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Analysis of x-ray diphractograms of organic crystalline solids
Stejkora, Jakub ; Žídek, Jan (referee) ; Salyk, Ota (advisor)
Derivates of diketopyrrolopyrrole are colored pigments with potential use in field of organic semiconductor structures. Their electrical attributes such as conductivity, photocon¬¬ductivity and electroluminescence relate to their crystal structures that determine charge transport path through the compound. For crystallographic structure determination from RTG diffractometry it is needed to grow a measurable single crystal. Growing crystals of derivates of diketopyrrolopyrrols is very difficult due to their poor solubility in all solvents. Several relatively suitable – perhaps even measurable – samples were obtained throughout the testing of series of methods. One of these samples was measured with RTG diffractometry and on the ground of this measurement it was possible to find and solve the crystallographic structure.
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Micro-turning applications in high precision manufacturing performed by diamond tools
Švorc, Josef ; Dvořák, Jaromír (referee) ; Žídek, Jan (advisor)
Bachelor thesis is focused on micro-turning. The work takes the form of a literary research, which aims to make an overview of the production technology. First, it deals with the definition of the topic itself and with the physical properties and phenomena that occur during micro-machining. Then it discusses the construction of micro lathes and their division into categories and compares them to each other. It also deals with the cutting tools suitable for this machining process and their production and shaping. The last part of the thesis is focused on the application and utilization of micro-turning in industry and on the creation of non-rotational components and micro-structures.
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Evaluation of the quality of collagen samples in solid phase using circular dichroism
Ďubašák, Matej ; Žídek, Jan (referee) ; Vojtová, Lucy (advisor)
Diplomová práca sa zaoberá novou kvalitatívnou analýzou kolagénových vrstiev pomocou cirkulárneho dichroizmu v pevnej fáze. Teoretická časť opisuje kolagén a jeho sekundárnu štruktúru, spektroskopické metódy cirkulárneho dichroizmu (CD) a zoslabenej úplnej reflektancie (ATR). Experimentálna časť sa zaoberá prípravou homogénnych a transparentných kolagénových filmov a optimalizáciou objemu, koncentrácie a sušenia. Následne sa zmerala a vyhodnotila kalibračná krivka s rôznymi pomermi kolagénu a želatíny. Získaná rovnica lineárnej regresie sa použila na stanovenie obsahu kolagénu v modifikovaných vzorkách. Výsledky hodnotených modifikovaných vzoriek boli porovnané s meraniami ATR spektroskopie. Merania ATR ukázali vyšší obsah kolagénu ako CD merania. Vzorky s najnižším a najvyšším obsahom kolagénu sú pre obe metódy rovnaké. Dokazuje to, že môžme porovnávať vzorky s rôznym obsahom kolagénu navzájom, ale nemôžeme určiť presný obsah kolagénu pripojením týchto dvoch metód. Optimalizovaná metóda CD sa môže použiť na prípravu a meranie presného obsahu kolagénu vo vzorkách, najmä v rámci výroby kolagénu, aby sa dosiahla konštantná kvalita kolagénu v každom kroku výroby.
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Influence of Solvent on Deformation Behavior of Hydrogels
Kulovaná, Eva ; Bartlová, Milada (referee) ; Mráček, Aleš (referee) ; Žídek, Jan (advisor)
The thesis deals with molecular dynamic simulation of the influence of water on the deformation of hydrogels. Hydrogels are model materials formed from macromolecular networks solvated with water. It was found that water can form bridges between macromolecules that take the form of temporary ionic crosslinks. These bridges affect the behavior of the network during deformation. Water bridges are water molecules that have a limited radius of motion in the space between two macromolecules. The concentration of the water bridges was regulated by a partial charge on the macromolecular chain in the organic network. Bridges are a type of interaction that is relatively strong but significantly delocalized. It is not possible to dissociate the water bridge, after dissociation it will be re-created in another place in a short time. The influence of water bridges was compared with other types of network crosslinks, especially covalent and physical bonds. Covalent crosslinks are modeled as a simple binding interaction between two macromolecules. They are undissociable and are local throughout the simulation. Physical bonds are modeled as micelles, where hydrophobic groups form the core and hydrophilic groups form the micelle shell. Physical bonds have the nature of dissociable bonds that are local. Different types of crosslinks have different effects on deformation properties. The deformation of a network containing a combination of two types of crosslinks was simulated: (i) physically-covalent, (ii) ionically-covalent, and (iii) physically-ionic networks and (iv) ternary physically-covalent-ion networks. For individual and combined networks, the behavior depending on simple networks was verified. The number of water bridges was fundamentally affected by the primary structure of the chains. When the PEG chain was replaced with hydrophobic polyoxymethylene (POM) or polyoxytrimethylene (POTM), their solvation and mechanical behavior deteriorated.
