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Structural characterization of materials for energy applications using NMR spectroscopy
Mahun, Andrii ; Kobera, Libor (advisor) ; Hrabal, Richard (referee) ; Lebl, Tomas (referee)
Development of new, safe, highly efficient, and environmentally friendly energy storage and conversion devices is demanded in today's world. This includes the synthesis, characterization, and application of new advanced materials. Promising materials such as polymer electrolytes, conductive polymers, and perovskites have drawn the great attention of scientists worldwide and are under intensive investigation. These substances are believed to be capable of solving some issues and improving the existing energy storage and conversion technologies. The presented thesis is dedicated to the investigation of above-mentioned materials for energy applications. The research was focused on the elucidation of structure-properties relation in the compounds of interest and optimization of their composition to get better properties in terms of potential application in the energy field. Among all experimental techniques used within the thesis, NMR spectroscopy was comprehensively employed and chosen as the main tool for the structural characterization of the investigated samples. Various liquid-state as well as solid-state NMR techniques were used, and some of them were optimized for specific purposes of the research. During the investigation of polymer electrolyte systems, NMR spectroscopy was utilized to study...
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Microplastics in deep-sea fish
Fürychová, Barbora ; Cajthaml, Tomáš (advisor) ; Innemanová, Petra (referee)
Microplastics have become a significant problem in marine ecosystems, posing a serious threat to the biodiversity and stability of these environments. This bachelor's thesis focuses on investigating the presence of microplastics in the digestive tracts of deep-sea fish in the Indian Ocean. These fish represent interesting model organisms that can aid in understanding the distribution of microplastics in the marine water column. The introductory part of the paper summarizes the existing knowledge on microplastics, their occurrence, methods of analysis and the presence of microplastics in the aquatic environment. Particular attention is paid to deep- sea fishes, whose role in marine ecosystems is crucial. In the experimental part, detailed analyses of fish digestive tract samples were performed to detect and identify microplastics. The study confirmed the presence of microplastics in the digestive tracts of deep-sea fish, and various types of polymers were identified, including polystyrene, nylon, polyethylene terephthalate, polyvinyl chloride and polyester. This undergraduate thesis is the first study ever to demonstrate that microplastics are found in deep- sea fish in the western Indian Ocean. The conclusions of this thesis underscore the urgency of the situation regarding contamination of the...
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Optimisation of polyethylene glycol hydrogels preparation by polymerisation and their subsequent characterisation
Fornůsek, Jakub ; Trudičová, Monika (referee) ; Smilek, Jiří (advisor)
The goal of this bachelor’s thesis was the optimization of the preparation of polyethyleneglycol hydrogels by radical polymerization and their subsequent characterization by the means of rheometry, swelling experiments and examination of transport properties through the absorption of an active substance and its subsequent desorption. To examine these hydrogels, UV photopolymerization was chosen due to its simplicity and reproducibility. As part of the optimalization, hydrogels were prepared under varying conditions and then characterised by the previously mentioned methods. The effect of the presence of the cross-linking agent ethylenglycol dimethacrylate on the properties of the resulting hydrogels was also investigated. These examined gels represent a new type of chemically cross-linked hydrogels, which are part of a basic research project applications by GAČR. From rheometric measurements, it was confirmed that a higher molecular weight of the measured sample corresponded to lower values of viscoelastic moduli. The effect of the cross-linking agent on these values was negligible. The mesh density played a significant role in swelling and transport experiments. As its value increased, the swelling capacity of the hydrogel decreased and therefore a smaller amount of water was absorbed. The presence of the cross-linking agent was also noticeable, as it contributed to a creation of higher density polymer networks.
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Modelling of shear strength of concrete beams
Večeře, Jakub ; Lehký, David (referee) ; Novák, Drahomír (advisor)
The bachelor thesis deals with the modeling of reinforced concrete beams and compares their load-deflection (L-D) curves with curves obtained in an extensive experiment at the University of Lodz under the guidance of Prof. Renata Kotynia, Dr.Hab. For comparison, data from two selected beams with identical shapes, lengths, and concrete strengths were used – one reinforced with steel and the other with a composite made of glass fiber-reinforced polymer (GFRP). Modeling is carried out using nonlinear fracture mechanics of finite elements (2D) in the ATENA software. Emphasis is particularly placed on accurately modeling the bond between concrete and reinforcement. Modeling was performed in both 2D and 3D.
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Assessment of 3D printing technology as an alternative in manufacturing
Balvín, Patrik ; Šafl, Pavel (referee) ; Binar, Tomáš (advisor)
This bachelor thesis is devoted to 3D printing. The main methods od 3D printing, widely used materials (their production, their properties and the advantages and disadvantages of using them), degradation due to enviromental conditions, other common methods of producing polymer parts and mechanical test are described in the theoretical part. This paper also compares the advantages of using 3D printing for prototyping. The experimental section is dedicated to measuring the impact of material degradation on the toughness, hardness, and tensile strength of PLA and PA6 CF15 materials. The case study focuses on the design of an engine spark coil holder and a mobile workstation for 3D printing.
