|
| |
|
|
Polymer nanocomposites with PMMA matrix
Kostková, Jana ; Žídek, Jan (referee) ; Jančář, Josef (advisor)
This bachelor thesis deals with s study of mechanical and viscoelastic properties of nanocomposites with PMMA matrix filled with different types of surface-modified silica, which differed by the specific surface area, surface treatment and particle size. Nanocomposites were prepared by dissolving, where nanofillers were injected into the dissolved matrix. Nanocomposite samples were tested in tensil and viscoelastic properties were determined till the softening point by dynamic-mechanical analysis (DMA). All types of nanofillers had almost no effect on tensile modulus of nanocomposites at room temperature (it was not reduced) one type of silica at a content 2 %, which was also confirmed by the DMA. The temperature DMA measurements showed that samples containing 2 % of silica were generally thermally more stable compared with nanocomposites containing 1 % of silica. Storage modulus of nanocomposites, except two ones, were similar or lower such pure PMMA to temperature 66 C, then the trend reversed. Loss modulus of all samples was one order of magnitude lower then the elastic modulus.
|
|
|
Dynamic surface tension in study of hyaluronan-surfactant interactions
Herzog, Milan ; Žídek, Jan (referee) ; Pekař, Miloslav (advisor)
The main task was to characterize interactions between negatively charged biopolymer sodium hyaluronate and two cationic surfactants: cetyltrimethylammonium bromide (CTAB) and tetradecyltrimethylammonium bromide (TTAB). Interactions between sodium hyaluronate and these surfactants are based on their different charge and can be detected by changes of surface tension. The influence of constant addition of sodium hyaluronate (MW = 90 and 1400 kDa) on interface tension values at increasing bubble lifetime was observed. For this purpose, the maximum bubble pressure method was choosen. The measurements were performed in water and in 0,15 mol•l-1 NaCl solution. The obtained results can be used as for description of dynamic properties of hyaluronate-surfactant systems as, e.g., in targeting drug delivery.
|
|
|
Molecular simulation study of aqueous solutions of alifatic alcohols
Peštuka, Martin ; Žídek, Jan (referee) ; Janeček, Jiří (advisor)
The aim of this bachelor thesis was to carry out set of molecular dynamic simulations of aqueous solutions of aliphatic alcohols in infinite attenuation. In order to work with molecular dynamic simulations it was necessary to become familiar with the program equipment to perform molecular dynamic simulations and analyze the results. Within the work the basic simulation boxes contained 300, 400, 500 and 1000 water molecules and one molecule of aliphatic alcohol. From the simulated trajectories we evaluated the volume change associated with the insertion of one particle of alcohol and the radial distribution functions around the molecule of solute. The results were compared with experimental data.
|
|
|
Polymeric nanocomposites - preparation methods
Černý, Miroslav ; Žídek, Jan (referee) ; Kučera, František (advisor)
Literature search of bachelor thesis was focused to methods of CaCO3 nanoparticles preparation, surface modification and PS/CaCO3 nanocomposites processing. Experimental part was based on two methods of PS/CaCO3 nanocomposites preparation: emulsion and bulk technique of styrene radical polymerization in presence of CaCO3 and by compounding CaCO3 with PS in Brabender mixer at 220 °C. Prepared samples were observed using electron microscope.
|
|
|
Application of nanofillers into thermoplastics
Žák, Luboš ; Žídek, Jan (referee) ; Kučera, František (advisor)
Bachelor thesis is focused on the search of the state of knowledge in the preparation, properties and applications of nanocomposites with thermoplastics polymer matrix and different types of nanofillers in theoretical part. Methods for the preparation of nanocomposites and techniques used for their characterization are clearly describes. The first method for preparing nanocomposites is an application of nanofiller to the polymer solution with subsequent removal of the solvent. The second method is the dispersion polymerization of nanofiller in the monomer. The last one is the application of nanofiller in the dispersion of ethanol into the polymer melt. The experimental part deals with the preparation of foils for characterization of rheological properties of nanocomposites at first. Polystyrene was polymer matrix and selected nanofillers was applied to the polymer solution and then it was removed the solvent. The second method was the preparation of nanocomposites dispersion polymerization of nanofillers in the monomer. The method in-situ preparation of nanocomposite is based on the thermal initiated polymerisation of styrene in the dispersion of nanofillers with the selected type radical initiator. The third proposed method was the application of ethanol dispersion of fillers into the polymer melt in the Brabender mixer.
|
|
|
Modification of polyurethane by biodegradable poly(hydroxybutyrate)
Kupka, Vojtěch ; Žídek, Jan (referee) ; Vojtová, Lucy (advisor)
Cílem předložené bakalářské práce byla syntéza elastomerního polyuretanu plněného biodegradabilním polyhydroxybutyrátem. Vzorky byly podrobeny analýze morfologie pomocí rastrovací elektronové mikroskopie, mechanické vlastnosti byly testovány jednoosou tahovou zkouškou. Práce se taktéž zabývá předpovědí mechanických vlastností na základě teorií kaučukové elasticity. Bylo zjištěno, že výsledný materiál je částicový kompozit, kde se vzrůstajícím hmotnostním obsahem plniva v materiálu vzrůstá modul pružnosti. Predikce tahových křivek pomocí softwaru SEC.exe ukazovala pro reálný průběh křivky nereálné hodnoty hustot polymerních řetězců. U modelů, které vykazovaly reálné hodnoty hustot, byly naopak hodnoty napětí vyšší, než ve skutečnosti naměřené.
|
|
| |
|
|
Study of structural and mechanical properties of dendrimers
Ščudlová, Jolana ; Legut,, Dominik (referee) ; Žídek, Jan (advisor)
This thesis deals with the research on organized supermolecular structures. These structures are present in many polymeric materials. Mainly in bio-materials, they cause biological activity. Collagen fibril and dendrimers are suitable materials for molecular modeling. Collagen is natural protein with long, fibrous structure. Its fibrils show high elasticity. This property makes the material useful for certain applications. Dendrimers are synthetic macromolecules with regular and highly branched architecture. Modeling of their properties can be useful for improvement of various molecular models. The molecular structure of collagen fibril and dendrimers was studied by molecular dynamics simulations. The structures were built in the GROMACS software. Elastic deformation of collagen fibril was investigated. In case of dendrimers, shape and gyration radii were calculated from molecular models. Properties of these two materials are well described in literature. Therefore, modeling results can be compared to experimentally measured properties.
|
|
| |
guest ::
RSS feed.