TY - JOUR A1 - Kulla, Hannes A1 - Fischer, Franziska A1 - Benemann, Sigrid A1 - Rademann, K. A1 - Emmerling, Franziska T1 - The effect of the ball to reactant ratio on mechanochemical reaction times studied by in situ PXRD N2 - The effect of the reactant powder mass on reaction times for the mechanochemical formation of a soft matter model system was studied by in situ PXRD. The syntheses were performed at a constant ball mass in a shaker mill with and without glassy SiO2 as an inert additive. Reaction times decreased with the increase of the ball to reactant ratio (BRR). The kinetic influence of the SiO2 powder was excluded. The decrease in the reaction time with decreasing mass of reactants was related to the rise in the stress energy transferred to the powder by a higher ball impact. The BRR had no effect on the induction time. But the product conversion was accelerated by raising the BRR. While a certain temperature is needed for the activation of reactants in the induction phase, the conversion of soft matter reactants is rather controlled by impact than temperature. KW - XRD KW - Mechanochemistry PY - 2017 UR - http://pubs.rsc.org/en/content/articlehtml/2017/ce/c7ce00502d DO - https://doi.org/10.1039/c7ce00502d VL - 19 IS - 28 SP - 3902 EP - 3907 AN - OPUS4-41197 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dreßler, Martin A1 - Reinsch, Stefan A1 - Schadrack, Reinhard A1 - Benemann, Sigrid T1 - Burnout behavior of ceramic coated open cell polyurethane (PU) sponges N2 - Open cell rigid foams made from polyurethane (PU) are frequently used in ceramic processing for preparation of porous ceramics by the so-called replica technique. This work presents data regarding the PU burnout, shrinkage characteristics as well as the morphology of the ceramic coated PU sponges during heating up. Shrinkage of the ceramic coated PU sponges closely follows the mass loss due to PU decomposition. Two temperatures (i) 267 °C and (ii) 380 °C were identified at which PU decomposition reaches local maxima. Shrinkage measurements on ceramic coated PU sponges reveal that both PU decomposition stages lead to similar extends of shrinkage in the ceramic coated PU sponge. Differential thermal analysis (DTA) showed that the two decomposition related temperatures (267 and 380 °C) differ concerning the energy release. While the low-temperature signal is endothermic, an exothermic signal was detected at 380 °C. The morphology of the ceramic coated PU sponges was investigated with scanning electron microscopy (SEM) which gave insight into the formation of hollow ceramic struts-a well known feature of ceramics being prepared by the replica technique. KW - Polyurethane (PU) KW - Porous ceramics KW - Mass spectrometry KW - Thermal analysis PY - 2009 DO - https://doi.org/10.1016/j.jeurceramsoc.2009.07.025 SN - 0955-2219 SN - 1873-619X VL - 29 IS - 16 SP - 3333 EP - 3339 PB - Elsevier CY - Oxford AN - OPUS4-20092 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Aßmus, Kristin A1 - Binkowski, Sigrid A1 - Hübner, Wolfgang A1 - Klaffke, Dieter A1 - Benemann, Sigrid A1 - Neumann, Christine A1 - Pyzalla, A. A1 - Pinto, H. ED - Portella, Pedro Dolabella T1 - Verformung und Gefügetransformation bei Schwingungsverschleiß von austenitischen FeCrNi-Legierungen T2 - 37. Metallographie-Tagung CY - Berlin, Deutschland DA - 2003-09-17 PY - 2004 SN - 3-88355-322-0 SN - 0343-3579 N1 - Serientitel: Sonderbände der praktischen Metallographie – Series title: Sonderbände der praktischen Metallographie IS - 35 SP - 207 EP - 212 PB - Werkstoff-Informationsges. CY - Frankfurt AN - OPUS4-3147 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Binkowski, Sigrid A1 - Hübner, Wolfgang A1 - Aßmus, Kristin A1 - Benemann, Sigrid A1 - Österle, Werner ED - Portella, Pedro Dolabella T1 - Charakterisierung des Gefüges der austenitischen FeCrNi-Legierung 1.4876 nach Reibbeanspruchung bei 37 K T2 - 37. Metallographie-Tagung CY - Berlin, Deutschland DA - 2003-09-17 PY - 2004 SN - 3-88355-322-0 SN - 0343-3579 N1 - Serientitel: Sonderbände der praktischen Metallographie – Series title: Sonderbände der praktischen Metallographie IS - 35 SP - 213 EP - 218 PB - Werkstoff-Informationsges. CY - Frankfurt AN - OPUS4-3420 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mach, Reinhard A1 - Maneck, Heinz-Eberhard A1 - Röhl-Kuhn, Barbara A1 - Peplinski, Burkhard A1 - Benemann, Sigrid A1 - Strauß, Birgid A1 - Schütz, W. A1 - Kühn, Gerhard A1 - Friedrich, Jörg Florian ED - Pershin, L. T1 - Modification of graphite powders in a thermal RF induction plasma T2 - 17th International Symposium on Plasma Chemistry (ISPC-17) CY - Toronto, Canada DA - 2005-08-07 PY - 2005 SP - 1(?) EP - 6(?) CY - Toronto AN - OPUS4-11942 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fischer, Franziska A1 - Heidrich, Adrian A1 - Greiser, Sebastian A1 - Benemann, Sigrid A1 - Rademann, K. A1 - Emmerling, Franziska T1 - Polymorphism of mechanochemically synthesized cocrystals: a case study N2 - The liquid-assisted grinding cocrystallisation of theophylline with benzamide leading to polymorphic compounds was