsband Heuchel, M.; Hölck, Ole; Böhning, Martin; Siegert, R.; Hofmann, D. Qi, Y.; H.E. Fang, ; N. Reynolds, ; Liu, Z.-K. Knowledge-based approach to gas sorption in glassy polymers by combining experimental and molecular simulation techniques We present a method which allows to calculate gas sorption in complex polymers where, as slow processes, gas induced plasticization and volume dilation are important factors. Since the relaxational swelling of the polymer matrix that is observed at elevated gas concentrations takes hours or days, the swelling process is orders of magnitudes too slow to simulate the respective molecular dynamics in reasonable time and effort. To address this apparent incompatibility of experiment and simulation, we use single representative reference states from experiment and construct atomistic packing models according to these specifications. Gas sorption of CO2 and CH4 was successfully calculated on polysulfone, a 6FDA-polyimide, and a polymer of intrinsic microporosity, PIM-1, at 308 K and pressures up to 50 bar. Materials Research Society 2009 MRS Fall Meeting 2008 - Symposium W - Computational Materials Design via Multiscale Modeling (Proceedings) 1130 MRS Fall Meeting 2008 - Symposium W - Computational Materials Design via Multiscale Modeling Boston, MA, USA 2008-12-01 2008-12-05 W06 W10 10.1557/PROC-1130-W06-10 2016-02-19 OPUS4-20018 Vortrag Böhning, Martin Gas sorption in glassy polymers - Comparative characterization using experimental and molecular modeling techniques 2009 EUROMEMBRANE 2009 Conference EUROMEMBRANE 2009 Conference Montpellier, France 2009-09-06 2009-09-10 2016-02-19 OPUS4-38735 Zeitschriftenartikel Becker, D.; Konnertz, Nora; Böhning, Martin; Schmidt, J.; Thomas, A. Light-switchable polymers of intrinsic microporosity The interest in (micro)porous systems is greater than ever before with microporous polymers finding application in areas such as gas storage/separation and catalysis. In contrast to the vast majority of publications on microporous polymers seeking ever higher values for surface area or uptake capacity for a particular gas, this work presents a means to render a microporous system responsive to electromagnetic stimuli. The incorporation of a diarylethene (DAE) derivative in the backbone of a polymer of intrinsic microporosity (PIM) produces a microporous system that exhibits photochromism as proven by UV-vis absorption and NMR studies. In the resulting DAE-PIM, surface area is not a fixed unalterable property but can be influenced by the external and nondestructive stimulus light in a reversible manner. Furthermore, in combination with Matrimid, free-standing membranes can be produced that display light-switchable diffusivity and permeability for carbon dioxide and oxygen. In this way, material scientists are offered the potential to employ only one system that can assume several states with different properties for each. Whashington,DC ACS 2016 Chemistry of Materials 28 23 8523 8529 10.1021/acs.chemmater.6b02619 2016-12-20 OPUS4-39169 Zeitschriftenartikel Konnertz, Nora; Ding, Yi; Harrison, W.J.; Budd, P.M.; Schönhals, Andreas; Böhning, Martin Molecular mobility and gas transport properties of nanocomposites based on PIM-1 and polyhedral oligomeric phenethyl-silsesquioxanes (POSS) Polymers with intrinsic microporosity (PIMs) are of great interest in the field of gas separation membranes. Already the first synthesized PIM-1 shows extraordinary permeability and selectivity. Unfortunately, PIM-1 is susceptible to physical aging and thus gradually loses its outstanding properties. In this study a polyhedral oligomeric silsesquioxane with phenethyl substituents (PhenethylPOSS) was used as a nanofiller (0-40 wt%) in the PIM-1 matrix to potentially improve the gas transport properties and prevent physical aging. The molecular mobility of the solution-cast nanocomposite films was analyzed by Broadband Dielectric Spectroscopy (BDS). Furthermore, gas permeability was determined with the time lag method (0-20 bar upstream pressure) at 35 °C for N2, O2, CH4 and CO2. Amsterdam Elsevier B.V. 2017 Journal of Membrane Science 529 274 285 10.1016/j.memsci.2017.02.007 2017-02-20 OPUS4-43808 Zeitschriftenartikel Zorn, R.; Yin, Huajie; Lohstroh, W.; Harrison, W.; Budd, P.M.; Pauw, Brian Richard; Böhning, Martin; Schönhals, Andreas Anomalies in the low frequency vibrational density of states for a polymer with intrinsic microporosity - the Boson peak of PIM-1 Polymers with intrinsic microporosity are promising candidates for the active separation layer in gas separation membranes. Here, the vibrational density of states (VDOS) for PIM-1, the prototypical polymer with intrinsic microporosity, is investigated by means of inelastic neutron scattering. The results are compared to data measured for a more conventional high-performance polyimide used in gas separation membranes (Matrimid). The measured data show the characteristic low frequency excess contribution to VDOS above the Debye sound wave level, generally known as the Boson peak in glass-forming materials. In comparison to the Boson peak of Matrimid, that of PIM-1 is shifted to lower frequencies. This shift is discussed considering the microporous, sponge-like structure of PIM-1 as providing a higher compressibility at the molecular scale than for conventional polymers. For an annealed PIM-1 sample, the Boson peak shifts to higher frequencies in comparison to the un-annealed sample. These changes in the VDOS of the annealed PIM-1 sample are related to changes in the microporous structure as confirmed by X-ray scattering. The Royal Society of Chemistry 2018 Physical Chemistry Chemical Physics 20 3 1355 1363 10.1039/C7CP07141H 2018-01-18 OPUS4-44683 Zeitschriftenartikel Yin, Huajie; Chua, Y. Z.; Yang, B.; Schick, C.; Harrison, W.; Budd, P.; Böhning, Martin; Schönhals, Andreas First clear cut experimental evidence for a glass transition in a polymer with intrinsic microporosity: PIM-1 Polymers with intrinsic microporosity (PIMs) represent a novel, innovative class of materials with great potential in various applications from high-performance gas separation membranes to electronic devices. Here for the first time, for PIM-1, as the archetypal PIM, fast scanning calorimetry provides definitive evidence for a glass transition (Tg=715 K, heating rate 3·10^4 K/s) by decoupling the time-scales responsible for glass transition and decomposition. As the rigid molecular structure of PIM-1 prevents any conformational changes, small-scale bend and flex fluctuations must be considered the origin of its glass transition. This result has strong implications for the fundamental understanding of the glass transition and for the physical aging of PIMs and other complex polymers, both topical problems of materials science. ACS 2018 Journal Physical Chemistry Letters 9 8 2003 2008 10.1021/acs.jpclett.8b00422 2018-04-13 OPUS4-48142 Vortrag Böhning, Martin Characterization of high-performance membrane polymers for gas separation using broadband dielectric spectroscopy In recent years superglassy polymers exhibiting intrinsic microporosity established a new perspective for a number of applications, especially for gas separation membranes as These polymers Combine extremely high permeabilities with attractive selectivities. The essential factor governing the structure Formation in the solid film or layer is either a contorted rigid Backbone (polymers of intrinsic microporosity - PIMs) or extremely bulky side groups (polynorbornenes and polytricyclonenenes). For a deeper understanding of both types of such high-Performance polymers for gas separation membranes and their further development broadband dielectric spectroscopy (BDS) can provide a substantial contribution. BDS addresses molecular relaxations characterizing the dynamics of the solid polymer as a major factor determining the gas transport properties but also the physical aging behavior which is an essential issue for such polymers. BDS is applied on PIMs where fluctuations of molecular dipoles connected to the backbone can be directly monitored. Furthermore, also polynorbornenes were investigated which carry no dipole moment in their repeat unit - the high resolution of modern equipment allows for the detailed analysis also for very small dielectric losses originating from partially oxidized moieties or marginal catalyst residues. Additionally, from interfacial polarization phenomena, such as Maxwell-Wagner-Sillars (MWS) polarization due to blocking of charge carriers at internal interfacial boundaries on a mesoscopic length scale, valuable information on the intrinsic microporosity and its changes induced by physical aging can be obtained. Finally, also conductivity can be characterized in detail in such polymeric systems revealing contributions of interactions of aromatic moieties (π-π-stacking) or the drift motion of charge carriers. These features also determine the structure formation in the solid state. 