Showing papers in "Thermochimica Acta in 1997"

TL;DR: A review of the history of the temperature dependence of reaction rate in reaction kinetics can be found in this article, where various equations which are in use today for expressing this dependence were delineated by van't Hoff almost one hundred years ago.

TL;DR: In this paper, the authors evaluated the performance of temperature-programmed reduction spectra of α-Fe2O3 and Auα-Fe 2O3 systems and established that gold influences only the first reduction step Fe2O2 → Fe3O4.

TL;DR: In this paper, peak maximum evolution methods and isoconversional methods are compared, and specific characteristics of each method are shown, from a mathematical viewpoint and by using simulated data, and a convenient way of correcting the activation energy of the Ozawa method is proposed.

TL;DR: In this paper, a phase angle between heating rate and heat-flow rate is derived from material intrinsic properties, where heat does not propagate but flows, and the timeconsuming heat transfer into the sample yields an additional phase angle.

TL;DR: In this paper, the thermal decomposition of ZnSO4·7H2O was studied under non-isothermal conditions in air and the kinetics of particular stages were evaluated from the dynamic weight losses data by means of integral method.

TL;DR: The thermal decomposition course MnO2 → MnO was examined in various gas atmospheres (O2, air, N2 and H2) by temperature-programmed studies employing thermogravimetry and differential thermal analysis as discussed by the authors.

TL;DR: In this article, the peculiarities of polymers as objects of calorimetric studies were discussed and the CalorIMetric apparatus used at author's laboratory was characterized, and the main results of the studies of heat capacity, temperatures and enthalpies of physical transitions in polymers, as well as thermodynamic parameters of polymerization reactions were reported.

TL;DR: In more than 50 years since its publication, a paper in the Transactions of the Faraday Society by Prout and Tompkins has been extensively cited in the literature The paper dealt with the kinetics of the thermal decomposition of crystals of potassium permanganate, and suggested a rate equation for use in the kinetic analysis of solid-state reactions as mentioned in this paper.

TL;DR: In this paper, the kinetics of isothermal pyrolysis of lignins occurring in hardwood found in the north of Argentina was studied using thermogravimetric techniques (TG/TGA).

TL;DR: In this paper, a series solution for the constant heating rate Arrhenius integral is proposed for determining the kinetic parameters of a single-step reaction from temperature scanning experiments, without any assumptions about the reaction order or the form of the conversion function.

TL;DR: In this paper, the authors examine the reasons for the concurrent changes of Arrhenius frequency factors and activation energies in solid-state decompositions, and three classes can be distinguished.

TL;DR: In this paper, a novel method, pulse thermal analysis (PTA), is proposed to carry out gas-solid reactions with a controllable reaction progress at the desired temperature, which provides the opportunity of simultaneous monitoring of changes in the composition of the gas and solid phases during the reaction.

TL;DR: In this article, the authors compared heat capacity spectroscopy HCS and differential scanning calorimetry DSC results for eight polymers (especially for polyisobutylene (PIB) and a random copolymer of n -butyl methacrylate with 8% styrene) and glycerol.

TL;DR: In this paper, the authors discuss the application of TG-MS in relation to the various factors affecting thermal stability of polymeric materials, thermoplastics, thermosets and elastomers.

TL;DR: The literature associated with the thermal behavior of mineral sulphides has been selectively and critically reviewed in this paper, where the importance of characterising the starting material, as well as intermediate products, and the effect of experimental variables on the thermal analysis results are presented.

TL;DR: In this article, a quantitative model for the progress of a nucleation and growth controlled reaction during heating at a constant rate is derived for the DSC data on precipitation in Al-Si alloys.

TL;DR: A comparison of the kinetic characteristics of MgCO 3, CaMg(CO 3 ) 2, CaCO 3, SrCO 3 and BaCO 3 decomposition in vacuum available in the literature, with the data calculated for three possible paths of the process has shown the one involving intermediate hydroxide formation to be most probable.

TL;DR: In this article, the quantitative performance of differential scanning calorimeters is reviewed and temperature calibration is discussed in terms of an isothermal correction plus a contribution from thermal lag, this can be derived from individual curves and is valid in both, heating and cooling, and it is emphasised that baselines that are drawn to thermal events, such as melting and transition phenomena, must have thermodynamic significance.

TL;DR: In this paper, the influence of several experimental parameters such as concentration of the analyzed species, temperature, flow rate and properties of the carrier gas, on the sensitivity of the mass spectrometric analysis in a TA-MS system was investigated.

TL;DR: In this paper, the present state of the MTDSC method with regard to chemical reactions and melting is summarised and a more extensive treatment of the glass transition is given. But this paper is based on a modified-temperature differential scanning algorithm.

TL;DR: In this article, the authors discussed the coupling of mass spectrometers, Fourier transform infrared spectroscopy and gas chromatography with thermal analysis methods from a practical point of view.

TL;DR: In this article, temperature-programmed reduction (TPR) and temperatureprogrammed desorption (TPD) studies of Au α- Fe 2 O 3 and α-Fe 2 O3 samples have been carried out.

TL;DR: The application of temperature-modulated calorimetry is reviewed in this article, with a focus on temperature scanning and frequency-dependent heat capacity experiments, in view of measured dynamic specific heat.

TL;DR: In this article, the authors traced the long path to an understanding of heat capacity from isothermal and adiabatic calorimetries to the most recent three methods of isoperibol, scanning, and temperature-modulated calorimetry (TMDSC).

TL;DR: In this article, the activity of various aluminosilicate catalysts in the degradation of high-density polyethylene (HDPE) was investigated and it was shown that amorphous silica-alumina significantly reduced the apparent activation energy as compared with uncatalysed thermal processes.

TL;DR: In this article, the phase transformation from xerogel to amorphous TiO2 and then to anatase and rutile successively was consistent with the peaks in TGA for a weight loss of 25% at 82°C and two extra endothermic peaks in DTA at 382 and 573°C.

TL;DR: In this paper, the authors investigated the working mechanism of oleic acid on isolated human stratum corneum (SC) sheets using two in vitro techniques, differential thermal analysis and freeze-fracture electron microscopy.

TL;DR: In this article, the authors proposed three methods of establishing heat capacity: (1) the traditional method of scanning thermal analysis by finding the heat flow into the sample during a measured temperature increase; (2) the quasi-isothermal method by determining the maximum amplitude of the periodic heat flow in response to a temperature modulation at a constant base temperature; and (3) the pseudo-isodynamic analysis of a temperature-modulated scanning experiment by subtracting the effect due to the underlying (usually constant) heating rate.

TL;DR: In this paper, the thermodynamic data of the complexation reaction between the ligand cucurbituril and different alkylmonoamine and alkyldiamine hydrochlorides have been studied in aqueous formic acid.

TL;DR: In this paper, a normalized mobility factor, which is directly based on the experimental heat capacity evolution, is proposed to quantify the change in the rate of reaction due to mobility restrictions when T g of the reacting system approaches T.