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Thermal analysis of fuels
Šrámek, Zbyněk ; Hrnčířová, Michaela (referee) ; Moskalík, Jiří (advisor)
The main goal of this thesis is to introduce the field of thermal analysis as an independent scientific discipline. The first section is mostly informative and introduces into a concept of thermal analysis. The second part describes the most fundamental and essential methods of thermal analysis and the last section is focused on evaluating a real thermogravimetric experiment which deals with biomass sample.
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Derivatization of Sodium Hyaluronate as a Possible Tool for Increasing of the Stability of Model Artificial Synovial Fluid
Hrochová, Eliška ; Mravec, Filip (referee) ; Kalina, Michal (advisor)
This master thesis deals with the optimization of the procedure of modification of hyaluronic acid structure for the use in the artificial synovial liquids. Based on the literature research, the amino acid alanine was used for the modification of carboxylic group in the glucuronic acid. The main subject of study is the improvement of the stability and mechanical properties of synovial liquid. DLS microrheology, macrorheology, thermogravimetric analysis (TGA), multi-angle light scattering with flow-field flow fractionation (AF4-MALS) and infrared spectroscopy (FTIR) were used for characterization. The theoretical part of this theses submits review of the musculoskeletal system, role of hyaluronic acid in metabolism and summary of synovial liquid. The experimental part focuses on the measurement of the stability and mechanical properties of three artificial samples (first with no modification, second with modified hyaluronic acid and third with modified hyaluronic acid and chondroitin sulphate). These samples were compared with real horse synovial fluid and artificial viscosupplement Orthovisc®.
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Testing of commercial rubber sealing components exposed to different ambient conditions
Jančaříková, Marie ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
Diploma thesis studies the effect of temperature (75 and 105 °C) and the effect of 3 kinds of liquids (silicone and hydraulic oil and coolant) at room temperature and at 105 °C on change of the structure of 3 species butadiene-acrylonitrile (NBR) seals (o-ring and two types of bolts). The seals are inspected by the thermogravimetric analysis, differential scanning calorimetry and infrared spectroscopy, the influence of 105 °C on the o-rings is also evaluated in terms of changes in tensile properties. The greatest changes in the composition and structure are observed on o-rings particularly due to temperature of 105 °C, there was a significant reduction in dilatability and an increase in stiffness and glass transition temperature. The root cause is the surface and centre additive decomposition and oxidation. The bolts have suffered from decomposition of the protective surface layer and the additives in the centre, structural change was minor. Exposure to 75 °C has resulted in a gradual loss of low molecular weight substances. Liquids at room temperature didn‘t affect the structure of the seals, at 105 °C it caused a loss of weight due to decomposition of the protective surface layer and release of additives and the products of their decomposition. Results showed that the common use of the NBR seals at 105 °C is unsuitable, at 75 °C it leads to gradual changes, loss in mechanical and sealing properties.
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New materials for Li-ion batteries with conversion mechanism
Petr, Jakub ; Straková Fedorková, Andrea (referee) ; Sedlaříková, Marie (advisor)
This thesis is interested in new materials for lithium – ion batteries. Two different samples were investigated, one intercalation and one conversion cathode material. The theoretical part is focused to the structure of cells, their advantages and disadvantages compared to other secondary batteries. Also other materials used in batteries are described. The practical part describes the preparation of cathode materials for subsequent testing by scanning elektron microscopy and thermogravimetric analysis. In conclusions two different materials were evaluated and compared with each other.
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Correlation of Thermoanalytical Data with Primary Properties of Humified Substrata
Kislinger, Jiří ; Šimon, Peter (referee) ; Tesařová, Marta (referee) ; Schaumann, Gabriele (referee) ; Pekař, Miloslav (advisor)
Tato dizertační práce je napsána jako termoanalytická studie humifikovaných substrátů, tj. huminových látek a půdních vzorků, získaných z několika různých zdrojů tak, aby byl pokryt co nejširší rozsah primárních charakteristik. Práce hledá lineární korelace (s využitím Pearsonova korelačního koeficientu) mezi kinetikou termo-oxidační degradace (sledovanou pomocí termogravimetrie (TGA) a vyjádřenou konverzním časem stanoveným neizotermickou izokonverzní metodou) a standardními charakteristikami, jako je množství aromatického a karboxylového uhlíku přítomného v huminových látkách stanoveného spektroskopií nukleární magnetické rezonance (NMR). Hlavním cílem této práce je objasnit proces termo-oxidační degradace humifikované části přírodní organické hmoty a hledat závislosti mezi primární a sekundární strukturou huminových látek. Dalším úkolem je nalezení korelace mezi termogravimetrickým úbytkem hmotnosti půdních vzorků a jejich mikrobiální stabilitou měřenou v laboratorních experimentech jakožto půdní respirace (tedy uvolňování oxidu uhličitého). Účelem je zjistit, zdali vzájemné propojení vůbec existuje, a objasnit jaké druhy procesů, které provázejí půdní respiraci, je možné jednoduše odhalit pomocí TGA. Výsledky práce skýtají detailnější pohled na termickou analýzu půdních vzorků a jiných humifikovaných materiálů. Hlavním přínosem této práce je prezentace vyskytujících se aplikací termické analýzy pro charakterizaci půdní organické hmoty a dále také příspěvek k rozvoji aplikací technik termické analýzy v půdní vědě.
