Ústav teoretické a experimentální elektrotechniky

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Comparing efficiencies of polypropylene treatment by atmospheric pressure plasma jets
(WILEY-V C H VERLAG GMBH, 2023-07-11) Polášková, Kateřina; Ozkan, Alp; Klíma, Miloš; Jeníková, Zdeňka; Buddhadasa, Madhuwanthi; Reniers, François; Zajíčková, Lenka
Plasma treatment of polypropylene (PP) is a well-established method of improving its surface properties. However, the efficiencies of different plasma discharges are seldom compared. Herein, we discuss the differences in PP treated by three arc-based commercial plasma jets working in dry air, Plasmatreat rotating plasma jet (PT-RPJ), AFS PlasmaJet & REG; (AFS-PJ), and SurfaceTreat gliding arc jet (ST-GA), and by the low-temperature RF plasma slit jet (RF-PSJ) working in argon. The AFS-PJ has a significantly different reactive species composition dominated by nitrogen oxides. It induced higher thermal loads leading to surface damage. The other arc-based jets (PT-RPJ and ST-GA) created the PP surface with higher oxygen and nitrogen concentration than the low-temperature RF-PSJ. It induced a higher adhesion strength measured on PP-aluminum joints.
Enhanced Adhesion of Electrospun Polycaprolactone Nanofibers to Plasma-Modified Polypropylene Fabric
(MDPI, 2023-03-28) Janů, Lucie; Dvořáková, Eva; Polášková, Kateřina; Janůšová, Martina; Ryšánek, Petr; Chlup, Zdeněk; Kruml, Tomáš; Galmiz, Oleksandr; Nečas, David; Zajíčková, Lenka
Excellent adhesion of electrospun nanofiber (NF) to textile support is crucial for a broad range of their bioapplications, e.g., wound dressing development. We compared the effect of several low- and atmospheric pressure plasma modifications on the adhesion between two parts of composite-polycaprolactone (PCL) nanofibrous mat (functional part) and polypropylene (PP) spunbond fabric (support). The support fabrics were modified before electrospinning by low-pressure plasma oxygen treatment or amine plasma polymer thin film or treated by atmospheric pressure plasma slit jet (PSJ) in argon or argon/nitrogen. The adhesion was evaluated by tensile test and loop test adapted for thin NF mat measurement and the trends obtained by both tests largely agreed. Although all modifications improved the adhesion significantly (at least twice for PSJ treatments), low-pressure oxygen treatment showed to be the most effective as it strengthened adhesion by a factor of six. The adhesion improvement was ascribed to the synergic effect of high treatment homogeneity with the right ratio of surface functional groups and sufficient wettability. The low-pressure modified fabric also stayed long-term hydrophilic (ten months), even though surfaces usually return to a non-wettable state (hydrophobic recovery). In contrast to XPS, highly surface-sensitive water contact angle measurement proved suitable for monitoring subtle surface changes.
Testing an Impedance Non-destructive Method to Evaluate Steel-Fiber Concrete Samples
(DE GRUYTER POLAND SP ZOO, 2018-03-01) Komárková, Tereza; Fiala, Pavel; Steinbauer, Miloslav; Roubal, Zdeněk
Steel-fiber reinforced concrete is a composite material characterized by outstanding tensile properties and resistance to the development of cracks. The concrete, however, exhibits such characteristics only on the condition that the steel fibers in the final, hardened composite have been distributed evenly. The current methods to evaluate the distribution and concentration of a fiber composite are either destructive or exhibit a limited capability of evaluating the concentration and orientation of the fibers. In this context, the paper discusses tests related to the evaluation of the density and orientation of fibers in a composite material. Compared to the approaches used to date, the proposed technique is based on the evaluation of the electrical impedance Z in the band close to the resonance of the sensor-sample configuration. Using analytically expressed equations, we can evaluate the monitored part of the composite and its density at various depths of the tested sample. The method employs test blocks of composites, utilizing the resonance of the measuring device and the measured sample set; the desired state occurs within the interval of between f=3 kHz and 400 kHz.
Designing Multi-Functional Magnetic Storage Cubes for Use in Modern Homes and Schools
(MDPI, 2024-03-20) Zach, Martin; Tauber, Jiří; Dohnal, Přemysl; Svoboda, Jaroslav
Using modern methodologies in the sectors and subareas of industrial design, where they currently find only marginal application, brings a potential for interrelating technology, the arts, and fine arts. To illustrate this, we present model procedures and options for designing a versatile storage cube that integrates magnetic structural components facilitating easy and quick assembly. In addition to being an item of real furniture, portable and readily convertible into a table or soft stool, the cube supports children’s creative games and helps to develop their overall skills in the present-day household and in pre-primary and primary education. The basic material rests in birch plywood, and the joint edges between the individual walls are covered with smooth plastic guards manufactured via additive 3D printing from corn fodder-based filament. Thus, an interesting structural detail, namely, plastic edges, is generated, reinforcing the entire product. The walls comprise decorative, multicolor, polyurethane foam-based elements that can be removed and reinserted. Regarding the manufacturing technology, CNC machining and laser shaping are widely employed on the main parts, and the plastic edges are 3D-printed. In terms of the original idea, the product responds to customer requirements within a specific design project. The robustness and stability tests have proved that the cubes fully satisfy the relevant standards.
Automated Design and Integration of Asset Administration Shells in Components of Industry 4.0
(MDPI, 2021-03-12) Arm, Jakub; Benešl, Tomáš; Marcoň, Petr; Bradáč, Zdeněk; Schröder, Tizian; Belyaev, Alexander; Werner, Thomas; Braun, Vlastimil; Kamenský, Pavel; Zezulka, František; Diedrich, Christian; Dohnal, Přemysl
One of the central concepts in the principles of Industry 4.0 relates to the methodology for designing and implementing the digital shell of the manufacturing process components. This concept, the Asset Administration Shell (AAS), embodies a systematically formed, standardized data envelope of a concrete component within Industry 4.0. The paper discusses the AAS in terms of its structure, its components, the sub-models that form a substantial part of the shell's content, and its communication protocols (Open Platform Communication-Unified Architecture (OPC UA) and MQTT) or SW interfaces enabling vertical and horizontal communication to involve other components and levels of management systems. Using a case study of a virtual assembly line that integrates AASs into the technological process, the authors present a comprehensive analysis centered on forming AASs for individual components. In the given context, the manual AAS creation mode exploiting framework-based automated generation, which forms the AAS via a configuration wizard, is assessed. Another outcome consists of the activation of a virtual assembly line connected to real AASs, a step that allows us verify the properties of the distributed manufacturing management. Moreover, a discrete event system was modeled for the case study, enabling the effective application of the Industry 4.0 solution.

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