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Properties of fibers based on polyhydroxybutyrate
Štulrajterová, Lujza ; Tocháček, Jiří (referee) ; Přikryl, Radek (advisor)
Táto práca sa zaoberá zvlákňovaním biopolymérov z taveniny. V teoretickej časti sú zhrnuté doterajšie poznatky o zvlákňovaní poly(3-hydroxy butyrátu) (PHB) a poly(mliečnej kyseliny) (PLA). Následne boli zvláknené polymérne zmesi na báze PHB s rôznym zložením, čo umožnilo štúdium vplyvu PLA, zmäkčovadiel a ich množstva na vlastnosti pripravených vlákien. Boli použité tri komerčné zmäkčovadlá (ATBC, PEG, A6) a dva experimentálne syntetizované. Zvláknenie bolo prevedené na troch rôznych zvlákňovacích linkách. Konvenčné zvlákňovacie linky s odťahovými rýchlosťami nad 150 m/min sa preukázali ako nevhodné pre spracovanie našich zmesí. Kvôli nedostatočnej pevnosti taveniny sú potrebné nízke odťahové rýchlosti. Boli pripravené vlákna s dĺžiacim pomerom 6,4; ktoré boli následne analyzované pomocou GPC, MDSC a ťahovej skúšky. Na základe nameraných teplôt skelného prechodu zmäkčovadlá ATBC a PEG vykázali lepšiu schopnosť zmäkčiť skúmané PLA/PHB zmesi. Vlákna obsahujúce A6 vykazovali najvyššiu pevnosť v ťahu (250 MPa) a modul pružnosti (2,7 GPa). Nakoniec bol skúmaný vplyv starnutia, tepla a vriacej vody na mechanické vlastnosti týchto vlákien.
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Ceramic nanofiber-reinforced composites
Bocian, Luboš ; Přikryl, Radek (referee) ; Poláček, Petr (advisor)
This thesis investigated how the addition of unsilanized and silanized ceramic SiO2 nanofibers into particle reinforced composite affects flexural strength, fracture toughness, total fracture work and temperature dependence of viscoelastic properties. Fracture surfaces were analyzed with SEM. Flexural strength always decreased with addition of nanofibers. Composites with silanized nanofibers showed higher flexural strength than those with unsilanized nanofibers. Fracture toughness was higher with addition of nanofibers. Fracture toughness of composites with silanized nanofibers was always lower than that of systems with unsilanized nanofibers. Total fracture work was lower with addition of nanofibers, but sharply increased in composites with 5 % of nanofibers. Glass transition temperature almost always increased with addition of nanofibers. Storage modulus increased with addition of nanofibers. Storage modulus was always lower in composites with silanized nanofibers.
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Study of structure-property relationship of diketopyrrolopyrrole derivatives
Vrchotová, Jana ; Přikryl, Radek (referee) ; Weiter, Martin (advisor)
This master´s thesis deals with new perspective organic molecular materials. A theoretical part contains search themed on organic materials for optical and electronic devices with emphasis on diketopyrrolopyrrole derivatives. The aim of the experimental part was preparation of solutions, thin layers and prototypical planar electronic components from chosen diketopyrrolopyrrole derivatives and their optical and electric characterization. Obtained results are interpreted with perspective on application in organic electronic.
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Short fiber reinforced composite for dental use: preparation and characterization
Henkrichová, Jana ; Přikryl, Radek (referee) ; Poláček, Petr (advisor)
This diploma thesis studies short fiber reinforced composites for dental applications. Barium particulate filler, nanosilica and short glass and polyvinylalcohol fibers were added to the matrix consisting of four dimethacrylate types of monomers. The effect on material properties was observed. For characterization of different types of composite materials following methods were used: thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), three point bending test for notched and un-notched samples and scanning electron microscopy (SEM). Viscoelastic properties, modulus of elasticity and strength, critical values of stress intensity factor and strain energy release rate and polymerization shrinkage of composite materials were determined. It is possible to improve these properties of composite materials by adding short fibres to particulate reinforced composite. To make this modification more efficient, it is necessary to change surface treatment of fibres and preparation method of short fiber reinforced composites. Viscosity of material has raised after adding short fibers and processing of these types of dental material in dental laboratory is considered difficult to provide.
