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Reactive extrusion of polymers by peroxides
Červený, Ladislav ; Petruš, Josef (referee) ; Kučera, František (advisor)
Diploma thesis deals with processing of two types of PP, HDPE, LDPE, PET, PA, PS, PMMA and ABS by reactive extrusion in presence of peroxides. The theoretical part summarizes existing knowledge about processing of used polymers. Reactive extrusion was carried out with a single screw extruder at 260 °C, 30 rpm and 60 rpm depending on peroxide used. One type of PP was processed in presence of Luperox 101, hydrogen peroxide, dicumyl peroxide and potassium persulfate. Luperox 101 and hydrogen peroxide were chosen for reactive extrusion of other polymers. The efficiency of selected peroxides on radical modifications of individual polymers during processing was evaluated by methods of rheological (MFI), structural (FTIR) and thermal (DSC) analysis.
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Preparation of Poly(3-hydroxybutyrate) based acrylic monomer
Liška, Marek ; Přikryl, Radek (referee) ; Figalla, Silvestr (advisor)
The main aim of this thesis is to research and prepare acrylic (methacrylic) monomers derived from poly(3-hydroxybutyrate). The monomers were prepared in two-step syntheses. In the first step P3HB was depolymerised with selected alcohols and afterwards, products of those syntheses were used as substrate and mixed with polymethylmethacrylate to produce their methacrylic derivates. The selected alcohols for the alcoholysis were ethanol and ethylene glycol. In total, four substances were prepared. Products of alcoholysis were ethyl-3- hydroxybutyrate, 2-hydroxyethyl-3-hydroxybutyrate and their methacrylic derivates. Significant part of this thesis is aimed towards the analysis of prepared substances and the analysis of reactions. In the process, titrations and instrumental methods, such as gel permeation chromatography (GPC), infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), thermogravimetry (TGA) and differential scanning calorimetry (DSC) were used. This work describes preparation and analysis of polymers prepared from methacrylates from the mentioned syntheses. Cross-linked polymers, because of their low glass-transition temperature are elastomers.
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Evaluation of the influence of machining technologies on the analysis of the surface texture of technical plastics
Škeřík, Filip ; Dobrocký, David (referee) ; Sedlák, Josef (advisor)
The diploma thesis deals with the influence of machining technologies (turning, milling, grinding and polishing) on the surface texture of functional surfaces of selected materials from technical plastics. In the first part of the thesis there is a theoretical analysis of the possibilities of machining plastic materials. Furthermore, an analysis of the most commonly used parameters for evaluating the roughness of the machined surface and their effect on functionality is performed. The experimental part of the thesis describes samples preparation, analysis of measured data and subsequent evaluation with benefits for machinery industry.
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Application of renewable and recyclable raw materials for preparation of new polymers
Horák, Pavel
This thesis deals with optimalization of flexible polyurethane foam recycling with using of natural polyols based on rape seed oil and fish oil and it explores applications of depolymerized polyol product by formulations of new polyurethane materials. The experiments of depolymerisation showed that both tested natural oil (rape seed oil and fish oil) can be used as effective reagents for polyurethane recycling. Reaction conditions of depolymerisation were optimised with model flexible polyurethane foam and applied on waste foam from real conditions. Gain of depolymerisation is one-faze low viscosity (to 1500 mPa.s) liquid polyol products with content of hydroxyl groups ca 3 mmol/g. These polyols can be used for polymerisation of new materials. First application of recycled polyols was formulation of polyurethane foam systems. Through optimising of formula was prepared low-density semirigid foam containing 100 percentage of recycled polyol. Properties of these foams correspond to commercial foams. To prepare of homogenous cast polyurethane system based on recycled polyols it was necessary to add proper solvent, therefor extent of application has been lowered. On that account the systems were tested for study of polyaddition reaction and for following properties of the material. In these tests, the reactivity...
