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Journal ArticleDOI

Decomposition reactions of solids (an experiment in reviewing)

01 Sep 1984-Thermochimica Acta (Elsevier)-Vol. 79, pp 323-370
About: This article is published in Thermochimica Acta.The article was published on 1984-09-01. It has received 40 citations till now.
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Journal ArticleDOI
TL;DR: In this paper, the model-free and model-fitting approaches have been applied to data for nonisothermal and isothermal thermal decompositions of HMX and ammonium dinitramide.

1,168 citations

Journal ArticleDOI
TL;DR: In this paper, the authors compare the performance of isothermal and nonisothermal experiments for the decomposition of ammonium dinitramide (ADN) and show that the identical dependencies of activation energy on the extent of conversion are not obtained for isothermal or non-isothermal data.
Abstract: Thermogravimetric data for the decomposition of ammonium dinitramide (ADN) have been obtained under isothermal and nonisothermal conditions in order to determine the efficacy of different methods for analyzing the kinetics of solid-state reactions. A widely used model-fitting method gives excellent fits to the experimental data but yields highly uncertain values of the Arrhenius parameters when applied to nonisothermal data because temperature and extent of conversion are not independent variables. Therefore, comparison of model fitting results from isothermal and nonisothermal experiments is practically meaningless. Conversely, model-free isoconversional methods of kinetic analysis yield similar dependencies of the activation energy on the extent of conversion for isothermal and nonisothermal experiments. Analysis of synthetic data generated for a complex kinetic model suggests that, in the general case, the identical dependencies are unlikely to result from experiments obtained under isothermal and noni...

241 citations

Journal ArticleDOI
TL;DR: In this paper, the role of extended crystallographic structures in controlling the course of the bond rearrangements that occur during the conversion of a solid reactant into solid products is discussed.

212 citations

Journal ArticleDOI
TL;DR: A critical appraisal of the recent literature concerned with the kinetics and the mechanisms of thermal reactions, particularly research using the methods of thermal analysis (TA) is made in this article, concluding that many features of the theories and the practices in customary use are inadequate and/or unsatisfactory.

166 citations

Journal ArticleDOI
TL;DR: The proposed introduction of this term, E (variable), is a retrograde step, unlikely to advance science through the development of theory, and its use is not recommended for reasons that are explained.

136 citations

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Journal ArticleDOI
01 Jan 1964-Nature
TL;DR: In this article, a thermocouple is used to measure the sample temperature in a Stanton HT-D thermobalance, the bead of which is positioned in or near the sample, depending on crucible design.
Abstract: THE use of thermogravimetric data to evaluate kinetic parameters of solid-state reactions involving weight loss (or gain) has been investigated by a number of workers1–4. Freeman and Carroll2 have stated some of the advantages of this method over conventional isothermal studies. To these reasons may be added the advantage of using one single sample for investigation. However, the importance of procedural details, such as crucible geometry, heating rate, pre-history of sample, and particle size, on the parameters has yet to be fully investigated. It is also necessary to ensure accurate temperature measurement, both for precision and also to detect any departure from a linear heating rate due to endo- or exo-thermic reactions. (The effect of these may be largely eliminated by the use of small samples.) In our present work (using a Stanton HT–D thermobalance) the sample temperature is measured directly by means of a thermocouple the bead of which is positioned in or near the sample, depending on crucible design, the wires of which run down a twin-bore rise rod. The connexion between the end of the thermocouple wires on the balance arm and the terminal block is made by 0.001 in. platinum and platinum/rhodium wires5. It has been shown that these wires do not affect the performance of the balance but act merely as a subsidiary damping. From the terminal block compensated cable leads to the cold junction and a potentiometric arrangement for direct measurement of the thermocouple output.

5,770 citations

Journal ArticleDOI
01 Dec 1966-Nature
TL;DR: In this article, the activation energy of a chemical reaction is calculated from the angle between the straight line and the abscissa of the chemical reaction, and the results are then plotted as ln b/Tm2 against 1/tm, where Tm is the peak temperature in ° K, and b is the rate of heating.
Abstract: A NUMBER of articles have been published dealing with the differential thermal analysis (DTA) of chemical reaction kinetics1–5. Only one of these, however, gives a direct method for determining the activation energy (E) of the chemical reaction4. In this method, DTA curves are recorded at several different rates of heating. The results are then plotted as ln b/Tm2 against 1/Tm, where Tm is the peak temperature in ° K (the temperature of point B, Fig. 1), and b is the rate of heating. The magnitude of E is calculated from the angle between this straight line and the abscissa. This procedure has two principal shortcomings: (1) it is necessary to record several DTA curves with various rates of heating; and (2) it is necessary to use a special programming device to control the temperature. This device must be capable of providing linear heating at a number of rates of heating. The latter condition imposes serious technical difficulties, because all the DTA apparatuses at present available are adjusted for only one rate of heating.

443 citations