scholarly journals On the nature of crystallization water using thermal analysis. - The application to some hydrates with different cations

1999 ◽  
Vol 64 (12) ◽  
pp. 737-744
Author(s):  
Lucia Odochian ◽  
Magdelena Pantea ◽  
Irina Calugareanu ◽  
Dana Ionescu ◽  
Olga Vicol
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Kinetic Parameters ◽  
Compensation Effect ◽  
Crystallization Water ◽  
Water Elimination ◽  
Thermogravimetric Data ◽  
Dta Analysis ◽  
Derivative Thermogravimetry

The nature of the crystallization water in some hydrates with different cations, namely: MnSO4?H2O; FeSO4?7H2O; CoSO4?7H2O; NiSO4?7H2O, has been studied by the application of the following non-isothermal techniques: thermogravimetry (TG), derivative thermogravimetry (DTG), and differential thermal analysis (DTA). Analysis of the characteristic thermogravimetric data (Tm, W ) and of the kinetic parameters (n, Ea) calculated from DTG and DTA data - with CuSO4?5H2O as a reference - demonstrated the existence of crystallization and anionwater in the studiedhydrates. The activation energy of the process of anion water elimination does not depend on the nature of the cation. This conclusion was confirmed by the absence of the compensation effect in this process.

Thermal Degradation of Flame Retardant Cotton Cellulose

2010 ◽  
Vol 168-170 ◽  
pp. 380-383
Author(s):  
Ming Gao ◽  
Fa Chao Wu
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Thermal Decomposition ◽  
Differential Thermal Analysis ◽  
Thermal Degradation ◽  
Flame Retardant ◽  
Kinetic Parameters ◽  
Oxygen Index ◽  
Decomposition Temperature ◽  
Limiting Oxygen Index

Cellulose treated with flame retardant was studied by thermogravimetry (TG), differential thermal analysis (DTA), limiting oxygen index (LOI) and IR. The kinetic parameters for the thermal degradation are obtained following the method of Broido. For the flame retardant cellulose, the activation energy and decomposition temperature were much decreased while char yield and LOI were increased. The main thermal decomposition of the samples with higher LOI occurs at lower temperatures, while that with lower LOI occurs at higher temperatures.

Kinetics of temperature-programmed reactivation of a hydrodesulphurization catalyst

1983 ◽  
Vol 48 (12) ◽  
pp. 3340-3355 ◽  
Author(s):  
Pavel Fott ◽  
Pavel Šebesta
Keyword(s):  
Carbon Dioxide ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Thin Layer ◽  
Kinetic Parameters ◽  
Diffusion Region ◽  
Reaction Heat ◽  
Gaseous Products ◽  
Temperature Programmed ◽  
Kinetics Of

The kinetic parameters of reactivation of a carbonized hydrodesulphurization (HDS) catalyst by air were evaluated from combined thermogravimetric (TG) and differential thermal analysis (DTA) data. In addition, the gaseous products leaving a temperature-programmed reactor with a thin layer of catalyst were analyzed chromatographically. Two exothermic processes were found to take part in the reactivation, and their kinetics were described by 1st order equations. In the first process (180-400 °C), sulphur in Co and Mo sulphides is oxidized to sulphur dioxide; in the second process (300-540 °C), in which the essential portion of heat is produced, the deposited carbon is oxidized to give predominantly carbon dioxide. If the reaction heat is not removed efficiently enough, ignition of the catalyst takes place, which is associated with a transition to the diffusion region. The application of the obtained kinetic parameters to modelling a temperature-programmed reactivation is illustrated on the case of a single particle.

scholarly journals A thermal degradation study of Y and La methanesulfonates

2006 ◽  
Vol 71 (8-9) ◽  
pp. 905-915
Author(s):  
Moura de ◽  
Jivaldo Matos ◽  
Farias de
Keyword(s):  
Thermal Analysis ◽  
Differential Scanning Calorimetry ◽  
Differential Thermal Analysis ◽  
Thermal Degradation ◽  
Degradation Process ◽  
Oxide Formation ◽  
Scanning Calorimetry ◽  
Degradation Study ◽  
Thermogravimetric Data ◽  
Thermal Degradation Process

The synthesis, characterization and thermal degradation of yttrium and lanthanum methanesulfonates is reported. The prepared salts were characterized by elemental analysis and infrared spectroscopy. The thermal degradation study was performed using thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC).Using the thermogravimetric data, a kinetic study of the dehydration ofY and Lamethanesulfonates was performed employing the Coats-Redfern and Zsak?methods. It was verified that under heating, yttrium and lanthanum methanesulfonates undergo three main processes: dehydration, thermal degradation and oxide formation. Furthermore, depending on the nature of the atmosphere, i.e., inert or oxidant, the thermal degradation process could be endothermic (N2) or exothermic (air).

