Tomas Bata University in Zlín
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Effect of repeated thermoplastic processing of polypropylene matrix on the generation of low-molecular-weight compounds
No full textThis study investigates the effects of repeated reprocessing on polypropylene (PP) and the associated release of low-molecular-weight substances into liquid and gaseous phases. Specifically, virgin polypropylene (Mosten TB 003) was mechanically reprocessed 1, 5, 10, 15, and 18 times to simulate its participation in the mechanical recycling cycle. The mechanical properties of all PP samples were evaluated, along with their potential migration into water. The stability of PP was assessed using differential scanning calorimetry (DSC), while molecular weight distribution was determined via high-temperature gel permeation chromatography (GPC) with refractometric and viscosimetric detection. GPC and DSC analyses of PP's mechanical properties revealed that reprocessing led to chain shortening and reduced thermal stability, evidenced by material yellowing. For PP recycled 18 times—representing the maximum feasible number of reprocessing cycles—the molecular weight decreased by approximately 30 % compared to virgin PP. The potential release of volatile substances (odorants) into the environment during PP processing was monitored using headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC–MS). Two extraction temperatures were examined: 90 °C, simulating the maximum temperature PP reaches indoors, and 120 °C, representing outdoor conditions. The least volatile substances were detected in the most extensively reprocessed PP (18x). At 120 °C, the most significant compounds identified included phenolic substances such as 2,4-di‑tert-butylphenol, 2,6-di‑tert‑butyl‑p-benzoquinone, 4-hydroxybenzaldehyde, estragole, and 2-phenoxyethanol. The number of reprocessing cycles was indicated by the presence of 4-methyl-1,6-heptadien-4-ol.Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; European Just Transition Fund; Ministerstvo Životního Prostředí, MŽP, (CZ.10.03.01/00/22_003/0000045, CZ.02.01.01/00/23_021/0009004); Ministerstvo Životního Prostředí, MŽP; Tomas Bata University in Zlín, TBU, (RP/CPS/2024-28/002); Tomas Bata University in Zlín, TBUEuropean Just Transition Fund within the Operational Programme: Just Transition under the aegis of the Ministry of the Environment of the Czech Republic; Ministry of Education Youth and Sports of the Czech Republic, Operational Programme Johannes Amos Comenius OP JAC "Application potential development in the field of polymer materials in the context of circular economy compliance (POCEK) " [CZ.02.01.01/00/23_021/0009004]; Centre of Polymer Systems, Tomas Bata University in Zlin; Ministry of Education Youth and Sports of the Czech Republic [RP/CPS/2024-28/002]; [CZ.10.03.01/00/22_003/0000045
Turning plastic waste immiscibility into an advantage: Efficiency improvement of PVDF-based energy harvesters using post-consumer thermoplastics
Get PDFThe immiscibility of plastic waste, which is often a limiting factor in traditional recycling processes, is considered in this study as a key feature for functional material design. Polyvinylidene fluoride (PVDF), renowned for its exceptional triboelectric and piezoelectric properties, is combined with post-consumer thermoplastic waste from the packaging industry to create a novel, sustainable energy-harvesting solution. Immiscible compounds of wasted high-density polyethylene, polypropylene, polystyrene, and polyethylene terephthalate form physical mixtures of domains of individual polymers within the melt, which enhance mechano-electric conversion when paired with PVDF to achieve a remarkable output voltage of 800 V, with short-circuit current and charge densities reaching 260 µAcm⁻2 and 710 nCm⁻2, respectively, surpassing traditional PVDF-nanoparticle composites. This method not only reduces reliance on costly nanomaterials but also demonstrates the potential of repurposed plastic waste for energy applications. The design of the sensors is examined to distinguish the contribution of piezo- and tribo-electrifications. Examples of low-cost sustainable sensors constructed from PVDF and thermoplastic waste films demonstrate efficient energy conversion and sensitivity to mechanical stimuli and highlight the potential of repurposing immiscible plastic waste not only as a solution to pollution but also as a contributor to green energy technologies.Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT, (RP/CPS/2024‐28/005); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMTMinisterstvo Scaron;kolstv, Mldezcaron;e a Tecaron;lovchovy [RP/CPS/2024-28/005]; Ministry of Education, Youth, and Sports of the Czech Republi
Wearable sensors and computational intelligence in alpine skiing analysis
Get PDFThe integration of wearable sensors with artificial intelligence forms the base for analyzing physical activities through digital signal processing, numerical methods, and machine learning. Computational intelligence and communication technologies enable personalized monitoring, training, and rehabilitation, with applications in sports, neurology, and biomedicine. This paper focuses on motion analysis in alpine skiing using real accelerometric, gyroscopic, positioning, and video data to evaluate ski movement patterns. The proposed methodology employs functional transforms to estimate motion patterns and utilizes artificial intelligence for signal segmentation and feature classification related to lower limb movement. Machine learning results indicate differences in energy distribution before and after ski turns and demonstrate the feasibility of classifying associated motion patterns with accuracies of 98.1% and 90.7%, respectively, using a two-layer neural network. The interdisciplinary application of computational intelligence in this domain enhances motion analysis, injury prevention, and performance optimization. This study highlights the unifying role of digital signal processing, which uses similar mathematical tools across various applications.European Commission, EC, (CZ.02.01.01/00/22_008/0004590); European Commission, EC; Czech Ministry of Education, Youth, and Sports, (SENDISO-CZ.02.01.01/00/22_008/0004596)European Union under the project Robotics and Advanced Industrial Production (ROBOPROX) in the Area of Machine Learning [CZ.02.01.01/00/22_008/0004590]; Operational Program Johannes Amos Comenius - European Structural and Investment Funds; Czech Ministry of Education, Youth, and Sports [SENDISO-CZ.02.01.01/00/22_008/0004596
