@misc{51133, abstract = {{In order to standardize spray flame synthesis (SFS) studies, intensive work has been done in recent years on the design of burner types. Thus, in 2019, the so-called SpraySyn1 burner was introduced (SS1), which was subsequently characterized in numerical and experimental studies. Based on this research, a modification of the nozzle design was proposed, which has now been considered in the successor model, SpraySyn2 (SS2). As little is known about the effect of the nozzle adaptation on the particle formation, we operated both burners under identical operating conditions to produce maghemite. The final powder comparison showed that SS2 yielded considerable higher specific surface areas (associated with smaller primary particle sizes), lower polydispersity, and higher phase purity. To obtain further information on the size distributions of aggregates and agglomerates generated by SS2, aerosol samples were extracted by hole in a tube (HIAT) sampling and characterized by scanning mobility particle sizing (SMPS). Samples were extracted along the centerline at different heights above the burner (HAB) above the visible flame tip (>7 cm), and quenching experiments were performed to extract the aerosol samples at different dilution rates. Thereby, it was demonstrated that performing detailed quenching experiments is crucial for obtaining representative HIAT-SMPS data. In particular, agglomerates/aggregate sizes were overestimated by up to ~70 % if samples were not sufficiently diluted. If sufficient dilution was applied, distribution widths and mean particle mobility diameters were determined with high accuracy (sample standard derivation <5 %). Our data suggested the evolution of primary particle sizes was mostly completed <7 cm HAB and it was shown aggregates/agglomerates present above the visible flame were compact in structure (non- fractal). The mean diameter of the particle ensemble grew along the centerline from 6.9 nm (7 cm) to 11.4 nm (15 cm), while distribution widths grew from 1.42 to 1.52.}}, booktitle = {{Applications in Energy and Combustion Science}}, editor = {{Tischendorf, Ricardo and Massopo, Orlando and Schmid, Hans-Joachim and Pyrmak, Olek and Dupont, Sophie and Fröde, Fabian and Pitsch, Heinz and Kneer, Reinhold}}, keywords = {{Flame Spray Pyrolysis, SpraySyn2, Spray flame synthesis, Maghemite nanoparticles, Gas to particle-conversion, Hole in a tube sampling}}, publisher = {{Elsevier}}, title = {{{Maghemite nanoparticles synthesis via spray flame synthesis and particle characterization by hole in a tube sampling and scanning mobility particle sizing (HIAT-SMPS)}}}, doi = {{https://doi.org/10.1016/j.jaecs.2023.100235}}, year = {{2024}}, } @article{52357, author = {{Beimdiek, Janis and Schmid, Hans-Joachim}}, issn = {{2073-4433}}, journal = {{Atmosphere}}, keywords = {{surrogate aerosols, indoor air cleaners, ultra-fine particles, COVID-19, test method, field experiments: clean air delivery rate}}, number = {{3}}, publisher = {{Multidisciplinary Digital Publishing Institute (MDPI)}}, title = {{{Evaluation of Surrogate Aerosol Experiments to Predict Spreading and Removal of Virus-Laden Aerosols}}}, doi = {{ 10.3390/atmos15030305}}, volume = {{15}}, year = {{2024}}, } @inproceedings{61350, author = {{Massopo, Orlando and Schmid, Hans-Joachim and Reddemann, Manuel and Kneer, Reinhold and Bieber, Malte}}, publisher = {{6th International Symposium Gas-Phase Synthesis of Functional Nanomaterials: Fundamental Understanding, Modeling and Simulation, Scale-up and Application}}, title = {{{Influence of Dispersion Gas and Resulting Reaction Zone on the Particle Formation in Spray Flame Synthesis (Presentation)}}}, year = {{2024}}, } @misc{61345, author = {{Zink, Timm Florian and Massopo, Orlando and Jesinghausen, Steffen and Schmid, Hans-Joachim}}, title = {{{Untersuchung des Lösungsmitteleinflusses auf die Synthese von Manganoxid-Nanopartikeln in der Flammenspraypyrolyse}}}, year = {{2024}}, } @misc{61347, author = {{El Gabbouhi, Abderazzak and Massopo, Orlando and Jesinghausen, Steffen and Schmid, Hans-Joachim}}, title = {{{Einfluss der Zerstäubungsparameter auf die Partikelbildung und die Eigenschaften der Endproduktpulver (Studienarbeit)}}}, year = {{2024}}, } @misc{51149, author = {{Reimer, Jens and Massopo, Orlando and Schmid, Hans-Joachim}}, title = {{{Entwicklung einer Datenbank hergestellter Nanomaterialien mittels Gasphasensynthese (Studienarbeit)}}}, year = {{2024}}, } @inproceedings{56958, author = {{Neukötter, Moritz and Jesinghausen, Steffen and Schmid, Hans-Joachim}}, location = {{Leeds}}, title = {{{Particle-induced Instabilities in Uniaxially Elongated Thermoplastic Polymer Blends }}}, year = {{2024}}, } @inproceedings{47626, author = {{Rüther, Moritz Johannes and Klippstein, Sven