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Enhancing of sedimentation stability using bentonit based clays
Michal, Lukáš ; Vimmr, Jan (referee) ; Roupec, Jakub (advisor)
The diploma thesis is focused on the issue of sedimentation stability of magnetorheological fluids, whis represents one of the most important characteristics determining the reliability of these fluids. Higher sedimentation stability can by achieved in several ways. Methods that are further examined in the thesis include particle polymerization and the addition of clay mineral additives. Both achieve positive results by schowing increased sedimentation stability. However, in the case of additives, the effect is much higher. In particular, the CLAYTONE 40 additive achieves a lower particle sedimentation rate while maintaining the same viscosity as the commercial LORD-122ED. The results provide significant knowledge in the field and can bring magnetorheological fluids closer to wider commercial use.
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Preparation and characterization of magnetorheological suspensions with high sedimentation stability
Oharek, Lukáš ; Krouská, Jitka (referee) ; Smilek, Jiří (advisor)
The introduced diploma thesis focuses on the preparation of magnetorheological suspensions with high sedimentation stability. The theoretical part generally describes these suspensions and their properties, it also focuses on the possibilities of improving sedimentation stability, for example by modifying the surface of the particles or adding additives. A research based on the topic of preparation of sedimentation stable magnetorheological suspensions was also carried out. The experimental part focuses on two types of magnetorheological suspensions. The first type of suspension consisted of a water-in-oil emulsion and carbonyl iron particles that were modified by chemisorption of the surfactant Tween 80. Another type of suspension contained thixotropic organoclay along with untreated iron particles. In both types of magnetorheological suspensions, the process of their preparation was optimized, together with the composition of carrier fluids for the preparation of the most sedimentation-stable magnetorheological suspension. The measurement of sedimentation stability by a dispersion analyser confirmed the positive effect of particle modification and the addition of thixotropic agent on the sedimentation stability of suspensions.
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Study on stability of bidisperse MR fluid and its magnetorheological effect
Dvořáček, Ondřej ; Mazůrek, Ivan (referee) ; Roupec, Jakub (advisor)
The diploma thesis deals with the study of the behaviour of bidisperse MR fluids. The introduction gives brief research and analysis of previously published studies. In the main part of this thesis, the sedimentation properties of monodispersions and bidispersions are investigated influencing on the primary and secondary particles size, the ratio between the fractions, the total concentration of the particles dispersed in the MR fluid and the carrier fluid viscosity. The initialization sedimentation rate is used to assess sediment stability. Subsequently, MR samples are tested on a slit-flow rheometer, and flow curves are measured at different temperatures and in the presence of various magnetic fields intensities. The MR effect is evaluated by the yield stress. The study contains results describing the behaviour of investigated MR fluid samples.
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Enhancing of sedimentation stability using bentonit based clays
Michal, Lukáš ; Vimmr, Jan (referee) ; Roupec, Jakub (advisor)
The diploma thesis is focused on the issue of sedimentation stability of magnetorheological fluids, whis represents one of the most important characteristics determining the reliability of these fluids. Higher sedimentation stability can by achieved in several ways. Methods that are further examined in the thesis include particle polymerization and the addition of clay mineral additives. Both achieve positive results by schowing increased sedimentation stability. However, in the case of additives, the effect is much higher. In particular, the CLAYTONE 40 additive achieves a lower particle sedimentation rate while maintaining the same viscosity as the commercial LORD-122ED. The results provide significant knowledge in the field and can bring magnetorheological fluids closer to wider commercial use.
|
|
|
Preparation and characterization of magnetorheological suspensions with high sedimentation stability
Oharek, Lukáš ; Krouská, Jitka (referee) ; Smilek, Jiří (advisor)
The introduced diploma thesis focuses on the preparation of magnetorheological suspensions with high sedimentation stability. The theoretical part generally describes these suspensions and their properties, it also focuses on the possibilities of improving sedimentation stability, for example by modifying the surface of the particles or adding additives. A research based on the topic of preparation of sedimentation stable magnetorheological suspensions was also carried out. The experimental part focuses on two types of magnetorheological suspensions. The first type of suspension consisted of a water-in-oil emulsion and carbonyl iron particles that were modified by chemisorption of the surfactant Tween 80. Another type of suspension contained thixotropic organoclay along with untreated iron particles. In both types of magnetorheological suspensions, the process of their preparation was optimized, together with the composition of carrier fluids for the preparation of the most sedimentation-stable magnetorheological suspension. The measurement of sedimentation stability by a dispersion analyser confirmed the positive effect of particle modification and the addition of thixotropic agent on the sedimentation stability of suspensions.
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Study on stability of bidisperse MR fluid and its magnetorheological effect
Dvořáček, Ondřej ; Mazůrek, Ivan (referee) ; Roupec, Jakub (advisor)
The diploma thesis deals with the study of the behaviour of bidisperse MR fluids. The introduction gives brief research and analysis of previously published studies. In the main part of this thesis, the sedimentation properties of monodispersions and bidispersions are investigated influencing on the primary and secondary particles size, the ratio between the fractions, the total concentration of the particles dispersed in the MR fluid and the carrier fluid viscosity. The initialization sedimentation rate is used to assess sediment stability. Subsequently, MR samples are tested on a slit-flow rheometer, and flow curves are measured at different temperatures and in the presence of various magnetic fields intensities. The MR effect is evaluated by the yield stress. The study contains results describing the behaviour of investigated MR fluid samples.
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