Search Results

You are looking at 71 - 80 of 4,465 items for :

  • "decomposition" x
  • All content x
Clear All

Summary Gun propellants are per definition instable substances. During their lifetime a slow decomposition process is going-on. During this decomposition process the heat that is generated accelerates the process, which could result to an unsafe situation, or an unexpected explosion of the material. The temperature to initiate the explosion of a propellant is of importance for the storage conditions of such a substance. The method used so far to evaluate this temperature is based on an extrapolation of the Kissinger equation at zero heating rate. A new proposal is the use of the invariant kinetic parameters (IKP) method to determine the iso-kinetic temperature and extrapolating it to zero heating rate as an alternative method. The results are discussed for some examples.

Restricted access

Abstract  

ZnS(1-x)MSx(x=0.01 and M=Mn2+, Cu2+ and Eu2+) compounds have been obtained by precipitation from homogeneous solutions of zinc, copper, manganese and europium salts, with S2- as the precipitating anion, formed by the decomposition of thioacetamide. The thermal study of the milled zinc acetate, thioacetamide, copper acetate, manganese acetate and europium nitrate, respectively, was studied for thermal analyis TG/DSC. XRD respect exhibits a zinc blend crystal structure.

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: V. M. Abdul Mujeeb, K. Muraleedharan, M. P. Kannan, and T. Ganga Devi

fumes of bromine when heated to decomposition. Thermoanalytical studies Information about the thermal stability of solid materials of all kinds is of great practical and technological importance [ 6 – 8 ]. Thermogravimetric

Restricted access

Abstract  

Thermal decomposition of borax has been researched by thermal, XRD and FTIR methods as well as SEM microscopy. Study have revealed that it proceeds according to the mechanism of internal reactions in the structure of the precursor as a medium. The following stages of the process have been distinguished: (1) dehydration, (2) internal structure reconstitution—formation of tincalconite, (3) amorphization of crystal structure, (4) gradual dehydroxylation and crystallization of Na2O2B2O3 inside the amorphous matrix.

Restricted access

szuverén fix kamatozású forintkötvények hozamdekompozíciója [Decomposition of the Hungarian sovereign forint bond yields]. Hitelintézeti Szemle 2012(5): 462–475. Monostori Z Magyar

Restricted access

Abstract  

The Modified Entrainment Method developed by Faktor et al. [1] is an attractive yet not very popular method to determine vapour pressures in the range of 0.002 to 0.1 bar at 10–1000°C. The method consists of evaporating a solid or liquid from a small bulb through a capillary into a flowing inert gas, e.g. argon. The vapour pressure of the sample is related to the rate of evaporation and some easily controlled experimental parameters. In the present paper a new convenient experimental set-up is described and its use to study the decomposition of metal complexes is illustrated.

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: Nopsiri Chaiyo, Rangson Muanghlua, Surasak Niemcharoen, Banjong Boonchom, Panpailin Seeharaj, and Naratip Vittayakorn

analysis of thermogravimetric curves. The calculations, based on multiple rates of thermogravimetric curves, are so-called iso-conversional calculation procedures [ 3 ]. Thermal decomposition of metal oxalates has been the subject of many researches

Restricted access

Thermal decomposition of sabugalite

A controlled rate thermal analysis study

Journal of Thermal Analysis and Calorimetry
Authors: R. Frost, J. Kristóf, W. Martens, M. Weier, and E. Horváth

The mineral sabugalite (HAl)0.5[(UO2)2(PO4)]2⋅8H2O, has been studied using a combination of energy dispersive X-ray analysis, X-ray diffraction, dynamic and controlled rate thermal analysis techniques. X-ray diffraction shows that the starting material in the thermal decomposition is sabugalite and the product of the thermal treatment is a mixture of aluminium and uranyl phosphates. Four mass loss steps are observed for the dehydration of sabugalite at 48°C (temperature range 39 to 59°C), 84°C (temperature range 59 to 109°C), 127°C (temperature range 109 to 165°C) and around 270°C (temperature range 175 to 525°C) with mass losses of 2.8, 6.5, 2.3 and 4.4%, respectively, making a total mass loss of water of 16.0%. In the CRTA experiment mass loss stages were found at 60, 97, 140 and 270°C which correspond to four dehydration steps involving the loss of 2, 6, 6 and 2 moles of water. These mass losses result in the formation of four phases namely meta(I)sabugalite, meta(II)sabugalite, meta(III)sabugalite and finally uranyl phosphate and alumina phosphates. The use of a combination of dynamic and controlled rate thermal analysis techniques enabled a definitive study of the thermal decomposition of sabugalite. While the temperature ranges and the mass losses vary due to the different experimental conditions, the results of the CRTA analysis should be considered as standard data due to the quasi-equilibrium nature of the thermal decomposition process.

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: E. M. Schwartz, I. M. Vitola, G. S. Sergeiyeva, G. O. Piloyan, and O. V. Drozdova

The thermal decompositions of dicitratoborates M1[B(C6H6O7)2]·nH2O (n=0–2, M1=Rb, K, Li, NH4) and M11[B(C6H6O7)2]2·8H2O (M11=Co, Ni, Mn, Cu, Zn, Cd) were investigated by means of TG, DTA and DTG methods. It was found that these thermal decompositions involve three successive stages: dehydration, the endothermal decomposition of the ligand, and oxidation of the residual organic component. The volatile products of decomposition in each stage were detected by means of gas chromatography. The method of TG-curve transformation into the curvedm/d T vs.m, wherem is the loss of weight at each moment of time, was used for a more detailed study of dehydration. The optimal conditions for TG-curve modification were found.

Restricted access

Abstract  

The thermal stability of polypyrrole (PPy) samples has been studied by thermogravimetry/mass spectrometry and pyrolysis-gas chromatography/mass spectrometry in inert atmospheres. PPy has been prepared by chemical oxidative polymerization using ferric sulfate as an oxidant and anionic surfactants, such as dodecylbenzenesulfonic acid and sodium dodecylbenzenesulfonate as co-dopants. For comparison we have studied polypyrrole (PPy-SO4) prepared without any additive. It was found that the presence of anionic surfactants improved the thermal stability of PPy. The decomposition of PPy doped with ferric sulfate and anionic surfactants occurs at relatively high temperature indicating that chemical interactions exist between the polymer and the surfactants.

Restricted access