2019 257th ACS National Meeting - Symposium "Transport in Polymer Membranes" Orlando, FL, USA 31.03.2019 04.04.2019 2019-06-04 OPUS4-48226 Zeitschriftenartikel Erdmann, Maren; Kupsch, Andreas; Müller, Bernd R.; Hentschel, Manfred P.; Niebergall, Ute; Böhning, Martin; Bruno, Giovanni Erdmann, Maren Diesel-induced transparency of plastically deformed high-density polyethylene High-density polyethylene becomes optically transparent during tensile drawing when previously saturated with diesel fuel. This unusual phenomenon is investigated as it might allow conclusions with respect to the material behavior. Microscopy, differential scanning calorimetry, density measurements are applied together with two scanning X-ray scattering techniques: wide angle X-ray scattering (WAXS) and X-ray refraction, able to extract the spatially resolved crystal orientation and internal surface, respectively. The sorbed diesel softens the material and significantly alters the yielding characteristics. Although the crystallinity among stretched regions is similar, a virgin reference sample exhibits strain whitening during stretching, while the diesel-saturated sample becomes transparent. The WAXS results reveal a pronounced fiber texture in the tensile direction in the stretched region and an isotropic orientation in the unstretched region. This texture implies the formation of fibrils in the stretched region, while spherulites remain intact in the unstretched parts of the specimens. X-ray refraction reveals a preferred orientation of internal surfaces along the tensile direction in the stretched region of virgin samples, while the sample stretched in the diesel-saturated state shows no internal surfaces at all. Besides from stretching saturated samples, optical transparency is also obtained from sorbing samples in diesel after stretching. US Springer US 2019 Journal of Materials Science 54 17 11739 11755 10.1007/s10853-019-03700-8 2019-06-20 OPUS4-51147 Zeitschriftenartikel Zorn, R.; Lohstroh, W.; Zamponi, M.; Harrison, W.; Budd, P.; Böhning, Martin; Schönhals, Andreas Molecular mobility of a polymer of intrinsic microporosity revealed by quasielastic neutron scattering Quasielastic neutron scattering by employing a combination of time-of-flight and backscattering techniques is carried out to explore the molecular mobility of a polymer of intrinsic microporosity (PIM-1) at microscopic time scales in comparison with a high-performance polyimide. Molecular fluctuations can change the structure of the temporary network of micropores and open or close pathways for gas molecules. Therefore, the investigation might help to understand the selectivity of PIMs in gas separation processes. The performed neutron scattering experiments provide evidence for a low-temperature relaxation process, which was assigned to methyl group rotation. This methyl group rotation was analyzed in terms of jump diffusion in a three-fold potential. The analysis results in a fraction of methyl groups which are immobilized. For PIM-1 it was found that the fraction of immobilized methyl groups decreases with increasing temperature up to 350 K. At higher temperatures the number of immobilized methyl group increases gain due to an underlying relaxation process. This motional process on a somewhat larger length scale might lead to a reversible structural rearrangement which partially hinders the strongly localized methyl group rotation. In addition, it was found that the activation energy for the methyl group rotation for PIM-1 and the polyimide is significantly higher than for conventional polymers. Washington, DC American Chemical Society 2020 Macromolecules 53 15 6731 6739 10.1021/acs.macromol.0c00963 2020-09-02 OPUS4-51165 Zeitschriftenartikel Zorn, R.; Szymoniak, Paulina; Kolmangadi, Mohamed Aejaz; Wolf, M.; Alentiev, D.; Bermeshev, M.; Böhning, Martin; Schönhals, Andreas Low frequency vibrational density of state of highly permeable super glassy polynorbornenes - The Boson peak Inelastic incoherent neutron time-of flight scattering was employed to measure the low frequency density of states for a series of addition polynorbornenes with bulky side groups. The rigid main chain in combination with the bulky side groups give rise to a microporosity of these polymers in the solid state. The microporosity characterized by the BET surfaces area varies systematically in the considered series. Such materials have some possible application as active separation layer in gas separation membranes. All investigated materials show excess contributions to the Debye type density of states characteristic for glasses known as Boson peak. The maximum position of the Boson peak shifts to lower frequency values with increasing microporosity. Data for PIM-1 and Matrimid included for comparison are in good agreement to this dependency. This result supports the sound wave interpretation of the Boson peak. Royal Chemical Society 2020 Physical Chemistry Chemical Physics 22 33 18381 18387 10.1039/d0cp03360j 2020-09-09 OPUS4-51196 Zeitschriftenartikel Kolmangadi, Mohamed Aejaz; Szymoniak, Paulina; Smales, Glen Jacob; Alentiev, D.; Bermeshev, M.; Böhning, Martin; Schönhals, Andreas Molecular Dynamics of Janus Polynorbornenes: Glass Transitions and Nanophase Separation For the first time, dielectric and calorimetric investigations of an homologous series of Janus polynorbornenes with rigid main backbones and flexible -Si(OR)3 side groups, of differing length alkyl chains (R = Propyl, Butyl, Hexyl, Octyl, Decyl) is reported. Generally, this class of polymers has some potential for applications in the field of gas separation membranes. Two dielectrically active processes are observed at low temperatures, denoted as β- and α- relaxation. The former can be assigned to localized fluctuations, whilst the latter is related to the glassy dynamics of the flexible -Si(OR)3 side groups, creating a nanophase separation in both the alkyl chain rich and backbone rich domains. This is confirmed through temperature modulated DSC measurements and X-ray scattering experiments. The glass transition temperatures of the backbone rich domains, which are beyond or near to their degradation temperatures in terms of conventional DSC, are determined for the first time using Fast Scanning Calorimetry employing both fast heating and cooling rates. This is complimented with scattering experiments that show how the size of the alkyl chain rich domains increases with chain length. Alongside these results, a significant conductivity contribution was observed for all poly(tricyclononenes) with -Si(OR)3 side groups, which is interpreted in terms of a percolation model. ACS 2020 Macromolecules 53 17 7410 7419 10.1021/acs.macromol.0c01450 2020-09-10 OPUS4-51000 Zeitschriftenartikel Erdmann, Maren; Kleinbub, Sherin; Wachtendorf, Volker; Schütter, Jan David; Niebergall, Ute; Böhning, Martin; Koerdt, Andrea Photo-oxidation of PE-HD affecting polymer/fuel interaction and bacterial attachment In the present study, a simple approach was used to investigate the effect of UV-exposure on two high density Polyethylene materials (PE-HD), commonly used for storage