Correction. Estimation of Preexponential Factor from Thermal Decomposition Curve of an Unweighed Sample.

1967 ◽  
Vol 39 (12) ◽  
pp. 1405-1405
Author(s):  
R N. Rogers ◽  
L C. Smith
Keyword(s):  
Thermal Decomposition ◽  
Preexponential Factor ◽  
Decomposition Curve

Thermal Decomposition Kinetics of Ammonium Aluminum Carbonate Hydroxide

2008 ◽  
Vol 368-372 ◽  
pp. 1577-1579
Author(s):  
Hai Jun Zhang ◽  
En Xia Xiu ◽  
Xiu Juan Wang ◽  
Quan Li Jia ◽  
Hong Wei Sun ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
Preexponential Factor ◽  
Decomposition Kinetics ◽  
Algebraic Expression ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carbonate Hydroxide ◽  
Kinetics Of ◽  
Scanning Electron

The thermal decomposition of ammonium aluminum carbonate hydroxide was studied under non-isothermal conditions in air. The decomposition kinetics were evaluated from data of TG-DTA by means of the Kissinger equation and the Coats-Redfern equation. The values of the activation energy E, the preexponential factor A and the algebraic expression of integral G(α) functions of the thermal decomposition were calculated. The ammonium aluminum carbonate hydroxide (AACH) was characterized by X-ray diffraction, differential thermal analysis and thermogravimetric and field emission scanning electron microscopy.

Thermal decomposition in the solid state

1975 ◽  
Vol 28 (6) ◽  
pp. 1169 ◽  
Author(s):  
W Ng
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Equation ◽  
Solid State ◽  
Conventional Method ◽  
Differential Form ◽  
Kinetic Equations ◽  
Decomposition Kinetics ◽  
Solid State Decomposition ◽  
Decomposition Time ◽  
Decomposition Curve

The foundation of solid state decomposition kinetics is based on the well known theory of nucleation and nucleus growth put forward by Jacobs and Tompkins. It has now been shown that all the kinetic equations thus derived can be represented by a general differential form: ������������������������� dα/dt = kα1-p(1-α)1-q in which α, t and k are respectively the fractional decomposition, time and rate constant; while p and q are parameters lying between zero and unity inclusively. A method has been suggested to find p and q experimentally, thereby enabling one to find the appropriate kinetic form for the chemical decomposition. The conventional method involves the testing of various existing equations to the decomposition data. Different equations are found to fit over different ranges of the decomposition curve so that it is difficult to decide which is the correct kinetic equation for a particular reaction. The present approach however eliminates this complication.

scholarly journals Thermal Decomposition Behavior of Melaminium Benzoate Dihydrate

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
N. Kanagathara ◽  
M. K. Marchewka ◽  
K. Pawlus ◽  
S. Gunasekaran ◽  
G. Anbalagan
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Effective Activation Energy ◽  
Preexponential Factor ◽  
Effective Activation ◽  
Heating Rates ◽  
Monoclinic System ◽  
Model Free ◽  
Thermal Decomposition Behavior ◽  
Decomposition Behavior

Crystals of melaminium benzoate dihydrate (MBDH) have been grown from aqueous solution by slow solvent evaporation method at room temperature. Powder X-ray diffraction analysis confirms that MBDH crystallizes in the monoclinic system (C2/c). Thermal decomposition behavior of MBDH has been studied by thermogravimetric analysis at three different heating rates: 10, 15, and 20°C/min. Nonisothermal studies of MBDH revealed that the decomposition occurs in three stages. The values of effective activation energy (Ea) and preexponential factor (ln A) of each stage of thermal decomposition for all heating rates were calculated by model free methods: Arrhenius, Flynn-Wall, Friedman, Kissinger, and Kim-Park methods. A significant variation of effective activation energy (Ea) with conversion (α) indicates that the process is kinetically complex. The linear relationship between the A and Ea values was established (compensation effect). Avrami-Erofeev model (A3), contracting cylinder (R2), and Avrami-Erofeev model (A4) were accepted by stages I, II, and III, respectively. DSC has also been performed.

scholarly journals Kinetic Analysis of the Thermal Decomposition of Latex Foam according to Thermogravimetric Analysis

