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Synthesis of Mineral Oils by Oligomeration of 1-alkenes
Porubský, Tomáš ; Kučera, František (referee) ; Petrůj, Jaroslav (advisor)
The theoretical part presents a summary of existing information and procedures for the oligomerization of 1 alkenes. It also introduces suggestion of the new method for preparing poly(1-hexene) by controlled or living polymerization with nitroxyl radicals. In the experimental part was synthesized oligomer of 1-hexene with DBP or AIBN radical initiators and coordination Ziegler-Natta catalysts, which consisted of TiCl4 and organometallic compounds TIBA or TNHA. GC/MS analysis of the radical polymerization reaction mixture, showed no oligomer formation even after 6 hours. Effect of Ti/Al ratio, temperature and type of organoaluminium compund on conversion and molecular weight were investigated. Reaction products were analyzed by 1H NMR and GC/MS spectrometry. Results showed that the obtained oligomer was a mixture of oligomers with a degree of polymerization 2-9 and average molecular weight of 220-270 g/mol. Monomer conversion reached values of 72 98 %.
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Automated measurement system for ethene polymerization
Janošík, Zdeněk ; Richtera, Lukáš (referee) ; Přikryl, Radek (advisor)
Thanks to macromolecular chemistry development polymers become essential materials for wide range of applications. Research of catalytic systems used for production of polymers plays a key role in development of new polymer-based materials. The aim of this work was to develop system providing automated kinetic measurement of catalytic systems used in ethylene solution polymerization. The theoretical part of the thesis provides basic overview on chemical process taking part in ethylene polymerization and technical instruments used for its automation. Description of the devised system, its technical solutions and performed experiments used for verification its proper function are presented in the experimental part. Acquired data were compared with published results obtained with the same catalytic systems. Texts are accompanied by schemes, screenshots and photos.
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Extraction of beta-Sitosterol from the Stinging Nettle Root with Supercritical CO2
Sajfrtová, Marie ; Bártlová, Milena ; Sovová, Helena
The stinging nettle root contains both polar and non-polar biologically active substances. beta-Sitosterol (BS), the most important component of its neutral lipids, is active in the root extracts used for various alternative medicine treatments, including the reduction of enlarged prostate. Dry roots contaning 0.28 g/kg BS were extracted with CO2 at pressure 12-60 MPa and temperature 40-80 C. Though the maximum yield of BS was only 89 %, its concentration in extract was increased by 13 % compared to the extraction with hexane. Changing vials where the CO2 extract was collected, fractions with double and higher BS concentration could be obtained. The fractionation was simulated using a mathematical kinetic model of multicomponent extraction.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22013110513041 - PDF
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Kinetics and temperature dependance of cellulose degrading enzymes in the Arctic soils
VAZAČ, Jan
Kinetics and temperature dependance of ?-glucosidase and cellobiosidase was investigated in Arctic soil. These enzymes are key in cellulose degradation, while ?-glucosidase produces the final product of cellulose degradation, the glucose, which si readily available to soil microbes and can influence the CO2 production. The enzymes activities was measured using fluorogenic substrates.
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Differences in CO2 Extraction of Vegetable Oils, Essential Oils, and Minor Components from Plants
Sovová, Helena
Significant progress in understanding the phenomena that control supercritical fluid extraction from plants was made in the last years and is reflected in the literature. Combination of chemical engineering approach and botanical knowledge has appeared to be fruitful for the choice of extraction model and even for the prediction of extraction kinetics. This contribution refers to the papers utilizing knowledge of plant microstructure and location of extracted substances together with extraction equilibrium and attempts to specify the differences among extraction kinetics of vegetable oils, essential oils, and other substances. The most abundant substances like vegetable oils in seeds can be regarded in first approximation as non-interacting with plant matrix, in contrast to the minor components whose equilibrium concentration in CO2 is affected by their adsorption on matrix and often also by co-extracted substances.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22012102414100 - PDF
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A Simplified Calculation of a Continuous Flow Packed Contactor with Help of Characteristic Times
Sovová, Helena
The proposed approach is illustrated on several examples of supercritical fluid extraction kinetics. Simple expressions for the calculation of characteristic times of both extraction and individual extraction steps are derived from mass balance equations and applied on experimental data from typical extractions from plants with supercritical CO2, as the extraction of oils from seeds or the extraction of essential oils from aromatic plants.
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Kinetics of polymer crystallization
Kratochvíl, Jaroslav ; Sikora, Antonín
Kinetics of three steps of complex crystallization of poly(N-methyldodecano-12-lactam) were studied by DCS using an Avrami model. Mechanism of respective isothermal steps involves mixed heterogeneous/homogeneous nucleation (primary melt crystallization) or missing nucleation phase (additional crystallization and recrystallization) followed by two-dimensional growth.
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