investigated. A solvent screening with seventeen different solvents was performed. The dipole moment of the solvent used in the synthesis determines the structure of the polymorphic product. A detailed investigation leads to the determination of the kinetically and thermodynamically favored product. In situ observations of the formation pathway during the grinding process of both polymorphs show that the thermodynamically favored cocrystal is formed in a two-step mechanism with the kinetic cocrystal as intermediate. KW - cocrystal KW - mechanochemistry KW - theophylline KW - benzamide KW - milling KW - polymorphism PY - 2016 DO - https://doi.org/10.1021/acs.cgd.5b01776 SN - 1528-7483 SN - 1528-7505 VL - 16 IS - 3 SP - 1701 EP - 1707 AN - OPUS4-35618 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kulla, Hannes A1 - Greiser, Sebastian A1 - Benemann, Sigrid A1 - Rademann, K. A1 - Emmerling, Franziska T1 - Knowing When To Stop-Trapping Metastable Polymorphs in Mechanochemical Reactions N2 - The cocrystal formation of pyrazinamide (PZA) with malonic acid (MA) was studied in situ. The mechanochemical reaction proceeds via conversion of a crystalline intermediate (PZA:MA II) into the thermodynamically more stable form (PZA:MA I) upon further grinding. The information derived from in situ powder X-ray diffraction (PXRD) enabled the isolation of this new metastable polymorph. On the basis of the PXRD data, the crystal structure of the 1:1 cocrystal PZA:MA II was solved. The polymorphs were further characterized and compared by Raman spectroscopy, solid-state NMR spectroscopy, differential thermal analysis/thermogravimetric analysis, and scanning electron microscopy. Our study demonstrates how monitoring mechanochemical reactions by in situ PXRD can direct the discovery and isolation of even short-lived intermediates not yet accessed by conventional methods. KW - Mechanochemistry KW - Polymorphs KW - Metastable KW - In situ PXRD KW - Cocrystal KW - Pyrazinamide PY - 2017 DO - https://doi.org/10.1021/acs.cgd.6b01572 SN - 1528-7483 SN - 1528-7505 VL - 17 IS - 3 SP - 1190 EP - 1196 AN - OPUS4-39420 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kulla, Hannes A1 - Greiser, Sebastian A1 - Benemann, Sigrid A1 - Rademann, K. A1 - Emmerling, Franziska T1 - In Situ Investigation of a Self-Accelerated Cocrystal Formation by Grinding Pyrazinamide with Oxalic Acid N2 - A new cocrystal of pyrazinamide with oxalic acid was prepared mechanochemically and characterized by PXRD, Raman spectroscopy, solid-state NMR spectroscopy, DTA-TG, and SEM. Based on powder X-ray diffraction data the structure was solved. The formation pathway of the reaction was studied in situ using combined synchrotron PXRD and Raman spectroscopy. Using oxalic acid dihydrate the initially neat grinding turned into a rapid self-accelerated liquid-assisted grinding process by the release of crystallization water. Under these conditions, the cocrystal was formed directly within two minutes. KW - in situ KW - cocrystal KW - mechanochemistry KW - pyrazinamide KW - hydrate PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-372357 DO - https://doi.org/10.3390/molecules21070917 SN - 1420-3049 VL - 21 IS - 7 SP - Article 917, 1 EP - 9 AN - OPUS4-37235 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fischer, Franziska A1 - Scholz, G. A1 - Benemann, Sigrid A1 - Rademann, K. A1 - Emmerling, Franziska T1 - Evaluation of the formation pathways of cocrystal polymorphs in liquid-assisted syntheses N2 - The synthesis of the polymorphic cocrystal caffeine:anthranilic acid was investigated to obtain a better understanding of the processes leading to the formation of different polymorphic forms. In the case of these cocrystal polymorphs synthesized by liquid-assisted grinding a distinct influence of the dipole moment of the solvent was found. A pre-coordination between the solvent molecules and the caffeine:anthranilic acid cocrystal could be identified in the formation of form II. In the case of form II the solvent can be regarded as a catalyst. The formation pathway of each polymorph was evaluated using synchrotron X-ray diffraction. KW - cocrystal KW - synchrotron X-ray diffraction KW - caffeine PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-313222 DO - https://doi.org/10.1039/c4ce00472h SN - 1466-8033 VL - 16 IS - 35 SP - 8272 EP - 8278 CY - London, UK AN - OPUS4-31322 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scheibe, Maximilian A1 - Binkowski, Sigrid A1 - Benemann, Sigrid A1 - Saliwan Neumann, Romeo T1 - Comparing different preparation techniques for the characterisation of niobium carbides N2 - Of the up to 85.000 tons of niobium that are produced at the present, 90% are used as a property defining micro alloying element [1,2] in: a. High- and highest strength alloys for car bodies, b. Structural steels in the construction industry and, c. Steels for pipelines and the petrochemical industry, whereby it is mostly added for alloying in the ränge of 80-250 ppm. PY - 2014 IS - 19 SP - 1 EP - 12 AN - OPUS4-32432 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -