scholarly journals Using the Coats-Redfern Method during Thermogravimetric Analysis and Differential Scanning Calorimetry Analysis of the Thermal Stability of Epoxy and Epoxy/Silica Nanoparticle Nanocomposites

2020 ◽  
Vol 55 (4) ◽  
Author(s):  
Subhi A. Al-Bayaty ◽  
Raheem A.H. Al-Uqaily ◽  
Najwa J. Jubier
Keyword(s):  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
Thermal Decomposition ◽  
Thermogravimetric Analysis ◽  
Heating Rate ◽  
Silica Nanoparticle ◽  
Frequency Factor ◽  
Inert Atmosphere ◽  
Diffusion Control ◽  
Scanning Calorimetry

In this paper, we provide a study of the thermal decomposition behavior of epoxy and epoxy/silica nanoparticle nanocomposites by using thermogravimetric analysis and differential scanning calorimetry techniques at temperatures ranging from 25°C to 600°C, using a constant heating rate of 10°C per minute under inert atmosphere. With increasing silica nanoparticle percentages of 2%, 4%, 6% and 8%, the kinetic parameters of the activation energy, frequency factor, and thermodynamics property were determined at conversion ranges between 20% to 80% using the Coats-Redfern method for diffusion control reaction (Janders) model. The Arrhenius equation for epoxy decomposition at a heating rate of 10°Cper minute equaled 5.7278x e185.984/RT. Thermal decomposition occurred through two stages: (1) with volatile removal and (2) with a random chain break. The effects of variation of silica nanoparticle percentages on glass transition temperature was investigated. The activation energy, frequency factor, rate constant, and other thermodynamic properties increased with additional silica nanoparticle content due to more bonding, as it needed more heat to break.

The solid state isomerization and thermal decomposition of pentamminethiocyanatocobalt(III) salts [Co(NH3)5SCN] X2 (X = Cl, SCN)

1974 ◽  
Vol 27 (7) ◽  
pp. 1391 ◽  
Author(s):  
MR Snow ◽  
RJ Thomas
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Decomposition ◽  
Solid State ◽  
Thermogravimetric Analysis ◽  
Water Solution ◽  
Scanning Calorimetry ◽  
Thiocyanate Complex ◽  
Lower Temperature ◽  
Intramolecular Process ◽  
Tracer Experiments

Radiochemical tracer experiments show that in the thiocyanate complex, [Co(NH3)5SCN] [SCN]2, thermal isomerization to the isothiocyanate salt proceeds with incorporation of anionic thiocyanate. At least 45% of the isomerization process proceeds by a dissociative path. This contrasts with the mechanism in water solution where isomerization occurs without exchange with thiocyanate in solution. The result also shows the inadequacy of the generally made assumption that isomerization in the solid state is an intramolecular process. The chloride and thiocyanate salt were subjected to simultaneous thermogravimetric analysis and differential scanning calorimetry. The thiocyanate salt deamminates at a much lower temperature (from 100�C) than the chloride (from 160�C), but no process corresponding to the isomerization could be detected.

Thermal Decomposition of Pyrite FeS2 under Reducing Conditions

2010 ◽  
Vol 654-656 ◽  
pp. 2398-2401 ◽  
Author(s):  
Ludovic Charpentier ◽  
Patrick J. Masset
Keyword(s):  
Mass Spectrometry ◽  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
Thermal Decomposition ◽  
Scanning Calorimetry ◽  
Reaction Progress ◽  
Reducing Atmosphere ◽  
Reducing Conditions

The thermal decomposition of pyrite was investigated under reducing atmosphere, e.g. p(O2)~10-6 bar. Thermogravimetric measurements were coupled with differential scanning calorimetry and mass spectrometry. Multi-scan method was used to calculate the values of the activation energy of the reaction of thermal decomposition of the pyrite. It was shown that the value of the activation energy of the decomposition of pyrite into pyrrhotite varies with the reaction progress. The values of activation energy vary from 250 to 350 kJ.mol-1.

scholarly journals Calculation of Kinetic Parameters of the Thermal Decomposition of Residual Waste of Coniferous Species: Cedrus Deodara

2018 ◽  
Vol 21 (2) ◽  
pp. 75-80 ◽  
Author(s):  
Alok Dhaundiyal ◽  
Muammel M. Hanon
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Kinetic Parameters ◽  
Frequency Factor ◽  
Inert Atmosphere ◽  
Kissinger Method ◽  
Heating Rates ◽  
Cedrus Deodara ◽  
Coniferous Species ◽  
Competitive Reactions