Reinforced fluorinated copolymer and polyurethane electrospun layered nanofiber-based membranes for effective model water dead-end microfiltration
No full textThe research presented herein describes the preparation of electrospun homogeneous nanofibrous structures with customized morphology and properties, as well as textile support for necessary reinforcement for microfiltration applications. Findings report membranes comprising a polyurethane or fluorinated copolymer nanofibrous layer and polyethylene terephthalate nonwoven textile as support were evaluated. The investigation encompassed various constructions of materials, which include the influence of nanostructure morphology, the process of membrane cleaning by backwashing, and factors affecting flux, filtration efficacy, and working life. Application of membrane support made from polyethylene terephthalate with a large distribution of polymer chain provides a sufficiently strong connection with a layer of nanofibers with minimum penetration into the nanostructure involved in flux improvement. It was discerned that nanostructures with a morphology of six layers from thick (fiber diameter ~ 500 nm) and thin (fiber diameter ~ 180 nm) nanofibers with mean pore size 0.67 μm in comparison with membranes prepared from thin nanofibers only (mean pore size 0.26 μm) exhibited improved flux (17 times higher after 150 min of filtration process). In contrast, the filtration efficacy of both membranes for filtering submicron particles remained stable and highly efficient. It also proved to smooth out the surfaces of the novel membranes, which simplifies the removal of caked-up debris. Cleaning the filter by backwashing renewed the efficacy of the developed membranes for filtration and extended their working life. Finally, repeatedly backwashing the thin nanofiber layer membrane raised the water flux measured as 230 L m−2 h−1, that is, six times higher than without backwashing.European Just Transition Fund; Centre of Polymer Systems; Ministerstvo Školství, Mládeže a Tělovýchovy, MEYS; Tomas Bata University in Zlín, TBU, (RP/CPS/2024-28/002); Tomas Bata University in Zlín, TBU; Ministerstvo Životního Prostředí, MoE, (CZ.02.01.01/00/23_021/0009004, CZ.10.03.01/00/22_003/0000045); Ministerstvo Životního Prostředí, MoECentre of Polymer Sysrems, Tomas Bata University in Zlin [CZ.10.03.01/00/22_003/0000045]; European Just Transition Fund within the Operational Programme: Just Transition under the aegis of the Ministry of the Environment of the Czech Republic [CZ.02.01.01/00/23_021/0009004]; Operational Programme Johannes Amos Comenius OP JAC [RP/CPS/2024-28/002]; Tomas Bata University in Zlin; Ministry of Education Youth and Sports of the Czech Republi
Carbonization and activation of leather buffing dust to a biocarbon and its conductivity
No full textBuffing dust, one of the collagenous wastes produced in the footwear industry, was carbonized at 400–1200 °C in an inert atmosphere to microfibrous nitrogen-containing biocarbons enriched with chromium. The evolution of molecular microstructure with increasing carbonization temperature or exposure time was followed with FTIR and Raman spectra. The resistivity of the powdered products was determined by van der Pauw four-point method and recorded as a function of applied pressure in the 0.1–10 MPa range. The highest conductivity 13.9 S cm−1 at 10 MPa was found after the carbonization at 1200 °C. The mechanical properties, such as the change of sample volume with applied pressure, are also discussed. The specific surface area was low, ca 5–7 m2g−1, independent of the carbonization temperature. This parameter was enhanced by the chemical activation with ammonium peroxydisulfate or potassium hydroxide by two orders of magnitude, while the conductivity decreased at the same time by less than one order of magnitude.Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Technology Agency of the Czech Republic, TACR, (TK03030157); Technology Agency of the Czech Republic, TACR; DKRVO, (RP/UNI/2024-28/001, RP/CPS/2024-28/005, RP/CPS/2024-28/007)Ministry of Education, Youth and Sports of the Czech Republic [DKRVO RP/UNI/2024-28/001, RP/CPS/2024-28/005, RP/CPS/2024-28/007]; Technology Agency of the Czech Republic [TK03030157
Silk fibroin surface engineering using phase separation approaches for enhanced cell adhesion and proliferation
No full textDue to excellent mechanical properties and biocompatibility, materials based on silk fibroin are increasingly included in advanced biomedical research and applications. However, their poor supporting properties for cell adhesion and proliferation represent limiting factors of the utilization. To eliminate this deficiency, we developed a series of phase-separation approaches allowing for tunable texturing of planar and 3D printed fibroin surfaces from nano to macro levels. The formation of surface structures presented is based on a combination of good and poor solvents, whereas no potentially problematic templates or additives, diminishing biocompatibility of the resulting material, are required. A critical factor in obtaining and scaling of the textures is control over the degree of transformation of fibroin secondary structures between prevalently amorphous Silk I and semicrystalline Silk II forms before and during surface treatment. Employing a set of optimized procedures, selectively or hierarchically structured fibroin surfaces can be prepared at the nano, micro, and macro level, which are characterized by long-term stability in physiological environments, allowing enhanced adhesion and proliferation of human keratinocytes as well as skin fibroblast cultivations.Grantová Agentura České Republiky, GAČR, (22-33307S)Grantov? Agentura Cesk? Republiky [22-33307S]; Czech Science Foundatio
