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Solid-state compounds of 2-methoxybenzylidenepyruvate with some bivalent metal ions

Synthesis, characterization and thermal behavior studies

Journal of Thermal Analysis and Calorimetry
Authors: M. Kobelnik, E. Schnitzler, and M. Ionashiro

Abstract  

Solid-state M-2-MeO-BP compounds, where M represents bivalent Mn, Fe, Co, Ni, Cu, Zn and 2-MeO-BP is 2-methoxybenzylidenepyruvate have been synthesized. Simultaneous thermogravimetry-differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy, elemental analysis and complexometry were used to characterize and to study the thermal stability and thermal decomposition of these compounds. The results led to information about the composition, dehydration, crystallinity and thermal decomposition of the isolated compounds.

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Abstract  

Non-isothermal decomposition of iron (III)-diclofenac anhydrous salt was investigated by thermogravimetry (TG) under different conditions in opened and closed α-alumina pans under nitrogen atmosphere. To estimate the activation energy of decomposition, the Capela and Ribeiro isoconversional method was applied. The results show that due to the lid cover different activation energies were obtained. From these curves a tendency can be seen where the plots maintain the same profile for closed lids and almost run parallel to each other. Independently of the different experimental conditions no remarkably different results have been obtained.

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Abstract  

PHB [poly (3-hydroxybutyrate)], post-consumer soft-drink bottles poly (ethylene terephthalate) PET (herein named PET-R) and PHBPET-R (blends of PHB and PET-R in several compositions) samples were evaluated by differential scanning calorimetry (DSC) and scanning electronic microscopy (SEM) in order to verify their thermal properties and porosity according to amounts of PET-R added the blends. The DSC curve showed that the solvents used to solve the polymer mixture cause changes in the thermal behavior of PET-R films and in PHBPET-R blends. SEM studies of the PHBPET-R blends show that with a gradual mass increase of PET-R, there are gradual increases in the porosity of the films.

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Journal of Thermal Analysis and Calorimetry
Authors: Marcelo Kobelnik, Douglas Lopes Cassimiro, Clóvis. A. Ribeiro, Jorge M. V. Capela, Diogines S. Dias, and Marisa S. Crespi

Abstract

The thermal behaviour of Mg-diclofenac compound was evaluated by simultaneous TG-DTA and DSC. The profile of the DSC curves showed that this compound possesses two transition phases: endothermic and exothermic between 170–180 °C and 185–195 °C, respectively. The endothermic reaction is reversible (enantiotropic). Thus, different experimental conditions, i.e. masses sample, open and crimped lids crucible, static and dynamic atmospheres were utilized for DSC analysis for evaluation of this transition phase. In a static atmosphere the enantiotropic reaction was not observed. The obtained data were utilized to obtain the kinetic parameters, which were calculated by the Capela and Ribeiro method. The results show that the activation energy for the transition phase depends on the different experimental conditions.

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Journal of Thermal Analysis and Calorimetry
Authors: Marcelo Kobelnik, Clóvis A. Ribeiro, Diógenes dos Santos Dias, Sonia de Almeida, Marisa Spirandeli Crespi, and Jorge M. V. Capela

Abstract

The Co(II)–diclofenac complex was evaluated by simultaneous thermogravimetry-differential thermal analysis (TG-DTA) and differential scanning calorimetry (DSC). The DTA curve profile shows one exothermic peak because of the transition phase of the compound between 170 and 180 °C, which was confirmed by X-ray powder diffractometry. The transition phase behavior was studied by DSC curves at several heating rates of a sample mass between 1 and 10 mg in nitrogen atmosphere and in a crucible with and without a lid. Thus, the kinetic parameters were evaluated using an isoconversional non-linear fitting proposed by Capela and Ribeiro. The results show that the activation energy and pre-exponential factor for the transition phase is dependant on the different experimental conditions. Nevertheless, these results indicate that the kinetic compensation effect shows a relationship between them.

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