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CHARACTERIZATION OF WRAPPAGING FILMS BASED ON POLYETHYLENE AND POLYPROPYLENE
Bělašková, Marie ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
By seven kinds of coextruded and blown packing polyethylene and polypropylene based films, which are supplied by Granitol were characterized in this bachelor thesis. The following methods were used for characterization: thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, confocal laser scanning microscopy , and scanning electron microscopy. The methods made possible to determine the composition of the films and to evaluate the degree of crystallinity.
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Polyhydroxybutyrate modification by grafting of functional groups
Melčová, Veronika ; Tocháček, Jiří (referee) ; Přikryl, Radek (advisor)
Presented bachelor thesis deals with a characterization of the effect of chemical grafting on thermal and mechanical properties of poly(3-hydroxybutyrate). Two grafting methods were chosen, chlorination and fluorination of PHB. The aim of the theoretical part of the work was to create a complete literature review containing basic information about polyhydroxybutyrate and the latest scientific evidence about possibilities of chemical modification of this polymer. The experimental part describes the chemical treatment of the material itself, as well as preparation of samples for testing and performing the selected analysis. Chemically grafted polymers were subjected to thermogravimetric analysis to determine their thermal stability. Thermal behavior of materials was studied by differential scanning calorimetry. Also non-isothermal crystallization of samples was observed in order to evaluate the influence of the grafted halogen atom onto the nucleation activity of the polymer. Selected samples were also subjected to dynamic mechanical analysis and tensile test.
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Issues of stopping the hydration of alkali-activated slag using organic substances
Chadima, Jan ; Novotný, Radoslav (referee) ; Bílek, Vlastimil (advisor)
This thesis deals with the stopping of hydration of alkali activated slag by organic solvents and investigates to what extent the selected organic solvent affects the results of the analyses. The solvents used were acetone, diethyl ether, ethanol, isopropanol and methanol, and this is because these are the most commonly used organic solvents in practice. Thermogravimetric analysis along with differential thermal analysis was used to assess the degree of influence of organic solvents on the alkali activated slag and Portland cement samples. Methanol and acetone affected the samples the most and the longer the sample was stored in the solvent, the more it reacted with the organic solvent. The adverse interaction of organic solvent was greatest for the Portland cement samples. Samples that were rinsed with diethyl ether prior to analysis had lower mass losses than samples that were not rinsed. In the case of alkali activated slag, it was found that the way in which the thermogravimetric results were affected by organic solvents was highly dependent on the activator used, with the smallest effect observed for Na2CO3 activation, while the largest effect was observed for NaOH activation at temperatures below 600 °C, and for higher temperatures for water glass activation.
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The influence of recycled material on weathering and accelerated aging of high density polyethylene
Borguľová, Eva ; Tocháček, Jiří (referee) ; Bálková, Radka (advisor)
The thesis deals with the testing of moulded high-density polyethylene (HDPE) samples that have been exposed to natural weather conditions for 9 months and accelerated ageing at 65 °C for 1000 hours. One sample was white in colour (made from commercial granulate) and four were black, one of which would have been prepared from 10 year old recycled material (recyclate), the other three were blends of this with white HDPE at 30, 60 and 90 % ratios. Infrared spectroscopy with ATR technique, static and dynamic tensile testing, differential compensation calorimetry and thermogravimetric analysis were used to characterize the changes in composition, structure and mechanical properties. The results showed that photooxidation occurred in all samples after the 1st month of exposure. Inhibition of degradation was noted after 3 months but increased again with time. The change in the mechanistic properties over time is a response of cleavage and recombination, but also of crystallization or crosslinking. The black color proved to be a stabiliser, as the clear samples remained largely tough after accelerated ageing, in contrast to the white sample which became quite brittle, as confirmed by the highest carbonyl index value. Thus, it can be assumed that with moderate UV stabilization the recyclable material is reusable for production, especially the proportion of 30 % (higher proportions caused a decrease in toughness).
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Utilization of physico-chemical and spectroscopical methods in study on microbial extremofiles
Dobešová, Kateřina ; Enev, Vojtěch (referee) ; Sedláček, Petr (advisor)
The aim of this bachelor thesis is the determination od polyhydroxyalkanoates in the cells of extremophille bacterie, preformed by several methods. The chosen bacterium was Schlegelella thermodepolymerans DSM 15 344 Thermogravimetric analysis, infrared spectroscopy with Fourier transformation, and Raman spectroscopy were used in this thesis. The TGA method was used for the determination of extracellular and intracellular water in samples. The FTIR method was used in order to observe the amount od PHA, but aslo to observe the physical properties of the polymer in the sample, specifically to determine either amorphous or crystalline featuers of this polymer. Raman spectroscopy was used in oder to confirm the presence of PHA in the samples. All results e´were compared eith the results accomplished by gas chromatografy.
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