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Productive milling of aluminum alloys
Dvořák, Jakub ; Žídek, Jan (referee) ; Jaroš, Aleš (advisor)
This bachelor thesis is focused on milling of aluminum alloys, where the technology of milling is described in the first place, then the cutting materials and aluminum alloys. The main subject of the work was to carry out the experiment. The Experiment was focused on influence of cutting conditions on the final quality of the surface with regard to machine time. The aluminum workpiece was milled at different cutting speeds and various feed per tooth. At the same time the quality of the surface was examened and machine times were calculated. The Experiment showed us, whether it pays to use higher cutting speeds and feed per tooth, keeping the set of limited values of surface roughness with respect to the machine time. The result of the experiment is the following - the increasing feed per tooth deteriorates the quality of machined surface, but machine time is reduced.
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Preparation and characterization of self assembled polymer nanocomposites
Lepcio, Petr ; Žídek, Jan (referee) ; Jančář, Josef (advisor)
Polymerní nanokompozity na bázi polyhedrálních oligomerních silsesquioxanů (POSS) představují slibnou oblast výzkumu, která potenciálně může využít samouspořádávní při navrhování nových materiálů. Tato diplomová práce popisuje postup přípravy oktafenyl-POSS/PS, oktafenyl-POSS/PMMA a oktamethyl-POSS/PS systémů a charakterizaci jejich termomechanických vlastností v pevné fázi a reologických vlastností v roztoku. Získané výsledky jsou diskutovány s přihlédnutím k teoriím zabývajících se stavem disperze nanočástic.
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Cutting tools manufacturing for micro-milling
Tkadlec, Jiří ; Dvořák, Jaromír (referee) ; Žídek, Jan (advisor)
This bachelor work is focused on the research of the problems of micro-cutting, exactly of micro-milling and manufacturing of cutting tools. The introduction contains basic analysis of micro-milling and specification of micro-milling. The main aim of this work is analysis of the manufacturing of cutting tools and analysis of cutting tools materials used for micro-milling.
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Reactive Modification of Polypropylene
Matláková, Jana ; Žídek, Jan (referee) ; Lehocký, Marián (referee) ; Kučera, František (advisor)
The theoretical part describes the principles of the free-radical induced grafting and the influence of various parameters on the reactions course. The literature research summarizes the latest knowledge in the field of the reactive modification of polypropylene (PP), it is mainly focused on the PP modification using an unsaturated acid anhydrides. Theoretical part describes the various procedures and modification of technology in order to increase the grafting yield of maleation. The experimental part is determined by the influence of the stabilizers concentration, the peroxide structure, and the binary mixture of monomers on the grafting yield and the reaction course. In the first part, the critical stabilizers concentration was determined based on the experimentally obtained relationship between the grafting yield and the stabilizers concentration. A kinetic schema of grafting of MAH onto PP in the presence of stabilizers has been proposed and compared with the experimental results. The effect of the stabilizers on the extent of the undesirable b-scission was evaluated based on the melt flow rate (MFR) and the rheological curves of PP-g-MAH. In the second part, the effect of the peroxide structure and the concentration of reactants on the grafting yield of PP modification with MAH and itaconic anhydride (IAH) was observed. The initial grafting yield Rg has been experimentally determined and compared with a defined area of theoretical values of Rg. The extent of b-scission was significantly influenced by the structure and the concentration of peroxide, as shown by the results of MFR and the rheological curves of PP-g-MAH. The last part of the doctoral thesis is focused on the assessment of the combination of MAH and IAH as comonomers on the grafting yield. At first, the reference polymers were prepared using the solution polymerization of MAH, and IAH, and copolymerization of MAH with IAH. The reference polymers were analyzed by FTIR, DSC, WAXS to confirm the probable copolymerization of MAH and IAH. The dependence of the reaction enthalpy on the reaction time was observed using simulations of bulk polymerization of MAH, IAH and mixtures MAH and IAH "in situ" in isothermal calorimeter. PP was subsequently modified with a combination of MAH and IAH as comonomers in order to assess its effect on the grafting yield
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Effects of material and 3D printing technology on the properties of auxetic structures
Kuchtová, Štěpánka ; Žídek, Jan (referee) ; Jančář, Josef (advisor)
This thesis deals with the behaviour of auxetic structures. In particular, the focus is on the effect of the 3D printer, material filament and number of unit cells on the deformation response of auxetics. Specimens were prepared on two printers with a direct and a bowden extruder made of PET-G (polyethylene terephthalate glycol) and TPU (thermoplastic polyether polyurethane) materials. The prepared structures were subjected to a static compression test, during which video recordings were taken. From the video recordings the Poisson's ratio and porosity of the samples were subsequently evaluated. A software application was written in Python programming language to evaluate the Poisson's ratio and porosity. The type of 3D printer had a significant effect on the properties of the prepared auxetic structures. The specimens prepared by the bowden extruder printer exhibited lower stiffness and yield strength and higher Poisson's ratio compared to the samples prepared by the direct extruder printer. Furthermore, the influence of the number of unit cells and influence of the material with low (TPU) and high (PET-G) elastic modulus on the auxetic behaviour was investigated. In the case of the flexible material, specimens with fewer unit cells exhibited tougher response, whereas the opposite was true for PET-G. At the same time, attention was paid to the deformation response of single cells within the sample, where TPU exhibited a different deformation behaviour mechanism than PET-G. This has been reflected in different spatial distribution of auxetic behaviour within the specimens.
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