Helge and Schmid, Hans-Joachim}}, booktitle = {{PARTEC International Congress on Particle Technology - Book of Abstracts}}, isbn = {{ 978-3-18-990139-9}}, issn = {{0083-5560}}, location = {{Nürnberg}}, pages = {{172 -- 176}}, publisher = {{VDI Verlag GmbH}}, title = {{{Correlation between SLS-Powder processability and particle properties }}}, year = {{2023}}, } @inproceedings{46764, abstract = {{Polymer composites represent the industry standard in injection molding for the production of plastic components with increased requirements in terms of heat resistance and stiffness. In the field of laser sintering (LS), these materials are less common so far. In order to extend the available material variety for the LS process, new ceramic-filled Polyamide 613 powders are investigated within the scope of this work. Here, the resulting properties from two different powder production methods are compared. One filled powder is produced by dry blending and the other powder with the same filler and filling ratio is produced by encapsulating the filler particles inside the polymer particles within the dissolution-precipitation process. It was found that encapsulating the filler particles can provide certain benefits for the processability, for example an improved powder flowability or better filler dispersion. However, encapsulating the filler also alters the thermal properties of the precipitated powder.}}, author = {{Kletetzka, Ivo and Neitzel, Fabian and Schmid, Hans-Joachim}}, booktitle = {{Proceedings of the 34th Annual International Solid Freeform Fabrication Symposium}}, editor = {{Beaman, Joseph}}, location = {{Austin}}, publisher = {{Laboratory for Freeform Fabrication and University of Texas}}, title = {{{Assessing the Impact of the Powder Production Method on Ceramic-filled Polyamide Composites made by Laser Sintering}}}, volume = {{34}}, year = {{2023}}, } @misc{51136, abstract = {{Iron oxide nanoparticles are very interesting for many applications in different industrial sectors. A promising process to manufacture these nanoparticles is flame spray pyrolysis (FSP). A lack of understanding of the individual sub-processes in FSP makes it challenging to tailor nanoparticle properties. This work provides insights into the formation of iron oxide nanoparticles in a turbulent spray flame using Large Eddy Simulations (LES), which are based on a comprehensive model, including customized submodels. Highlights are the adaption of a turbulent combustion model and a bivariate hybrid method of moments for modeling nanoparticle dynamics. The work focuses on the SpraySyn burner, which is a standardized laboratory burner and was operated with a precursor-solvent mixture of ethanol and iron(III) nitrate nonahydrate. For studying the relevance of precursor chemistry, LES using an evaporation-limited precursor chemistry model is compared with a model that includes detailed iron chemistry. A further novelty is the inclusion of adsorption in the simulation, which defines a third model for comparison. Sufficient validation is achieved for the undoped LES using experimental data from the literature. A strong impact of the detailed iron chemistry and adsorption is found on the precursor consumption and the aggregate and primary particle formation. Comparing the particle diameters with experimental measurements from the literature and data generated for this work is found unsuitable to asses the precursor chemistry model and revealed an urgent need for future experimental and numerical research. This work serves as a step forward in realizing a reliable model.}}, booktitle = {{Applications in Energy and Combustion Science}}, editor = {{Fröde, Fabian and Grenga, Temistocle and Pitsch, Heinz and Dupont, Sophie and Kneer, Reinhold and Tischendorf, Ricardo and Massopo, Orlando and Schmid, Hans-Joachim}}, keywords = {{Flame spray pyrolysis, Iron oxide formation, Large eddy simulation, Method of moments, SpraySyn}}, publisher = {{Elsevier}}, title = {{{Large eddy simulation of iron oxide formation in a laboratory spray flame}}}, doi = {{https://doi.org/10.1016/j.jaecs.2023.100191}}, year = {{2023}}, } @inproceedings{51145, author = {{Massopo, Orlando and Schmid, Hans-Joachim and Gonchikzhapov, Munko and Kasper, Tina}}, keywords = {{Absolute particle concentration, Flame Spray Pyrolysis, SMPS, Mass Spectrometry}}, location = {{Málaga, Spain }}, title = {{{Nanoparticle Concentration Measurement in Flame Spray Pyrolysis (Poster)}}}, year = {{2023}}, } @inproceedings{51218, abstract = {{Polymer composites represent the industry standard in injection molding for the production of plastic components with increased requirements in terms of heat resistance and stiffness. In the field of laser sintering (LS), these materials are less common so far. In