scholarly journals An Overview of Thermal Analysis of Polymers

2017 ◽  
Vol 3 (1) ◽  
pp. 36-54
Author(s):  
DR Hardy Chan Sze On
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Kinetic Parameters ◽  
Physical Meaning ◽  
Thermomechanical Analysis ◽  
Special Focus ◽  
Modes Of Operation ◽  
Polymer Reaction

This article presents an up-to-date overview of the application of thermoanalytical methods in the study of polymers with special focus on thermogravimetry, differential thermal analysis, diferential scening calorimetry and thermomechanical analysis. The working principles behind the variouse thermoanalytical methods together with modes of operation are described. Their usefulness in the characterisation of polymers is cowered comprehensively with examples cited in the litearture. The question of validity of data obtained from thermokinetic studies of polymers is examined and it is felt that the kinetic parameters generated carry little physical meaning about the kinetic of the polymer reaction.

Thermal Stability vs. Crystallization of the Lithiumsilicate Glasses with Addition Zirconium Dioxide and Titanium Dioxide

2008 ◽  
Vol 39-40 ◽  
pp. 399-401
Author(s):  
Viliam Pavlík ◽  
Eugen Jóna ◽  
Martina Sapietová ◽  
Soňa Šnircová
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Thermal Analysis ◽  
Titanium Dioxide ◽  
Differential Thermal Analysis ◽  
Structural Analysis ◽  
Zirconium Dioxide ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Relationship

The glasses with composition of Li2O . 2 SiO2 . n ZrO2 . n TiO2 (where n = 0; 0.015; 0.031; 0.050; 0.075; 0.1; 0.15; 0.2) were prepared and the relationship between structural and selected parameters of thermal stability vs. crystallization has been studied by differential thermal analysis. Structural analysis was provided by X–ray diffraction. The order of thermal stability vs. crystallization representing of activation energy of studied glass systems which increase with higher addition both oxides. The same order was obtained from the values of XRD. On the comparison the glasses with zero addition titanium dioxide their activation energy was much higher.

About Thermostability of Fe-Ni-P Amorphous Alloys

2012 ◽  
Vol 188 ◽  
pp. 21-26
Author(s):  
Aurel Raduta ◽  
Mircea Nicoară ◽  
Cosmin Locovei
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Amorphous Alloys ◽  
Structural Changes ◽  
P System ◽  
X Rays ◽  
Heating Rates ◽  
Planar Flow Casting ◽  
Activation Energy Of Crystallization

A research program has been completed in order to analyze structural changes during heating of amorphous alloys belonging to Fe-Ni-P system. Special attention has been given to thermodynamics and mechanism of crystallization, to determine some aspects of development for crystalline phases. Experimental material used to determine characteristics of crystallization consisted in long ribbons, 30 thick and 18 mm wide, fabricated by mean of “Planar Flow casting” as amorphous Fe42Ni38P16B4alloy. Differential Thermal Analysis (DTA) and X-rays diffraction have been used to determine crystallization temperature of this alloy. Curves of differential thermal analysis for heating rates ranging between 1°C/minute and 20 °C/minute have been used to determine activation energy of crystallization.

Crystal Growth in Amorphous Binary Alloys of Zr-Ni System

2007 ◽  
Vol 26-28 ◽  
pp. 675-678 ◽  
Author(s):  
Takeshi Fukami ◽  
I. Noda ◽  
M. Asada ◽  
D. Okai ◽  
T. Yamasaki
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Crystal Growth ◽  
Crystallization Process ◽  
Isothermal Annealing ◽  
Binary Alloys ◽  
Isothermal Condition ◽  
Amorphous State ◽  
Dta Curves

A crystallization process in an amorphous state under isothermal condition is examined for binary alloys ZrNi and ZrNi2 by differential thermal analysis (DTA). Time dependence of DTA curves is measured at several constant temperatures just below crystallization temperature. The fraction of crystallized volume in amorphous state and its time evolution during isothermal annealing are measured. These data are analyzed by the Johnson-Mehl–Avrami formula. The Avrami exponent is 2.4±0.1 for ZrNi and 3~4 depending on the set temperature for ZrNi2. The activation energy for crystallization of amorphous ZrNi and ZrNi2 was estimated by plots of lnt1/2 vs. 1/T.

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