Tomas Bata University in Zlín
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Sustainable polysaccharide and protein hydrogel-based packaging materials for food products: A review
Get PDFSustainable food packaging is a necessary element to ensure the success of a food system, the accomplishment of which is weighed in terms of quality retention and ensured products safety. Irrespective of the raised environmental concerns regarding petroleum-based packaging materials, a sustainable analysis and a lab to land assessment should be a priority to eliminate similar fates of new material. Functionalized bio-based hydrogels are one of the smartest packaging inventions that are expected to revolutionize the food packaging industry. Although in this review, the focus relies on recent developments in the sustainable bio-based hydrogel packaging materials, natural biopolymers such as proteins and polysaccharides from which hydrogels could be obtained, the challenges encountered in hydrogel-based packaging materials and the future prospects of hydrogel-based food packaging materials are also discussed. Moreover, the need for 'Life Cycle Assessment' (LCA), stress on certifications and a sustainable waste management system is also suggested which can bring both food and packaging into the same recycling bins.Horizon 2020, (810630); Eesti Maaülikool, EMÜEuropean Union [810630
Tensile fracture analysis of 3D printed Inconel 718
Get PDFThe article deals with the fracture analysis of uniaxial tensile stressed samples made of Inconel 718 alloy by DMLS (Direct Metal Laser Sintering) technology. The samples were heat treated according to AMS 5664 procedure. The material sheet of the EOS Nickel Alloy IN718 provides the tensile properties of the heat-treated samples built only in Z-direction, so the authors decided to also explore the tensile behaviour of the 3D-prinied samples in individual X- and Y-directions. Further to tensile testing, fracture surface observations were performed to identify the principal failure modes. Fractographic investigation on tensile fractures, revealed predominantly a quasi-ductile failure mechanism, showing fine size dimple formation.Ministerstvo školstva, vedy, výskumu a športu Slovenskej republiky, (APVV-19-0550); Kultúrna a Edukacná Grantová Agentúra MŠVVaŠ SR, KEGA, (005TUKE-4/2021
Bidisperse magnetorheological fluids utilizing composite polypyrrole nanotubes/magnetite nanoparticles and carbonyl iron microspheres
Get PDFConductive polypyrrole nanotubes were synthesized with a two-step one-pot synthesis. During synthesis, the nanotubes were decorated with magnetite nanoparticles at different concentrations granting them magnetic properties. The characterization of the tubes revealed differences from the theoretical reactions. A bidisperse magnetorheological fluid (MRF) was prepared by mixing the composite polypyrrole nanotubes/magnetite nanoparticles with commercial carbonyl iron spherical microparticles in silicone oil. The rheological properties of the bidisperse system were studied under the presence of magnetic field at room and elevated temperature. An enhancement of the MR effect with the presence of the nanotubes was observed when compared with a standard MRF consisted only of magnetic microparticles. Due to the faster magnetic saturation of the nanotubes, this enhancement is exceptionally high at low magnetic fields. The stability of the system is studied under dynamic conditions where it is revealed that the nanotubes keep the standard particles well dispersed with the sedimentation improving by more than 50%.Internal Grant Agency of Tomas Bata University in Zlín, (IGA/CPS/2022/004, RP/CPS/2022/003); National Technical Library in Prague; Tomas Bata University in Zlin, TBU; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT, MŠMT; en:MEYS, (RP/CPS/2022/007); Univerzita Tomáše Bati ve ZlíněNational Technical Library in Prague; Internal Grant Agency of Tomas Bata University in Zlin [IGA/CPS/2022/004]; project DKRVO [RP/CPS/2022/007, RP/CPS/2022/003]; Ministry of Education, Youth and Sports of the Czech Republi
Tribological and micro-mechanical properties of injected polypropylene modified by electron radiation
Get PDFToday, more and more importance is given to the improvement of polymer materials' wear resistance, i.e., their micro-mechanical and tribological properties, which could widen their application in practice. The properties of materials can be modified by several methods, among them exposure to electron radiation. This study focuses on the effect of varying radiation intensity (15 kGy to 99 kGy), depth of penetration, and subsequent structure modification of injection-molded polypropylene on tribological and micro-mechanical properties. Electron radiation influences the structure of individual layers, thus improving or degrading their properties. Hence, the depth of penetration can be examined by instrumented hardness tests and scratch tests. Due to irradiation, surface properties and wear resistance increased by