order to extend the available material variety for the LS process, new ceramic-filled Polyamide 613 powders are investigated within the scope of this work. Here, the resulting properties from two different powder production methods are compared. One filled powder is produced by dry blending and the other powder with the same filler and filling ratio is produced by encapsulating the filler particles inside the polymer particles within the dissolution-precipitation process. It was found that encapsulating the filler particles can provide certain benefits for the processability, for example an improved powder flowability or better filler dispersion. However, encapsulating the filler also alters the thermal properties of the precipitated powder. }}, author = {{Kletetzka, Ivo and Neitzel, Fabian and Schmid, Hans-Joachim}}, booktitle = {{Proceedings of the 34th Annual International Solid Freeform Fabrication Symposium}}, editor = {{Beaman, Joseph}}, keywords = {{Additive Manufacturing, Laser Sintering, Filled Materials, Composites, Polyamide 613}}, location = {{Austin}}, title = {{{Assessing the Impact of the Powder Production Method on Ceramic-filled Polyamide Composites made by Laser Sintering}}}, doi = {{https://doi.org/10.26153/tsw/50931}}, year = {{2023}}, } @inproceedings{46862, abstract = {{The high flammability of components manufactured by laser sintering (LS) using standard polyamide 12 (PA12) powder still severely restricts their use in industries such as electronics, aviation, and transportation. A key factor for the further establishment of LS is the expansion of the material portfolio with, for example, refreshable and halogen-free flame-retardant (FR) powder materials. Accordingly, various halogen-free FRs are investigated in this work and evaluated with respect to their use in LS. First, their decomposition behavior and mode of action are examined. Subsequently, the additives are dry blended with PA12 to investigate properties relevant for LS, such as particle morphology, thermal behavior and melt viscosity. Afterwards, test specimens for UL94 vertical flame-retardancy tests are produced by processing the dry blends on an EOS P3 LS system. Finally, the process stability of the process-aged powder blends is investigated by again examining the thermal behavior and melt viscosity.}}, author = {{Neitzel, Fabian and Kletetzka, Ivo and Schmid, Hans-Joachim}}, booktitle = {{Proceedings of the 34th Annual International Solid Freeform Fabrication Symposium}}, editor = {{Beaman, Joseph}}, keywords = {{Additive Manufacturing, Laser Sintering, Flame Retardant, Polyamide 12}}, location = {{Austin}}, title = {{{Halogen-Free Flame Retardant Powder Materials for Laser Sintering: Evaluation and Process Stability Analysis}}}, doi = {{https://doi.org/10.26153/tsw/50926}}, year = {{2023}}, } @article{36983, abstract = {{AbstractThe use of structured measuring systems to prevent wall slip is a common approach to obtain absolute rheological values. Typically, only the minimum distance between the measuring surfaces is used for further calculation, implying that no flow occurs between the structural elements. But this assumption is misleading, and a gap correction is necessary. To determine the radius correction $$\Delta r$$ Δ r for specific geometries, we conducted investigations on three Newtonian fluids (two silicon oils and one suspension considered to be Newtonian in the relevant shear rate range). The results show that $$\Delta r$$ Δ r is not only shear- and material-independent, but geometry-dependent, providing a Newtonian flow behaviour in a similar viscosity range. Therefore, a correction value can be determined with only minute deviations in different Newtonian fluids. As the conducted laboratory measurements are very time-consuming and expensive, a CFD-approach with only very small deviations was additionally developed and compared for validation purposes. Therefore, simulation is an effective and resource-efficient alternative to the presented laboratory measurements to determine $$\Delta r$$ Δ r for the correction of structured coaxial geometries even for non-Newtonian fluids in the future.