tanks, on fuel sorption behavior and colonization by microorganisms. The aim was to investigate whether the sorption behavior of the fuels (diesel/biodiesel) and the colonization by microorganisms, frequently occurring in the fuel, is affected and may lead to undesirable or safety-relevant material changes. We showed that the UV-irradiation leads to significant changes of the sorption behavior due to chemi-crystallization and crosslinking. The fuel Sorption is affected by the UV-induced formation of polar carbonyl and hydroxyl groups predominantly occurring at the surface. With respect to microbial colonization behavior for Bacillus subtilis and Pseudomonas aeruginosa, isolated from a contaminated diesel sample, differences of the initial adhesion could be shown depending on the initial type of polyethylene as well as on the degree of UV-induced degradation. Nature Partner Journals 2020 Materials Degradation 4 1 Article number: 18 urn:nbn:de:kobv:b43-510001 10.1038/s41529-020-0122-1 https://creativecommons.org/licenses/by/4.0/deed.de 2020-07-13 OPUS4-50913 Zeitschriftenartikel Erdmann, Maren; Niebergall, Ute; Wachtendorf, Volker; Böhning, Martin Evaluation of UV-induced embrittlement of PE-HD by Charpy impact test The impact fracture behavior of two common high-density polyethylene grades for container applications were intensively studied by the instrumented Charpy impact test after well-defined exposure to UV-irradiation. Individual stages of the impact event, such as crack initiation and crack propagation energy as well as maximum impact load, were investigated from the recorded load-deflection curves. UV-induced material property changes were further investigated by infrared spectroscopy, differential scanning calorimetry, and dynamic-mechanical analysis as well as density measurements. Based on the results of the Charpy impact test, three indicators were identified to describe the extend of photooxidation on high-density polyethylene: (a) a reduced Charpy impact strength—at least to half of its initial value for a distinctly brittle impact fracture, (b) a marked decrease in the crack propagation contribution to the impact strength, and (c) an increase of the brittle features of the fracture surface. Wiley 2020 Journal of Applied Polymer Science 137 36 49069 urn:nbn:de:kobv:b43-509130 10.1002/APP.49069 https://creativecommons.org/licenses/by/4.0/deed.de 2020-06-22 OPUS4-35616 Zeitschriftenartikel Konnertz, Nora; Böhning, Martin; Schönhals, Andreas Dielectric investigations of nanocomposites based on matrimid and polyhedral oligomeric phenethyl-silsesquioxanes (POSS) Matrimid and Matrimid/PhenethylPOSS nanocomposites films were prepared by solution casting. They can be considered as potential membrane materials for gas separation. Theire dielectric properties were investigated using Broadband Dielectric Spectroscopy (BDS) in combination with standard techniques. Matrimid shows one relaxation process assigned as beta*-relaxation and a conductivity contribution. The relaxation process has a high activation energy of 99 kJ/mol. Thus this process is supposed to be of cooperative nature due to a π-π stacking of the phenyl rings of Matrimid. The influence of the thermal history on Matrimid was analyzed with BDS as well where an annealing effect is found. The Matrimid/PhenethylPOSS nanocomposites show up to a concentration of about 4 wt% PhenethylPOSS a miscibility on a molecular level. For higher concentrations a phase separated structure was indicated. The conductivity of both systems is explained by π-π stacking of the phenyl rings which enhances charge transport. Elsevier Science 2016 Polymer 90 89 101 10.1016/j.polymer.2016.02.060 2016-03-31 OPUS4-35541 Posterpräsentation Konnertz, Nora; Böhning, Martin; Schönhals, Andreas; Ding, Yi Molecular mobility and gas transport properties of PIM-1 and nano composites based on PIM-1 and phenethylPOSS Polymers with intrinsic microporosity are of highly interest in the field of gas separation membranes. Especially the first synthesized PIM-1 shows extraordinary permeabilities and selectivities. Unfortunately, PIM-1 tends to physical aging and loses its good properties. Physical aging is related to the molecular mobility of PIM-1 which was here investigated by broadband dielectric spectroscopy (BDS). Besides the studies on pure PIM-1 a polyhedral oligomeric silsesquioxane with phenethyl substituents (PhenethylPOSS) was used as nanofiller (0 - 40 wt-%) in the PIM-1 matrix to improve the gas transport properties and prevent physical aging. The molecular mobility of the solution casted nano composite films was analyzed by BDS as well. Furthermore, gas transport properties were determined with the time lag method (0 - 20 bar) in a temperature range of 35°C to 65°C with N2, O2, CH4 and CO2. 2016 80. Jahrestagung der DPG und DPG-Frühjahrstagung Regensburg, Germany 06.03.2016 11.03.2016 2016-03-18 OPUS4-35798 Zeitschriftenartikel Konnertz, Nora; Ding, Yi; Harrison, W.J.; Budd, P.M.; Schönhals, Andreas; Böhning, Martin Molecular mobility of the high performance membrane polymer PIM-1 as investigated by dielectric spectroscopy The increasing demand for energy efficient separation processes fosters the development of new high performance polymers as selective separation layers for membranes. PIM-1 is the archetypal representative of the class of polymers of intrinsic microporosity (PIM) which are considered most promising in this sector, especially for gas separations. Since their introduction, PIMs stimulated a vast amount of research in this field and meanwhile evolved to the state of the art in membrane technology for gas separation. The major obstacle for extending the practical membrane application is their strong tendency to physical aging. For the first time, investigations by broadband dielectric spectroscopy (BDS) addressing molecular dynamics and conductivity in PIM 1 are presented. As chain packing during film formation from the casting solution and physical aging are key factors determining the separation performance of PIMs as membrane materials, characterization of the molecular mobility in such materials as revealed by BDS will provide valuable information for further development and optimization. Washington, DC, USA ACS American Chemical Society 2016 ACS Macro Letters 5 4 528 532 10.1021/acsmacrolett.6b00209 2016-04-21 OPUS4-35369 Zeitschriftenartikel Niebergall, Ute; Zanotto, M.; Wachtendorf, Volker; Böhning, Martin Impact of biodiesel sorption on tensile properties of PE-HD for container applications In previous papers, we investigated the influence of biodiesel or diesel on mechanical properties of a high-density polyethylene (PE-HD) for tank applications using Charpy impact tests and dynamicmechanical analysis (DMA). In this work, covering two more PE-HD materials, we extend our study to addressing the tensile properties, especially changes of Young's modulus, after immersion in biodiesel or diesel at 60 °C. As we cover sorption and desorption behavior, during desorption, i.e. storage at 60 °C in a circulating air oven, ageing or degradation phenomena were also observed and characterized in some detail using spectral reflectance measurements and FT-IR spectroscopy. The results obtained here support the concept of co-oxidation, i.e. the faster oxidation of the PE-HD matrix if the samples were previously saturated with biodiesel, itself easily oxidizable. Elsevier 2016 Polymer Testing 50 315 324 10.1016/j.polymertesting.2016.01.025 2016-03-15 OPUS4-34994 Zeitschriftenartikel Agroui, K.; Collins, G.; Oreski, G.; Böhning, Martin; Hadj Arab, A.; Ouadjaout, D. Effect of crosslinking on EVA-based encapsulant properties during photovoltaic module fabrication process The key objective of this work is to create a comprehensive comparison between experimental analysis methods for detecting crosslinking reaction in EVA encapsulant material during PV module fabrication process. Several analytical methods, spanning from classical gel content extraction measurements over different thermo-analytic and mechanical approaches to spectroscopic analysis as Thermally Stimulated Current (TSC), have been investigated as to their ability to reveal the crosslinking state of ethylene vinyl acetate (EVA). The basic results show that TSC complements perfectly other thermal analysis methods like as Differential Scanning Calorimetry (DSC), Dynamic Mechanical Thermal Analysis (DMTA) to determine fundamental properties of EVA such as molecular mobility characteristics and also to monitor the crosslinking reaction. Exothermic peak as revealed by DSC analysis can be used to estimate the crosslinking rate of EVA during PV module encapsulation process as fast quality control test. ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ L'objectif principal de ce travail est de permettre une meilleure compréhension entre les différentes techniques analyses expérimentales pour détecter la réaction de réticulation au niveau de l’encapsulant Ethylène-Vinyle Acétate (EVA), durant le process de fabrication d'un module PV. Plusieurs méthodes d'analyse, allant du test classique d'extraction du taux de gel aux différentes techniques d'analyses thermomécaniques ainsi que les techniques d'analyse de spectroscopie comme le courant stimulé thermiquement (TSC), ont été étudiés pour permettre de révéler le phénomène de la réaction de réticulation de l'encapsulant l'EVA. Les résultats de base montrent que la TSC complète parfaitement d'autres méthodes d'analyses thermiques comme la calorimétrie différentielle à balayage (DSC), l'analyse mécanique dynamique (DMTA) pour déterminer les propriétés fondamentales de l'EVA. Ces techniques permettent de déterminer les caractéristiques relatives à la mobilité moléculaire et aussi pour mieux mettre en évidence la réaction de réticulation. Le pic exothermique comme révélé par l'analyse par DSC, peut être utilisé pour estimer le taux de réticulation de l'EVA au cours du process d'encapsulation du module PV comme un test rapide de contrôle de qualité. Centre de développement des energies renouvelables, Algeria 2015 Revue des energies renouvelables 18 2 303 314 2016-02-20 OPUS4-35918 Zeitschriftenartikel Jaunich, Matthias; Böhning, Martin; Braun, Ulrike; Teteris, G.; Stark, W. Investigation of the curing state of ethylene/vinyl acetate copolymer (EVA) for photovoltaic applications by gel content determination, rheology, DSC and FTIR The cure behaviour of a specific ethylene vinyl acetate material as used for encapsulation of photovoltaic modules was analysed by rheometer, differential scanning calorimetry and Fourier transform infrared spectroscopy to test for a suitable replacement for the laborious determination of gel content. The results show that all applied methods are capable of describing the effects of the cross-linking process. Some provide results very similar to those yielded by analysis of the insoluble content, but the question remains as to whether indirect methods should be preferred over the direct measurement of physical properties, e.g. as performed by the curemeter. A material stored for one year was also tested to demonstrate the effect of extended storage on cure behaviour and how this is detected by different methods. This complements the other methods, which were clearly able to detect the different cure behaviour of the aged EVA, whereas determination of the gel content could not. Oxford, UK Elsevier Ltd. 2016 Polymer Testing 52 1 133 140 10.1016/j.polymertesting.2016.03.013 2016-05-04 OPUS4-48617 Zeitschriftenartikel Yin, Huajie; B, Yang; Chua, Y. Z.; Szymoniak, Paulina; Carta, M; Malpass-Evans, R; McKeown, N; Harrison, W; Budd, P; Schick, C; Böhning, Martin; Schönhals, Andreas Effect of backbone rigidity on the glass transition of polymers of in-trinsic microporosity probed by fast scanning calorimetry Polymers of Intrinsic Microporosity (PIMs) of high performance have developed as materials with a wide application range in gas separation and other energy-related fields. Further optimization and long-term behavior of devices with PIMs require an understanding of the structure-property relationships including physical aging. In this context the glass transi-tion plays a central role, but with conventional thermal analysis a glass transition is usually not detectable for PIMs be-fore their thermal decomposition. Fast scanning calorimetry provides evidence of the glass transition for a series of PIMs, as the time scales responsible for thermal degradation and for the glass transition are decoupled by employing ultrafast heating rates of tens of thousands K s-1. The investigated PIMs were chosen considering the chain rigidity. The estimated glass transition temperatures follow the order of the rigidity of the backbone of the PIMs. ACS Publications 2019 ACS Macro letters 8 8 1022 1028 10.1021/acsmacrolett.9b00482 2019-08-05 OPUS4-48560 Zeitschriftenartikel Musil, B.; Böhning, Martin; Johlitz, M.; Lion, A. On the inhomogenous chemo-mechanical ageing behaviour of nitrile rubber: experimental investigations, modelling and parameter identification Elastomers are used in almost all areas of industrial applications, such as tires, engine mounts, bridge bearings, seals or coatings. During their use in operation, they are exposed to different environmental influences. These include, in particular, climatic factors such as air oxygen, high temperatures, light (UV radiation) and the influence of media (e.g. oils, fuels). A very important result of these factors is the chemical ageing of elastomers. In this case, the elastomer degenerates and changes its chemical structure in the aged regions, which leads to an irreversible change in the material properties in connection with the reduction in its usability. In this paper, chemical ageing of nitrile butadiene rubber (NBR) is investigated. Especially in case of thermo-oxidative ageing at elevated operating temperatures, the ageing processes run inhomogeneously. These effects are known as diffusion-limited oxidation (DLO) and are associated with the diffusion-reaction behaviour of atmospheric oxygen with the elastomer network. For these reasons, NBR samples are artificially aged in air and subjected to different experimental methods, which are presented and discussed. Additional results from inhomogeneous mechanical tests and permeation tests indicate the causes of the DLO-effect, show the influence of chemical ageing and are subsequently used for parameter identification in relation to the diffusion-reaction equation. A continuum-mechanical modelling approach is also presented here, which describes the finite hyperelasticity, diffusion-reaction processes as well as chemical degradation and reformation of the elastomer network. This multifield problem leads to a system of partial and ordinary differential equations and constitutive equations and is solved within the finite element method. Heidelberg Springer 2019 Continuum Mechanics and Thermodynamics 32 1 127 146 10.1007/s00161-019-00791-1 2019-07-29 OPUS4-49957 Vortrag Böhning, Martin The glass transition temperature of Polymers of Intrinsic Microporosity (PIMs) as determined by fast scanning calorimetry Polymers of intrinsic microporosity (PIMs) have recently emerged as novel materials for a broad range of high-performance applications from gas separation to electronic devices. The very rigid, contorted polymer chains show only limited molecular mobility and therefore pack inefficiently giving rise to intrinsic microporosity with pore sizes generally smaller than 1 nm resulting in BET surface areas larger than 700 m2/g. Using conventional thermal analysis techniques, no glass transition temperature (Tg) of PIMs could be unambiguously detected up to now. Employing fast scanning calorimetry (FSC) based on a one chip sensor, decoupling the time scales responsible for the glass transition and the thermal decomposition is a reliable strategy to overcome this limitation. The FSC device is capable to heat and cool a small sample (ng-range) with ultrafast rates of several ten thousand K/s. Evidence of a glass transition is obtained for a series of PIMs with different chain rigidities. Local small-scale fluctuations are held responsible for the glass transition of highly rigid PIMs rather than segmental motions as in conventional polymers. 