Abstract This paper deals with pyrolysis decomposition of Cedrus deodara leaves with the help of thermogravimetric analysis (TGA). Experiments are performed in the presence of inert atmosphere of nitrogen. Experiments are conducted at three different heating rates of 5 °C∙min-1, 10 °C∙min-1 and 15 °C∙min-1 within temperature range of 35 °C to 700 °C. Arrhenius parameters such as activation energy and frequency factor are estimated by Flynn Wall and Ozawa (FWO), Kissinger-Akahira-Sonuse (KAS) and Kissinger. The activation energy and frequency factor calculated by using Kissinger method are 67.63 kJ∙mol-1 and 15.06 . 104 min-1 respectively; whereas the averaged values of the same parameters through FWO and KAS methods are 89.59 kJ∙mol-1 and 84.748 kJ∙mol-1, 17.27 . 108 min-1 and 62.13 . 107 min-1 respectively. Results obtained through Kissinger method represent the actual values of kinetic parameters. Conversely, FWO and KAS methods reflect the apparent values of kinetic parameters, as they are highly influenced by the overlapping of competitive reactions occur during pyrolysis.

Kinetic Study of PVC Pyrolysis in Air by Thermogravimetric Analysis Using the Friedman Method

2012 ◽  
Vol 427 ◽  
pp. 64-69 ◽  
Author(s):  
Bin Han ◽  
Yu Long Wu ◽  
Wei Feng ◽  
Zhen Chen ◽  
Ming De Yang
Keyword(s):  
Activation Energy ◽  
Thermogravimetric Analysis ◽  
Thermal Degradation ◽  
Heating Rate ◽  
Inert Atmosphere ◽  
Nitrogen Atmosphere ◽  
Pyrolysis Process ◽  
Pyrolysis Mechanism ◽  
Second Stage ◽  
Friedman Method

The thermal degradation of PVC in air ambience was investigated by the thermogravimetric analysis (TGA). The experiments were carried out at different heating rate of 5, 10, 20 and 40°C/min, respectively. The activation energy was calculated by the Friedman method. The pyrolysis mechanism of PVC in air was discussed and compared with that in Nitrogen atmosphere. The pyrolysis process of PVC in air could be divided into two main stages: 200 °C ~ 380 °C and 400 °C ~ 600 °C, which obtained by TGA at the heating rate of 5°C/min. The second stage could be further subdivided into two parts by 465 °C. It can be concluded that the oxygen in air affected the second stage more obviously than that of the first one, in comparison with inert atmosphere. The activation energy of the second stage was still larger than the first stage.

SURFACE AND VOLUME CRYSTALLIZATION OF METALLIC GLASS (Ni50Zr50)99.9P0.1 AS INVESTIGATED BY EXOELECTRON EMISSION (EEE) AND DIFFERENTIAL THERMAL ANALYSIS (DTA)

2002 ◽  
Vol 16 (03) ◽  
pp. 87-92 ◽  
Author(s):  
CZ. GÓRECKI ◽  
T. GÓRECKI ◽  
S. SZYMURA
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Differential Scanning Calorimetry ◽  
Differential Thermal Analysis ◽  
Metallic Glass ◽  
Heating Rate ◽  
Surface Crystallization ◽  
Exoelectron Emission ◽  
Ozawa Method ◽  
Scanning Calorimetry

Surface and volume crystallization of amorphous, melt-quenched (Ni50Zr50)99.9P0.1 alloy has been investigated by measurements of the temperature dependencies of the intensity of photostimulated exoelectron emission (EEE) and by differential scanning calorimetry (DSC). A comparison of these dependencies enables one to assess the tendency of the investigated materials to premature surface crystallization. For the (Ni50Zr50)99.9P0.1 alloy the surface crystallization occurs at temperatures distinctly lower than that for the crystallization in bulk. The activation energy for the surface crystallization, determined by the Ozawa method, i.e. from the shift of EEE peak corresponding to the surface crystallization on changing the heating rate, is also much lower than that for the volume crystallization.

Study of the Cure of a Diglycidyl-Ether of Bisphenol-a (DGEBA) / Triethylenetetramine (TETA) Epoxy System by Non-Isothermal Differential Scanning Calorimetry (DSC)

2006 ◽  
Vol 514-516 ◽  
pp. 1094-1098
Author(s):  
Rosa Losada ◽  
José Luís Mier ◽  
Fernando Barbadillo ◽  
Ramón Artiaga ◽  
Angel Varela ◽  
...  
Keyword(s):  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
Bisphenol A ◽  
Inert Atmosphere ◽  
Diglycidyl Ether ◽  
Exothermic Peak ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Reaction Heat ◽  
Marine Coatings

A diglycidyl-ether of bisphenol-A (DGEBA)/Triethylenetetramine (TETA) system was studied by non-isothermal differential scanning calorimetry (DSC) to establish its kinetics of cure. The DGEBA resin was Araldite GZ 601 X75 used in the marine coatings formulations. Previously, the optimum resin/hardener ratio was determined by the reaction heat measuring (.Hc) calculated from the curing exothermic peak. Tests at different heating rates (10, 15, 20, 25 and 30°C/min) under inert atmosphere were carried out in order to study the reaction kinetics. The activation energy of the cure (Ea) was obtained from these tests data by Borchardt-Daniels, autocatalytic, Duswalt and isoconversional Ozawa methods. Once the activation energy was determined, the master curves method was applied to find the kinetic model which best describes the measured DSC data. The Sestak-Berggren model SB (m,n) was found to be the most adequate for the system studied.

