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Dynamic viscosity of electroinsulating liquids
Míka, Petr ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
This work deals with persepective environmentally friendly electroinsulating liquids. Important properties of currently used electroinsulating liquids are listed. Physical nature of viscosity of liquids and its temperature dependance are described and methods of its measuring are listed. Also temperature dependance of density is described from physical point of view. Measurement of density and of temperature dependance of viscosity of chosen vegetable and mineral oils was performed. On the basis of this measurement was calulated the activation energy of these samples. Two methods of dynamic viscosity measurement were used for some samples.
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Diagnostics of the perspective insulating liquids
Spohner, Milan ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
This work deals with the classification and diagnosis of electrical insulating liquids. Furthermore, the theoretical part describes the mathematical and physical principles of these liquids. The automated workplace was compiled with development environment VEE Pro for measurement of viskosity and control thermostat medingen and modifiable components for measuring complex permittivity in the frequency range. In the experimental part was carried out measurements of selected material parameters, investigated the effect of difficult conditions and made the mathematical evaluation of physical phenomena.
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Insulation and dielectric properties of water
Grill, Jiří ; Frk, Martin (referee) ; Špinka, Jiří (advisor)
This master´s thesis deals about insulation and dielectric properties of water. It describes the structure of water, covalent and hydrogen bonds. It outlines primary chemical and physical properties of water and then it describes parameters of water - dynamic viscosity, conductivity, surface tension, pH and also describes dielectric properties - dielectric loss, loss factor, permittivity, polarization. Part of the work is practical section, which includes measurements of deionized water, destilled water, tap water and shows primary dependence such as dependence loss factor on frequency or relative permittivity on frequency.
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Diagnostics of electroinsulating liquids properties
Makówka, Tomasz ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
The diploma thesis deals with the liquid insulators, their properties and their use in the electrical industry. The general aim is to study the physical essence of the dynamic viscosity, the electric conductivity and the diagnostic methods for monitoring these variables. The experimental part contains measuring the dynamic viscosity and the electric conductivity of the mineral transformer oils ESTO BNX, RENOLIN ELTEC and the biodegradable oil MIDEL 7131 during the degradation. The Walden rule is applied on measured results.
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Label Adhesives with Enhanced Humidity Resistance
Kotrlová, Janka ; Jančovičová, Viera (referee) ; Dzik, Petr (advisor)
The main topic of the thesis was to examine the hydrophobicity of labeling adhesives in the state before drying, it means their resistance against condensated moisture. The problem was solved by measuremensts of contact angle between the drop of water and glue. Measurements of dynamic viscosity and wet tack were also performed for the sake of complex characterization of the glue properties. Comparison of properties among single-component adhesives based on the acrylic copolymers alkalised with various agents was made. The impact of starches and industrial additives on glues was determined by the analysis of primary physical and chemical parameters. The purpose of the measurements was to develop a formula of the glue with enhanced atmospheric moisture resistance, that also would have the required parameters in the equilibrium. Finally, some selected glue samples were practically tested for condensation water resistance. These tests were performed in a climatic chamber with water condensating conditions.
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Dependence of adherence on viscosity for water-based polymeric glues.
Kotrlová, Janka ; Novák,, Igor (referee) ; Kapusta, Jozef (advisor)
There was examined wet tack and dynamic viscosity of mono adhesives and found out their interdependence in the thesis. Adhesives containing PVAl hydrolyzed from 85 % and various types of acrylic copolymers neutralized with alkaline agents were compared. The purpose of the measurements was to determine the polymer with the highest wet tack at the lowest dynamic viscosity at the desired level of wet tack. Furthemore, the impact of the degree of neutralization of acrylic copolymer, the impact of used alkaline agent for apparent viscosity and wet tack of acrylic copolymer was detecting and also was determined limit viscosity number of PVAl.
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