}}, author = {{Josch, Sebastian and Jesinghausen, Steffen and Dechert, Christopher and Schmid, Hans-Joachim}}, issn = {{0035-4511}}, journal = {{Rheologica Acta}}, keywords = {{rheology, rheometry, suspension, coaxial, correction}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Experimental and simulative determination and correction of the effective gap extension in structured coaxial measuring systems}}}, doi = {{10.1007/s00397-023-01383-2}}, year = {{2023}}, } @inproceedings{43236, author = {{Rüther, Torben and Schmid, Hans-Joachim}}, keywords = {{CDMA}}, location = {{Paderborn}}, title = {{{CDMA: Centrifugal Differential Mobility Analyzer - Ein Messprinzip zur Bestimmung von Multidimensionalen Partikeleigenschaften (Vortrag)}}}, year = {{2023}}, } @article{43034, abstract = {{Abstract The accessibility to rheological parameters for concrete is becoming more and more relevant. This is mainly related to the constantly emerging challenges, such as not only the development of high-strength concretes is progressing very fast but also the simulation of the flow behaviour is of high importance. The main problem, however, is that the rheological characterisation of fresh concrete is not possible via commercial rheometers. The so-called concrete rheometers provide valuable relative values for comparing different concretes, but they cannot measure absolute values. Therefore, we developed an adaptive coaxial concrete rheometer (ACCR) that allows the measurement of fresh concrete with particles up to d max = 5.5 mm {d}_{{\rm{\max }}}=5.5\hspace{.5em}{\rm{mm}} . The comparison of the ACCR with a commercial rheometer showed very good agreement for selected test materials (Newtonian fluid, shear thinning fluid, suspension, and yield stress fluid), so that self-compacting concrete was subsequently measured. Since these measurements showed a very high reproducibility, the rheological properties of the fresh concrete could be determined with high accuracy. The common flow models (Bingham (B), Herschel–Bulkley, modified Bingham (MB) models) were also tested for their applicability, with the Bingham and the modified Bingham model proving to be the best suitable ones.}}, author = {{Josch, Sebastian and Jesinghausen, Steffen and Schmid, Hans-Joachim}}, issn = {{1617-8106}}, journal = {{Applied Rheology}}, keywords = {{Condensed Matter Physics, General Materials Science}}, number = {{1}}, publisher = {{Walter de Gruyter GmbH}}, title = {{{Development of an adaptive coaxial concrete rheometer and rheological characterisation of fresh concrete}}}, doi = {{10.1515/arh-2022-0140}}, volume = {{33}}, year = {{2023}}, } @article{43128, author = {{Rüther, Moritz Johannes and Klippstein, Sven Helge and Ponusamy, SathishKumar and Rüther, Torben and Schmid, Hans-Joachim}}, issn = {{0032-5910}}, journal = {{Powder Technology}}, keywords = {{General Chemical Engineering}}, publisher = {{Elsevier BV}}, title = {{{Flowability of polymer powders at elevated temperatures for additive manufacturing}}}, doi = {{10.1016/j.powtec.2023.118460}}, volume = {{422}}, year = {{2023}}, } @inproceedings{44244, author = {{Ponusamy, SathishKumar and Schmid, Hans-Joachim}}, location = {{Braunschweig}}, title = {{{Dynamisch-mechanische Polymerpartikelverrundung zur Verbesserung der Fließfähigkeit für das selektive Lasersintern}}}, year = {{2023}}, } @inproceedings{44103, author = {{Neukötter, Moritz and Jesinghausen, Steffen and Schmid, Hans-Joachim}}, location = {{Berlin}}, title = {{{Particles as Seeds for Instabilities in Uniaxially Elongated Polymer Suspension Filaments (Presentation)}}}, year = {{2023}}, } @article{46815, abstract = {{In this work, the influence of the filler–matrix adhesion on the tensile properties of laser-sintered parts built with Polyamide 613 filled with glass beads was investigated. For this purpose, dry blends of glass beads with and without organosilane coupling agents and polyamide powder were prepared and processed into tensile specimens on an EOS P396 laser sintering system. The samples were tested both in the dry state and after an accelerated conditioning in a climate chamber. Furthermore, finite element method (FEM) simulations were performed to model the extreme cases of optimum adhesion and no adhesion. By correlating the tensile tests with the simulation results and by analyzing the fracture surfaces, it was shown that the filler–matrix adhesion is sufficient in the dry state but is strongly degraded by conditioning. Even the presence of various organosilane thin films could not prevent a strong deterioration of the filler–matrix adhesion and the associated deterioration of the mechanical properties. Since a comparison with an injection-molded sample of the same polymer filler combination shows identical behavior after conditioning, it is assumed that this problem is not limited to additively manufactured parts.}}, author = {{Kletetzka, Ivo and Kosanke, Maren and Meinderink, Dennis and Neßlinger, Vanessa and Grundmeier, Guido and Schmid, Hans-Joachim}}, issn = {{2363-9512}}, journal = {{Progress in Additive Manufacturing}}, keywords = {{Industrial and Manufacturing Engineering}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Influence of the filler–matrix adhesion and the effects of conditioning on tensile properties of laser-sintered parts built with polyamide–glass bead dry blends}}}, doi = {{10.1007/s40964-023-00501-z}}, year = {{2023}}, }