Showing papers in "Thermochimica Acta in 1992"

TL;DR: In this article, a simple method of kinetic analysis of thermal analysis (TA) data is described, which allows one to find the appropriate model characterizing the process studied as well as the calculation of the kinetic parameters.

TL;DR: In this paper, a simple two-body and three-body interactional mixing model is used to derive expressions for the mathematical representation of experimental solute solubilities and activity coefficients in binary solvent mixtures.

TL;DR: It is shown that there are three isoconversion methods in which relations at a given conversion and at the maximum rate of conversion are used for estimating activation energy that can be derived from a common fundamental equation which includes the reduced time.

TL;DR: An advantageous algorithm is proposed for correcting the Doyle approximation for the popular Ozawa-Flynn-Wall analysis to make a model-free evaluation of the activation energy from a series of non-isothermal measurements carried out at different heating rates.

TL;DR: The history of the Kinetics Committee of the International Confederation for Thermal Analysis (ICTA) is reviewed in this article, along with some of the author's opinions on the development of thermal analysis kinetics over the past thirty years.

TL;DR: In this article, the authors derived the mechanism of thermal decomposition of aminotetrazoles based on the content of products and the kinetic consideration, and derived two routes of the splitting of tetrazole ring leading either to elimination nitrogen or hydrogen azide.

TL;DR: In this article, eleven potential retarders, calcium gluconate, glucose, glycolic acid, molasses, sodium borate, sodium citrate, sodium heptonate, sodium hexametaphosphate, Sodium pyrophosphate and sugar-free calcium lignosulfonate and sucrose, were added to Portland cement in dosages ranging from 0.025% to 1.2%.

TL;DR: The thermal behavior of di-, tri-and tetravalent metal soaps (carboxylates) is reviewed in this paper, with reference to both the phase behaviour and thermal decomposition.

TL;DR: In this article, a method of identifying the reaction mechanism in non-isothermal kinetics is presented based on the symmetry, width and height of the DTG curve, which can be used to identify the mathematical expression which describes the reaction.

TL;DR: Differential thermal analysis (DTA) thermogravimetry (TG) and pyrolysis-field ionization mass spectrometry (Py-FIMS) were compared in studies of soil organic matter (SOM) in particle-size fractions in different years of a long-term soil formation experiment with loamy marl as discussed by the authors.

TL;DR: In this article, the thermal analysis of α-amino acids using simultaneous TG-DSC measurements and kinetic calculations by the dynamic TG technique have been carried out, where compounds with similar structures can be grouped by their thermograms which have the same shape, although this does not give enough information on their thermal structural variation.

TL;DR: The decomposition of CaSO4 · 2H2O under the conditions of TA consists of two consecutive reactions, firstly CaSO 4 · 0.5H 2O and then Ca SO4III being formed.

TL;DR: In this article, the applicability of the empirical kinetic model in thermal analysis is discussed and it is shown that for a reliable kinetic analysis of a single experimental curve the value of the true activation energy should be known a priori.

TL;DR: In this article, denaturation temperatures and enthalpies of bovine serum albumin (BSA) and HSA measured by DSC at different pH values and protein concentrations are compared with the literature data on BSA, or SH-blocked BSA.

TL;DR: The theoretical behavior of complex reactions as a function of heating rate is discussed in this paper, where single-step reactions (competitive and multiple reactions) and sequential reactions are compared and it is found that it is easier to identify the sequential nature of the reaction if a low activation energy reaction is followed by a high energy reaction.

TL;DR: In this article, the AM1 quantum-chemical method was used to study carbonaceous aggregates, C20, and revealed a bowl-shaped structure of C5v symmmetry, which was treated as an equimolar mixture of two enantiomers.

TL;DR: Differential thermal analysis (DTA), thermogravimetry (TG), and pyrolysis-field ionisation mass spectrometry (Py-FIMS) were compared in investigations of soil organic matter in particle-size fractions and bulk soil samples of two treatments (untreated and farmyard manure) of a 108 year old long-term agricultural experiment as discussed by the authors.

TL;DR: In this paper, the new possibilities offered by isoconversional methods as applied to the solution of practical kinetic problems are considered, and the problems have been solved by algorithms based on the transformation-degree dependence of the activation energy calculated by the isocversional method.

TL;DR: The proposed software makes it possible to establish the complex character of a process and its type, to evaluate the activation energies of parallel reactions and to predict the kinetics of its proceeding outside the experimental temperature range.

TL;DR: In this paper, an account of non-isothermal kinetics with respect to origin, usefulness, limitations, successes and failures compared with isothermal kinetic as applied to solid state heterogeneous reactions is presented and discussed.

TL;DR: In this article, the thermal decomposition of manganese(II) acetate tetrahydrate was studied using isothermal and dynamic thermogravimetric techniques, and it was shown that the reactions are best described by the phase boundary and random nucleation models.

TL;DR: The tridecameric aluminum polymer [AlO4Al12(OH)24(H2O)12]7+ is prepared by forced hydrolysis of an Al(NO3)3 solution by NaOH up to an OH:Al mol ratio of 2.2.

TL;DR: In this article, the authors reconstructing TG graphs from the predetermined set of Arrhenius parameters and applying different kinetic mechanisms to the calculations, it is apparent that the sharpness of the onset and final temperature is due to kinetic factors-especially the kinetic mechanism.

TL;DR: In this article, the influence of particle size on the kinetic parameters of the thermal decomposition of calcite is investigated and the new constant rate thermal analysis (CRTA) technique which allows considerably better control of the heat and mass transfer phenomena is used.

TL;DR: It is shown that, on the basis of isoconversional methods, the complete kinetic description can be built in the coordinates E, w, T, and it is accepted as an alternative to the traditional approach.

TL;DR: The thermal decomposition of 5-aminotetrazole (5-AT) has been studied by thermogravimetry, thermal volumetric, DSC, DTA and EGA as mentioned in this paper.

TL;DR: In this article, the thermodynamic and kinetic data of the thermal decomposition process of α-amino acids in the solid phase are presented and correlated with the features of the four classes into which these compounds are classified in the liquid phase.

TL;DR: A review of the literature on the thermal decomposition of chemical compounds containing a tetrazole heterocycle is given in this article, where it is shown that there are two radically different pathways of the tetrazoles cycle fragmentation connected with the formation of a molecule of nitrogen or azides.

TL;DR: In this article, the effects of various sugars and polyols, such as ethylene glycol, glycerol, ribose, glucose, fructose, mannose, galactose, sucrose, maltose and raffinose, on the gel-sol transition of kappa-carrageenan gels were studied by differential scanning calorimetry.

TL;DR: In this paper, the authors investigated the form of the transformation-degree dependence of the effective activation energy of parallel independent reactions and found that the shape of these dependences is determined by the ratio of the rates of individual reactions and their partial contribution to the gross transformation degree.