scholarly journals Thermal Analysis On The Kinetics Of Magnesium-Aluminum Layered Double Hydroxides In Different Heating Rates

2015 ◽  
Vol 60 (2) ◽  
pp. 1357-1359 ◽  
Author(s):  
Y. Hongbo ◽  
C. Meiling ◽  
W. Xu ◽  
G. Hong
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Layered Double Hydroxides ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Exponential Factor ◽  
Thermal Kinetic Parameters ◽  
Double Hydroxides ◽  
Kinetics Of ◽  
Dsc Curves

Abstract The thermal decomposition of magnesium-aluminum layered double hydroxides (LDHs) was investigated by thermogravimetry analysis and differential scanning calorimetry (DSC) methods in argon environment. The influence of heating rates (including 2.5, 5, 10, 15 and 20K/min) on the thermal behavior of LDHs was revealed. By the methods of Kissinger and Flynn-Wall-Ozawa, the thermal kinetic parameters of activation energy and pre-exponential factor for the exothermic processes under non-isothermal conditions were calculated using the analysis of corresponding DSC curves.

scholarly journals Formation of metal oxide-based hydroxysodalite by alkali-activation of kaolinite

Chemija ◽  
2020 ◽  
Vol 31 (3) ◽  
Author(s):  
Ehab AlShamaileh ◽  
Muayad Esaifan ◽  
Qusay Abu-Afifeh
Keyword(s):  
Activation Energy ◽  
Metal Oxide ◽  
Alkali Activation ◽  
Dsc Analysis ◽  
X Ray Diffraction ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Xrd Study ◽  
Dsc Curves

The formation of metal oxide-based hydroxysodalite by alkali-activation of kaolinite is studied using X-ray diffraction (XRD) study and differential scanning calorimetry (DSC) analysis. Different metal oxides (CoO, MgO, FeO and SiO2) were used to form the metal oxide-based hydroxysodalite. The transformation from kaolinite into hydroxysodalite is confirmed by XRD. In the thermodynamic study, the maximum peak temperatures for DSC curves at various heating rates were used to determine the activation energy (Ea) of the hydroxysodalite formation. With magnesium oxide and cobalt oxide, the formation process was found to be exothermic while it was endothermic with iron oxide.

scholarly journals Non-Isothermal Sublimation Kinetics of 2,4,6-Trinitrotoluene (TNT) Nanofilms

Molecules ◽  
2019 ◽  
Vol 24 (6) ◽  
pp. 1163 ◽  
Author(s):  
Walid Hikal ◽  
Brandon Weeks
Keyword(s):  
Activation Energy ◽  
Analytical Techniques ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Absorbance Spectroscopy ◽  
Calculated Activation Energy ◽  
Sublimation Kinetics ◽  
Sublimation Rates ◽  
First Time ◽  
Kinetics Of

Non-isothermal sublimation kinetics of low-volatile materials is more favorable over isothermal data when time is a crucial factor to be considered, especially in the subject of detecting explosives. In this article, we report on the in-situ measurements of the sublimation activation energy for 2,4,6-trinitrotoluene (TNT) continuous nanofilms in air using rising-temperature UV-Vis absorbance spectroscopy at different heating rates. The TNT films were prepared by the spin coating deposition technique. For the first time, the most widely used procedure to determine sublimation rates using thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC) was followed in this work using UV-Vis absorbance spectroscopy. The sublimation kinetics were analyzed using three well-established calculating techniques. The non-isothermal based activation energy values using the Ozawa, Flynn–Wall, and Kissinger models were 105.9 ± 1.4 kJ mol−1, 102.1 ± 2.7 kJ mol−1, and 105.8 ± 1.6 kJ mol−1, respectively. The calculated activation energy agreed well with our previously reported isothermally-measured value for TNT nanofilms using UV-Vis absorbance spectroscopy. The results show that the well-established non-isothermal analytical techniques can be successfully applied at a nanoscale to determine sublimation kinetics using absorbance spectroscopy.

scholarly journals The non-isothermal kinetics of hydroxyapatite formation in kaolin - natural phosphate mixtures

2019 ◽  
Vol 9 (1) ◽  
pp. 1-7
Author(s):  
Fateh Chouia ◽  
Hocine Belhouchet ◽  
Toufik Sahraoui
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Exothermic Peak ◽  
Isothermal Kinetics ◽  
Heating Rates ◽  
Natural Phosphate ◽  
Isothermal Conditions ◽  
Kinetics Of ◽  
Hydroxyapatite Formation

