Tomas Bata University in Zlín
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Evaluation of cross-linked polyamide 6 micro-indentation properties: TAIC concentration and electron radiation intensity
Get PDFNowadays, technical practice puts emphasis on improving selected material properties of polymers which could lead to new applications. Material properties can be modified in numerous ways, among which is radiation treatment. This study looks into the influence of beta radiation on several properties of polyamide 6, e.g., indentation hardness, modulus and creep. Main changeable parameters were the concentration of triallyl isocyanurate (TAIC), which promotes cross-linking, and intensity of radiation. The concentration was in the range from 2 to 6 wt.%, while the radiation dose was 0, 66, 99 and 132 kGy. The treated materials were measured for indentation hardness, modulus and creep. Degree of cross-linking was verified by thermo-mechanical analysis (TMA), while degradation processes was investigated by Fourier-transform infrared spectroscopy (FTIR). The results indicate that electron radiation positively affects the tested material properties. The best results were seen in polyamide with 6 wt.% of TAIC, which demonstrated a 38% improvement in mechanical properties after exposure to 132 kGy. This improvement in properties affects the final parts and their application (e.g., in the automotive industry—engine parts; in electrical engineering—insulation of wires and cables; and in industry—pipes for underfloor heating, etc.).IGA/FT/2023/005project TBU in Zlin Internal Grant Agency [IGA/FT/2023/005
The essential role of symmetry in understanding 3He chemical shifts in endohedral helium fullerenes
No full textThe 3He atom is an excellent NMR probe, particularly when enclosed in endohedral helium fullerenes. The 3He chemical shift, δ(3He), in fullerenes spans a range from ca. −50 to +10 ppm, and changes sensitively between different cages, isomers, and external substituents. Reduction of the fullerenes to anions changes the δ(3He) dramatically and unexpectedly, particularly for the most symmetric and also the most abundant C60 and C70 cages. While the 3He atom is shielded by ∼43 ppm upon charging the He@C60 to He@C606−, it is correspondingly deshielded by ∼37 ppm in the He@C70/He@C706− pair. Here, we show that such puzzling differences in δ(3He) relate to the high symmetry of the host fullerene cages. While similar shielding is induced at the 3He atom by the core orbitals of different cages, the symmetry of the cage allows or quenches large paramagnetic, i.e., deshielding orbital interactions of frontier orbitals upon charging of the cage, which is directly responsible for the large observed chemical shift range of endohedral 3He.RP/CPS/2022/007; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Grantová Agentura České Republiky, GA ČR: 21-17806S; Academy of Finland, AKA: 331008; Kvantum-instituutti, Oulun Yliopisto: CZ LM2018140Czech Science Foundation [21-17806S]; Ministry of Education, Youth, and Sports of the Czech Republic - DKRVO [RP/CPS/2022/007]; Academy of Finland [331008]; Ministry of Education, Youth and Sports of the Czech Republic; Kvantum Institute of the University of Oulu; [e-INFRA CZ LM2018140
Influence of fusion temperature on nonisothermal crystallization kinetics of polyamide 6
Get PDFThe effect of fusion temperature and duration on the nonisothermal crystallization kinetics of polyamide 6 (PA6) was investigated using differential scanning calorimetry (DSC) and a polarized optical microscope (OM). The rapid cooling method involved heating the polymer above its melting point, holding it at this temperature to ensure complete melting, and then rapidly cooling it to the crystallization temperature. By monitoring the heat flow during cooling, the crystallization kinetics of PA6 were characterized, including the degree of crystallinity, crystallization temperature, and crystallization rate. The study found that changing the fusion temperature and duration significantly impacted the crystallization kinetics of PA6. Increasing the fusion temperature decreased the degree of crystallinity, with smaller nucleation centers requiring a higher degree of supercooling for crystallization. The crystallization temperature shifted towards lower temperatures, and the crystallization kinetics slowed down. The study also found that lengthening the fusion time raised the relative crystallinity, but any further increase did not result in a significant change. The study showed that an increase in fusion temperature led to a longer time needed to reach a given level of crystallinity, reducing the crystallization rate. This can be explained by the thermodynamics of the crystallization process, where higher temperatures promote molecular mobility and crystal growth. Moreover, the study revealed that decreasing a polymer's fusion temperature can lead to a greater degree of nucleation and faster growth of the crystalline phase, which can significantly impact the values of the Avrami parameters used to characterize the crystallization kinetics.Tomas Bata University in Zlin, TBU: IGA/FT/2023/008Tomas Bata University in Zlin [IGA/FT/2023/008
Wearable and stretchable SEBS/CB polymer conductive strand as a piezoresistive strain sensor