University preparation of kindergarten teachers for English teaching in the Czech Republic
No full textAn ever-increasing trend of early foreign language teaching requires adequate responses to the university training of future kindergarten teachers. However, research in this area, including policies, suggests that the situation is not entirely satisfactory. This paper aims to determine the level of preparation of future teachers for teaching English to pre-prima-ry children at individual universities in the Czech Republic. It presents findings obtained through quantitative content analysis of the syllabi of eight universities that provide education in the field of teacher training for kindergartens and focus on the preparation of future teachers for English tuition. The results show that courses for English tuition in kindergarten are not implemented by every university. Universities differ in their emphasis on foreign language tuition in kindergarten, which is reflected in the number and content of provided courses
Application of de La Vallée Poussin type inequalities to half-linear Euler type equations
No full textThe paper is devoted to the application of de la Vallée Poussin type inequalities to half-linear differential Euler type equations. Four studied equations seen as perturbations of the nonoscillatory Euler equation with the oscillation constant are considered, and a new theorem for the cases where the perturbation is in both terms is presented. Several different corollaries of de la Vallée Poussin type inequalities for Euler type equations, which can help in estimating the distance between consecutive zero points of their solutions, are formulated
Circular intentions, minimal actions: The psychology of doing less in hospitality – An integrative review
Get PDFDespite growing interest in sustainability, the adoption of circular economy (CE) practices in hospitality remains largely symbolic and limited to low-effort actions. This paper explores why hotels, despite expressing genuine interest and facing external pressures, often avoid deeper CE strategies. First, a systematic literature review and bibliometric mapping identify key behavioural, structural, social and market-related barriers that constrain CE action. These barriers shape managerial thinking and contribute to disengagement from ambitious practices. Building on this, an explanatory analysis draws on psychological mechanisms, particularly cognitive dissonance and moral licensing, to explain why external limitations become internally justified. This rationalisation process fosters a 'So What?' mindset, where minimal actions are viewed as sufficient in light of perceived barriers. As a result, the gap between sustainability intentions and behaviour and further action widens. The study helps us understand how hotel managers' beliefs and thinking patterns influence whether and how they apply CE principles.This work was supported by Tomas Bata University in Zl\u00EDn under Grant RO/FaME/2024/07 and FSR 2024 FaME/001.Tomas Bata University in Zlin [RO/FaME/2024/07, FSR 2024 FaME/001
Decision-making support system for travel planning for people with disabilities based on fuzzy set theory
Get PDFResearch background: In recent years, there has been increasing attention to the needs of tourists with disabilities. Several international studies confirm that this target group has been marginalized in tourism due to physical, economic, social, and environmental barriers. However, the integration of intelligent decision-support systems can significantly enhance accessibility and inclusion in tourism.
Purpose of the article: This research aims to develop effective methods and algorithms for constructing intelligent systems and software that generate precise and high-quality travel plans for tourists with disabilities. The primary objective is to create a decision support system for trip planning, using the example of Visegrad Group countries (the Czech Republic, Hungary, Poland, Slovakia).
Methods: The decision support system is structured around two core components: the data level and the knowledge level. The data layer compiles a structured database of actual visits by disabled tourists. The knowledge layer consists of mathematical models forming a comprehensive decision-making framework. The formalization of the system employs fuzzy set theory, fuzzy logic, expert evaluation, and intelligent knowledge analysis. This research introduces: an information model for assessing the accessibility of destinations; fuzzy method of determining the degree of accessibility of destination, considering the level of limited capabilities of the participant of the tourist movement; decision-making method when travel planning on the accessibility of the region on goal needs.
Findings & value added: The decision-making support system was verified and tested on real data from 41 participants in the Visegrad Group countries. A distinctive feature of this research is the development of a dynamic, adaptive decision-support mechanism that evolves with real-world user data. Unlike standard accessibility evaluation approaches, this system provides personalized travel recommendations and continuously refines its ranking model based on user experiences. This ensures a long-term impact on smart tourism, sustainable travel planning, and enhanced accessibility for people with disabilities.Ministerstvo školstva, vedy, výskumu a športu Slovenskej republiky; Slovenská Akadémia Vied, SAV, (1/0700/25); Slovenská Akadémia Vied, SAVScientific Grant Agency of the Ministry of Education, Science, Research, and Sport of the Slovak Republic; Slovak Academy Sciences [1/0700/25