Thermal and viscosity characterization of two asphalt emulsions

Journal of Thermal Analysis and Calorimetry - Asphalt emulsion is a versatile product that can be used for different waterproofing applications in civil construction and highway constructions....     

Thermal Behavior of Sr(II) and Ba(II)‐Diclofenac Complexes in Solid State: Study of the Dehydration and Thermal Decomposition

Solid state compounds of general formula Sr(Diclof)₂·5.7H₂O and Ba(Diclof)₂·4.8H₂O were obtained. Thermogravimetry (TG), differential scanning calorimetry (DSC), X‐ray diffraction powder patterns and microscopy analysis were used to characterize these compounds. Details concerning the dehydration and thermal decomposition as well as data of kinetic parameters have been described here. The kinetic behaviors of these stages were evaluated from several heating rates with samples masses of 2 and 5 mg in open crucibles under a nitrogen atmosphere. The results of the present study improve the knowledge on these compounds including their dehydration and thermal stability. The obtained data depend on the mass of the sample which results in two kinetic behavior patterns.     

Study of the thermal behavior of Al(III) and In(III)-diclofenac complexes in solid state

The Al and In-diclofenac compounds were prepared. Thermogravimetry (TG) and X-ray diffraction powder patterns were used to characterize these compounds. Details concerning the dehydration and thermal decomposition as well as data of kinetic parameters have been described here. The kinetic studies of these stages were evaluated from several heating rates with mass sample of 2 and 5 mg in open crucibles under nitrogen atmosphere. The results of the present study improve the knowledge on these compounds including their dehydration and thermal stability. The obtained data leads to a dependence on the sample mass, which results in two kinetic behavior patterns.     

Thermal behavior of residues (sludge) originating from the sugarcane industry

The Brazilian sugarcane industry shows a great amount of generated sludge which should be utilized adequately. Two sludge samples, aerobic and anaerobic, were collected. Both were evaluated by thermogravimetry and differential thermal analysis (DTA) as well as X-ray power diffraction. These compounds show variations of mass between 30 and 140 °C due to the dehydration stage. The DTA curves show that the compounds have an exothermic reaction between 450 and 550 °C, which indicates that this can be used as an energy source. Details concerning the kinetic parameters of the dehydration and thermal decomposition have also been described here. The kinetic study of these stages was evaluated in open crucibles under nitrogen atmosphere. The obtained data were evaluated with the isoconversional kinetic method. The results show that different activation energies were obtained for thermal decomposition.     

Calorimetric and SEM studies of PHB–PET polymeric blends

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.     

Preparation of the Ca–diclofenac complex in solid state

Two ONNO type naphtaldehyde derivative Schiff base compounds were reduced and two symmetric phenol-amine ligands containing naphthalene groups were obtained; bis-N,N′[(2-hydroxy-1-naphtyl) methyl]-1,3-propanediamine (NAFL^H) and bis-N,N′[(2-hydroxy-1-naphtyl) methyl]-2,2′-dimetyhyl-1,3-propanediamine (NAFLDM^H). Homotrinuclear Ni(II) complexes of these ligands were prepared. The solid-state molecular structures of representative nickel complex of NAFLDM^H were determined using single crystal X-ray diffraction analysis. The terminal Ni(II) ions were found to be situated in between the donor atoms of the organic ligand. The central Ni(II) ion was observed to be bonded via two different μ-bridges. The phenolic oxygens and carboxylate ion were seen to form two different μ-bridges. TG analysis proved that the compounds have different thermal characteristics than those cited in literature. The complexes showed extreme exothermic degradation reactions in inert atmosphere. The complexes are ruptured with a two stepped exothermic reaction which appears huge heat over 300 °C. The heat appeared in O₂ atmosphere is observed to be higher than the heat appeared in inert atmosphere. Revealed heat is observed to be higher than the conventional explosive materials.     

Thermal studies on protein isolates of white lupin seeds (<Emphasis Type="Italic">Lupinus albus</Emphasis>)

This study used TG, DSC, and SDS-PAGE techniques to study protein isolates (PIs) in the powder form obtained from lupin seeds flour Lupinus albus. Different methods of preparing PIs were tested, resulting in final products that were different only in relation to the yield and protein content. The results of the protein analysis by SDS-PAGE showed that the same protein fractions were present in the lupin seeds and in the obtained PIs. This result shows that the process of extraction was not damaging to the composition of the original protein. On the other hand, the results of the thermal analysis (DSC and TG–DTG curves) obtained for the different PIs, led to the detection of changes in the protein conformation through the ΔH values, which in general decreased with increasing values of pH and ionic strength in the experimental conditions of extraction.     

Preparation and thermal study of Mg-diclofenac compound in solid state

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.     

Kinetic study of crystallization of PHB in presence of hydroxy acids

Poly(3-hydroxybutyrate), PHB, has been structurally modified through reaction with hydroxy acids (HA) such as tartaric acid (TA) and malic acid (MA). The crystallization kinetic of the samples was evaluated by isoconversional method through nonlinear fitting to obtain the estimation for activation energy (E _a ) and pre-exponential (A) values. The thermal behavior of the crystallization temperature, 44.8 and 58.9 °C at 5 °C/min, and results obtained to the average activation energy, 73 ± 9 kJ mol⁻¹ and 63 ± 1 kJ mol⁻¹, to PHB/MA and PHB, respectively, are suggesting that malic acid may be deriving plasticizer units from its own PHB chain. PHB/TA show increase in the medium value of E _a, 119 ± 2 kJ mol⁻¹ and T _c = 48.2 °C (at 5 °C/min), indicating that tartaric acid is probably interacts in different way to the of PHB chain (E _a=73 ± 9 kJ mol⁻¹, T _c = 44.8 °C at 5 °C/min).