Thermal Decomposition of Hydroxylamine Nitrate Studied by Differential Scanning Calorimetry Analysis and Density Functional Theory Calculations

2017 ◽  
Vol 42 (4) ◽  
pp. 334-343
Author(s):  
Jianguo Liu ◽  
Zhentao An ◽  
Qian Zhang ◽  
Chaoyang Wang
Keyword(s):  
Activation Energy ◽  
Density Functional Theory ◽  
Differential Scanning Calorimetry ◽  
Thermal Decomposition ◽  
Density Functional ◽  
Probable Mechanism ◽  
Thermal Decomposition Mechanism ◽  
Scanning Calorimetry ◽  
Functional Theory ◽  
Mechanism Function

The thermal stability and kinetics of hydroxylamine nitrate (HAN) decomposition were studied by differential scanning calorimetry (DSC) and the thermal decomposition reaction mechanism was determined by density functional theory (DFT). With the help of parameter values from the non-isothermal DSC curves of HAN, the thermal decomposition activation energy and pre-exponential constant were obtained by the Kissinger and Ozawa methods. Then, the most probable mechanism function was calculated by the Šatava–Šesták method. Seven different paths for the thermal decomposition mechanism of HAN were formulated and DFT at the B3LYP/6-311++G(d,p) level was used to carry out the dynamics analysis. The calculated results show that the values of the activation energy calculated by the Kissinger and Ozawa methods are 67.892 and 70.412 kJ mol−1 respectively. The most probable mechanism function calculated by the Šatava–Šesták method is [Formula: see text]. The path being favoured energetically in the dynamics is in the order: Path6 > Path5 > Path4 > Path1 > Path2 > Path7 > Path3.

Thermal Stability of N-Heterocycle-Stabilized Iodanes – A Systematic Investigation

2019 ◽  
Author(s):  
Andreas Boelke ◽  
Yulia A. Vlasenko ◽  
Mekhman S. Yusubov ◽  
Boris Nachtsheim ◽  
Pavel Postnikov
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Thermogravimetric Analysis ◽  
Systematic Investigation ◽  
Scanning Calorimetry ◽  
Thermal Stability Of

<p>The thermal stability of pseudocyclic and cyclic <i>N</i>-heterocycle-stabilized (hydroxy)aryl- and mesityl(aryl)-l<sup>3</sup>-iodanes (NHIs) through thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) is investigated. NHIs bearing <i>N</i>-heterocycles with a high N/C-ratio such as triazoles show among the lowest descomposition temperatures and the highest decomposition energies. A comparison of NHIs with known (pseudo)cyclic benziodoxolones is made and we further correlated their thermal stability with reactivity in a model oxygenation. </p>

scholarly journals Comprehensive Thermal Characteristics of Different Cultivars of Flaxseed Oil (Linum usittatissimum L.)

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1958
Author(s):  
Jolanta Tomaszewska-Gras ◽  
Mahbuba Islam ◽  
Liliana Grzeca ◽  
Anna Kaczmarek ◽  
Emilia Fornal
Keyword(s):  
Differential Scanning Calorimetry ◽  
Heating Rate ◽  
Fatty Acid Content ◽  
Thermal Characteristics ◽  
Principal Component ◽  
Flaxseed Oil ◽  
Scanning Calorimetry ◽  
Total Oxidation ◽  
Increasing Temperature ◽  
Linear Correlations

The aim of this study was to describe the thermal properties of selected cultivars of flaxseed oil by the use of the differential scanning calorimetry (DSC) technique. The crystallization and melting profiles were analyzed depending on different scanning rates (1, 2, 5 °C/min) as well as oxidative induction time (OIT) isothermally at 120 °C and 140 °C, and oxidation onset temperatures (Ton) at 2 and 5 °C/min were measured. The crystallization was manifested as a single peak, differing for a cooling rate of 1 and 2 °C/min. The melting curves were more complex with differences among the cultivars for a heating rate of 1 and 2 °C/min, while for 5 °C/min, the profiles did not differ, which could be utilized in analytics for profiling in order to assess the authenticity of the flaxseed oil. Moreover, it was observed that flaxseed oil was highly susceptible to thermal oxidation, and its stability decreased with increasing temperature and decreasing heating rate. Significant negative linear correlations were found between unsaturated fatty acid content (C18:2, C18:3 n-3) and DSC parameters (OIT, Ton). Principal component analysis (PCA) also established a strong correlation between total oxidation value (TOTOX), peroxide value (PV) and all DSC parameters of thermo-oxidative stability.

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