2019 International Polymer Processing Society (PPS) - Europe-Africa 2019 Regional Conference (PPS2019) Pretoria, South Africa 18.11.2019 21.11.2019 2019-12-11 OPUS4-40327 Zeitschriftenartikel Frasca, Daniele; Schulze, Dietmar; Böhning, Martin; Krafft, Bernd; Schartel, Bernhard Chlorbutylkautschuk/Multilayergraphen-Nanocomposites In den letzten Jahren werden zunehmend Nanopartikel als Füllstoff für Polymere vorgeschlagen und auch erfolgreich in Elastomer-Nanocomposites eingesetzt. In dieser Arbeit wird Multilayergraphen (MLG) als Nanofüllstoff näher untersucht, der sich bereits bei geringen Konzentrationen als effizient erweist. MLG besteht aus nur etwa zehn Graphenlagen. Chlorbutylkautschuk (CIIR)/MLG-Nanocomposites mit verschiedenen MLG-Gehalten wurden mit Hilfe eines ultraschallunterstützen Mischverfahrens in Lösung hergestellt und auf einem Walzwerk weiterverarbeitet. Das Einmischen von MLG führt zu einer deutlichen Verbesserung der rheologischen und mechanischen Eigenschaften, des Vernetzungsverhaltens sowie der Barrierewirkung gegenüber Gasen. Bereits der Zusatz von 3 phr MLG zu CIIR führt zu einem mehr als zweifach höheren E-Modul und zu einer Reduktion der Permeabilität von O2 und CO2 um 30 %. Höhere Konzentrationen an Nanofüllstoff resultieren in einer weiteren Verbesserung der Eigenschaften der Nanocomposites. Weiterhin zeigten die CIIR/MLG-Nanocomposites auch eine geringere Entflammbarkeit. Ratingen Dr. Gupta Verlag Dr. Heinz B.P. Gupta 2017 GAK Gummi Fasern Kunststoffe 70 5 311 322 2017-05-23 OPUS4-45766 Zeitschriftenartikel Schilling, Markus; Niebergall, Ute; Alig, I.; Oehler, H.; Lellinger, D.; Meinel, Dietmar; Böhning, Martin Crack propagation in PE-HD induced by environmental stress cracking (ESC) analyzed by several imaging techniques Different imaging techniques were employed to monitor Full Notch Creep Test (FNCT) experiments addressing environmental stress cracking in more detail. The FNCT is a well-established test method to assess slow crack growth and environmental stress cracking of polymer materials, especially polyethylene. The standard test procedure, as specified in ISO 16770, provides a simple comparative measure of the resistance to crack growth of a certain material based on the overall time to failure when loaded with a well-defined mechanical stress and immersed in a liquid medium promoting crack propagation. Destructive techniques which require a direct view on the free fracture surface, such as light microscopy and laser scanning microscopy, are compared to non-destructive techniques, i.e. scanning acoustic microscopy and xray micro computed tomography. All methods allow the determination of an effective crack length. Based on a series of FNCT specimens progressively damaged for varied Durations under standard test conditions, the estimation of crack propagation rates is also enabled. Despite systematic deviations related to the respective Imaging techniques, this nevertheless provides a valuable tool for the detailed evaluation of the FNCT and its further development. Elsevier 2018 Polymer Testing 70 544 555 10.1016/j.polymertesting.2018.08.014 2018-08-23 OPUS4-47268 Zeitschriftenartikel Erdmann, Maren; Böhning, Martin; Niebergall, Ute Physical and chemical effects of biodiesel storage on high-density polyethylene: Evidence of co-oxidation The physical and chemical effects of diesel and biodiesel fuels on two high-density polyethylene (PE-HD) types were investigated. Both semi-crystalline PE-HD are common thermoplastic materials for container and storage tank applications. Biodiesel, a composition of unsaturated fatty acid esters from renewable resources, was chosen as it is regarded a possible green alternative to fossil fuels. The study aims at identifying significant differences between biodiesel and conventional diesel fuels based on the differences in the chemical nature of the two. The physical effects of the fuels on the polymer at first comprises the sorption behavior, i.e. kinetics and final equilibrium concentration. Not only are both fuels absorbed by the amorphous phase of the semi-crystalline PE-HD, they also induce a plasticization effect that modifies the molecular mobility and therefore also the characteristic yielding properties, manifest in the obtained stress-strain curves. The chemical effects related to degradation phenomena is investigated by a long-term storage scenario using partially immersed tensile test specimens in diesel and biodiesel. We were able to confirm the proposed co-oxidation mechanism by Richaud et al. for polyethylene-unsaturated penetrant systems on a larger scale based on practical tensile tests. One of the investigated polyethylene grades subjected to tensile drawing showed a significant loss of plastic deformation and the onset of premature failure after 150 days of storage in biodiesel. Further biodiesel storage showed a systematically reduced elongation at break before necking. None of these effects were observed in diesel. Oxidation of fuels and polymer after progressing storage times were analyzed by the evolution of carbonyl species in FT-IR/ATR spectroscopy. Amsterdam Elsevier 2019 Polymer Degradation and Stability 161 1 139 149 10.1016/j.polymdegradstab.2019.01.018 2019-01-29 OPUS4-47408 Buchkapitel Böhning, Martin; Frasca, Daniele; Schulze, Dietmar; Schartel, Bernhard Yaragalla, S.; Kumar Mishra, R.; Thomas, S.; Kalarikkal, N.; Maria, H. J. Multilayer Graphene/Elastomer Nanocomposites Elastomers are usually reinforced by large amount of fillers like carbon black (CB) or silica in order to improve various mechanical properties, such as Young's modulus, hardness, tear resistance, abrasion resistance, and gas barrier properties. In recent years, such improvements were also obtained by using nanoparticles at significantly lower filler loadings. Graphene is a twodimensional (2D) sheet of a thickness in the atomic scale, composed of a honeycomb structure of sp2 carbon atoms. Besides significant mechanical reinforcement, graphene harbors the potential to be used as a multifunctional filler, as it can also increase the conductivity and weathering stability of elastomer matrices. Ultraviolet (UV) irradiation and oxidative agents can lead to the degradation of elastomers due to a multistep photooxidative process, including the formation of radicals. Carbon-based fillers have an influence on these reactions, as they can absorb UV radiation and act as radical scavengers. This chapter summarizes the results of our larger project on multilayer graphene (MLG)/elastomer nanocomposites, previously published, which present a comprehensive case study of MLG as a multifunctional nanofiller in elastomer/graphene nanocomposites. Different elastomeric matrices are compared in order to demonstrate the outstanding impact of MLG as a general benefit. The dependency of this effect on concentration is discussed in detail. Taking into account the key role of dispersion, different mixing procedures are compared, evaluating a facile implementation of graphene nanocomposites into conventional rubber processing. Finally, the most probable commercial uses of MLG nanofillers in combination with conventional CB are studied. The nanocomposites were prepared in the kg scale in order to obtain enough specimens to investigate various properties of the uncured and vulcanized rubbers at the highest quality level, including rheology, curing, morphology, several mechanical properties, abrasion, conductivity, gas permeation, burning behavior, and weathering stability. The structure property relationships are asserted and questioned, for example, by investigating the radical scavenging ability or aspect ratio of the MLG. This chapter illustrates the state of the art of graphene/rubber nanocomposites targeted for commercial mass applications. Elsevier 2019 Carbon-based Nanofillers and their