up to 105% (from 38 MPa to 78 MPa). As the results show, an increase in mechanical properties was recorded in the direction towards the center of the sample (from 72 MPa to 82 MPa). Micro-mechanical tests were also confirmed by the observation of cross-linking changes (gel test) as well as crystallinity increases (wide-angle X-ray diffraction and microtome cuts). This finding could have a significant effect on the manufacturing and subsequent modification of injection-molded polypropylene parts, which opens new possibilities in practice for this material. The increased surface wear resistance enables the use of parts for which the durability and abrasion resistance of the surface are demanded, especially in applications facing exposure to long-term cyclical loads (e.g., gears).TBU in Zlin Internal Grant Agency, (IGA/FT/2023/005)TBU in Zlin Internal Grant Agency [IGA/FT/2023/005
Tuning of morphological and antibacterial properties of poly(3,4-ethylenedioxythiophene):peroxodisulfate by methyl violet
Get PDFThis study demonstrates a one-step synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) in the presence of the methyl violet (MV) dye. The structural properties of PEDOT:peroxodisulfate were studied using Raman and MALDI-TOF spectroscopies. The use of the MV dye in the polymerization process resulted in a change in the typical irregular morphology of PEDOT:peroxodisulfate, leading to the formation of spherical patterns. SEM and TEM analyses revealed that increasing the dye concentration can produce larger spherical aggregates probably due to the hydrophobic and π–π interactions. These larger aggregates hindered the charge transport and reduced the electrical conductivity. Interestingly, at higher dye concentrations (0.05 and 0.075 M), the PEDOT:peroxodisulfate/MV films exhibited significantly improved antibacterial activity against Staphylococcus aureus and Escherichia coli. Furthermore, the PEDOT:peroxodisulfate films with the incorporated MV dye exhibited a well-defined and repeatable redox behavior. The remarkable amalgamation of their optical, electrochemical and antibacterial properties provides the PEDOT:peroxodisulfate/MV materials with an immensely diverse spectrum of applications, including in optical sensors and medical devices.DKRVO, (RP/CPS/2022/001); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Akademie Věd České Republiky, AV ČR, (RVO 61389013
Integration of alarm security systems
No full textThe alarm security system is increasingly used in industrial, commercial or residential buildings. Since there is an increasing demand for several types of security systems, a suitable solution is to integrate them, thereby speeding up and making their communication between individual systems more efficient to minimize the risk of threats. The most common security systems suitable for integration with an alarm security system are a fire detection and fire alarm system, a camera system, an access control system and an alarm receiving centre.Internal Grant Agency of Tomas Bata University in Zlnn; Department of Security Engineering, Faculty of Applied Informatics; [IGA/FAI/2023/001
Design and fabrication of TiO2/Nd polyurethane nanofibers based photoreactor: A continuous flow kinetics study for Estriol degradation and mechanism
No full textNovel polyurethane (PU) nanofibers incorporated with the neodymium (Nd) doped TiO2 nanoparticles were fabricated by electrospinning process and employed for the photocatalytic degradation of the estriol (E3) hormone. Nanofibers possessed high porosity (0.47 μm) and uniform mesh-like structure while suitable incorporation of TiO2/Nd nanoparticles with increasing concentrations (5, 10, and 20 %) was obtained. The TiO2/Nd incorporated PU nanofiber photocatalytic activity under UV and visible light was evaluated using a continuous drip flow biofilm reactor. To establish sufficient adherence to the PU matrix necessary to maintain durability during crossflow reactor, the as-prepared nanofibers were thermally pressed on polyethylene terephthalate (PET) sheets to avoid any potential folding. The nanofibers performed better in UV than visible, with maximum degradation rates of ∼90.2 % and 30.4 %, respectively, at pH 7 in 120 min. The degradation performance of nanofibers increased with an increase in the number of layers and decreased with the E3 solution flow rate. The experimental data best fitted for the pseudo-first-order kinetic model with regression coefficient (R2) > 0.9. The highest degradation removal capacities were 2.436 and 0.847 mg/g under UV and visible light irradiation, respectively. The results showed that TiO2/Nd incorporated PU nanofibers exhibit a potential to degrade hormones from environmental water.DKRVO, (RP/CPS/2022/002, RP/CPS/2022/007); TBU in Zlin, (IGA/CPS/2023/006); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMTMinistry of Education, Youth, and Sports of the Czech Republic-DKRVO [RP/CPS/2022/002, RP/CPS/2022/007]; Internal Grant Agency (IGA) of TBU in Zlin [IGA/CPS/2023/006