Get PDFA wearable and stretchable strain sensor with a gauge factor above 23 was prepared using a simple and effective technique. Conducting nanocomposite strands were prepared from styrene-b-(ethylene-co-butylene)-b-styrene triblock copolymer (SEBS) and carbon black (CB) through a solvent-processing method that uses a syringe pump. This novel nanocomposite preparation technique is a straightforward and cost-effective process and is reported in the literature for the first time. The work included two stages: the flexible nanocomposite preparation stage and the piezoresistive sensor stage. Depending on its molecular structure, the thermoelastic polymer SEBS is highly resilient to stress and strain. The main aim of this work is to fabricate a highly flexible and piezoresistive nanocomposite fibre/strand. Among the prepared composites, a composite corresponding to a composition just above the percolation threshold was selected to prepare the strain sensor, which exhibited good flexibility and conductivity and a large piezoresistive effect that was linearly dependent on the applied strain. The prepared nanocomposite sensor was stitched onto a sports T-shirt. Commercially available knee and elbow sleeves were also purchased, and the nanocomposite SEBS/CB strands were sewn separately on the two sleeves. The results showed a high sensitivity of the sensing element in the case of breathing activity (normal breathing, a 35% change, and deep breathing at 135%, respectively). In the case of knee and elbow movements, simultaneous measurements were performed and found that the sensor was able to detect movement cycles during walking.Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: RP/CPS/2022/006, RP/CPS/2022/007; Univerzita Tomáše Bati ve Zlíně: IGA/CPS/2020/008Ministry of Education, Youth and Sports of the Czech Republic [RP/CPS/2022/006, RP/CPS/2022/007]; Tomas Bata University [IGA/CPS/2020/008
Assessing carbon emissions reduction by incorporating automated monitoring system during transit: A case study
Get PDFThe green concept in operations is becoming an inevitable part of global maritime logistics activities and has an important influence on the improvement of efficiency and environmental performance. This paper aims to assess the continuous monitoring and tracking of container shipments at the ports in order to reduce carbon emissions thus improving environmental performance. In this research, near real-time RFID data tracing and tracking container cargo are shared by the automated monitoring system. The collected data gathered via digitalization is further analyzed to ensure a greener maritime logistics system. The significant findings of the study for the literature show that the actual fuel consumption is reduced when automated monitoring systems are used at the ports (Ports and CFS (Container freight station)). The reduced fuel consumption during the transit between the ports and CFS has resulted in a reduction in carbon emissions of environmental performance. The results show a 6 % reduction in emissions from port to CFS and 23% from CFS to ports. Thus, effective practices in Green Logistics are considered to be beneficial for carbon emissions. These findings contribute to the understanding and development of effective strategies for logistic operations using technologies to create a green performance. The study was performed in a certain set of environmental dimensions and the results may vary depending on the organization, which can be studied further in future research.IGA/FaME/2021/002, IGA/FaME/2022/005Internal Grant Agency of FaME TBU in Zlin [IGA/FaME/2021/002, IGA/FaME/2022/005
Polymer-based electrochemical sensor: Fast, accurate, and simple insulin diagnostics tool
Get PDFStudy of the use of polymers with higher conductivity like polypyrrole, and polyaniline in the electrochemical insulin sensors can overcome the drawbacks arising from the ongoing use of non-conductive polymer membrane. Conductive polymer membranes maintain the positive properties of polymers, like improved stability, reproducibility, and even increase the current response of the prepared sensor toward insulin oxidation. Three different screen-printed electrodes modified with polyaniline, polypyrrole, or chitosan with electrochemically deposited nickel nanoparticles ensuring insulin oxidation were prepared. The electrode morphology was examined via SEM with EDX analysis. Also, the electroactive surface area and stability were determined by voltammetric methods. Based on the results, the SPCEs modified by polypyrrole and nickel nanoparticles were determined as the most appropriate for the insulin determination. The NiNPs-PPy-SPCE exhibited a linear range (500 nM–5 µM), a low-down limit of detection (38 nM), high sensitivity (3.98 µA/µM), and excellent result from insulin determination in real samples (human blood serum). The results confirmed the high potential of developed sensor for future research focused on detection of insulin via electrochemistry methods in clinical samples.RP/CPS/2022/005; European Commission, EC: CZ.02.2.69/0.0/0.0/18_053/0017879; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Agentúra na Podporu Výskumu a Vývoja, APVVSlovak Research and Development Agency [APVV-PP-COVID-20-0036]; Ministry of Education, Youth and Sports of the Czech Republic (DKRVO) [RP/CPS/2022/005]; Operational Program for Research, Development and Education; European Union [CZ.02.2.69/0.0/0.0/18_053/0017879
Perchlorate sensing—Can electrochemistry meet the sensitivity of standard methods?
