TY - JOUR A1 - Secker, C. A1 - Brosnan, S.M. A1 - Limberg, F.R.P. A1 - Braun, Ulrike A1 - Trunk, M. A1 - Strauch, P. A1 - Schlaad, H. T1 - Thermally induced crosslinking of poly(N-propargyl glycine) N2 - As polypeptoids become increasingly popular, they present a more soluble and processable alternative to natural and synthetic polypeptides; the breadth of their potential functionality slowly comes into focus. This report analyzes the ability of an alkyne-functionalized polypeptoid, poly(N-propargyl glycine), to crosslink upon heating. The crosslinking process is analyzed by thermal analysis (differential scanning calorimetry and thermogravimetric analysis), Fourier-transform infrared, electron paramagnetic resonance, and solid-state NMR spectroscopy. While a precise mechanism cannot be confidently assigned, it is clear that the reaction proceeds by a radical mechanism that exclusively involves the alkyne functionality, which, upon crosslinking, yields alkene and aromatic products. KW - Fourier-transform infrared KW - Metal-free crosslinking KW - Polypeptoid KW - Propargyl KW - Solid-state NMR PY - 2015 U6 - https://doi.org/10.1002/macp.201500223 SN - 1022-1352 SN - 1521-3935 VL - 216 IS - 21 SP - 2080 EP - 2085 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-35265 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lukowiak, M.C. A1 - Wettmarshausen, Sascha A1 - Hidde, Gundula A1 - Landsberger, Petra A1 - Boenke, Viola A1 - Rodenacker, K. A1 - Braun, Ulrike A1 - Friedrich, Jörg Florian A1 - Gorbushina, Anna A1 - Haag, R. T1 - Polyglycerol coated polypropylene surfaces for protein and bacteria resistance N2 - Polyglycerol (PG) coated polypropylene (PP) films were synthesized in a two-step approach that involved plasma bromination and subsequently grafting hyperbranched polyglycerols with very few amino functionalities. The influence of different molecular weights and density of reactive linkers were investigated for the grafted PGs. Longer bromination times and higher amounts of linkers on the surface afforded long-term stability. The protein adsorption and bacteria attachment of the PP-PG films were studied. Their extremely low amine content proved to be beneficial for preventing bacteria attachment. PY - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-325406 SN - 1759-9954 SN - 1759-9962 VL - 6 IS - 8 SP - 1350 EP - 1359 AN - OPUS4-32540 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dümichen, Erik A1 - Javdanitehran, M. A1 - Erdmann, Maren A1 - Trappe, Volker A1 - Sturm, Heinz A1 - Braun, Ulrike A1 - Ziegmann, G. T1 - Analyzing the network formation and curing kinetics of epoxy resins by in situ near-infrared measurements with variable heating rates N2 - Near-infrared spectroscopy (NIR) turned out to be well suited for analyzing the degree of cure for epoxy systems. In contrast to dynamic scanning calorimetry (DSC), where the released heat of reaction determines the degree of epoxy conversion indirectly, NIR spectroscopy is able to determine the conversion directly by analyzing structural changes. Therefore, a new heatable NIR cell was equipped with an integrated thermocouple, which enables the real sample temperature to be controlled and monitored in situ during epoxy curing. Dynamic scans at different heating rates were used for kinetic modelling, to define kinetic parameters and to predict real curing processes. The kinetic models and their parameters were validated with an isothermal and a more complex multi-step curing scenario. Two available commercial epoxy systems based on DGEBA were used with an anhydride and with an amine hardener. NIR results were compared with DSC data. The simulated conversion predicted with a model fitted on the basis of NIR and DSC dynamic scans showed good agreement with the conversion measured in the isothermal curing validation test. Due to the proven reliability of NIR in measuring the reaction progress of curing, it can be considered a versatile measurement system for in situ monitoring of component production in the