Rubber Nanocomposites 978-0-12-817342-8 139 200 2019-02-21 OPUS4-42484 Zeitschriftenartikel Schilling, Markus; Niebergall, Ute; Böhning, Martin Full notch creep test (FNCT) of PE-HD - Characterization and differentiation of brittle and ductile fracture behavior during environmental stress cracking (ESC) The damage mechanisms slow crack growth (SCG) and environmental stress cracking (ESC), relevant for PE-HD materials are characterized based on improved full notch creep testing (FNCT) of two selected typical PE-HD materials for container applications. In this context, a distinction of the failure mechanisms as well as a categorization of involved media is suggested. Employing a novel FNCT device, elongation data were obtained in addition to conventional time-to-failure results of stress-dependent as well as temperature-dependent measurements. Changes in failure behavior, as determined by fracture surface analysis based on light microscopy (LM) and laser scanning microscopy (LSM), are correlated with FNCT results and used to introduce an additional possibility for the identification of brittle/ductile fracture behavior. Amsterdam Elsevier 2017 Polymer Testing 64 156 166 10.1016/j.polymertesting.2017.09.043 2017-10-12 OPUS4-41354 Zeitschriftenartikel Yin, Huajie; Chapala, P.; Bermeshev, M.; Schönhals, Andreas; Böhning, Martin Molecular Mobility and Physical Aging of a Highly Permeable Glassy Polynorbornene as Revealed by Dielectric Spectroscopy Polymeric membranes represent a cost- and energy efficient solution for gas separation. Recently superglassy polymers with high free volume outperform many conventional dense polymers in terms of gas permeability and selectivity. However, such polymers are prone to pronounced physical aging, resulting in a dramatic reduction in the gas permeability. Molecular mobility of polymer segments plays an important role in the physical aging and the gas transport performance of polymeric membranes. Molecular mobility and physical aging of a representative superglassy polynorbornene with very high gas permeability, PTCNSi2g, was monitored by using dielectric spectroscopy with state-of-the-art high-resolution analyzers. This work helps to shed some light on the structure−property relationship of superglassy polymers on a molecular level and to provide practical "design rules" for the development of high performance polymers for gas separation. Washington DC, USA ACS 2017 ACS Macro Letters 6 8 813 818 10.1021/acsmacrolett.7b00456 2017-08-16 OPUS4-41885 Zeitschriftenartikel Schilling, Markus; Böhning, Martin; Oehler, H.; Alig, I.; Niebergall, Ute Environmental stress cracking of polyethylene high density (PE-HD) induced by liquid media - Validation and verification of the full-notch creep test (FNCT) The full-notch creep test (FNCT) is widely used to characterize the slow crack growth (SCG) behavior of polyolefin materials in "inert" media as well as effects of environmental stress cracking (ESC) in which the medium has decisive influence on damage mechanism and time to failure. The test is of greatest importance for pipe and blow molding types of polyethylene, high density (PE-HD). Usually the full-notch creep test is applied as a standardized testing method (ISO 16770) using a few universal liquid media, such as solutions of Arkopal N 100. In our study, selected relevant polyethylene, high density materials are investigated also in real media - practical formulations as well as representative pure chemicals - and influences of temperature and geometry of specimen and notch are explicitly addressed. Furthermore, the investigations comprise also the environmental stress cracking behavior of polyethylene, high density in media that are sorbed to a significant extent - examples are diesel and biodiesel - based on comparison with samples previously saturated with those media. Thus, also the underlying diffusion controlled sorption process has to be assessed before. The investigations were performed using a full-notch creep testing device with 12 individual sub-stations, each equipped with individual electronic stress and temperature control and continuous online monitoring of the specimen elongation. Weinheim Wiley-VCH 2017 Materials Science & Engineering Technology 48 9 846 854 10.1002/mawe.201700065 2017-09-11 OPUS4-47838 Zeitschriftenartikel Yin, Huajie; Chapala, P.; Bermeshev, M.; Pauw, Brian Richard; Schönhals, Andreas; Böhning, Martin Influence of Trimethylsilyl Side Groups on the Molecular Mobility and Charge Transport in Highly Permeable Glassy Polynorbornenes Superglassy polymers with a large fractional free volume have emerged as novel materials with a broad range of applications, especially in the field of membrane separations. Highly permeable addition-type substituted polynorbornenes with high thermal resistance and chemical stability are among the most promising materials. The major obstacle for extending the practical membrane application is their strong tendency to physical aging, leading to a partial decline in their superior transport performance over time. In the present study, broadband dielectric spectroscopy with complementary X-ray scattering techniques were employed to reveal changes in microporous structure, molecular mobility, and conductivity by systematic comparison of two polynorbornenes with different numbers of trimethylsilyl side groups. Their response upon heating (aging) was compared in terms of structure, dynamics, and charge transport behavior. Furthermore, a detailed analysis of the observed Maxwell−Wagner−Sillars polarization at internal interfaces provides unique information about the microporous structure in the solid films. The knowledge obtained from the experiments will guide and unlock potential in synthesizing addition-type polynorbornenes with versatile properties. Washington DC ACS 2019 ACS Applied Polymer Materials 1 4 844 855 10.1021/acsapm.9b00092 2019-04-18 OPUS4-58835 Forschungsdatensatz Schilling, Markus; Marschall, Niklas; Niebergall, Ute; Böhning, Martin Dataset of comprehensive Full-notch creep tests (FNCT) of selected high-density polyethylene (PE-HD) materials The dataset provided in this repository comprises data obtained from a series of full-notch creep tests (FNCT) performed on selected high-density polyethylene (PE-HD) materials (for further details, see section 1 Materials in this document) in accordance with the corresponding standard ISO 16770. The FNCT is one of the mechanical testing procedures used to characterize polymer materials with respect to their environmental stress cracking (ESC) behavior. It is widely applied for PE-HD materials, that are predominantly used for pipe and container applications. It is based on the determination of the time to failure for a test specimen under constant mechanical load in a well-defined and temperature controlled liquid environment. The test device used here also allows for continuous monitoring of applied force, specimen elongation and temperature. Geneva Zenodo Bundesanstalt für Materialforschung und -prüfung (BAM) 2023 10.5281/zenodo.10143351 https://creativecommons.org/licenses/by/4.0/deed.de 2023-11-17 OPUS4-57568 Zeitschriftenartikel Strommer, Bettina; Battig, Alexander; Schulze, Dietmar; Agudo Jacome, Leonardo; Schartel, Bernhard; Böhning, Martin Shape, orientation, interaction, or dispersion: valorization of the influence factors in natural rubber nanocomposites The addition of nanoparticles as reinforcing fillers in elastomers yields nanocomposites with unique property profiles, which opens the door for various new application fields. Major factors influencing the performance of nanocomposites are studied by varying the type and shape of nanoparticles and their dispersion in the natural rubber matrix. The industrial applicability of these nanocomposites is put into focus using two types of graphene and a nanoscale carbon black, all commercially available, and scalable processing techniques in the form of a highly filled masterbatch production via latex premixing by simple stirring or ultrasonically assisted dispersing with surfactant followed by conventional two-roll milling and hot pressing. Different processing and measurement methods reveal the potential for possible improvements: rheology, curing behavior, static and dynamic mechanical properties, swelling, and fire behavior. The aspect ratio of the nanoparticles and their interaction with the surrounding matrix prove to be crucial for the development of superior nanocomposites. An enhanced dispersing method enables the utilization of the improvement potential at low filler loadings (3 parts per hundred of rubber [phr]) and yields multifunctional rubber nanocomposites: two-dimensional layered particles (graphene) result in anisotropic material behavior with strong reinforcement in the in-plane direction (157% increase in the Young's modulus). The peak heat release rate in the cone calorimeter is reduced by 55% by incorporating 3 phr of few-layer graphene via an optimized dispersing process. Lawrence (KA), USA Allen Press 2023 Rubber Chemistry and Technology 96 1 40 58 10.5254/rct.23.77961 2023-06-05 OPUS4-57711 Vortrag Böhning, Martin Environmental Stress Cracking in PE-HD - Assessment of Crack Propagation and Mechanisms by Optical Methods Slow crack growth (SCG) under the influence of external fluid media, usually termed environmental stress cracking (ESC), is still one of the most frequent origins of severe damage and failure of polymeric materials. For polyethylene (PE) this is relevant for mass products, like bottles for consumer products, but also for high-performance materials for pipes or industrial packaging, including containers for chemicals and other dangerous goods. Especially for high-density polyethylene (PE-HD) the susceptibility to SGC and ESC is depending on the complex interplay between molecular weight and architecture and the resulting semicrystalline morphology, especially the formation of tie-molecules. A reliable assessment of the resistance against this damage phenomenon is essential for demanding as well as safety-critical applications and has to take into account suitable testing methodologies and conditions in combination with environmental media reflecting the properties representative for typical fillings and relevant components causing ESC. In this context a better understanding of different influencing factors, such as sorption, swelling or surface activity is necessary together with a detailed characterization of different stages of crack propagation and underlying mechanisms. Therefor well-established testing methods, such as the Full Notch Creep Test (FNCT), were complemented by detailed fracture surface analysis using e.g. LSM and SEM in combination with a time-dependent optical monitoring of the progressing crack growth. For the crack growth also the ratio of fibrillated craze zone to crack opening is important for the deeper understanding of crack propagation and related material parameters which can be additionally addressed by X-ray computed tomography. 2023 34th Polymer Degradation Disscussion Group (PDDG) Conference Dubrovnik, Croatia 12.06.2023 15.06.2023 2023-06-20 OPUS4-57459 Beitrag zu einem Sammelband Thuy, Maximilian; Brauch, N.; Niebergall, Ute; Alig, I.; Oehler, H.; Böhning, Martin Environmental Stress Cracking of PE-HD Induced by Liquid Test Media Representing Crop Protection Formulations Packaging containers for dangerous goods that include aggressive liquids require that any packaging material that is based on high-density polyethylene has a high degree of stability and durability. This work is focused on testing the environmental stress cracking of the high-density polyethylenes used for such containers in contact with crop protection formulations, in particular, two model liquids established in Germany as standardized test media representatives for crop protection formulations containing the various admixtures typical for such products. One of the liquids is water-based and contains mostly surface-active ingredients, while the other is solvent-based and includes some emulsifiers. Originally established for pin impression tests, these model liquids and their individual components were here used for the first time as environmental media in the Full Notch Creep Test, which addresses the resistance against environmental stress cracking. The Full Notch Creep Test was carried out on five high-density polyethylene types with both model liquids, and also on one selected material with its components. The evaluation was focused on the fracture surface structures, which were visualized by a scanning electron microscope and by optical in situ imaging of the notch opening. While the water-based model liquid and its surface-active individual components induced environmental stress cracking with the characteristic pattern for a craze-crack mechanism and so-called brittle fracture on the surface, the solvent-based model liquid and its soluble ingredients exhibited rather ductile failure behavior, caused by the plasticizing effect on the polymer that reduced the yield stress of the high-density polyethylene. For both cases, fracture surface analysis, together with side views of the crack opening, showed a clear relation between surface pattern, notch deformation (e.g., by blunting), or crack opening due to crack growth with time to failure and the solubility of the liquids in high-density polyethylene. West Conshohocken, PA (USA) ASTM International 2023 Advances in Accelerated Testing and Predictive Methods in Creep, Fatigue, and Environmental Cracking 317 341 10.1520/STP164320210095 2023-05-15 OPUS4-57972 Zeitschriftenartikel Szymoniak, Paulina; Kolmangadi, Mohamed A.; Juranyi, Fanni; Böhning, Martin; Zorn, Reiner; Schönhals, Andreas Low-Frequency Vibrational Density of State of Janus-Polynorbornenes: The Dependence of the Boson Peak on the Nanophase-Separated Structure Inelastic incoherent neutron time-of-flight scattering was employed to investigate the low-frequency vibrational density of states (VDOSs) for a series of glassy Janus-poly(tricyclononenes), which consist of a rigid main chain and flexible alkyl side chains. Here, the length of the flexible side chains was systematically varied from propyl to octyl. Such materials have potential applications as active separation layers in gas separation membranes as a green future technology, especially for the separation of higher hydrocarbons. From the morphological point of view, the Janus polynorbornenes undergo a nanophase separation into alkyl side chain-rich nanodomains surrounded by a rigid polynorbornene matrix. Here, the influence of the nanophase-separated structure on the low-frequency VDOS is investigated from a fundamental point of view. The low-frequency VDOSs of these Janus polynorbornene show excess contributions to the Debye type VDOS known as the Boson peak (BP) for all side chain lengths. Due to the high incoherent scattering cross-section of hydrogen, most of the scattering comes from the alkyl side chain-rich domains. Compared to conventional glass-forming materials, in the considered Janus polynorbornenes, the BP has a much lower intensity and its frequency position is shifted to higher values. These experimental results are discussed in terms of the nanophase-separated structure where the alkyl chain-rich domains were constrained by the surrounding matrix dominated by the rigid backbone. With increasing alkyl chain length, the size of the alkyl chain-rich domains increases. The frequency position of the BP shifts linearly to lower frequencies with the size of these nanodomains estimated from X-ray measurements. The obtained results support the sound wave interpretation to the BP ACS 2023 Macromolecules 1 10 10.1021/acs.macromol.3c00913 2023-07-24 OPUS4-59036 Vortrag Szymoniak, Paulina; Böhning, Martin; Zorn, Reiner; Schönhals, Andreas Inelastic and quasielastic neutron scattering experiments on microporous membranes fro green separation processes Polymers with intrinsic microporosity are promising candidates for the active separation layer in gas separation