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Design of boron cluster-containing nanostructuresin solution
Fernandez Alvarez, Roberto ; Matějíček, Pavel (advisor) ; Machalová Šišková, Karolína (referee) ; Cígler, Petr (referee)
Thesis The main objective of this thesis is the study of boron cluster compounds in solution, their interaction with polymers and the formation of nanostructures. Most of the work was focused around cobalt bis(dicarbollide) (COSAN) but the incorporation of carborane into polymers was also studied. The idea was to close the knowledge gap around the way COSAN aggregates and continue the line of the laboratory in leading this topic. Therefore, we performed in-depth analysis of isothermal titration calorimetry curves to determine the aggregation number at concentrations around the critical micellar concentration (CMC). Thus, the aggregation number obtained was an improvement over previous data obtained a much higher concentration. The use of acetonitrile as a cosolvent in the micellization process helped formulate a model describing how C-H bonds in the COSAN micelles are directed towards the inside of the micelle. Furthermore, COSAN was used as a model drug for loading nanocarriers composed of hydrophobic core and charged corona. The importance of this work relies on the creation of guidelines for drug loading into similar polymeric vectors in order to determine how the nanocarrier will be affected. With the help of coarse-grained simulations, we determined that changes in the hydrophobicity of the...
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Use of polymers in road constructions
Klusková, Jana ; Komenda, Radek (referee) ; Stehlík, Dušan (advisor)
The diploma thesis deals with the use of recycled polymers in asphalt mixtures. In the theoretical part of the thesis there is discussed the global issue of plastic waste including the experience of foreign countries, where this technology has already been introducted and used. The practical part is devoted to the proposal of using recycled plastic in asphalt mixture, description of used laboratory tests and the evaluating the effect of low-density polyethylen (LDPE) on the asphalt mixture type AC. There were performed tensile strenght tests, water resistant tests and stiffness modulus tests in the laboratory (E). The output of this work is an evaluation of measured values, processing of results and their interpretation depending on the possible use of this technology in Czech republic.
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Construction of gears with plastic teeth
Selzer, Tomáš ; Vrbka, Martin (referee) ; Křupka, Jiří (advisor)
The thesis discusses the matter of construction of gear trains using plastic parts in both lubricated and non-lubricated environment, trying to give an overview of an up-to-date information in the process. Nowadays, thanks to several years of development, polymer-based gear systems can be used in many cases as a replacement for metal-based ones. The undeniable advantage of such replacement is mostly the lower production cost and its lower weight, which, together with favorable friction properties of polymer materials, makes a number of technological applications much more effective. The first part is dedicated to listing and defining the typical characteristics of polymer materials, which are essential in the process of designing the gear. The next part focuses on evaluation of the available types of solutions for plastic gear trains construction. The last topic is centered around possible defects and the wear as well as the operation conditions and a real-life application of such plastic gear system. The most notable findings are summed up and commented on in the form a discussion. Thanks to the chosen topic, the bachelor’s thesis adds to a closer understanding of the construction and operation of the plastic gear systems.
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Design of single-crystal sample holder for high-frequency electron paramagnetic resonance
Gabriš, Andrej ; Kern, Michal (referee) ; Sojka, Antonín (advisor)
This bachelor's thesis discusses the design and manufacture of non-resonant sample holder for the study of oriented crystals, which is used for high-frequency electron paramagnetic resonance (HF-EPR). The first part of the thesis is a theoretical introduction to EPR with the application of high frequency (80-1100 GHz) and high magnetic field (16 T). This work further analyzes the topic of crystal samples anisotropy and introduces the review of materials suitable for a sample holder, which is used in low-temperature conditions (4 K). The practical part of the thesis deals with the constructional design of the rotary sample holder. This section also compares the manufacturing possiblities of the selected parts of the sample holder: machining (milling and turning) and 3D printing. Lastly, this work describes the development of the user interface for automatization of an EPR spectrum measurement.
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Electrical Properties Analysis Of Epoxy Resins With Various Fillers
Horák, Luděk
Presented thesis is focused on studying electroinsulating epoxy resin-based sealings. It describes a preparation of composite epoxy resin samples with different kinds of micro-ground siliceous sand as a filling. The samples given are measured on the temperature dependency of relative permitivity and dissipation factor.
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Dielectric Absorption of Electroinsulating Materials
Pavlinský, Branislav ; Krbal, Michal (referee) ; Pelikán, Luděk (advisor)
This bachelor thesis deals with the basic physical principles of dielectrics as well as the description of the phenomenon of dielectric absorption. The work presents diagnostic methods that use this phenomenon, based on the events taking place in the dielectric after the connection of DC voltage. Furthermore, the work deals with diagnostic methods for determining the state of insulation of various high-voltage electrical equipment. The work also deals with the properties and parameters of electrical insulating materials - specifically polymers. We obtain these parameters using the mentioned diagnostic methods. By knowing these parameters, we achieve enough information about the insulation to determine its condition and prevent possible damage.
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