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This work aims to characterize 3D-printed structures composed of a thermoplastic material (polylactic acid (PLA)) containing a combination of magnetic particles composed of iron(III) oxide (hematite) and iron(II)–iron (III) oxide (magnetite) with various infill densities and print orientations in regard to their possible processing by Fused Filament Fabrication additive technology. The correct processing temperatures have been determined using thermal analysis, and the paramagnetic and mechanical properties of the samples have been tested. The relative permeability has been identified to be strongly dependent on the topology parameters of the tested samples. The results of the inductance values for the samples without magnetic additives (infill densities 50% and 100%) have been detected to be comparable; nonetheless, the magnetic samples with 100% infill density has been found to be about 50% higher. A similar trend has been observed in the case of the values of the relative permeability, where the magnetic samples with 100% infill density have been measured as having an about 40% increased relative permeability in the comparison with the samples without magnetic additives (infill densities 20–100%). Finite Element Modelling (FEM) simulations have been applied to determine the magnetic field distributions and, moreover, to calculate the holding forces of all the printed samples. The maximum value of the holding force for the minimum distance of the plastic plate has been found to reach a value of almost 300 N (magnetic sample with 100% infill density). The obtained comprehensive characterization of the printed samples may be utilized for designing and tuning the desired properties of the samples needed in various industrial applications. [ABSTRACT FROM AUTHOR]

Membrane chemistry belongs to the field in which 3D printing can advantageously also be used because of enabling the production of prototypes with precisely defined dimensions. The presented work aimed to develop new polymeric compositions for heterogeneous cation exchange membranes manufactured using stereolithography (SLA) from commercially available materials. Three types of photo‐curable thermoset resins (acrylic resin and two types of epoxy resins) were used as polymer matrixes in combination with strong acid cation exchange resin (CER) powder. The membrane production consisted of several stages, namely mixing the photo‐curable resin with finely ground CER powder, processing using SLA, and appropriate post‐curing using UV light and elevated temperature. The work aimed to monitor the influence of the photo‐curable resin type and post‐curing on the microstructural, electrochemical, and mechanical properties of resulting membrane objects. The results revealed that heterogeneous cation exchange membranes could be processed using SLA from the mixture of the acrylic photo‐curable resin and CER powder (weight ratio of 60/40) without the need for post‐curing. These products exhibited high permselectivity (93%), high ion exchange capacity (2.23 meq⋅g−1), and sufficiently low electrical resistance (2200 Ω⋅cm), which predetermines them for efficient electrophoretic separation. [ABSTRACT FROM AUTHOR]

This work aims to characterize printing structures with various infill densities composed of a thermoplastic material containing magnetic particles composed of mainly Iron(III) oxides with regard to their possible processing with the additive technology of Fused Filament Fabrication. A polyethylene terephthalate glycol (PET-G) structural thermoplastic with the addition of Iron(III)) oxides has been selected, and correct processing temperatures have been determined using thermal analysis. The paramagnetic properties of printed products consisting of different filling densities have been tested. Relative permeability has been identified to be strongly dependent on the printed internal structures of tested products. The samples composed of the densest structure have shown relative permeability higher by 18% with respect to the sample printed with the least dense structure. Finite Element Modelling (FEM) simulations have been applied to determine magnetic field distributions and, moreover, to calculate the holding forces of all printed samples. The performed simulations confirmed that produced composites might be utilized as magnetic switches and sensors or as more advanced components for homogenizing electric motors' magnetic fields. Moreover, magnetic properties might be tuned according to the specific needs printing structure with the suitable density. [ABSTRACT FROM AUTHOR]

3D printing of reinforced polymeric materials, which provides products of excellent physical and mechanical properties, is at the forefront of interest in the field of additive technologies. To ensure material, time, and financial savings, 3D objects having reduced filling density are frequently prepared. The presented work aims to study the effect of different levels of filling density (18, 42, and 62% using a honeycomb filling pattern) in contrast to 100% solid fill of carbon fiber-reinforced polyamide 6.6 materials processed by Fused Filament Fabrication on their flammability and mechanical properties. Concurrently, the effect of a commercial flame retardant additive concerning the filling density was also evaluated. The flammability and mechanical properties of the 3D printed materials were evaluated according to cone calorimeter measurements, and tensile and bending tests, respectively. It was found that the reduction in the filling density led to a pronounced decrease in mechanical properties (of about 40–50% for tensile and bending stress) and also to the deterioration of flame resistance (of about 50–70% shorter burning time), with no unambiguous correlation with the respective filling density level used. If significant economic savings are preferred, 3D objects designed with low levels of filling density (18 or 42%) are advantageous to be manufactured from nylon stabilized with a flame retardant additive, resulting in acceptable fire-resistant properties. • Preparation and testing of various honeycomb fillings with regard to properties. • With increasing filling density, the samples show better mechanical properties. • With decreasing filling density, the samples release less smoke during burning. • Optimization of filling density ensures favorable fire performance and economic savings. [ABSTRACT FROM AUTHOR]

Nowadays, additive manufacturing—also called 3D printing—represents a well-established technology in the field of the processing of various types of materials manufacturing products used in many industrial sectors. The most common type of 3D printing uses the fused filament fabrication (FFF) method, in which materials based on thermoplastics or elastomers are processed into filaments. Much effort was dedicated to improving the properties and processing of such printed filaments, and various types of inorganic and organic additives have been found to play a beneficial role. One of them, calcium carbonate (CaCO3), is standardly used as filler for the processing of polymeric materials. However, it is well-known from its different applications that CaCO3 crystals may represent particles of different morphologies and shapes that may have a crucial impact on the final properties of the resulting products. For this reason, three different synthetic polymorphs of CaCO3 (aragonite, calcite, and vaterite) and commercially available calcite powders were applied as fillers for the fabrication of polymeric filaments. Analysis of obtained data from different testing techniques has shown significant influence of filament properties depending on the type of applied CaCO3 polymorph. Aragonite particles showed a beneficial impact on the mechanical properties of produced filaments. The obtained results may help to fabricate products with enhanced properties using 3D printing FFF technology. [ABSTRACT FROM AUTHOR]