In this work, the activation energy of hydroxyapatite formation in different composites under non-isothermal conditions was determined using differential thermal analysis (DTA). Seven compositions were prepared and studied while varying the percentage of the kaolin from 20 to 80 wt.% at 10% increments. The DTA conducted at heating rates of 10, 20 and 30 K min−1 showed an exothermic peak in all composites in the region 700°C–750°C associated with hydroxyapatite formation. The activation energies measured from non-isothermal treatments for seven compositions (20, 30, 40, 50, 60, 70 and 80 mass% of kaolin) were 194, 178, 178, 209, 162, 146 and 121 kJ mol−1, respectively.   Keywords:energy, kinetics,  kaolin - natural, phosphate mixtures

Crystallization Kinetics in Cu64.5Zr35.5 Binary Metallic Glass

2017 ◽  
Vol 727 ◽  
pp. 233-238 ◽  
Author(s):  
Qian Gao ◽  
Zeng Yun Jian ◽  
Jun Feng Xu ◽  
Man Zhu
Keyword(s):  
Activation Energy ◽  
Grain Growth ◽  
Crystallization Kinetics ◽  
Crystallization Process ◽  
Crystallization Kinetic ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Growth Activation ◽  
Local Activation Energy ◽  
Kinetics Of

The crystallization kinetics of melt-spun Cu64.5Zr35.5 amorphous alloy ribbons was investigated using differential scanning calorimetry (DSC) at different heating rates. Besides, the Kissinger and isoconversional approaches were used to obtain the crystallization kinetic parameters. As shown in the results, the activation energies for glass transition and crystallization process at the onset, peak and end crystallization temperatures were obtained by means of Kissinger equation to be 577.65 ± 34, 539.86 ± 54, 518.25 ± 20 and 224.84 ± 2 kJ/mol, respectively. The nucleation activation energy Enucleation is greater than grain growth activation energy Egrowth, indicating that the nucleation process is harder than grain growth. The local activation energy Eα decreases in the whole crystallization process, which suggests that crystallization process is increasingly easy.

Study on Kinetics of Nano-Ni(OH)2 Powder Ethanol Desorption Process

2014 ◽  
Vol 1015 ◽  
pp. 509-512
Author(s):  
Feng Pan ◽  
Zai Yuan Li ◽  
Chun Ji Li
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Shape Factor ◽  
Peak Shape ◽  
Desorption Process ◽  
Exponential Factor ◽  
Mechanism Function ◽  
Thermal Analysis Kinetics ◽  
Kinetics Of ◽  
Tga Analysis

This paper studies on the thermal analysis kinetics of nanometer powders ethanol desorption process.The DTA-TG-DTG curves obtain by SDT 2960 Simultaneous DSC-TGA analysis apparatus. Under the condition of N2atmosphere operation and rise temperature velocity was 10°C·min-1. The mechanism functionis used to calculate the kinetics factors. Reaction progressionnwas obtained by calculation of the kissinger peak shape factor method. The results showed that the apparent activation energy of nano-Ni(OH)2was 73.210 kJ·mol-1, the pre-exponential factor was 2.349×1012, the reaction progression was obtained as 1.2767, the kinetic equation is

scholarly journals Comparison of the dehydration kinetics of solid state compounds of 2-methoxybenzylidenepyruvate with some divalent metal ions

2010 ◽  
Vol 35 (1) ◽  
pp. 7-18
Author(s):  
M. Kobelnik ◽  
C. A. Ribeiro ◽  
D. S. Dias ◽  
G. A. Bernabé ◽  
M. S. Crespi
Keyword(s):  
Activation Energy ◽  
Solid State ◽  
Nitrogen Atmosphere ◽  
Divalent Metal ◽  
Point Of View ◽  
Conversion Degree ◽  
Divalent Metal Ions ◽  
Heating Rates ◽  
Exponential Factor ◽  
Kinetics Of

Divalent metal complexes of ligand 2-methoxybenzylidenepyruvate with Fe, Co, Ni, Cu and Zn as well as sodium salt were synthesized and investigated in the solid state. TG curves of these compounds were obtained with masses sample of 1 and 5mg under nitrogen atmosphere. Different heating rates were used to characterize and study these compounds from the kinetic point of view. The activation energy and pre-exponential factor were obtained applying the Wall-Flynn-Ozawa method to the TG curves. The obtained data were evaluated and the values of activation energy (Ea / kJ mol-1) was plotted in function of the conversion degree (α). The results show that due to mass sample, different activation energies were obtained. The results are discussed mainly taking into account the linear dependence between the activation energy and the pre exponential factor, where was verified the effect of kinetic compensation (KCE) and possible linear relations between the dehydrations steps of these compounds.

scholarly journals STUDY OF PRECIPITATION KINETICS OF AN AL-MG-SI ALLOY USING DIFFERENTIAL SCANNING CALORIMETRY

2017 ◽  
Vol 23 (2) ◽  
pp. 155 ◽  
Author(s):  
Ines Hamdi ◽  
Zakaria Boumerzoug ◽  
Foued Chabane
Keyword(s):  
Activation Energy ◽  
Natural Aging ◽  
Precipitation Process ◽  
Differential Scanning Calorimetric ◽  
Precipitation Kinetics ◽  
Scanning Calorimetry ◽  
Aging Alloy ◽  
Kissinger Model ◽  
Kinetics Of ◽  
Dsc Curves

