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Crystallization of binary polylactide blends and their morphology
Debnáriková, Michaela ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
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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The influence of environmental conditions of the recycling of solar modules
Langer, Filip ; Vaněk, Jiří (referee) ; Jandová, Kristýna (advisor)
This thesis is focused on experiments, goal of which is to separate protective glass apart from thin layer solar panel. This could lead to less expensive and more efficient recycling. We try to achieve the separation of the glass by thawing ethylene vinyl acetate layer, which serves as insulant and bonding material. Experiments are concluded in high temperature dryer and high temperature vacuum oven on samples of thin layer solar panel, which is for the purposes of experiments cut into same pieces by water jet cutting machine. The initiatory experiments in dryer and oven are to determine value of ethylene vinyl acetate thaw point in tested samples of panel. The thaw point is determined to be 340 °C. When exposed to this temperature, the ethylene vinyl acetate thaws enough for glass to be able to be extracted with minimal physical strength. The process is accompanied by fire destruction of tedlar layer and creation of exhaust gases. Following experiments in vacuum and nitrogen environment are to test their influence on thawing process. Exposing sample to temperature of 340 °C in vacuum led to no new results. Exposing sample to temperature of 340 °C in nitrogen environment prevented fire and achieved same level of thawing of ethylene vinyl acetate while creating less exhaust gases. Even though the fire was prevented, tedlar layer was still destroyed by the high temperature. Furthermore, particles of evaporated ethylene vinyl acetate condensed on surface of module in form of dust. Following experiments studied absorption of panel and influence of accessible solvents on thawing process. It was determined that panel is able to absorb approximately 2 % of acetone, 0,4 % of isopropyl alcohol and 0,11 % of distilled water in its own weight. Experiments with modules soaked in these solvents proved no new results in thawing process. By observing samples of ethylene vinyl acetate taken from module, thawed out of module after experiment in vacuum oven and dust condensed on surface of module after experiment in nitrogen environment, it was proven that the condensed dust is indeed ethylene vinyl acetate.
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Crystallization of binary polylactide blends and their morphology
Debnáriková, Michaela ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
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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The influence of environmental conditions of the recycling of solar modules
Langer, Filip ; Vaněk, Jiří (referee) ; Jandová, Kristýna (advisor)
This thesis is focused on experiments, goal of which is to separate protective glass apart from thin layer solar panel. This could lead to less expensive and more efficient recycling. We try to achieve the separation of the glass by thawing ethylene vinyl acetate layer, which serves as insulant and bonding material. Experiments are concluded in high temperature dryer and high temperature vacuum oven on samples of thin layer solar panel, which is for the purposes of experiments cut into same pieces by water jet cutting machine. The initiatory experiments in dryer and oven are to determine value of ethylene vinyl acetate thaw point in tested samples of panel. The thaw point is determined to be 340 °C. When exposed to this temperature, the ethylene vinyl acetate thaws enough for glass to be able to be extracted with minimal physical strength. The process is accompanied by fire destruction of tedlar layer and creation of exhaust gases. Following experiments in vacuum and nitrogen environment are to test their influence on thawing process. Exposing sample to temperature of 340 °C in vacuum led to no new results. Exposing sample to temperature of 340 °C in nitrogen environment prevented fire and achieved same level of thawing of ethylene vinyl acetate while creating less exhaust gases. Even though the fire was prevented, tedlar layer was still destroyed by the high temperature. Furthermore, particles of evaporated ethylene vinyl acetate condensed on surface of module in form of dust. Following experiments studied absorption of panel and influence of accessible solvents on thawing process. It was determined that panel is able to absorb approximately 2 % of acetone, 0,4 % of isopropyl alcohol and 0,11 % of distilled water in its own weight. Experiments with modules soaked in these solvents proved no new results in thawing process. By observing samples of ethylene vinyl acetate taken from module, thawed out of module after experiment in vacuum oven and dust condensed on surface of module after experiment in nitrogen environment, it was proven that the condensed dust is indeed ethylene vinyl acetate.
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