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Isolation, characterization and application of biomedically important polymer P(3HB-co-4HB)
Krupičková, Kristýna ; Přikryl, Radek (referee) ; Obruča, Stanislav (advisor)
This diploma thesis deals with the isolation and characterization of copolymer P(3HB-co-4HB). The teoretical part was prepared as a literature search which describe polyhydroxyalkanoates in general, their structure, synthesis, degradation and isolation. Furthermore, copolymers containing 4HB units are mentioned in this thesis and there is also no mentioned of the biosynthesis and biodegradation of copolymer P(3HB-co-4HB). The first aim of this diploma thesis was to find out which solvent is the best for copolymer extraction and then characterize obtained copolymer P(3HB-co-4HB). The isolated copolymer was characterized by gas chromatography, SEC-MALS, thermal analysis and SEM. In the second part of the thesis, release of model biologically active substance from the PHA films was studied. Rhodamine 6G dye was selected for the simulation, which was used to stain the copolymer films and the P(3HB) films. It was observed that film prepared from P(3HB-co-4HB) copolymer released entrapped substance much faster than film made from P3HB homopolymer, and, in addition, the copolymer was substantially more susceptible to enzyme degradation.
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Preparation of microfiber structures based on PHB copolymer
Kecíková, Alžbeta ; Brtníková, Jana (referee) ; Přikryl, Radek (advisor)
Master’s thesis deals with the preparation of microfibrous structures based on poly(3-hydroxybutyrate) (P3HB) and its copolymer with poly(4-hydroxybutyrate) using centrifugal spinning technology. The microfibers were modified by the addition of oligomer P3HB and a plasticizer. The centrifugal spinning process was optimized for each material by solution viscosity, polymer molecular weight, speed of spineret, and presence of solvent. One of the part of optimalization was the addition of formic acid and acetic acid to the dissolution system. Microfibrous structures have been investigated in terms of morphology, mechanical properties, wetting and biocompatibility. P3HB fibers were also surface treated with lipase solutions to reduce their hydrophobicity. The prepared bulky fiber cocoons have a suitable 3D microstructure for monitoring and testing biological properties in vitro. Thus, a potential application of microfiber structures is as 3D cell culture carriers in an scaffolds in vitro system.
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Additive in unsaturated polyester resin for pultrusion process
Vaněk, Martin ; Bábík, Adam (referee) ; Přikryl, Radek (advisor)
Theoretical part of bachelor’s thesis deals with composite materials based on fiberglass and unsaturated polyester resins. It focuses on Low profile aditives, which are added in matrix to lower polymerization shrinkage. The thesis studies the influence of additives on the changes of matrix behavior and mechanical composite properties. Nature of those changes was monitored by differential scanning calorimetry (DSC), scanning electronmicroscopy (SEM), touchscreen profilometry, tensile test and bending test. Influence of LPs on matrix polymerization shrinkage, roughness and geometry in fiberglass composites were evaluated. Matrix Polipol 3870 and aditive Norsolook A71074 were found to be the most suitable because the best result was observed.
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Properties of FDM technology 3D prints
Tertinská, Martina ; Přikryl, Radek (referee) ; Veselý, Michal (advisor)
This bachelor thesis is aimed at FDM 3D printing properties research. Theoretical part of the thesis sums up current knowledge about 3D printing such as it’s possible use cases and materials suitable for printing. The experimental part is focused on MakerBot Replicator Mini 3D printer and printing test samples from two different materials and testing their mechanical attributes using pull-test and break-test machinery.
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Study of biodegradation of poly(hydroxy alkanoates).
Wurstová, Agáta ; Přikryl, Radek (referee) ; Obruča, Stanislav (advisor)
The master‘s thesis is focused on the study of biodegradation of polyhydroxyalkanoates, namely polymer polyhydroxybutyrate. The first part of the thesis is focused on the study of biodegradation of polyhydroxybutyrate in the form of crystalline granules of PHB and PHB films using selected species of microorganisms from bacteria, yeasts and fungi. As a representative of bacteria was chosen microorganism Delftia acidorovans, as yeast was selected Aureobasidium pullulans and Aspergillus fumigatus as fungi. PHB depolymerase activity was measured employing turbidemtiric method with suspension of PHB granules as substrate. The results showed that D. acidorovans can partially degrade PHB. On the contrary A. pullulans cannot effectively degrade PHB. The most significant degradation ability revealed A. fumigatus, which was able to degrade PHB completely. Extracellular enzymes excreted by these microorganisms when cultivated on PHB materials as sole carbon sources were analyzed by SDS-PAGE. The second part of the thesis deals with the biodegradation of PHB in the form of PHB film, PHB hardened foil and PHB Nanoul fabric using standard composting test. Semi-solid cultivation showed positive results. In the interval from 14 days to two months were all forms of the PHB completely biodegraded. With semi-solid cultivation was also studied biodegradation rate of the polyurethane elastomeric films which were modified by partial replacement of polyester polyol by PHB. The test samples were prepared using PHB from Sigma and the PHB samples prepared at the Faculty of chemistry VUT. Samples with different concentrations of the dispersed PHB (1 %, 5 % and 10 %) in the polyurethane were also object of the study. At the end of the cultivation (after 2 months) were measured mechanical properties in tension of the material, then efficiency of biodegradation by gravimetric analysis and modification of the material surface by microscopic analysis.
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