<p class="AMSmaintext">This work has been carried out by differential scanning calorimetric (DSC) to study the precipitation kinetics in quenched and natural aging Al-Mg-Si alloy. DSC curves showed exothermic and endothermic peaks corresponding to the precipitation and the dissolution processes. The activation energy of the precipitation process has been calculated using Kissinger model. The results obtained showed a change in the activation energy values, the activation energy for the β″ and β determined for natural aging alloy were higher than that in the quenched alloy. </p>

Curing Kinetics of Octaepoxysilsesquioxane/DDS System

2011 ◽  
Vol 233-235 ◽  
pp. 1834-1837
Author(s):  
Zeng Ping Zhang ◽  
Jian Zhong Pei ◽  
Shuan Fa Chen ◽  
Hong Zhao Du ◽  
Yong Wen
Keyword(s):  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
Curing Kinetics ◽  
Scanning Calorimetry ◽  
Exponential Factor ◽  
Inorganic Hybrid ◽  
Oligomeric Silsesquioxane ◽  
Kinetics Of ◽  
Epoxy Groups ◽  
Important Kind

Polyhedral oligomeric silsesquioxane (POSS) can be incorporated into polymers to obtain organic/inorganic hybrid materials. Octaepoxysilsesquioxane (E-POSS) with eight reactive epoxy groups per molecule is an important kind of POSS. E-POSS was cured with 4,4'-diaminodiphenylsulfone diamine (DDS) in this study. The curing kinetics of the E-POSS/DDS system was studied by using differential scanning calorimetry (DSC). Kinssinger and Flynn-Wall-Ozawa methods were used to obtain the activation energy and pre-exponential factor of the curing reaction.

scholarly journals Kinetics of the austenitization in the Fe-Mo-C ternary alloys during continuous heating

Open Physics ◽  
2016 ◽  
Vol 14 (1) ◽  
pp. 695-702 ◽  
Author(s):  
Lingnan Kong ◽  
Yaohui Liu ◽  
Jia’an Liu ◽  
Yulai Song ◽  
Shasha Li ◽  
...  
Keyword(s):  
Ternary Alloys ◽  
Continuous Heating ◽  
Diffusion Activation Energy ◽  
Scanning Calorimetry ◽  
Austenite Grain Size ◽  
Exponential Factor ◽  
Kinetics Of ◽  
Dsc Curves ◽  
Diffusion Activation ◽  
Lamellar Pearlite

AbstractThe influence of molybdenum on the microstructure and kinetics of the austenization of the Fe-Mo-C ternary alloys is analyzed using differential scanning calorimetry (DSC) and the Johnson-Mehl-Avrami-Kolmogorov model (JMAK) in the temperature range from 293 K to 1373 K. The as-cast microstructure and microstructure after DSC test are obtained using optical microscopy (OM) and scanning electron microscopy (SEM). It was seen that with an increasing Mo concentration, the lamellar pearlite is spherized and the austenite grain size decreases. In addition, both DSC curves and the JMAK model show that the initial (Ac1) and the final (Ac3) temperature of the phase transition increases with an increasing Mo concentration. It was also seen that increasing the Mo concentration, the diffusion activation energy (DAE) increases and the pre-exponential factor of diffusion (DPEF) decreases due to a change in both the austenitic nucleation rate and the diffusion of the elements caused by the introduction of Mo.

The synthesis, characterization and polymerization kinetic study of a series of related addition polyimides

1994 ◽  
Vol 6 (1) ◽  
pp. 21-34 ◽  
Author(s):  
John M Barton ◽  
Ian Hamerton ◽  
John B Rose ◽  
David Wamer
Keyword(s):  
Thermal Analysis ◽  
Spectroscopic Techniques ◽  
Amino Groups ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Thermal Stabilities ◽  
Thermally Induced ◽  
Aromatic Residues ◽  
Polymerization Kinetic ◽  
Kinetics Of

A series of eight addition polymides (aspartimides) was prepared in which the imide and amino groups were attached to the ends of aromatic residues containing two or four phenylene rings. The co-monomers (bis-maleimides. BMIs, and diamines) were purified using column chromatography before being fully characterized by spectroscopic techniques. The thermally induced Michael addition and polymerization reactions of the blended co-monomers were monitored using differential scanning calorimetry (Dsc) at several heating rates to enable the kinetics of the processes to be investigated. The thermal stabilities of the thermoset products of these aspartimides were evaluated by thermogravimetric analysis (TGA). Dynamic mechanical thermal analysis (DMTA) was employed to test the physical properties of the neat resins.

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