Controlled structuring of hyaluronan films by phase separation and inversion
No full textThis work explores application of phase separation phenomena for structuring of films made from hyaluronan. A time-sequenced dispensing of different solution mixtures was applied under rotation of hyaluronan-covered substrates to generate surface textures. This method is applicable in direct surface modification or cover layer deposition. Changes in the surface topography were characterized by atomic force microscopy, optical microscopy, and contact and non-contact profilometry. The mechanical properties of the surface-modified self-supporting films were compared using a universal testing machine. Experimental results show that diverse hyaluronan-based surface reliefs and self-supporting films with improved mechanical properties can be prepared using a newly designed multi-step phase separation process without the need for sacrificial removable templates or additives.Grantová Agentura České Republiky, GA ČR, (22-33307S)Czech Science Foundation [22-33307S
Linkage between growth phenology and climate-growth responses along landscape gradients in boreal forests
No full textBoreal forests represent an important carbon sink and, therefore, significantly contribute to climate change mitigation. Tree-ring width series of boreal species reflect climate variation at the moment of tree-ring formation but also lagged climatic effects from dormancy preceding tree-ring formation and antecedent growing seasons. However, little is known about how the growth sensitivity to climate in specific intra-annual periods varies across the landscape. Here, we assessed growth responses to climate variation during the 45 months preceding the tree-ring formation for nine boreal stands of Picea glauca and Picea mariana distributed along the gradients of elevation and slope aspect. We combined process-based modeling of wood formation and remote sensing data to determine growth phenology at each site. Next, we classified intra-annual seasons with significant climate-growth correlations based on the timing of dormancy and growth periods. Both the phenology and the climate-growth relationships systematically shifted with elevation and, to a lower extent, also with slope orientation at the treeline. The mean duration of the growing season varied between 100 days at treelines above 900 m and 160 days at lowlands below 500 m. The growth at treelines was stimulated by temperature in the summer of the tree-ring formation year and two years before tree-ring formation. The period of significant climate-growth correlations during the current summer did not exceed three months in agreement with the local duration of the growing season. The growth of trees in lower elevations was instead stimulated by high temperature during the dormancy periods but restricted by high temperature in antecedent summer seasons. In conclusion, our study highlights the linkage between the timing of climate-growth sensitivity and growth phenology, primarily determined by proximity to the treeline. Consequently, accounting for landscape gradients in growth phenology is crucial for upscaling the climatic limits of boreal stands' growth as climate change progresses.Univerzita Karlova v Praze, UK, (23-05272S, UNCE/HUM 018); European Commission, EC, (871120); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT, (LTAUSA19137); Grantová Agentura České Republiky, GA ČR, (22-26519S); Akademie Věd České Republiky, AV ČR, (RVO 67985939)European Union [871120]; Czech Science Foundation [23-05272S, 22-26519S]; Charles University [UNCE/HUM 018]; Czech Ministry of Education, Youth and Sports [LTAUSA19137]; Czech Academy of Sciences [RVO 67985939
Effect of geometry and surface distribution of holes on sound and light absorption properties of 3D-printed PETG materials
No full textNoise and lighting are significant factors that have an impact on our health, environment, production quality, etc. The purpose of this paper is to investigate sound and light absorption properties of 3D-printed polyethylene terephthalate glycol (PETG) material specimens that were manufactured with two types of holes, namely with circular and square-shaped holes. In addition, the holes were printed with different dimensions, depths, shapes, and surface spacings. Different factors influencing the material's ability to absorb sound and light were evaluated in this paper. It was found in this study that the type of holes, their spacing and depth have a big influence on sound and light absorption properties of the investigated samples compared to the smooth PETG material.European Regional Development Fund in the Research Centre of Advanced Mechatronic Systems, (CZ.02.01.01/00/22_008/0004631, CZ.02.1.01/0.0/0.0/16_019/0000867); European Commission, ECEuropean Regional Development Fund in the Research Centre of Advanced Mechatronic Systems project [CZ.02.1.01/0.0/0.0/16_019/0000867]; European Union [CZ.02.01.01/00/22_008/0004631]; state budget of the Czech Republi