|
|
Monitoring of Electrode Changes of Negative Electrode for Lead-Acid Batteries by Operando Confocal Microscopy
Hálová, Hana ; Vanýsek, Petr (referee) ; Chladil, Ladislav (advisor)
The thesis is focused on the laser microscopy observation of the negative electrode for lead-acid batteries during their cycling. The surface changes are evaluated during both deep cycling and PSoC (Partial State of Charge) cycling. The mode leads to gradual degradation of the negative electrode – mostly because of irreversible sulfation. The speed of the sulfation can be influnced by additives of the negative active mass added already during production process. The active mass was firstly examined by electron microscope and X-ray diffractometer. The crystal growth during cycling was observed using confocal microscope Olympus Lext OLS4100.
|
|
|
Optimizing of Polymer Surface Treatment for Microscopic Examination
Horská, Pavlína ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
Supramolecular structure of eight commercial types of iPP, its blends with poly(L-lactide) (PP-PLLA) and copolymers with ethylene-propylene rubber (PP-EPR) together with four types of polyethylene (LDPE, HDPE) was uncovered and observed in this work. The spherulitic structure of iPP and PE homopolymers and PP copolymers was uncovered by etching of six different solutions of mineral acids with KMnO4 and by dissolution in four selected solvents. The latter was found to be ineffective. The structure of PP-PLLA blends was uncovered only after recrystallization (the change of structure by annealing and cooling rate). The uncovered crystalline structure was observed directly by confocal laser scanning microscope (CLSM) and SEM. Crystallinity together with a size distribution of crystallites was determined by DSC. It was proved that spherulitic supramolecular structure was easy to uncover by chemical etching only for molded samples and for fracture surfaces of injected samples. The efficiency of etchants varied but, generally, the samples with high degree of crystallinity were etched earlier. The etchants containing nitric acid and high content of sulphuric acid uncovered fine details of shperulites with respect to mixtures containing orthophosporic acid. It was also observed that not only the etchant (especially with nitric acid) itself but also its vapors were effective. The structure was revealed later but the appearance was plastic (3D) and the structure was very fine. The supramolecular structure of PP-PLLA blends differed with amount of each component. The ethylene-rubber phase came forth with increasing time of etching while PP spherulites disappeared in PP-EPR samples. CLSM was shown to be very good tool for observing supramolecular structure of studied samples with respect to SEM, which was proved to be entirely unsuitable for polyolefines. DSC is recommended to be performe before uncovering supramolecular structure for basic information about proportion of amorphous/crystalline phase and size of crystallites.
|
|
|
Monitoring of Electrode Changes of Negative Electrode for Lead-Acid Batteries by Operando Confocal Microscopy
Hálová, Hana ; Vanýsek, Petr (referee) ; Chladil, Ladislav (advisor)
The thesis is focused on the laser microscopy observation of the negative electrode for lead-acid batteries during their cycling. The surface changes are evaluated during both deep cycling and PSoC (Partial State of Charge) cycling. The mode leads to gradual degradation of the negative electrode – mostly because of irreversible sulfation. The speed of the sulfation can be influnced by additives of the negative active mass added already during production process. The active mass was firstly examined by electron microscope and X-ray diffractometer. The crystal growth during cycling was observed using confocal microscope Olympus Lext OLS4100.
|
|
|
Optimizing of Polymer Surface Treatment for Microscopic Examination
Horská, Pavlína ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
Supramolecular structure of eight commercial types of iPP, its blends with poly(L-lactide) (PP-PLLA) and copolymers with ethylene-propylene rubber (PP-EPR) together with four types of polyethylene (LDPE, HDPE) was uncovered and observed in this work. The spherulitic structure of iPP and PE homopolymers and PP copolymers was uncovered by etching of six different solutions of mineral acids with KMnO4 and by dissolution in four selected solvents. The latter was found to be ineffective. The structure of PP-PLLA blends was uncovered only after recrystallization (the change of structure by annealing and cooling rate). The uncovered crystalline structure was observed directly by confocal laser scanning microscope (CLSM) and SEM. Crystallinity together with a size distribution of crystallites was determined by DSC. It was proved that spherulitic supramolecular structure was easy to uncover by chemical etching only for molded samples and for fracture surfaces of injected samples. The efficiency of etchants varied but, generally, the samples with high degree of crystallinity were etched earlier. The etchants containing nitric acid and high content of sulphuric acid uncovered fine details of shperulites with respect to mixtures containing orthophosporic acid. It was also observed that not only the etchant (especially with nitric acid) itself but also its vapors were effective. The structure was revealed later but the appearance was plastic (3D) and the structure was very fine. The supramolecular structure of PP-PLLA blends differed with amount of each component. The ethylene-rubber phase came forth with increasing time of etching while PP spherulites disappeared in PP-EPR samples. CLSM was shown to be very good tool for observing supramolecular structure of studied samples with respect to SEM, which was proved to be entirely unsuitable for polyolefines. DSC is recommended to be performe before uncovering supramolecular structure for basic information about proportion of amorphous/crystalline phase and size of crystallites.
|
guest ::
