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Abstract  

A variety of isoconversional and model fitting approaches, all of which use multiple heating schedules, are used to analyze selected data from the ICTAC kinetics and lifetime projects as well as additional simulated data sets created for this work. The objective is to compare the accuracy and suitability of various approaches for various types of chemical reactions. The various simulated data sets show that model fitting and isoconversional methods have comparable reliability for extrapolation outside the range of calibration. First, there is as much variability in prediction for various isoconversional methods as there is between isoconversional methods as a group and different plausible explicit models. Of the three isoconversional models investigated, the Friedman method is usually the most accurate. This is particularly true for energetic materials that have a drop in apparent activation energy in the latter stages of reaction, which leads to a delayed onset of rapid autocatalysis at lower temperatures. It is difficult to determine a priori whether isoconversional or model fitting approaches will give more accurate predictions. The greatest reliability is attained by using both the isoconversional and model fitting approaches on a combination of isothermal and constant heating rate data.

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Abstract  

Temperature programmed combustions (TPC) of Yang-Quan anthracite, Liao-Cheng lean coal and Li-Yan bituminous coal in oxy-fuel atmosphere were conducted in a thermogravimetric analyzer and characteristic parameters were deduced from the TG-DTG curves. The results showed that combustion got harder to progress as the coalification degree increasing. Within range of 40%, effect of heightening O2 concentration favored the combustion process, but beyond this zone, the effect leveled off. The model-fitting mathematical approach was used to evaluated the kinetic triplet (f (α), E, A) through Coats–Redfern method. The calculation showed that D 3-Jander was the proper reaction model and the evaluations of E and A validated the experimental results.

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Abstract  

Thermal decomposition of cellulose has been widely studied for the past several years. It has been reported that the source of cellulose and its composition greatly affect its pyrolysis. One of the most widely used analytical tools for the study of cellulose pyrolysis is thermogravimetric (TG) analysis. Several model-fitting methods have been employed to study cellulose pyrolysis kinetics. An alternative to the model-fitting approach is the so-called model-free method developed by Vyazovkin. This isoconversional technique calculates the activation energy as a function of the degree of the conversion. In this article, the pyrolysis of cellulose in cotton fibers compared to microcrystalline cellulose (Avicel, PH 105) was investigated. TG curves were acquired as a function of the heating rates (4, 5, 8, 10, and 16 °C min−1) and the model-free method was used to analyze the data. Activation energies of cotton fibers and Avicel were obtained, and compared to the data reported in the literature. In addition, models for isothermal decomposition were calculated and compared with experimental data at the same temperature.

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1991 Model-free and model-fitting approaches to kinetic analysis of isothermal and nonisothermal data . J Polym Sci Polym Phys 29 : 601 – 608 10.1002/polb.1991.090290509 . 16. Vyazovkin

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. 27. Burnham , AK , Dinh , LN 2007 A comparison of iso-conversional and model-fitting approaches to kinetic parameter estimation and application predictions . J Therm Anal Calorim 89 : 479 – 490 10.1007/s10973

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Thermal decomposition of hydromagnesite

Effect of morphology on the kinetic parameters

Journal of Thermal Analysis and Calorimetry
Authors: D. Bhattacharjya, T. Selvamani, and Indrajit Mukhopadhyay

such as the Friedman isoconversion method, Flynn–Wall Method, Kissinger Method are far superior to that obtained by other model fitting approach such as the differential method [ 16 , 17 , 24 ]. Thermal decomposition of hydromagnesite has also been

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Journal of Thermal Analysis and Calorimetry
Authors: Dragica M. Minić, Maja T. Šumar-Ristović, Đenana U. Miodragović, Katarina K. Anđelković, and Dejan Poleti

can be applied when the form of the function p ( x ) is known. When studying kinetics of solid-state reactions two different approaches: “model-fitting approach” and “model-free approach” are in use. The model-fitting approach attempts

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Journal of Thermal Analysis and Calorimetry
Authors: Edjane F. B. Silva, Marcílio P. Ribeiro, Ana C. F. Coriolano, Ana C. R. Melo, Anne G. D. Santos, Valter J. Fernandes Jr., and Antonio S. Araujo

. Vyazovkin , S , Wight , CA . Model-free and model-fitting approaches to kinetic analysis of isothermal and nonisothermal data . Thermochim Acta . 1999 ; 340 : 53 – 68 . 10.1016/S0040-6031(99)00253-1 . 14

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Journal of Thermal Analysis and Calorimetry
Authors: F. M. Aquino, D. M. A. Melo, R. C. Santiago, M. A. F. Melo, A. E. Martinelli, J. C. O. Freitas, and L. C. B. Araújo

. Vyazovkin , S , Wight , CA 1999 Model-free and model-fitting approaches to kinetic analysis of isothermal and nonisothermal data . Thermochim Acta 340–341 : 53 – 68 10.1016/S0040-6031(99)00253-1 . 10

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state reactions [ 10 – 12 ]. Thermogravimetry (TG)—isothermal or nonisothermal - has been liberally used to obtain thermal stability parameters of solids [ 13 – 19 ]. It has been reported [ 17 ] that the popular model fitting approach gives

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