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Polyhydroxybutyrate derivates for paper coating
Hrnčiar, Milan ; Jašek, Vojtěch (referee) ; Figalla, Silvestr (advisor)
The work focuses on the preparation of polymer dispersion systems based on polyhydroxybutyrate and the application of the polymer as paper coating from aqueous dispersion or from melt, and the fundamental characterization of the coated paper was investigated. For the preparation of aqueous dispersions, the organic phase was polymer component in ethyl acetate. The aqueous phase contained potato starch as stabilizer and sodium dodecyl sulfate as surfactant. Dispersion of the individual phases was performed by ultrasound. To reduce the molecular weight of the polymer and hence the viscosity of the organic phase, controlled thermo-mechanical degradation of the polymer was used to achieve stable aqueous dispersions. Dispersion of the individual phases was accomplished by ultrasound. To reduce the molecular weight of the polymer and hence the viscosity of the organic phase, controlled thermo-mechanical degradation of the polymer was used to achieve stable aqueous dispersions. Molecular weights were determined by gel permeation chromatography (GPC). The polymer was applied on paper surface from prepared aqueous dispersion and from melt. In case of surfaces applied from aqueous dispersion, a part was additionally modified by pressing or sintering. The fundamental characterization of the prepared paper coating was performed by testing the resistance to water penetration, resulting in functional water-retaining polymer coatings. Such treated paper could have potential applications, for example, in the production of water resistant disposable packagings based on natural resources.
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Extraction of Poly(3-hydroxybutyrate) from Biomas
Jašek, Vojtěch ; Ing. Jiří Švrček, Ph.D (referee) ; Figalla, Silvestr (advisor)
Polyhydroxyalkanoates are a group of biopolymers which occur in cells of microorganisms. These biopolymers can be considered as alternatives to commonly used petrochemical materials such as polypropylene and polyethylene due to their physical and chemical properties. This bachelor thesis focuses on isolation of particular kind of PHA from biomass and contains both experimental and theoretical part. It consists of information about the origin and usage of PHA, challenges and problems of their biotechnological production and mainly various ways of downstream. Experimental part includes comparison of PHA extraction from biomass done by two ester solvents. Studied parameters were molecular weight of the polymer, solvent extraction ability and their resistance against hydrolysis. The main goal of this thesis was to verify the best process conditions of isolation done by nonhalogenated bio-solvent.
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Preparation and characterisation of coatings for controlled-release fertilizers
Jašek, Vojtěch ; Sedláček, Petr (referee) ; Figalla, Silvestr (advisor)
The literary research of this Master's thesis is dedicated to controlled-release fertilizers (CRF). There is written the description of particular representatives of this kind of fertilizer and it also contains principles of nutrition's release mechanisms. Theoretical part is mainly focused on coated fertilizers, materials used for their production, coating technological processes and on a mathematical description of the diffusion transport which is the key of the mass transfer through polymer coatings. The laboratory preparation of innovative coatings based on modified vegetable oils is the main part of the experimental part of the thesis. It consists of the precursors' synthesis which can be applied on the fertilizer's surface in a liquid phase and polymerized by the UV-radiation in combination with an appropriate photoinitiator. There is described the synthesis of additional modifiers of precursors' viscosity and coatings' diffusive properties based on bio-source reactants such as sorbitol or ethyl lactate. The synthesized products are characterized by various methods such as volumetry, FTIR method or viscosimetry. The last part of the thesis contains the description of diffusive characteristics of coatings prepared out of the synthesized precursors.
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Extraction of Poly(3-hydroxybutyrate) from Biomas
Jašek, Vojtěch ; Ing. Jiří Švrček, Ph.D (referee) ; Figalla, Silvestr (advisor)
Polyhydroxyalkanoates are a group of biopolymers which occur in cells of microorganisms. These biopolymers can be considered as alternatives to commonly used petrochemical materials such as polypropylene and polyethylene due to their physical and chemical properties. This bachelor thesis focuses on isolation of particular kind of PHA from biomass and contains both experimental and theoretical part. It consists of information about the origin and usage of PHA, challenges and problems of their biotechnological production and mainly various ways of downstream. Experimental part includes comparison of PHA extraction from biomass done by two ester solvents. Studied parameters were molecular weight of the polymer, solvent extraction ability and their resistance against hydrolysis. The main goal of this thesis was to verify the best process conditions of isolation done by nonhalogenated bio-solvent.
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