TY - JOUR AB - Magnetic nanoparticles can be used for medical and other purposes, but can also be integrated in polymeric or other nonmagnetic matrices of diverse shapes, for example, thin-films or fibers. In the latter case, it may be important how the magnetic nanoparticles are distributed in the matrix, a topic which is often not taken into account when such composites are investigated experimentally or theoretically. Especially for small magnetic nanoparticles of dimensions allowing coherent reversal, the magnetic properties of such polymer/magnet composites can change drastically in the case of agglomerations. Here, a method is suggested to quantify the influence of nanoparticle distributions inside nonmagnetic matrices. By changing the average distance between nanoparticles of varying diameters between highly distributed particles and perfectly packed clusters, different magnetization dynamics can be modeled by micromagnetic simulations. Here, this process is shown for various magnetic materials and diameter distributions of magnetic nano-spheres and present corresponding micromagnetic simulation results, which underline the importance of taking into account possible magnetic agglomerations in nonmagnetic space. AU - Blachowicz, Tomasz AU - Grzybowski, Jacek AU - Ehrmann, Andrea ID - 2027 IS - 1 JF - Macromolecular Symposia KW - iron KW - collapse KW - cross-section KW - permalloy KW - spherical coordinates KW - virtual sphere SN - 1022-1360 TI - Micromagnetic Simulations of Nanoparticles with Varying Amount of Agglomeration VL - 402 ER - TY - JOUR AB - During electrospinning, the flying nanofibers can be attracted by conductive areas such as copper tape on a nonconductive substrate, especially in case of magnetic nanofibers. The question arises, however, whether the conductivity or any other physical properties of these areas are responsible for this effect. Here, electrospinning polyacrylonitrile (PAN) on nonconductive polypropylene (PP) substrates is reported, modified with conductive copper tape as well as with diverse coatings with varying dielectric constants. The results show that in case of non-magnetic PAN fibers, especially BaTiO3 with its high dielectric constant strongly, attracts the fibers formed during electrospinning, which can be explained by local modification of the electric field due to the introduced dielectric. This process can be used to tailor the nanofiber mat thickness depending on the position. AU - Hellert, Christian AU - Storck, Jan Lukas AU - Grothe, Timo AU - Kaltschmidt, Bernhard AU - Hütten, Andreas AU - Ehrmann, Andrea ID - 1294 IS - 1 JF - Macromolecular Symposia SN - 1022-1360 TI - Positioning and Aligning Electrospun PAN Fibers by Conductive and Dielectric Substrate Patterns VL - 395 ER - TY - JOUR AU - Hellert, Christian AU - Storck, Jan Lukas AU - Grothe, Timo AU - Kaltschmidt, Bernhard AU - Hütten, Andreas AU - Ehrmann, Andrea ID - 2583 IS - 1 JF - Macromolecular Symposia SN - 1022-1360 TI - Positioning and Aligning Electrospun PAN Fibers by Conductive and Dielectric Substrate Patterns VL - 395 ER - TY - JOUR AB - Vacuum casting of polyurethane (PUR) in silicone molds is used industrially for the production of prototypes and small series as well as in various noncommercial research areas. This includes the reproduction of archeological findings, biological samples or electronic devices. In this study, the authors investigate the molding accuracy of different commercial silicones and PUR casting resins both on microscopic and macroscopic scales. For this, they used a variety of master models to generate silicone rubber casting molds. The resulting PUR castings are investigated by helium ion microscopy, confocal laser scanning microscopy, and optical 3D-scanning. AU - Wortmann, Martin AU - Frese, Natalie AU - Brikmann, Johannes AU - Ehrmann, Andrea AU - Moritzer, Elmar AU - Hüsgen, Bruno ID - 1618 IS - 1 JF - Macromolecular Symposia SN - 1022-1360 TI - Silicone Mold Accuracy in Polyurethane Vacuum Casting VL - 395 ER - TY - JOUR AB - 3D printed objects are nowadays not only used in prototyping, but also in small-scale production down to lot-size 1. While different 3D printing techniques can be applied for this purpose, a large amount of products is prepared by the simple and inexpensive fused deposition modeling (FDM) technique, applying a polymer which is molten, pressed through a nozzle, and deposited layer-by-layer on a printing bed and on the previous layers, respectively. This technology, however, has the disadvantage of often insufficient mechanical properties due to the available materials and due to the construction method, which often supports air cavities inside objects, reducing the adhesion between neighboring strands and thus the overall mechanical properties. Such problems can partly be solved by chemical after-treatments. Here, the authors report on tensile tests and load changes of the soft FDM materials FilaFlex and PLA soft (PLA = polylactic acid) in comparison with common PLA. They also show the different inner structure of objects 3D printed from these materials and their correlation with mechanical properties and material fatigue. AU - Cakar, Siver AU - Ehrmann, Andrea ID - 1620 IS - 1 JF - Macromolecular Symposia SN - 1022-1360 TI - 3D Printing with Flexible Materials – Mechanical Properties and Material Fatigue VL - 395 ER -