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Studium fotochemického síťování methakrylovaného PVAl
Králová, Marcela ; Čeppan, Michal (oponent) ; Dzik, Petr (vedoucí práce)
Práce se zabývá studiem radikálové fotoiniciované polymerace makromerů založených na polyvinylalkoholu obsahujícím postranní glycidylmethakrylátové skupiny. Tématem práce je zejména vliv koncentrace iniciátoru, síťujících skupin a případně dalších pomocných látek na rychlost polymerace, studium tepelných vlastností polymerujících makromerů, možnost ovlivnění skelného přechodu pomocí změkčovadel, kompatibilita s radikálovými fotoiniciátory atd. Pozornost je také věnována studiu vlastností připravených 3D polymerních sítí.
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Hydration and structure of humic acids studied by thermal analysis
Grebíková, Lucie ; Šmejkalová, Daniela (oponent) ; Kučerík, Jiří (vedoucí práce)
The aim of this work was to use thermal analysis and namely temperature-modulated differential scanning calorimetry (TMDSC) to reveal the changes in humic acids (HA) structure caused by regular wetting of HA by water and its repeated drying. The total number of rewetting cycles was five because further rewetting did not bring any other observable structural changes. Experiments carried out in this work have shown that water plays a role not only in swelling of the HA matrix and disruption of van der Waals forces but it also plays a role in disrupting of some hydrogen bonds, thus it had greater effect on reduction of the glass transition temperature, Tg. The changes in the glass transition temperatures were only of minor scale, so that water influenced predominantly the close proximity of amorphous domains (responsible for glass transition) than the domains themselves. The next task was to shed light on the role of free lipids in the stability of HA physical structure with respect to the repeated wetting and drying. Water periodically stabilized and destabilized HA structure, in the lipid free HA sample the effect of water was short-term, water required less time to cause changes in the sample, whereas in the HA sample the changes induced by water were continuous. The rewetting induced a decrease in the phase transition temperatures in every following cycle in comparison with the previous one and influenced especially kinetic processes, namely crystallization/crystalline reorganization. Furthermore, the rewetting caused redistribution and washing out of the hydrophilic molecules and thus making the HA structure more hydrophobic with every other cycle.
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Hydration and structure of humic acids studied by thermal analysis
Grebíková, Lucie ; Šmejkalová, Daniela (oponent) ; Kučerík, Jiří (vedoucí práce)
The aim of this work was to use thermal analysis and namely temperature-modulated differential scanning calorimetry (TMDSC) to reveal the changes in humic acids (HA) structure caused by regular wetting of HA by water and its repeated drying. The total number of rewetting cycles was five because further rewetting did not bring any other observable structural changes. Experiments carried out in this work have shown that water plays a role not only in swelling of the HA matrix and disruption of van der Waals forces but it also plays a role in disrupting of some hydrogen bonds, thus it had greater effect on reduction of the glass transition temperature, Tg. The changes in the glass transition temperatures were only of minor scale, so that water influenced predominantly the close proximity of amorphous domains (responsible for glass transition) than the domains themselves. The next task was to shed light on the role of free lipids in the stability of HA physical structure with respect to the repeated wetting and drying. Water periodically stabilized and destabilized HA structure, in the lipid free HA sample the effect of water was short-term, water required less time to cause changes in the sample, whereas in the HA sample the changes induced by water were continuous. The rewetting induced a decrease in the phase transition temperatures in every following cycle in comparison with the previous one and influenced especially kinetic processes, namely crystallization/crystalline reorganization. Furthermore, the rewetting caused redistribution and washing out of the hydrophilic molecules and thus making the HA structure more hydrophobic with every other cycle.
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Studium fotochemického síťování methakrylovaného PVAl
Králová, Marcela ; Čeppan, Michal (oponent) ; Dzik, Petr (vedoucí práce)
Práce se zabývá studiem radikálové fotoiniciované polymerace makromerů založených na polyvinylalkoholu obsahujícím postranní glycidylmethakrylátové skupiny. Tématem práce je zejména vliv koncentrace iniciátoru, síťujících skupin a případně dalších pomocných látek na rychlost polymerace, studium tepelných vlastností polymerujících makromerů, možnost ovlivnění skelného přechodu pomocí změkčovadel, kompatibilita s radikálovými fotoiniciátory atd. Pozornost je také věnována studiu vlastností připravených 3D polymerních sítí.
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