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Crystallization of binary polylactide blends and their morphology
Debnáriková, Michaela ; Poláček, Petr (oponent) ; Bálková, Radka (vedoucí práce)
Master thesis deals with the influence of polyvinylacetate, polycaprolactone, poly(butylene-adipate-co-terephtalate) and talc, ethylenevinylacetate, polyethylene glycol and monosodium citrate on the flow properties, mechanical properties and crystallization ability of PLA. The flow properties were studied using the melt flow index and mechanical properties were studied using a tensile test. The crystallinity was studied by differential scanning calorimetry and on a polarization optical microscope equipped with hot stage. Isothermal crystallization was performed at 95 and 105 °C for 3 h and non-isothermal crystallization was performed with a calorimeter at two cooling rates (1 and 10 °C/min). Upon the isothermal crystallization at 95 °C, the formation of denser crystalline structure was observed and the content of crystalline phase increased in most of the samples. The formation of spherulitic structure was observed at 105 °C in samples with 30 % PVAc, 30 % EVA and PEG. Reducing the cooling rate to 1 °C/min at non-isothermal crystallization had nearly no effect on the crystallization process of the most samples; the content of crystalline phase increased in the samples containing PBAT and PEG, which revealed double melting peak during subsequent heating. The crystalline fraction was the most significantly affected by the addition of PEG. All added polymers except PVAc affected the mechanical properties; PBAT, PCL, EVA and PEG increased the strain and decreased the strength and modulus of elasticity. The samples containing monosodium citrate showed unsatisfactory mechanical properties and could not be measured. The samples containing higher concentration of EVA copolymer showed the phase separation.
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Preparation of chitin film
Debnáriková, Michaela ; Abdelrahman, Rasha (oponent) ; Abdellatif, Abdelmohsan (vedoucí práce)
The bachelor thesis deals with the extraction, purification, dissolution and preparation of film based on chitin/ polyvinyl alcohol (PVA). The pure chitin was fully characterized by different techniques like potentiometric titration, FT-IR, TGA, XRD, SEM and solid NMR. The solubility, purity of extracted chitin was investigated and evaluated by measuring the protein percent, rheology, and time need for dissolution. The chitin/PVA films were prepared using different ratio between chitin and PVA solution and film was prepared by casting method. The surface morphology, rheological and mechanical properties of the film were measured and evaluated.
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Crystallization of binary polylactide blends and their morphology
Debnáriková, Michaela ; Poláček, Petr (oponent) ; Bálková, Radka (vedoucí práce)
Master thesis deals with the influence of polyvinylacetate, polycaprolactone, poly(butylene-adipate-co-terephtalate) and talc, ethylenevinylacetate, polyethylene glycol and monosodium citrate on the flow properties, mechanical properties and crystallization ability of PLA. The flow properties were studied using the melt flow index and mechanical properties were studied using a tensile test. The crystallinity was studied by differential scanning calorimetry and on a polarization optical microscope equipped with hot stage. Isothermal crystallization was performed at 95 and 105 °C for 3 h and non-isothermal crystallization was performed with a calorimeter at two cooling rates (1 and 10 °C/min). Upon the isothermal crystallization at 95 °C, the formation of denser crystalline structure was observed and the content of crystalline phase increased in most of the samples. The formation of spherulitic structure was observed at 105 °C in samples with 30 % PVAc, 30 % EVA and PEG. Reducing the cooling rate to 1 °C/min at non-isothermal crystallization had nearly no effect on the crystallization process of the most samples; the content of crystalline phase increased in the samples containing PBAT and PEG, which revealed double melting peak during subsequent heating. The crystalline fraction was the most significantly affected by the addition of PEG. All added polymers except PVAc affected the mechanical properties; PBAT, PCL, EVA and PEG increased the strain and decreased the strength and modulus of elasticity. The samples containing monosodium citrate showed unsatisfactory mechanical properties and could not be measured. The samples containing higher concentration of EVA copolymer showed the phase separation.
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Preparation of chitin film
Debnáriková, Michaela ; Abdelrahman, Rasha (oponent) ; Abdellatif, Abdelmohsan (vedoucí práce)
The bachelor thesis deals with the extraction, purification, dissolution and preparation of film based on chitin/ polyvinyl alcohol (PVA). The pure chitin was fully characterized by different techniques like potentiometric titration, FT-IR, TGA, XRD, SEM and solid NMR. The solubility, purity of extracted chitin was investigated and evaluated by measuring the protein percent, rheology, and time need for dissolution. The chitin/PVA films were prepared using different ratio between chitin and PVA solution and film was prepared by casting method. The surface morphology, rheological and mechanical properties of the film were measured and evaluated.
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