automotive, aerospace and wind energy sectors. KW - Epoxy resins KW - Curing kinetics KW - Near-infrared spectroscopy KW - DSC PY - 2015 U6 - https://doi.org/10.1016/j.tca.2015.08.008 SN - 0040-6031 SN - 1872-762X VL - 616 SP - 49 EP - 60 PB - Elsevier CY - Amsterdam AN - OPUS4-34187 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dümichen, Erik A1 - Braun, Ulrike A1 - Sturm, Heinz A1 - Kraemer, R. A1 - Deglmann, P. A1 - Gaan, S. A1 - Senz, R. T1 - A new molecular understanding of the thermal degradation of PA 66 doped with metal oxides: Experiment and computation N2 - The thermal molecular degradation of polyamide 66 (PA 66) doped with (partially supported) metal oxide particles (Fe2O3, ZnO, Al2O3) was investigated qualitatively and quantitatively using common analysis techniques like thermogravimetry coupled with IR-spectroscopic evolved gas analysis (TGA-FTIR). Using pyrolysis coupled with gas chromatography mass spectrometry (Py-GC-MS), qualitative conclusions were drawn about the complex hydrocarbon products. However, the combination of TGA with solid-phase extraction, followed by thermal desorption gas chromatography mass spectrometry (TED-GC-MS), allows qualitative and even semi-quantitative conclusions about the decomposition pathway of PA 66 in the presence of various metal oxide particles. The investigations under inert conditions showed that the presence of metal particles increases the rate of decarboxylation and deamination reactions, as well as the formation rate of cyclopentanone and pyridine derivatives. These species are a consequence of various condensation reactions. The condensation reactions release a large amount of water, thus triggering the hydrolysis of PA 66. Molecular thermal degradation mechanisms were developed for the main decomposition as well as for the condensation reactions and supported by quantum chemical calculations. The catalytic effect of the metal oxides in PA 66 increases in the following order: PA 66 = PA 66 – Al2O3 < PA 66 – Fe2O3 < PA 66 – ZnO. KW - PA 66 KW - Metal oxide particles KW - Thermal degradation KW - Solid-phase extraction KW - Molecular modeling PY - 2015 U6 - https://doi.org/10.1016/j.polymdegradstab.2015.07.011 SN - 0141-3910 SN - 1873-2321 VL - 120 SP - 340 EP - 356 PB - Elsevier Ltd. CY - London AN - OPUS4-33806 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dümichen, Erik A1 - Braun, Ulrike A1 - Kraemer, R. A1 - Deglmann, P. A1 - Senz, R. T1 - Thermal extraction combined with thermal desorption: A powerful tool to investigate the thermo-oxidative degradation of polyamide 66 materials N2 - Using thermogravimetric analysis (TGA) with a solid-phase adsorber for thermal extraction, followed by subsequently analysing the adsorber with thermo-desorption gas chromatography mass spectrometry (TDS-GC–MS) enables measurement of polymer degradation under oxidizing atmosphere, and the identification of certain complex hydrocarbon degradation products by chromatographic separation and defined mass patterns. This technique, thermal-extraction desorption gas chromatography mass spectrometry (TED-GC–MS) was used to investigate the thermo-oxidative degradation of PA 66 and PA 66 doped with 2 wt% of metal oxide particles. In TGA pure PA 66 formed more residue under an oxidizing atmosphere than an inert one. In contrast to the measurements under inert atmosphere, several condensed aromatic species containing nitrogen could be identified in thermo-oxidative measurements. These degradation products were formed through condensation reactions of primary amides originating from imide hydrolysis. The formation of such highly condensed species also causes higher char formation. Four metal oxides have shown an impact on the thermo-oxidative degradation of PA 66: Fe2O3 on η-Al2O3 < pure Fe2O3 = Fe2O3 on γ-Al2O3 < pure ZnO. For ZnO even a char-stabilizing effect could be observed. A catalytic effect of these metal oxides causes more condensed cyclopentanone and pyridine derivates. Thus, more water is formed and released, resulting in increased