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Hongwei Fan ◽  
Yongliang Chen ◽  
Dongmei Huang ◽  
Guoqin Wang
Keyword(s):  
Thermal Decomposition ◽  
Thermogravimetric Analysis ◽  
Preexponential Factor ◽  
Kinetic Mechanism ◽  
Heating Rates ◽  
Third Order ◽  
Before And After ◽  
Ft Ir ◽  
The Mean ◽  
Nonisothermal Method

The thermal decomposition of latex foam was investigated under nonisothermal conditions. Pieces of commercial mattress samples were subjected to thermogravimetric analysis (TG) over a heating range from 5°C min−1 to 20°C min−1. The morphology of the latex foam before and after combustion was observed by scanning electron microscopy (SEM), and the primary chemical composition was investigated via infrared spectroscopy (FT-IR). The kinetic mechanism and relevant parameters were calculated. Results indicate that the decomposition of latex foam in the three major degradation phases is controlled by third-order reaction (F3) and by Zhuravlev’s diffusion equation (D5). The mean E values of each phase as calculated according to a single heating rate nonisothermal method are equal to 41.91 ± 0.06 kJ mol−1, 86.32 ± 1.04 kJ mol−1, and 19.53 ± 0.11 kJ mol−1, respectively. Correspondingly, the preexponential factors of each phase are equal to 300.39 s−1, 2355.65 s−1, and 27.90 s−1, respectively. The mean activation energy E and preexponential factor A of latex foam estimated according to multiple heating rates and a nonisothermal method are 92.82 kJ mol−1 and 1.12 × 10−3 s−1, respectively.

scholarly journals Synthesis, Characterization, and Thermal Decomposition Kinetics of Manganese Complex of Methionine Hydroxy Analogue

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Mei-Ling Wang ◽  
Zhi-Xian Wu ◽  
Qing Zang ◽  
Guo-Qing Zhong
Keyword(s):  
Thermal Decomposition ◽  
Raw Materials ◽  
Manganese Sulfide ◽  
Kinetic Equations ◽  
Preexponential Factor ◽  
Decomposition Kinetics ◽  
Thermal Decomposition Kinetics ◽  
Manganese Complex ◽  
Monoclinic System ◽  
Manganese Ion

The manganese complex of methionine hydroxy analogue was synthesized with methionine hydroxy analogue and manganese chloride as main raw materials. The composition and structure of the complex were characterized by elemental analyses, infrared spectra, and X-ray powder diffraction. The formula of the complex was Mn(C5H9O3S)2. The experimental results indicated that the manganese ion was, respectively, coordinated by the carboxylic and hydroxyl oxygen atoms from the methionine hydroxy analogue ligand. The crystal structure of the complex belonged to monoclinic system with the lattice parameters ofa= 1.2775 nm,b= 1.5764 nm,c= 1.5764 nm, andβ= 94.06°. The thermal decomposition process of the complex was studied by thermogravimetry and differential thermal analysis. The decomposition of the complex has taken place above 200°C. The residue was mainly manganese sulfide, and the experimental and calculated percentage mass loss was also given. The parameters of thermal decomposition kinetics for the complex, such as activation energy, reaction order, and preexponential factor, were calculated by using Kissinger, Flynn-Wall-Ozawa, and Freeman-Carroll methods, and the kinetic equations of the thermal decomposition were obtained.

Applications of Photoelectron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 506-507
Author(s):  
William J. Baxter
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
Chemical Composition ◽  
Ultraviolet Radiation ◽  
Thin Layer ◽  
Edge Effects ◽  
Electron Optics ◽  
Surface Layers ◽  
Crystalline Orientation ◽  
Fluorescent Screen

In this form of electron microscopy, photoelectrons emitted from a metal by ultraviolet radiation are accelerated and imaged onto a fluorescent screen by conventional electron optics. image contrast is determined by spatial variations in the intensity of the photoemission. The dominant source of contrast is due to changes in the photoelectric work function, between surfaces of different crystalline orientation, or different chemical composition. Topographical variations produce a relatively weak contrast due to shadowing and edge effects.Since the photoelectrons originate from the surface layers (e.g. ∼5-10 nm for metals), photoelectron microscopy is surface sensitive. Thus to see the microstructure of a metal the thin layer (∼3 nm) of surface oxide must be removed, either by ion bombardment or by thermal decomposition in the vacuum of the microscope.