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Description of fatigue behavior of additively manufactured polymer metamaterial structure
Helešicová, Petra ; Ševeček, Oldřich (referee) ; Trávníček, Lukáš (advisor)
Metamateriály jsou v posledních letech velmi často zkoumanou oblastí, jelikož umožňují přizpůsobení mechanických vlastností vyráběných součástí, které není možné získat s využitím konvenčních materiálů. Aby bylo možné metamateriály bezpečně využívat v provozu, je nutné popsat jejich chování při zatěžování. Prezentovaná diplomová práce je zaměřena na popis únavového chování 3D tištěné polymerní metamateriálové struktury. Práce je rozdělena na teoretickou a praktickou část. V teoretické části je provedena rešerše metamateriálů a jejich rozdělení, poté rešerše metod 3D tisku vhodných pro polymerní materiály a nakonec jsou představeny základy mechanického chování polymerů. V praktické části jsou postupně prováděny kroky pro určení odhadu únavové životnosti uvažované metamateriálové struktury pomocí čtyř kritérií. Pomocí experimentálních testů jsou naměřeny mechanické vlastnosti uvažovaného materiálu, které jsou vloženy do vytvořeného numerického modelu. Okrajové podmínky a zatížení modelu jsou zvoleny tak, aby odpovídaly reálným podmínkám při zatěžování. Numerický model je využitý pro určení kritických lokací ve struktuře a pro predikci únavové životnosti. Ve dvou kritických místech jsou zaznamenávány hodnoty napětí a přetvoření představující jednotlivé fáze cyklického zatěžování. Tyto hodnoty jsou použity pro predikci únavové životnosti.
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Design of a cap sealing machine
Gáspár, Balázs ; Tůma, Zdeněk (referee) ; Hermanský, Dominik (advisor)
This bachelor thesis deals with the development of a structural design and CAD model of a lidding machine for the food industry. The introductory part of the thesis includes the classification of the lid-locking machines and the corresponding technological procedure. This part also contains current researches. Furthermore, the thesis deals with the recognition of the materials of the most common polymer jars. The second part of the thesis includes the actual structural design and the structural calculations required for this. Based on these, a 3D model and the necessary drawings have been made.
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Influence of underground installation conditions on crack propagation in polypropylene pipes
Tesař, Jakub ; Gratza, Roman (referee) ; Hutař, Pavel (advisor)
The thesis addresses the issue of buried polymer pipes and the impact of installation conditions on their lifetime. Based on data obtained from standards, the values of external loads acting on the polymer pipe are determined. To apply these values in numerical calculations, the conversion of individual load components is also provided. Various stress values, simulating different burial installation conditions, are applied to a 2D model. The numerical calculation of the 2D model includes the progression of tangential stresses and their comparison with the standard. Furthermore, the influence of installation conditions on the burial depth of the pipe is analyzed. The comparison of models is conducted for both 2D and 3D models against the standard. The comparison verifies that the models are equivalent and closely correspond to the basic calculations according to the standard. The 3D model is then extended to include a crack, and the propagation through the pipe wall under the most critical load conditions is modeled. The concept of linear elastic fracture mechanics is used to estimate the lifetime of the pipe.
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Influence of carbon based filler aplication to termoplastics and its properties observation
Lahoda, Ondřej ; Petruš, Josef (referee) ; Kučera, František (advisor)
This bachelor thesis focuses on studying the effect of expanded graphite (EG) on the properties of two thermoplastics with different supramolecular structures, amorphous PETG and semicrystalline PA6. The aim was to analyze how the electrical, mechanical, and flow properties of the prepared composites change depending on the volume concentration of EG. Samples with EG volume concentrations ranging from 3% to 27% were prepared using a Brabender measuring mixer. Experiments were performed using standardized methods, including MFI (melt flow index) measurements according to ISO 1133, tensile property testing, and electrical resistance measurements. The morphology of the prepared samples was analyzed using a scanning electron microscope. The crystallinity of the sample with PA6 matrix was analyzed using a differential scanning calorimetry. The effect of EG concentration on composite properties such as electrical conductivity, tensile modulus and flow properties was observed.
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Automatization of polymer hollow fibre heat exchanger production
Šindelka, Denis ; Hvožďa, Jiří (referee) ; Bartuli, Erik (advisor)
This bachelor’s thesis focuses on automatization of manufacturing of a shell and tube heat exchangers from polymer hollow fiber. The reaserch part of the thesis describes different types of heat exchangers. After that the thesis focuses on polymer hollow fiber heat exchangers and their properties, uses and means of manufacturing. The following chapter focuses on a creation of grafical user interface (GUI) in Python programing language. The GUI aims to make the manufacturing proces of a polymer hollow fiber heat exchanger on a X-Winder machine easier and more straight forward.
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