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Journal of Thermal Analysis and Calorimetry
Authors: Adelia Emilia de Almeida, Ana Luiza Ribeiro Souza, Douglas Lopes Cassimiro, Maria Palmira Daflon Gremião, Clóvis Augusto Ribeiro, and Marisa Spirandeli Crespi

activation energy from dynamic data can be obtained from the Flynn–Wall–Ozawa isoconversional method [ 26 – 28 ], with Doyle’s approximation of p ( x ). The p(x) is defined by equation , temperature integral or integral of Arrhenius [ 29 ] which involves

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thermal behavior through the TG-DTA and DSC techniques and to obtain the kinetic parameters for the thermal decomposition reaction. Kinetic parameters—non-linear isoconversional method The kinetic parameters for the thermal

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) KnowItAll search program and Gases&Vapours Database (code GS) and Organics&Polymers Database (code TU, SR) were used. The differential isoconversional method of Friedman [ 17 ] was applied to calculate the kinetic parameters. After baseline

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isoconversional method, namely, Flynn–Wall–Ozawa (F–W–O) method [ 37 , 38 ] that allows for evaluating kinetic parameters without choosing the reaction model was applied. F–W–O is a relatively simple method of determining activation energy directly from mass loss

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10% of H40 at different heating rates. As expected, this figure shows how a decrease in the heating rate displaces the curing curves down to lower temperatures. Applying the Ozawa isoconversional method to the thermal curing of the different

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Abstract  

This study presents an evaluation of the decomposition kinetic of low-grade nickeliferous laterite by thermogravimetric analysis. Kinetic parameters were calculated using the Ozawa and the iso-conversional Friedman methods. Simplified kinetics models like those based on the reaction order were also applied for the simulations. Two-dimensional shrinkage models of the reaction interface mechanism were adopted as describing the thermal transformation process from non-isothermal kinetic analysis. The iso-conversional method (model-free kinetics) reveals that the decomposition of low-grade nickeliferous laterite does not follow a single mechanism because the determined activation energies and pre-exponential factor are not constant during the course of the reaction.

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Abstract  

In this study, the temperature-heating rate diagram of the main crystallization process of two metallic glasses, Fe74Ni3.5Mo3B16Si3.5 and Fe41Ni38Mo3B18, was obtained from one experimental differential scanning calorimetry (DSC) scan and the knowledge of their activation energy as determined by an isoconversional method. A good concordance was observed between the diagram curves obtained by calculation (isoconversional approach) and the experimental data, which verifies the reliability of the method and the validity of the kinetic approach in these alloys.

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Some problems concerning the evaluation of non-isothermal kinetic parameters

Solid-gas decompositions from thermogravimetric data

Journal of Thermal Analysis and Calorimetry
Authors: P. Budrugeac, Alice Luminita Petre, and E. Segal

The validity of isoconversional methods used to evaluate the activation energy is discussed. The authors have shown that the Flynn-Wall-Ozawa and Friedman methods give results that agree with each other only if the activation energy does not change with the degree of conversion. A criterion for the reaction mechanism as expressed by the differential conversion function is suggested too.

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Abstract  

The thermal behaviour of an epoxy resin cured with an amine-POSS was studied using differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. The kinetic of polymerization reaction and the thermal degradation have been analyzed based on an iso-conversional model. The obtained results showed that the activation energies of both processes depend on the degree of conversion.

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Studies on (non) energetic compounds

Part 38. Kinetics of thermolysis of dichloroanilinium bromide salts

Journal of Thermal Analysis and Calorimetry
Authors: G. Singh, P. Srivastava, and J. Srivastava

Abstract  

Five salts of dichloroanilinium bromide (DCABr) were prepared and characterized by elemental and spectral studies. The thermal decomposition of DCABr was studied by using TG-DTG-DTA techniques and the results are discussed here. Kinetic parameters with the help of model fitting and isoconversional methods have been evaluated critically. A mechanism of decomposition has also been suggested.

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