No full textGrowing concerns about adverse effects of perchlorate (ClO4-) together with its relatively frequent occurrence the environment demand sensitive analytical methods. It is also anticipated that ClO4- sensors will find their application in future extra-terrestrial missions. Ion chromatography (IC) and mass spectroscopy (MS) provide sufficiently low detection limit (LOD) but lack transportability and field analysis possibility that are provided by most electrochemical analytical methods. On the other side, commercially available potentiometric ion-selective electrodes (ISEs) cannot compete with IC or MS in terms of sensitivity. To answer the question whether (and how) such drawback can be overcome, in this paper electrochemical methods of ClO4-determination are introduced and evaluated. Starting with potentiometric ISEs which can theoretically reach LOD suitable for assessment of WHO-set limits of ClO4-, it is further shown that ISEs operating in voltammetric mode are superior in terms of sensitivity. Next section covers impedimetric and capacitance ClO4- sensors, concluding that they can reach detection limits of IC or MS while retaining their advantages. In further sections related issues are discussed including biosensing or direct electrochemical reduction of perchlorate as well as diversity of (nano)materials applicable for perchlorate sensors preparation. This critical review thus shows that electrochemical ClO4- sensors can reach sensitivity of standard methods while retaining their portability and ease of operation.Grantová Agentura České Republiky, GA ČR: GAČR 20–27735Y; Univerzita Tomáše Bati ve Zlíně: IGA/FT/2022/006Czech Science Foundation [GAC ?, R 20-27735Y]; Tomas Bata University in Zl?n [IGA/FT/2022/006
A fuzzy multicriteria model of sustainable tourism: Examples from the V4 countries
No full textThe variability of the decision-making problems in the tourism sector is increasing and, thus, it requires studying several dimensions at the same time. Its complexity is also putting pressure on the use of demanding decision-making methods and algorithms that open a field for further investigation. The main goal of this article is to develop a fuzzy multicriteria model for evaluating the level of the image of the destination based on the dependence between costs, the number of days of stay, and the satisfaction of tourists as well as taking into account the levels of sustainable development of the example regions of the V4 countries. The model is verified and adjusted on the real data of 2343 tourists for the period 2017-2021 for the regions of the V4 countries; an approbation example is given on fragments of the data from 126 experts after a trip in 2020 in the three regions: the Zilina region (Slovakia), the Moravian-Silesian Region (the Czech Republic), and the Lesser Poland Voivodeship (Poland). The article results provide a valuable analytical platform for policy-makers, who have, thus, obtained a tool not only to evaluate the image and current sustainability of a region but also to forecast sustainability development.Internal Grant Agency of FaME Tomas Bata University in Zlin [RO/2022]; "CSR and enterprise sustainability in SME segment
Gender, teenagers and the motivations behind identity construction on social media: A conceptual study from the perspective of Czech Republic and Ghana
No full textThe attainment of ubiquity of social media (SM), also known as new media or new new media in people's lives continues to attract scholarship in varied perspectives. Although there is evidence that people of almost all ages are in one way or the other social media users, research indicating that young people constitute the most users of social media abound. There is extant literature on the effects (positive/negative) of social media usage on employees, students and others. However, scholarship on gender, how teenagers construct their identities on social media as well as the motivations behind the identity teenagers construct is scanty. Also, no study has explored a cross-cultural identity construction on social media by teenagers from the perspective of developed and developing countries. The main purpose of our study is to examine how teenagers from two 'worlds apart' (Czech Republic and Ghana) construct social media identity as well as the motivations behind these identity constructions of teenagers from these two countries. We also explore what roles gender play in such identity constructions. First, the authors employed a qualitative inquiry with specific focus on document analysis on the phenomenon by retrieving scholarly works from reputable databases such as Scopus, Web of Science, EBSCO, Google Scholar, ERIH Plus; opinions from experts as well as news items and editorials and weblogs in order to put the study in the right perspective. Second, the authors conceptualised a research model for future research design which could obtain rich naturally occurring data from teenagers from both Ghana and Czech Republic for Thematic analysis. This could be helpful in the validation of the proposed conceptual research model. Literature reviewed revealed that while some individuals construct their identity on social media to conform to ideals of society, others do so to reflect their individual aspirations in life. Also, a number of people, mostly young people create what is termed “ideal identity”. Even though the literature shows that gender has an influence on social media usage, scholarship is silent on its influence on identity construction. However, such individuals are in the minority. Research implications have been discussed in the concluding part of the study. © 8th European Conference on Social Media, ECSM 2021.Tomas Bata University in Zlin, TBU: IGA/FMK/2020/00
Can Alexa serve customers better? AI-driven voice assistant service interactions
No full textPurpose: This study aims to examine customers’ willingness to engage in service interactions enabled by artificial intelligence (AI) controlled voice assistants (VA). Drawing on the tenets of dual-factor theory, this study measures the impact of both enablers and inhibitors – mediated by trust in Alexa – on customers’ intentions to transact through VAs.
Design/methodology/approach: Data from a survey of 290 users of VAs from Japan was collected through “Macromill”. The authors used a covariance-based path analysis technique for data analysis after establishing the validity and reliability of the measures.
Findings: The results of this study demonstrate that convenience and status-seeking act as enablers and positively influence trust in VAs, whereas risk barrier acts as an inhibitor and negatively influence trust in VAs. In turn, trust in VAs positively influences the intention to use VAs for transactional service interactions. This association is positively moderated by technology comfort.
Originality/value: This study applies dual-factor theory to the context of VAs – a context that scholars have, to date, examined solely from a technology adoption perspective. For the first time, the authors adopt a dual-factor approach to identify a new set of antecedents for customers’ intentions to use VAs for transactional service interactions