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Influence of particle size of cosmetic pigments on final properties product
Obručová, Kateřina ; Hurčíková, Andrea (referee) ; Zemanová, Jana (advisor)
This diploma thesis is focused on the study of the influence of the of size cosmetics pigments on the properties of the final product. This effect was studied on samples of make-up given by industry partner. Make-up samples were measured by the rheology method and the yield stress of all samples was determined. Scanning electron microscopy was used to determine the size and shape of the pigment particles. Particle size was also measured by dynamic light scattering, but the results were influenced by forming aggregates. To easier determination of the types of pigments in the sample was determined elemental composition of the pigments (Ti, Fe, O, Al) by EDS detector. Due to the unknown composition of make-up, the information was supplemented by X-ray powder diffraction (XRD) analysis, and it was possible to determine the compounds TiO2 (anatase and rutile), FeOOH and Fe2O3. The results obtained by these methods showed what pigments can be found in make-up samples, what their sizes and shapes are. It has been shown that the smaller the pigments are, the higher the viscosity and yield stress of the final product. The higher these quantities, the harder it is to handle the product.
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Durability test of magnetorheological fluid at high temperature
Grygárek, David ; Strecker, Zbyněk (referee) ; Roupec, Jakub (advisor)
This bachelor’s thesis is focused on behaviour of magnetorheological fluid during the durability test. In the first part are described basic properties of MR fluid and is defi-ned parameter LDE (Lifetime Dissipated Energy), which is used for prediction of durability of MR fluid. Primary part of thesis devote to realization of experiment, which measures a part of durability test at 70°C and monitoring the yield stress, vis-cosity and residual magnetism.
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Effect of aggregate type on lime mortar rheology
Vozák, Rastislav ; Rovnaník, Pavel (referee) ; Vyšvařil, Martin (advisor)
The subject of this bachelor thesis is examining the effect of aggregate type on lime mortar rheology. In the theoretical part, the thesis describes types of liquids and basic rheological quantities. Afterwards there are described some of the rheological behaviour models of non-Newtonian fluids. Furthermore, the theoretical part characterizes measurement of the flow, devices used for the measurement including the oscillatory measurement and its individual modes. Scientific literature was used to describe the rheology of the lime mortars and it covers the effect of different additives on the rheological behaviour. There is also characterized the effect of aggregate on the properties of lime mortars. The experimental part talks about the effect of three various kinds of aggregate on rheological prop-erties of the fresh lime mortar. The chemical composition of aggregates and their granulometry was determined. Subsequently, flow measurements were carried out and evaluated into flow curves. The yield stress, coefficient of consistency and flow index were assayed. In the oscillatory measurement there were measured complex, elastic and viscous modulus and loss factor.
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Reological properties of cement pastes modified by amorphous SiO2
Zimmermann, Štěpán ; Rovnaník, Pavel (referee) ; Vyšvařil, Martin (advisor)
The subject of this thesis are the rheological properties of cement paste with the addition of amorphous silicon dioxide. The basic rheological parameters are that describe the behavior of cement pastes in the fresh state. The work also included rheological tests including measurement principle and method of evaluation. Effect of mineral admixtures with high content of amorphous SiO2 is summarized the available scientific articles. In the experimental part, the effects of impurities with a high content of amorphous SiO2 on the rheological properties of fresh cement paste. It was tested by substitution of up to 10 % by weight of cement in the cement pastes mineral admixtures of different chemical composition, particle size and pozzolanic activity. Flow measurement was measured yield value, viscosity, and flow index. The stability of cement pastes was investigated oscillatory measurements. To complement the behavior pastes in the fresh state was determined by calorimetry. Test results were compared with those determined by reference samples and compared the effect of various ingredients.
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Comparison of fatigue fracture criteria for torsion
Roh, Marek ; Slámečka, Karel (referee) ; Horníková, Jana (advisor)
The main goal of this bachelor thesis is to determine which criteria better suits the life prediction of the test sample loaded in the pulsating torsion. In the first part of this thesis fatigue failure will be examined, then fluctuating stresses will be characterized along with shear stress. Characteristics of the materials used will be specified in the second part. Lastly, the most appropriate criteria will be determined.
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Rheological properties of building binders in their fresh state
Hegrová, Michaela ; Rovnaník, Pavel (referee) ; Vyšvařil, Martin (advisor)
This thesis is devoted to the rheological properties of building binders. The theoretical part focuses on individual types of building binders, their rheological properties and basic parameters determinated during the rheological characterization of building binders. The practical part deals with the resultes obtained from the meansurements on a rotational rheometr using the geometry type of plate to plate. These results are subsequently evaluated.
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Hydrodynamic dampers on the principle of magnetic fluid
Přikryl, Matěj ; Fialová, Simona (referee) ; Pochylý, František (advisor)
This diploma thesis covers the topic of magnetic fluids and their utilisation in hydrodynamic dampers. The first part of the work consists of research on the current state of technology in hydraulic dampers with the focus on dampers using magnetorhelogical fluid. This chapter is followed by research on magnetic fluids with regard to their physical properties and mathematical description, which is used for CFD simulation of flow. The second part deals with the computational simulation of the flow of MR liquid in real MR damper in order to determine the damping characteristic and it's comparison with the experimental data.
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Computational analysis of leveling of square cross section rods
Šebek, František ; Návrat, Tomáš (referee) ; Petruška, Jindřich (advisor)
Current requirements in mechanical engineering require more accurate operations and more efficient technologies. The aim of this thesis is the analysis of the leveling of square rods. The main problem is the setting of the leveling machine for the specified material and geometric data so that the initially curved material, which passes through alternatively positioned offset rollers, is leveled as much as possible. The main factor in the leveling process is the plastification of the material used for the redistribution of the residual stress. Based on existing theo-retical knowledge in this field, programs are set up to simulate the passing of the rod through the leveling machine. Further, modifications leading to the improvement of the whole process are presented. Finally, there is a verification of the results which is made independently of the submitted solution and processed by the finite element method.
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Influence of cellulose ethers on rheological properties of lime
Hegrová, Michaela ; Rovnaník, Pavel (referee) ; Vyšvařil, Martin (advisor)
The subject of this diploma thesis is a study of the influence of cellulose ethers on the rheological properties of lime. The theoretical part focuses on rheological parameters, techniques and test equipment used in rheology measurements. Various types of cellulose ethers and their influence on the rheological properties of fresh mortars are described. The practical part deals with the study of the influence of different types and quantities of cellulose ethers on the properties of fresh lime pastes and mortars. The results were obtained from measurements on a rotational rheometer with a special geometry for building materials. Measuring methods used were flow and oscillatory tests. Yield stress, viscosity and flow index were determined by the flow measurement. The stability and stiffness of fresh materials were determined during the oscillation measurements. The measured results are then evaluated and compared.
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