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Národní úložiště šedé literatury Nalezeno 2 záznamů.  Hledání trvalo 0.00 vteřin. 
The antioxidant effect of humic acids
 Bakajová, Barbora ; Šimon, Peter (oponent) ; Kučerík, Jiří (vedoucí práce)
The main aim of the thesis was to study influence of humic acids and its salts on the thermo-oxidative stability and degradability of polyvinyl alcohol (PVA). For this purpose, thermogravimetry was employed. It has been demonstrated that small concentrations of humic acids caused an increase in stability of investigated PVA. In contrast, high concentrations showed only a slight stabilizing effect, in some cases the presence of humic acids lead even to the PVA destabilization. In the second part, the durability of polymer material was adjusted by the g-irradiation pretreatment. Obtained results indicated that presence of ammonium and sodium salts of humic acids caused a significant stabilization of the polymer material in comparison with the pure PVA and showed the stabilizing effect even after a long term g-irradiation exposition. The last task was to evaluate the ageing effect on the PVA/humic blends. It has been showed that no additional chemical reactions occurred in PVA/humic acids blends and thus the prepared material showed the constant physical properties during the several-months experiments.
Úplný záznam
The antioxidant effect of humic acids
 Bakajová, Barbora ; Šimon, Peter (oponent) ; Kučerík, Jiří (vedoucí práce)
The main aim of the thesis was to study influence of humic acids and its salts on the thermo-oxidative stability and degradability of polyvinyl alcohol (PVA). For this purpose, thermogravimetry was employed. It has been demonstrated that small concentrations of humic acids caused an increase in stability of investigated PVA. In contrast, high concentrations showed only a slight stabilizing effect, in some cases the presence of humic acids lead even to the PVA destabilization. In the second part, the durability of polymer material was adjusted by the g-irradiation pretreatment. Obtained results indicated that presence of ammonium and sodium salts of humic acids caused a significant stabilization of the polymer material in comparison with the pure PVA and showed the stabilizing effect even after a long term g-irradiation exposition. The last task was to evaluate the ageing effect on the PVA/humic blends. It has been showed that no additional chemical reactions occurred in PVA/humic acids blends and thus the prepared material showed the constant physical properties during the several-months experiments.
Úplný záznam

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