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Manufacturing of micro-structures by two-photon polymerization
Skalický, Jiří ; Petrůj, Jaroslav (referee) ; Richtera, Lukáš (advisor)
Utilization of focused laser beam for photo-polymerization represents an elegant and fast method how to manufacture microstructures in dimensions from hundreds of nanometres to tens of micrometres. Two-photon photo-polymerization is used with advantage to manufacture microstructures with sub-micrometre details. In this case the laser wavelength is about two times longer comparing to the spectral region of the highest photoresist sensitivity and the two-photon photo-polymerization is initiated only in the positions of sufficient optical intensity. Precise and controlled positioning of the photoresist with respect to the laser focus ensures only illumination of areas of future microstructure and initialization of photo-polymerization here. Fine details of manufactured microstructures depends, except the laser beam focusing, also on the chosen photoresist and quenching of polymerization in non-illuminated areas.
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Influence of catalysts on polyurethane formation
Chadima, David ; Petrůj, Jaroslav (referee) ; Kučera, František (advisor)
The bachelor thesis deals with the influence of catalysts on polyurethane formation. The theoretical part includes basic knowledge of polyurethane chemistry complemented by a literature review contains information about catalysis and reaction mechanism of polyurethane formation. In experimental part were studied effects of catalysts N,N,N',N' tetramethylethylenediamine, Stannous octoate, 1,4-Diazabicyclo[2.2.2]octane and Dibutyltin dilaurate at the rate of synthesis of the polyurethane resin. The measurement was based on measuring the time for which the reaction mixture reaches the maximum temperature. Effective concentrations of catalysts use were calculated. By additional measurement was performed simplified calculation of the activation energy for the demonstration of the effect of temperature on the observed reaction.
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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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Photopolymerization
Kučera, Vladimír ; Petrůj, Jaroslav (referee) ; Kučera, František (advisor)
The bachelor thesis deals with the photochemistry of macromolecular substances, especially with photopolymerization and photocrosslinking reactions. In the theoretical section there is at first a summary of the current knowledge from the area of the general photochemistry and principles of photochemical reactions which are also applied in photopolymerization. There are also both types of photopolymerization analysed – cationic and free-radical, photocrosslinking reactions and photopolymerization applications. In the experimental part, the testing of two fotopolymerization systems was performed. In both of them, styrene was used as a monomer. In one case benzoin was used as a photoinitiator, in the second one there was benzoin ethyl ether used. Furthermore, the photoinitiation ability of these two photoinitiators was compared at the base of conversion and molecular weight of products that were synthetized at different concentrations of photoinitiators and different time periods of irradiation of the mercury lamp.
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The Influence of Nanoparticles on The Properties of Hard Polyurethane Foams
Eliáš, Filip ; Kotlík, Josef (referee) ; Petrůj, Jaroslav (advisor)
The theoretical part of the thesis focuses on general principles of polyurethane chemistry. Nanotechnologies are also discussed, in particular using nanoparticles in the production of polyurethane foams. There are also mentioned selected preparation methods of silver and titanium dioxide nanoparticles. The experimental part describes mainly a novel method for synthesis of the concentrated solution of titanium dioxide nanoparticles in glycerol and their analysis by using confocal microscopy, scanning electron microscopy, dynamic light scattering and UV-VIS spectroscopy. Finally, there are suggested particular steps for further investigation of prepared nanoparticles for the production of rigid polyurethane foams, and also for other applications.
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Technological optimization of a pilot line for production PP-g-IAH
Arvai, Tomáš ; Petrůj, Jaroslav (referee) ; Kučera, František (advisor)
The bachelor thesis deals with optimization of a pilot line for production polypropylene grafted with itaconic anhydride. Theoretical part describes actual knowledge about radical grafting of polyolefins with emphasis on the variety of factors affecting melt grafting. Extruded mass per hour, torque and die pressure were measured during all extrusions within optimization. Two sets of samples were prepared in the co-rotating twin-screw extruder (Brabender 25 DSE L/D = 34). Sample set prepared at 200 °C ranged from 1:2 to 1:20 molar ratio of initiator/monomer, set prepared at 230 °C ranged from 1:4 to 1:20 molar ratio. Parameters set for all extrusions were 30 RPM, reaction time 3 minutes. All samples contained the same mass concentration of monomer 0.5 %, initiator selected 2,5-di(tert-butylperoxy)-2,5-dimethylhexane (Luperox 101). Degradation of samples was observed through MVR measurements, monomer content in extruded samples was analyzed by acid-base titration and FT-IR spectroscopy.
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Waste Recycling Possibilities of Rigid PU Foams from the Production of KingSpan CZ
Figalla, Silvestr ; Kučera, František (referee) ; Petrůj, Jaroslav (advisor)
The theoretical part of the bachelor thesis evaluates methods and trends of recycling polyurethane materials with the emphasis on rigid polyurethane foams used as thermo isolation building material. The experimental part is focused on glycerol process verification as an alcoholization agent in the regenerative process of polyol, together with perspective microwave heating of reaction mixture. The final part of the work suggests further steps in the development of above mentioned process with the aim of its transforming into technical practice.
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Thermal Dilatation Measurement of Elastomeric Plastic Sheets
Mahel, Jindřich ; Kučera, Jaroslav (referee) ; Petrůj, Jaroslav (advisor)
The aim of the thesis was to design and build an apparatus for measuring linear thermal expansion of plastic waterproofing sheets. In the theoretical part of the thesis the methods used for measuring linear thermal expansion of solids were compared and the principle of thermoelectric cooling was described . For the measuring the Abbe comparator has been chosen , which has been equipped with a tempered chamber with a cascade of thermoelectric Peltier elements for cooling and heating of specimen. The experimental part of the thesis deals with the construction of the device and the actual measuring in the specified temperature range.
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