Preparation and characterisation of vanadium pentoxide supported rhodium catalyst

1988 ◽  
Vol 46 ◽  
pp. 946-947
Author(s):  
A. Legrouri
Keyword(s):  
Aqueous Solution ◽  
Thermal Decomposition ◽  
Physicochemical Properties ◽  
Surface Area ◽  
Vanadium Pentoxide ◽  
High Purity ◽  
Gas Adsorption ◽  
Rhodium Catalyst ◽  
Optical Methods ◽  
Reducible Oxides

The industrial importance of metal catalysts supported on reducible oxides has stimulated considerable interest during the last few years. This presentation reports on the study of the physicochemical properties of metallic rhodium supported on vanadium pentoxide (Rh/V2O5). Electron optical methods, in conjunction with other techniques, were used to characterise the catalyst before its use in the hydrogenolysis of butane; a reaction for which Rh metal is known to be among the most active catalysts.V2O5 powder was prepared by thermal decomposition of high purity ammonium metavanadate in air at 400 °C for 2 hours. Previous studies of the microstructure of this compound, by HREM, SEM and gas adsorption, showed it to be non— porous with a very low surface area of 6m2/g3. The metal loading of the catalyst used was lwt%Rh on V2Q5. It was prepared by wet impregnating the support with an aqueous solution of RhCI3.3H2O.

Observations of the Thermal Decomposition of Brucite

1968 ◽  
Vol 26 ◽  
pp. 446-447
Author(s):  
P. L. Burnett ◽  
W. R. Mitchell ◽  
C. L. Houck
Keyword(s):  
Thermal Decomposition ◽  
Magnesium Oxide ◽  
Basal Plane ◽  
Magnesium Ions ◽  
A Value ◽  
Reaction Proceeds

Natural Brucite (Mg(OH)2) decomposes on heating to form magnesium oxide (MgO) having its cubic ﹛110﹜ and ﹛111﹜ planes respectively parallel to the prism and basal planes of the hexagonal brucite lattice. Although the crystal-lographic relation between the parent brucite crystal and the resulting mag-nesium oxide crystallites is well known, the exact mechanism by which the reaction proceeds is still a matter of controversy. Goodman described the decomposition as an initial shrinkage in the brucite basal plane allowing magnesium ions to shift their original sites to the required magnesium oxide positions followed by a collapse of the planes along the original <0001> direction of the brucite crystal. He noted that the (110) diffraction spots of brucite immediately shifted to the positions required for the (220) reflections of magnesium oxide. Gordon observed separate diffraction spots for the (110) brucite and (220) magnesium oxide planes. The positions of the (110) and (100) brucite never changed but only diminished in intensity while the (220) planes of magnesium shifted from a value larger than the listed ASTM d spacing to the predicted value as the decomposition progressed.

A magnetic super lattice

1987 ◽  
Vol 45 ◽  
pp. 360-361 ◽  
Author(s):  
M.D. Bentzon ◽  
J. v. Wonterghem ◽  
A. Thölén
Keyword(s):  
Thermal Decomposition ◽  
Oleic Acid ◽  
Magnetic Fluid ◽  
Magnetic Particles ◽  
Carbon Film ◽  
Thick Layer ◽  
Amorphous Iron ◽  
Super Lattice ◽  
Carrier Liquid ◽  
Median Diameter

We report on the oxidation of a magnetic fluid. The oxidation results in magnetic super lattice crystals. The “atoms” are hematite (α-Fe2O3) particles with a diameter ø = 6.9 nm and they are covered with a 1-2 nm thick layer of surfactant molecules.Magnetic fluids are homogeneous suspensions of small magnetic particles in a carrier liquid. To prevent agglomeration, the particles are coated with surfactant molecules. The magnetic fluid studied in this work was produced by thermal decomposition of Fe(CO)5 in Declin (carrier liquid) in the presence of oleic acid (surfactant). The magnetic particles consist of an amorphous iron-carbon alloy. For TEM investigation a droplet of the fluid was added to benzine and a carbon film on a copper net was immersed. When exposed to air the sample starts burning. The oxidation and electron irradiation transform the magnetic particles into hematite (α-Fe2O3) particles with a median diameter ø = 6.9 nm.

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