Isothermal kinetic analysis

References to a number of other kinetic studies of the decomposition of Ni(HC02)2 have been given [375]. Erofe evet al. [1026] observed that doping altered the rate of reaction of this solid and, from conductivity data, concluded that the initial step involves electron transfer (HCOO- - HCOO +e-). Fox et al. [118], using particles of homogeneous size, showed that both the reaction rate and the shape of a time curves were sensitive to the mean particle diameter. However, since the reported measurements refer to reactions at different temperatures, it is at least possible that some part of the effects described could be temperature effects. Decomposition of nickel formate in oxygen [60] yielded NiO and C02 only the shapes of the a—time curves were comparable in some respects with those for reaction in vacuum and E = 160 15 kJ mole-1. Criado et al. [1031] used the Prout—Tompkins equation [eqn. (9)] in a non-isothermal kinetic analysis of nickel formate decomposition and obtained E = 100 4 kJ mole-1. 

Major problems of distinguishability in isothermal kinetic analysis [4]... 

By analogy with the use of plots of a against reduced time in isothermal kinetic analysis to determine the appropriate conversion function, Meindl et al. [50] have... 

Several models have been proposed to describe the curing of thermoset resins [11-13]. The phenomenological model developed by Kamal [14] is mostly used for isothermal kinetic analysis. The general equation for an n order reaction [15, 16] can be written as ... 

It is clearly seen that imder conditions of polymer ignition and initial surface combustion, the mass loss for PP-MAPP-Cloisite 20A and its rate are noticeably lower then adequate values for the neat PP. An improvement in flame resistance of PP-MAPP-Cloisite 20A over the neat PP happens as a result of the char formation providing a transient protective barrier. In the present study this phenomena was interpreted in terms of isothermal kinetic analysis. 

Belyaeva, S. S. Arkhangelsky, L Makarenkob, V. Non-isothermal kinetic analysis of oxidative stabilization processes in PAN fibers. Thermochimica Acta 2010, 507-508, 9-14. 

Due to length limitation of this chapter, many theoretical approaches on the phenomenological aspects of polymer crystallization have to be skipped. The isothermal and non-isothermal kinetic analysis of overall crystallization appears as technically important in the data treatment of DSC measurements. Some theoretical considerations on the metastable aspects of crystal morphologies and their evolution under various circumstances appear as practically important and case sensitive (see Chap. 1). In this sense, a combination of this chapter with other contributions of this book will provide reader a broad cutting-edge knowledge about our basic understanding of polymer crystallization. 

The second-order decomposition of poly(vinyl methyl ether) (PVME) in nitrogen described in Section 3.4.4 is a good example of isothermal kinetic analysis. Isothermal TGA runs were conducted at four temperatures with 10°C steps. As shown in Fig. 3.14, these data gave a good lit to second-order kinetics where g(a) = [(1/1 - a) -1] [c Eq. (3.12) with n = 2]. Note that it took 100 min to reach 80% conversion at the highest temperature of 372 °C and 350 min to reach 70% conversion at the lowest temperature of 342 °C. 

Kinetic studies have traditionally been extremely useful in characterizing several physical and chemical phenomena in organic, inorganic and metallic systems. It provides valuable qualitative, quantitative and kinetic information on phase transformations, solid state precipitation, crystallization, oxidation and decomposition. Unfortunately, no single reference comprehensively presents non-isothermal kinetic analysis method for the study of complex processes, determining the actual mechanism and kinetic parameters. This book provides a new method for non-isothermal kinetics and its application in heterogeneous solid state processes. In the backdrop of limitations in existing methods, this book presents a brief review of the widely used isothermal and non-isothermal kinetic analysis methods. 

It is evident that a non-isothermal kinetic analysis, even in the case of a simple reaction, is very labor intensive and especially prone to errors. It stands to reason that the analysis of a system of reactions is usually much more complex. A kinetic analysis on the basis of mathematical-analytical relations is usually impossible. A kinetic analysis is only practicable by an interactive procedure between numeric calculations and experimental results on the basis of common optimization methods... 

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