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Determination of titanium dioxide nanoparticles in personal care products
Košík, Juraj ; Čáslavský, Josef (oponent) ; Vávrová, Milada (vedoucí práce)
The following master thesis deals with extraction of titanium dioxide nanoparticles (TiO2 NPs) from consumer care products, concretely sunscreens, and subsequent characterization of these particles. TiO2 nanoparticles are present in an increasing number of commercially available products. Therefore, there is an increasing need to evaluate the potential fate and indirect exposure of TiO2 NPs of different sizes and shapes and investigate their entire life cycle. Feasibility of using ultrafiltration and ultracentrifugation as an extraction method were investigated. Two extraction method for extracting TiO2 nanoparticles were developed and applied to sunscreen samples. Extracted particles can be used for ecotoxicological and mesocosmos experiments. Secondly, size of extracted particles was determined using dynamic light scattering (DLS) and transmission electron microscopy (TEM).
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Surface analysis of xGnP/PEI nanocomposite
Červenka, Jiří ; Klapetek, Petr (oponent) ; Čech, Vladimír (vedoucí práce)
This Diploma thesis deals with surface analysis of nanocomposite foil – polyetherimide matrix (PEI) reinforced by exfoliated graphite nanoplatelets (xGnP). The PEI foil without reinforcement and separate xGnP particles were also analysed. Samples of the nanocomposite and the PEI foil were etched for various times by argon plasma. Scanning electron microscopy (SEM) was used to characterize xGnP agglomerates dispersed over silicon wafer and pristine/etched samples of PEI foil and nanocomposite xGnP/PEI foil. Graphite nanoplatelets were identified at surface of etched nanocomposite foil. Atomic force microscopy (AFM) was used for surface topography imaging of separate nanoplatelets and those uncovered at the surface of etched nanocomposite. Surface roughness (root mean square, peak to peak) of etched nanocomposite increased with prolonged etching time. Atomic force acoustic microscopy (AFAM) was used to characterize elastic anisotropy of etched nanocomposite. Nanoindentation measurements were employed to characterize the local mechanical properties of PEI and nanocomposite foils.
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Waste heat storage systems using phase change materials
Abdelkader, Mohamed ; Řehořek, Lukáš (oponent) ; Čupera, Jan (vedoucí práce)
This bachelor thesis deals with waste heat storage systems using phase change materials as an efficient way to store thermal energy (e.g., industrial waste heat) and have the advantages of high storage density and isothermal nature. I.e., such systems have the ability to absorb a large amount of thermal energy, without increasing the temperature of the system itself. In practice, such a system can be achieved by creating a binary system of metals with complete insolubility in the solid state, in which the matrix (a metal with a higher melting point) ensures sufficient thermal conductivity and a filler metal with a low melting point and a high enthalpy ensures the accumulation of thermal energy. For example, it could be a binary system Al–Sn or Fe–Cu. Such systems could then be used for the accumulation and subsequent gradual release of thermal energy from components with complex shapes, on which this binary system could be applied using the cold spray method.
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Determination of titanium dioxide nanoparticles in personal care products
Košík, Juraj ; Čáslavský, Josef (oponent) ; Vávrová, Milada (vedoucí práce)
The following master thesis deals with extraction of titanium dioxide nanoparticles (TiO2 NPs) from consumer care products, concretely sunscreens, and subsequent characterization of these particles. TiO2 nanoparticles are present in an increasing number of commercially available products. Therefore, there is an increasing need to evaluate the potential fate and indirect exposure of TiO2 NPs of different sizes and shapes and investigate their entire life cycle. Feasibility of using ultrafiltration and ultracentrifugation as an extraction method were investigated. Two extraction method for extracting TiO2 nanoparticles were developed and applied to sunscreen samples. Extracted particles can be used for ecotoxicological and mesocosmos experiments. Secondly, size of extracted particles was determined using dynamic light scattering (DLS) and transmission electron microscopy (TEM).
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Surface analysis of xGnP/PEI nanocomposite
Červenka, Jiří ; Klapetek, Petr (oponent) ; Čech, Vladimír (vedoucí práce)
This Diploma thesis deals with surface analysis of nanocomposite foil – polyetherimide matrix (PEI) reinforced by exfoliated graphite nanoplatelets (xGnP). The PEI foil without reinforcement and separate xGnP particles were also analysed. Samples of the nanocomposite and the PEI foil were etched for various times by argon plasma. Scanning electron microscopy (SEM) was used to characterize xGnP agglomerates dispersed over silicon wafer and pristine/etched samples of PEI foil and nanocomposite xGnP/PEI foil. Graphite nanoplatelets were identified at surface of etched nanocomposite foil. Atomic force microscopy (AFM) was used for surface topography imaging of separate nanoplatelets and those uncovered at the surface of etched nanocomposite. Surface roughness (root mean square, peak to peak) of etched nanocomposite increased with prolonged etching time. Atomic force acoustic microscopy (AFAM) was used to characterize elastic anisotropy of etched nanocomposite. Nanoindentation measurements were employed to characterize the local mechanical properties of PEI and nanocomposite foils.
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