Authors:C. Ribeiro, W. de Souza, Marisa Crespi, J. Gomes Neto, and F. Fertonani
Tungsten carbide, WC, has shown dissimilar thermal behavior when it is heated on changeable heating rate and flow of oxidant
atmosphere. The oxidation of WC to WO3 tends to be in a single and slow kinetic step on slow heating rate and/or low flux of air. Kinetic parameters, on non-isothermal
condition, could be evaluated to the oxidation of WC to heating rate below 15°C min−1 or low flow of air (10 mL min−1). The reaction is governed by nucleation and growth at 5 to 10°C min−1 then the tendency is to be autocatalytic, JMA and SB, respectively.
Recently, Órfão obtained two simple equations for the estimation of the relative error in the activation energy calculated
by the integral methods . In this short communication, the validity of the equations has been evaluated by comparing the
results calculated by the equations with the results calculated by the equation from theoretical derivation without introducing
Authors:Loredana Feher, B. Jurconi, Gabriela Vlase, T. Vlase, and N. Doca
The thermooxidative degradation of three models of oily soils was studied under non-isothermal conditions, at heating rates
of 5, 10, 15 and 20�C min−1. Di-octyl-sebacate, as model for synthetic oil, was adsorbed on silica, alumina and silico-alumina, considered models for
the inorganic micelle of a soil. For a kinetic analysis, the TG data were processed by three methods: Flynn-Wall-Ozawa, Friedman
and NPK (Nomen-Sempere). The results indicate the NPK as the less speculative method that allows a separation of the elementary
steps and at the same time a separation of the temperature, respective conversion dependent part of the reaction rate.
The accuracy of the newly proposed approximation is tested by numerical analyses. Compared with other existed approximations
for the general temperature integral, the new approximation is significantly more accurate than other approximations.
Authors:T. Vlase, C. Pǎcurariu, R. Lazǎu, and I. Lazǎn
The crystallization kinetic of the basalt glass ceramic of the oxide composition, (%): SiO2 − 50.82; Al2O3 − 12.05; Fe2O3 − 9.28; CaO − 15.48; MgO − 11.08; Na2O+K2O − 1.14; TiO2 − 0.15, with addition of 10% TiO2 as nucleating agent has been studied using thermal analysis under non-isothermal conditions.
In this order, the non-isothermal DTA curves were obtained at different heating rates between 4 and 20°C min−1 in the temperature range of 25–1000°C using a Derivatograph-C (MOM, Hungary). The kinetic parameters of the crystallization
process were calculated on the basis of Ozawa-Flynn-Wall, Friedman, Budrugeac-Segal and non-parametric kinetic methods.
Authors:T. Vlase, Gabriela Vlase, Nicoleta Birta, and N. Doca
A comparative kinetic analysis on the thermal decomposition of tartaric acid and potassium tartrate under non-isothermal conditions
was performed. The non-isothermal kinetic parameters were determined by the following four methods: integral isoconversional
method suggested by Flynn-Wall-Ozawa (FWO method); differential isoconversional method suggested by Friedman; Budrugeac-Segal
method and Non-Parametric-Kinetic (NKP) method suggested by Sempere and Nomen and modified by Vlase and Doca. The comparison
of the results obtaining by these methods leads to interesting conclusions. The experimental data were obtained in dynamic
nitrogen atmosphere at heating rates of 5, 7, 10, 12 and 15 K min−1. The less speculative kinetic analysis was possible by the NPK method.
Authors:T. Vlase, Gabriela Vlase, Dorina Modra, and N. Doca
Thermal behavior of four food
dyes, i.e. tartrazine, crysoine, azorubine and amarant was studied under non-isothermal
conditions, in dynamic air atmosphere and at heating rates of 5, 10, 15 and
20C min–1. The TG data were correlated
to the FTIR spectra of each sample, before and after the thermal decomposition.
Kinetic study by processing the TG data was performed. The main conclusion
of this study is that the non-parametric kinetic method allows a separation
of the steps of a complex process and that the values of the activation energy
obtained by this method agree satisfactory with that of Flynn–Wall–Ozawa
and the steady-state approximation are used to present a demonstration of the fact that the evolution of the reaction rates
under non-isothermal conditions depends on the ratio of the activation energies and on the heating rate. At the same time,
it is shown that, under isothermal conditions, the ratio of the activation energies plays no role.
Authors:B. Zhou, S. Jiang, L. Zou, X. Wang, D. Wang, J. Liu, S. Shang, and D. Zhou
A new compound cyclohexyl-t-butyldimethylammonium tetraphenylborate, [C6H11N(CH3)2(C(CH3)3)]BPh4 has been prepared, and its decomposition mechanism was studied by TG. The IR spectra of the products of thermal decomposition were examined at every stage. Kinetic analysis for the first stage of thermal decomposition process was obtained by TG and DTG curves, and kinetic parameters were obtained from the analysis of the TG-DTG curves with integral and differential equations. The most probable kinetic function was suggested by comparison of kinetic parameters.
Authors:M. Badea, R. Olar, E. Cristurean, D. Marinescu, M. Brezeanu, M. Balasoiu, and E. Segal
This paper reports an investigation of the thermal stabilities of the class of coordination compounds containing lanthanide ions Ln(III) (Ln=La, Sm, Eu, Dy, Er), Co(II) ions and oxalate anions C2O
. The thermal decomposition steps were identified, and in some cases the values of the non-isothermal kinetic parameters were determined.