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Isoconversional analysis of solid state transformations
A critical review. Part II. Complex transformations
Introduction The second part of this review is devoted to the analysis of complex transformations. In particular, we will describe the use of the isoconversional methods introduced in the first part of this review (Part I [ 1
Abstract
Two glasses, the first one with the composition of Li2O·2SiO2 and the second one with the addition of CaO, P2O5 and CaF2 in the stoichiometric ratio corresponding to fluoroapatite were prepared and their tendency to crystallize has been studied by non-isothermal DTA analysis. The values of kinetic parameters calculated using the isoconversional integral method have been used to determine the temperature dependencies of both the length of isothermal induction period and the length of overall isothermal crystallization for both glasses. The estimated dependencies indicate that the glass containing CaO, P2O5 and CaF2 has a lower thermal stability.
Isoconversional analysis of solid-state transformations
A critical review. Part III. Isothermal and non isothermal predictions
Introduction Kinetic methods are routinely employed to determine the kinetic parameters of solid-state transformations from thermal analysis experiments. In particular, there are isoconversional methods which are model-free, i
the extent of conversion, was evaluated by the Kissinger–Akahira–Sunose (KAS), Ozawa–Flynn–Wall (OFW), Starink, Tang, and Vyazovkin isoconversional methods. The Avrami exponent “ n ” of the crystallization process was also evaluated using the Ozawa
Kinetics of thermolysis is evaluated from isothermal TG data using model-fitting as well as model-free isoconversional method [ 25 ]. The following equation was found to be hold under isothermal condition: where, α is the extent of conversion, E is
Thermal decomposition kinetics of some aromatic azomonoethers
Part II. Non-isothermal study of three liquid crystals in dynamic air atmosphere
Abstract
Thermal analysis of three azomonoether dyes, exhibiting liquid-crystalline properties, was performed in dynamic air atmosphere. Thermal stability studies and the evaluation of the kinetic parameters of each physical or chemical transformations are essential for a full characterization, before attempting accurate thin films’ depositions of such materials used in non-linear optical applications. New synthesized dyes with general formula:
Kinetics of thermal degradation of polymers
Complementary use of isoconversional and model-fitting methods
Abstract
The thermal degradation of polymers has been studied quite extensively using thermogravimetric measurements. For the kinetic description, most of the times single rate heating data and model-fitting methods have been used. Since the thermal degradation of the polymers is a very complex reaction, the choice of a reliable model or a combination of kinetic models is very important. The advantages or the disadvantages of using a single heating rate or multiple heating rates data for the determination of the kinetic triplet have been investigated. Also, the activation energy has been calculated with the isoconversional and model-fitting methods. The reaction model was determined with the model-fitting method. The limits of all these procedures were investigated with experimental data of the thermal degradation of the poly(ethylene adipate) (PEAd).
fraction, α, that depends on the reaction model, Q α is the activation energy. There are many methods for determining the activation energy from experiments under non-isothermal condition and a linear heating rate. Isoconversional methods, which permit
with acrylic–divinylbenzene matrix, evaluated the kinetic parameters by means of isoconversional methods, and observed that the apparent kinetic parameters are dependent on the cross-linking degree, granulation, exchange capacity, and heating rate
