Search Results
Thermal and kinetic analysis of uranium salts
Part 1. Uranium (VI) oxalate hydrates
energy has been determined, it is possible to find the kinetic model which best describes TG curve of the measurement. Thirteen model equations are used to fit kinetic curves. We used better linear correlation coefficient and agreement of activation
The integral Eqs. 3 – 6 are cited to obtain the values of E , A , and the most probable kinetic model function G ( α ) from a single non-isothermal TG curve [ 16 ]. Mac Callum–Tanner equation (4) Satava–Sestak equation (5) Agrawal
Comparative study of HMX and CL-20
Thermal analysis, combustion and interaction with aluminium
results are used to develop the global kinetic models of decomposition for both simple matters and energetic condensed systems (ECSs) on basis of them. According to literature data, an experimentally determined value of the activation energy E a of
suggested. The values of the activation energy, E∗ have been calculated by model-free Kissenger–Akahira–Sunose (KAS) and Flyn–Wall–Ozawa (FWO) methods [ 15 – 32 ]. The 13 model equations have been tested for the best kinetic models giving the highest
, 22 – 29 ] Comparing the kinetic parameters from the Achar and the Li–Tang equations, the probable kinetic model may be selected, which the values of E & and A were calculated with the better linear correlation coefficient and the activation
Steps in a minefield
Some kinetic aspects of thermal analysis
Abstract
This paper is a review of some of the controversial kinetic aspects of thermal analysis, starting from the ‘šesták questions’ posed in 1979 and looking at developments in some areas since that time. Aspects considered include: temperature programmes and variations, models and mechanisms, kinetic parameters, distinguishability and extent of fit of kinetic models, complementary evidence for kinetic models, the Arrhenius equation and the compensation effect. The value of the ideas of non-isothermal kinetics in chemical education is emphasized.
Kinetics of radionuclide interaction with suspended solids in modeling the migration of radionuclides in rivers
III. Variability of kinetic parameters
Abstract
The effect of variable composition of water and suspended solids in a small river on the kinetics of uptake of58Co and137Cs by the solids has been analyzed using two kinetic models describing the uptake by two consecutive or parallel reactions. At first, experimental data on the kinetics were obtained by laboratory batch experiments with 6 samples of unfiltered water taken under different flow conditions. Then, parameters of the kinetic models were determined by computer fitting of the experimental data. After subtracting the effect of the concentration of the solids, the variability of the parameters due to the variable composition was determined. The results proved that despite the variability, the description of the kinetics by the two-step kinetic models is more accurate than that using a one-step kinetic model. Approximately equal accuracy of the description with both two-step kinetic models was ascertained. It is recommended that kinetic and equilibrium parameters of radionuclide uptake by suspended solids should always be determined by experiments with repeatedly sampled unfiltered water.
as cracking reactions in the endothermic region of high temperature oxidation (HTO). Kinetic model approach for the cracking reaction In the present work, catalytic cracking denotes the transition of a complex substance in
], and decomposition of MgFe 2 (C 2 O 4 ) 3 into MgFe 2 O 4 could be simple reaction mechanisms. According to Eq. 3 , mechanism function g (α) and pre-exponential factor log A can be obtained. The results show that the kinetic model, which can
A DSC study was carried out of the isothermal melt crystallization kinetics of poly(L-lactic acid), PLLA, at 110, 115, 120, 125 and 130‡C. The experimental data were evaluated within the framework of the well-known Avrami kinetic model and an extended model involving an additional third kinetic parameter [8]. In order to perform the necessary numerical calculations, a number of functions built into the Mathematica® software system were used. The results showed that the isothermal melt crystallization kinetics of PLLA can be described adequately by both these kinetic models. It should also be stressed that the kinetic model of Urbanovici and Segal offers a better description of the experimental melt crystallization data of PLLA than the classical Avrami model.
