Authors:A. Souza, M. Tavares, D. Melo, M. Conceição, J. Espinola, and C. Airoldi
The thermal decomposition reactions of crystalline chelates of general formula Ln(thd)3 (Ln=La,Pr, Nd, Sm and Gd; thd=2,2,6,6-tetramethyl-3,5-heptanedione) have been studied by isothermal thermogravimetry. Several models were proposed initially
to calculate the kinetic parameters by isothermal method, thus the time reduced method was used to define the best kinetic
models. The Avrami–Erofeev (Am=2, 3 and 4) and R1 and R2 models presented good agreement with experimental data, as well as, linear correlation coefficient
(r) and standard deviation (s).
Authors:A. Souza, M. Oliveira, I. Santos, M. Conceição, L. Nunes, and J. Machado
The kinetics of thermal decomposition of solid In(S2CNR2)3 complexes, (R=CH3, C2H5, n-C3H7,i-C3H7, n-C4H9 and i-C4H9), has been studied using isothermal and non-isothermal thermogravimetry. Superimposed TG/DTG/DSC curves show that thermal
decomposition reactions occur in the liquid phase, except for the In(S2CNMe2)3 and In(S2CNPri2)3 compounds.
Authors:S. Silva, M. Conceiçăo, A. Souza, S. Prasad, M. Silva, V. Fernandes, A. Araújo, and F. Sinfrônio
The powder and the bran of algaroba pods, submitted to drying temperatures of 55, 65, 75, 85, 95 and 105C, were studied by
conventional and thermogravimetric methods. The dynamic thermogravimetric curves of the samples indicated the following thermal
stability order: 105>55>65>95>85>75C. The powder and the bran of algaroba pods, dried at 55C, presented protein content
higher and isothermal thermogravimetric profiles comparable. The calorimetric curves of samples, dried at 55C, indicated
the gelatinization of starch.
Authors:M. Bernardi, S. Crispim, A. Maciel, A. Souza, M. Conceiçăo, E. Leite, and E. Longo
The synthesis and the characterization of Al2O3-based nanocrystalline inorganic pigments are reported. The pigments were synthesized by the polymeric precursor (Pechini
method) using Cr2O3 as chromophore. XRD results only evidenced the corundum phase. The average particle size was about 34 nm. The samples were
also characterized by differential scanning calorimetry (DSC) and thermogravimetry (TG), and CIE-L*a*b* calorimetry. The pigments
obtained in this work presented different colors, ranging from green to rose.
Authors:H. Ouriques, M. Trindade, M. Conceiçăo, S Prasad, P. Filho, and A. Souza
The thermogravimetric curves of di-n-propylammonium, di-iso-propylammonium, di-n-butylammonium and di-iso-butylammonium chlorides showed similar profiles, characterized by mass loss in only one stage, corresponding to decomposition
of compounds. The following thermal stability order was obtained: [Bu2nNH2]Cl>[Pr2nNH2]Cl>[Pr2iNH2]Cl>[Bu2iNH2]Cl. The values of activation energy for non-isothermal data obtained by Ozawa and Coats-Redfern integral methods were in
agreement and stability order obtained by thermogravimetry were reproduced in both methods. The decomposition reactions of
[Pr2nNH2]Cl, [Pr2iNH2]Cl and [Bu2iNH2]Cl were better described by A3 model and [Bu2nNH2]Cl by A2 model.
Authors:J. Amorim, S. Eliziário, D. Gouveia, A. Simőes, J. Santos, M. Conceiçăo, A. Souza, and M. Trindade
The thermogravimetry (TG) is a technique used in the quality control of foods. In this work the moisture and ash contents
in the rice and by-products (bran and husk), the thermal stability and the gelatinization process by conventional, thermogravimetric
and calorimetric methods were studied. The moisture and ash contents obtained by TG and conventional methods did not present
significant differences. The rice presented higher starch content, while the bran presented higher protein content. The thermogravimetric
data presented the following thermal stability order: rice>bran>husk. The calorimetric curves indicated the gelatinization
of the starch. The kinetic parameters were compatible.
Authors:J. Santos, M. Conceiçăo, M. Trindade, A. Araújo, V. Fernandes, and A. Souza
The lanthanidic complexes of general formula Ln(C11H19O2)3 were synthesized and characterized by elementary analysis, infrared absorption espectroscopy, thermogravimetry (TG) and differential
scanning calorimetry (DSC). The reaction of thermal decomposition of complexes has been studied by non-isothermal and isothermal
TG. The thermal decomposition reaction of complexes began in the solid phase for Tb(thd)3, Tm(thd)3 and Yb(thd)3 and in the liquid phase for Er(thd)3 and Lu(thd)3, as it was observed by TG/DTG/DSC superimposed curves. The kinetic model that best adjusted the experimental isothermal thermogravimetric
data was the R1 model. Through the Ozawa method it was possible to find coherent results in the kinetic parameters and according
to the activation energy the following stability order was obtained: Tb(thd)3>Lu(thd)3>Yb(thd)3>Tm(thd)3>Er(thd)3
Authors:R. Candeia, J. Freitas, M. Souza, Marta Conceição, Iêda Santos, L. Soledade, and A. Souza
The most feasible alternative among fuels derived from biomass seems
to be the biodiesel, having the required characteristics for a total or partial
substitution of diesel oil. Therefore, the aim of this work is to evaluate
the thermal and rheological behavior of the blends of diesel with the methanol
biodiesel obtained from soybean oil, using B5, B15 and B25 blends. All thermogravimetric
curves exhibited one overlapping mass loss step in the 35–280C
temperature range at air atmosphere and one step between 37–265C
in nitrogen. The rheological study showed a Newtonian behavior (n=1) for all blends.