membranes. These polymers are characterized by a high permeability and reasonable permselectivity. The latter point is somehow surprising because for microporous systems a more Knudson-like diffusion is expected then a size dependent temperature activated sieving process. It was argued in the framework of a random gate model that molecular fluctuations on a time scale from ps to ns are responsible for the permselectivity. Here series of polymers of intrinsic microporosity (PIMs) as well as microporous polynorbornenes with bulky Si side groups and a rigid backbone are considered. The polymers have different microporosity characterized by high BET surface area values. First inelastic time-of-flight neutron scattering measurements were carried out to investigate the low frequency density of state (VDOS). The measured data show the characteristic low frequency excess contribution to the VDOS above the Debye sound wave level, generally known as the Boson peak in glass-forming materials. It was found that the frequency of the maximum position of the Boson peak correlates with the BET surface area value. Secondly elastic scans as well as quasielastic neutron scattering measurements by a combination of neutron time-of-flight and backscattering have been out. A low temperature relaxation process was found for both polymers. This process was assigned to the methyl group rotation. It was analysed in terms of a jump diffusion in a three-fold potential. The analysis of the dependence of the elastic incoherent structure factor on the scattering vector yields the number of methyl groups which might be immobilized. The neutron scattering experiments were accompanied by fast scanning calorimetry and broadband dielectric investigations as well as atomistic molecular dynamic simulations. 2023 Kolloquiumsvortrag an der Technischen Universität München Garching, Germany 20.11.2023 20.11.2023 2023-12-07 OPUS4-59503 Zeitschriftenartikel Emamverdi, Farnaz; Huang, J.; Mosane Razavi, Negar; Bojdys, M. J.; Forster, A. B.; Budd, P. M.; Böhning, Martin; Schönhals, Andreas Molecular Mobility and Gas Transport Properties of Mixed Matrix Membranes Based on PIM‑1 and a Phosphinine Containing Covalent Organic Framework Polymers with intrinsic microporosity (PIMs) are gaining attention as gas separation membranes. Nevertheless, they face limitations due to pronounced physical aging. In this study a covalent organic framework containing λ5-phosphinine moieties, CPSF-EtO were incorporated as a nanofiller (concentration range 0-10 wt%) into a PIM-1 matrix forming dense films with a thickness of ca. 100 μm. The aim of the investigation was to investigate possible enhancements of gas transport properties and mitigating effects on physical aging. The incorporation of the nanofiller occurred on aggregate level with domains up to 100 nm as observed by T-SEM and confirmed by X-ray scattering. Moreover, the X-ray data show that the structure of the microporous network of the PIM-1 matrix is changed by the nanofiller. As the molecular mobility is fundamental for gas transport as well as for physical aging, the study includes dielectric investigations of pure PIM-1 and PIM-1/CPSF-EtO mixed matrix membranes to establish a correlation between the molecular mobility and the gas transport properties. Using the time-lag method the gas permeability and the permselectivity were determined for N2, O2, CH4 and CO2 for samples with variation in filler content. A significant increase in the permeability of CH4 and CO2 (50 % increase compared to pure PIM-1) was observed for a concentration of 5 wt% of the nanofiller. Furthermore, the most pronounced change in the permselectivity was found for the gas pair CO2/N2 at a filler concentration of 7 wt%. ACS Publications 2024 Macromolecules 57 4 1829 1845 urn:nbn:de:kobv:b43-595031 10.1021/acs.macromol.3c02419 https://creativecommons.org/licenses/by/4.0/deed.de 2024-02-12 OPUS4-59677 Zeitschriftenartikel Emamverdi, Farnaz; Huang, J.; Szymoniak, Paulina; Bojdys, M. J.; Böhning, Martin; Schönhals, Andreas Structure and molecular mobility of phosphinine-based covalent organic frameworks - glass transition of amorphous COFs Two-dimensional covalent organic frameworks (COFs) based on phosphinine and thiophene building blocks have been synthesized with two different side groups. The materials are denoted as CPSF-MeO and CPSF-EtO where CxxF correspond to the covalent framework, whereas P and S are related to heteroatoms phosphorous and sulfur. MeO and EtO indicate the substituents, i.e. methoxy and ethoxy. Their morphologies were studied by scanning electron microcopy and X-ray scattering. The absence of crystalline reflexes in the X-ray pattern reveal that both materials are amorphous and can be considered as glasses. Furthermore, N2 adsorption measurements indicate substantial Brunauer-Emmett-Teller (BET) surface area values pointing to the formation of three-dimensional pores by stacking of the aromatic 2D layer. An analysis of the porosity of both COFs showed a mean radius of the pores to be of ca. 4 nm, consistent with their chemical structure. The COFs form nanoparticles with a radius of around 100 nm. The thermal behavior of the COFs was further investigated by fast scanning calorimetry. These investigations showed that both COFs undergo a glass transition. The glass transition temperature of CPSF-EtO is found to be ca. 100 K higher than that for CPSF-MeO. This large difference in the glass transition is discussed to be due to a change in the interaction of the COF sheets induced by the longer ethoxy group. It might be assumed that for CPSF-EtO more individual COF sheets assemble to larger stacks than for CPSF-MeO. This agrees with the much larger surface area value found for CPSF-EtO compared to CPSF-MeO. To corroborate the results obtained be fast scanning calorimetry dielectric measurements were conducted which confirm the occurrence of a dynamic glass transition. The estimated temperature dependence of the relaxation rates of the dielectric relaxation and their absolute values agrees well with the data obtained by fast scanning calorimetry. Considering the fragility approach to the glass transition, it was further found that CPSF-MeO is a fragile glass former whereas CPSF-EtO behaves as a strong glass forming material. This difference in the fragility points also to distinct differences in the interaction between the 2D COF molecules in both materials. Royal Society of Chemistry (RSC) 2024 Materials Advances 1 10 urn:nbn:de:kobv:b43-596770 10.1039/d3ma01123b https://creativecommons.org/licenses/by/4.0/deed.de 2024-03-18 OPUS4-59741 Zeitschriftenartikel Zaghdoudi, M.; Kömmling, Anja; Böhning, Martin; Jaunich, Matthias Ageing of elastomers in air and in hydrogen environment: A comparative study EPDM, HNBR and FKM materials were exposed at 150 ◦C to air under atmospheric pressure and to hydrogen at 50 bar for different ageing times. All measurements after hydrogen exposure were conducted on samples in degassed condition to assess irreversible effects resulting from that exposure and to compare them to those after ageing in air. Density, hardness, tensile properties, compression set, and hydrogen permeability of all samples were analysed. In both ageing environments, HNBR exhibited the most significant changes of material properties. However, for both EPDM and HNBR, considerably less severe ageing effects were observed under hydrogen in comparison to ageing in air. On the other hand, FKM showed about the same low level of deterioration in both ageing environments but exhibited poor resistance against damage due to rapid gas decompression in hydrogen environment that can lead to seal failure. The obtained results may serve as a guidance toward a better understanding for design and utilisation of elastomeric materials in future hydrogen infrastructure components. Elsevier B.V. 2024 International Journal of Hydrogen Energy 63 207 216 urn:nbn:de:kobv:b43-597417 10.1016/j.ijhydene.2024.03.053 https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de 2024-03-25