hydrolysis of the imides and degradation at lower temperatures. KW - PA 66 KW - Metal oxide particles KW - Thermo-oxidation KW - Thermogravimetry KW - Solid-phase extraction PY - 2015 U6 - https://doi.org/10.1016/j.jaap.2015.08.006 SN - 0165-2370 SN - 1873-250X VL - 115 SP - 288 EP - 298 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-34338 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dümichen, Erik A1 - Barthel, Anne-Kathrin A1 - Braun, Ulrike A1 - Bannick, Claus Gerhard A1 - Brand, K. A1 - Jekel, M. A1 - Senz, R. T1 - Analysis of polyethylene microplastics in environmental samples, using a thermal decomposition method N2 - Small polymer particles with a diameter of less than 5 mm called microplastics find their way into the environment from polymer debris and industrial production. Therefore a method is needed to identify and quantify microplastics in various environmental samples to generate reliable concentration values. Such concentration values, i.e. quantitative results, are necessary for an assessment of microplastic in environmental media. This was achieved by thermal extraction in thermogravimetric analysis (TGA), connected to a solid-phase adsorber. These adsorbers were subsequently analysed by thermal desorption gas chromatography mass spectrometry (TDS-GC-MS). In comparison to other chromatographic methods, like pyrolyse gas chromatography mass spectrometry (Py-GC-MS), the relatively high sample masses in TGA (about 200 times higher than used in Py-GC-MS) analysed here enable the measurement of complex matrices that are not homogenous on a small scale. Through the characteristic decomposition products known for every kind of polymer it is possible to identify and even to quantify polymer particles in various matrices. Polyethylene (PE), one of the most important representatives for microplastics, was chosen as an example for identification and quantification. KW - Microplastic KW - Identification and quantification of polymers KW - Thermogravimetric analysis KW - Evolved gas analysis KW - Gas chromatography mass spectroscopy PY - 2015 U6 - https://doi.org/10.1016/j.watres.2015.09.002 SN - 0043-1354 VL - 85 SP - 451 EP - 457 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-34337 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Deußing, G. A1 - Dümichen, Erik A1 - Braun, Ulrike T1 - Der Fänger im Spülgas N2 - Durch die intelligente Anbindung an eine in der GC/MS gängige Extraktionstechnik (SBSE) lassen sich Zersetzungsprodukte der thermogravimetrischen Analyse (TGA) von Polymeren auf effiziente Weise anreichern, anschließend trennen und sicher identifizieren. KW - Polymeranalytik KW - Thermische Extraktion PY - 2015 UR - http://www.laborpraxis.vogel.de/so-erweitern-sie-die-moeglichkeiten-der-tga-a-490995/index2.html UR - https://files.vogel.de/vogelonline/vogelonline/issues/6773.pdf SN - 0344-1733 VL - 39 IS - 6 SP - 24 EP - 27 PB - Vogel Business Media AN - OPUS4-42149 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Braun, Ulrike A1 - Eisentraut, Paul A1 - Fuchs, S. A1 - Deglmann, P. T1 - Sulphurous additives for polystyrene: Influencing decomposition behavior in the condensed phase N2 - The thermal decomposition behaviour of polystyrene (PS) containing sulphur and phosphorus additives was investigated, using thermogravimetry coupled with Fourier transform infrared spectroscopy (TGA-FTIR). It was found that the additives influence the decomposition process of the polymer in the condensed phase, resulting in a decrease in styrene monomer formation and an increase in styrene oligmer derivatives. Via reference measurements with binary mixtures it was found that the presence of sulphur additives influences the radicalic decomposition process of PS. In combination with quantum chemical calculations it was concluded that this is due to the formation of radicals that abstract hydrogen from the polymer matrix at lower temperatures, disfavouring the radicalic decomposition pathway leading to styrene. KW - Degradation KW - Theory and modeling KW - Thermogravimetric analysis KW - Polystyrene PY - 2015 U6 - https://doi.org/10.1002/APP.41665 SN - 0021-8995 SN - 1097-4628 VL - 132 IS - 12 SP - 41665, 1 EP - 13 PB - Wiley InterScience CY - Hoboken, NJ AN - OPUS4-32380 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bannick, Claus Gerhard A1 - Bierl, R. A1 - Braun, Ulrike A1 - Brand, K. A1 - Dümichen, Erik A1 - Jekel, M. A1 - Klein, S. A1 - Knepper, T.P. A1 - König, F. A1 - Miklos, D. A1 - Rechenberg, B. A1 - Steffens, I. T1 - Mikroplastik in der aquatischen Umwelt - Ein Beitrag zur aktuellen Diskussion in Deutschland N2 - Plastics are important materials in households and industry and therefore a crucial part of our everyday life. Since the beginning of the 1970s the occurrence of plastic particles in coastal waters has been explicitly described. Meanwhile, besides the marine environment, microplastics were also detected in other environmental media, biota and water management facilities. This work gives an overview of the occurrence and first known effects of microplastics in the environment. Furthermore, current scientific proceedings are considered and pending issues are discussed. In this regard it is of central importance to develop an environmentally comprehensive, harmonized scientific proceeding for miroplastics, which enables an evaluation of relevant material flows in adaption to necessary assessment concepts. N2 - Kunststoffe sind wichtige Werkstoffe und heutzutage aus Haushalt und Wirtschaft nicht mehr wegzudenken. Seit Anfang der 1970er-Jahre wird das Vorkommen von Kunststoffpartikeln in Küstengewässern beschrieben. Inzwischen ist Mikroplastik nicht nur im marinen Bereich, sondern auch in weiteren Umweltkompartimenten, Biota und technischen Einrichtungen der Wasserwirtschaft nachgewiesen worden, in dieser Arbeit wird ein Überblick über das Vorkommen von Mikroplastik in der aquatischen Umwelt und ersten bekannten Auswirkungen gegeben. Darüber hinaus werden die aktuellen Untersuchungsverfahren von Probenahme, Probenaufbereitung und Analytik betrachtet und offene fragen diskutiert. Zentral erscheint in diesem Zusammenhang die Entwicklung einer harmonisierten medienübergreifenden Untersuchungsmethodik, die eine Auswertung relevanter Stoffströme ermöglicht und auf notwendige Bewertungskonzepte abgestimmt ist. KW - Water management KW - Plastics KW - Microplastics KW - Environment KW - Analysis KW - Mikroplastik KW - Kunststoff KW - Wasserwirtschaft KW - Analytik KW - Umwelt PY - 2015 SN - 0083-6915 VL - 113 IS - 1 SP - 7 EP - 14 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-33105 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bajer, Kamila A1 - Braun, Ulrike A1 - Hintersteiner, I. T1 - The memory effect in polyolefinic products: A tool for confirming the steam sterilization process N2 - DSC-Messungen von dampfsterilisierten medizinischen Produkten aus Polyolefinen zeigen beim ersten Heizvorgang als auffällige Besonderheit eine zusätzliche Stufe, bekannt als Temperpeak. Das Ziel dieser Untersuchungen ist, dieses Phänomen nachzuvollziehen und zu verstehen, um es als Nachweis für die Dampfsterilisation nutzen zu können. Dafür wurden PP- und PE-Proben unter verschiedenen Bedingungen dampfsterilisiert und im Ofen thermisch behandelt. Anschließend wurden die Proben mittels DSC untersucht und die Einflüsse der thermischen Behandlung und der mechanischen Beanspruchung analysiert. Um den Einfluss unterschiedlicher Materialspezifikationen zu prüfen, wurden zusätzlich verschiedene Referenzmaterialien (PE und PP) untersucht und GPC-Messungen durchgeführt. Des Weiteren wurde die Beständigkeit des Signals gegenüber der Zeit und der Temperatureinflüssen betrachtet. Die Untersuchungen zeigen, dass sich ein stabiler Memory-Effekt erzeugen lässt. KW - Memory effect KW - Steam sterilization KW - Polypropylene KW - Polyethylene KW - DSC PY - 2015 U6 - https://doi.org/10.3139/120.110722 SN - 0025-5300 VL - 57 IS - 4 SP - 316 EP - 323 PB - Hanser CY - München AN - OPUS4-33104 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -