Authors:M. Zayed, F. El-Dien, A. El-Gany, and K. Györyöva
The 5,7-dichloro, 5,7-dibromo, 5,7-diiodo and 5,6-dinitro derivatives of oxine (ligandsL1,−L4) were used to prepare uranyl chelates (A1–A4). Thermal analysis (DTA) and mass spectroscopic studies were performed. The stoichiometries of the chelates were determined
by elemental analysis, molecular weight determination applying an α-spectroscopic liquid scintillation counter and mass spectral
measurements. The uranyl∶ligand ratios were found to be 1∶1 for A1, 1∶3 for A2, 1∶2 (monohydrate) for A3, and 1∶2 forA4. The correlation between the thermal analysis and mass spectra was examined. The activation energy required for each step
of thermal degradation of the ligands and chelates was calculated. The natures of most of the molecular ions obtained in the
mass spectra were also explained.
Thermal analysis was first used to investigate the pattern of dissociation of hydrated ordinary Portland cement. Portlandite
(Ca(OH)2) decomposes at about 500C. This was confirmed by kinetic calculations. Thermal analysis was then performed to establish
the effect of varying the cement content on the percent mass loss associated with the decomposition of Ca(OH)2 in cement mortar cured for 28 days. An increasing relation was obtained. Standard concrete cubes were then prepared with
cement contents ranging from 200 to 450 kg m-3. The loss in mass on heating, up to 750C, of concrete samples cured for 28 days was then related to the cement content in
concrete. The relation obtained was tested for concrete cubes of known cement content and found to be in better agreement
than the results obtained by conventional chemical analysis. This method can be used for an approximate determination of the
cement content in concrete.
Authors:K. Andjelković, M. Šumar, and I. Ivanović-Burmazović
Results of our research on synthesis and characterization of complexes with acylhydrazone derivatives are described in this
review paper. Structural characterization of newly synthesized complexes by thermal analysis (TG, DTA, DSC) is particularly
emphasized in this paper. Thermal analysis enabled us to study not only structural changes of substances during thermal treatment,
but also the mode of coordination and degree of deprotonation of acylhydrazones, as well as geometry of the coordination sphere
of complexes, the structure of which had not been determined by X-ray analysis. Topics in this paper are as follows: complexes
of dioxomolybdenum(VI) with tridentate hydrazones, usnic acid derivatives and their Cu(II) complexes, as well as transition
metal complexes with 2,6-diacetylpyridine bis(hydrazones).
The peak temperature (Tp) and different temperature (ΔT) are the basic information in the differential thermal analysis (DTA). Considering the kinetic relation and the heat equilibrium
in DTA, a correctional differential kinetic equation (containing Tp and ΔT parameter) is proposed. In the dehydration reaction of CaC2O4·H2O, the activation energy calculated from the new equation showed some smaller than that from Kissinger equation, but some
bigger than that from Piloyan equation.
Authors:Cheila G. Mothé, Michelle G. Mothé, Alan T. Riga, and Kenneth S. Alexander
as a predictive model for human skin behavior. The present study focuses on evaluation of the attributes of some shedded snake skins in comparison with human skin by thermalanalysis.
Inverse numerical techniques have been applied in a range of different thermal studies in the past. These techniques require
measurements of boundary conditions and temperatures at known position within the sample in order to determine thermal properties
of the material of interest. Typically, they have been applied to highly specific applications and designs. In the current
work the authors have designed a novel instrument in order to measure apparent specific heats of a range of different materials
during continuous heating. Measurements of surface heat flux, surface and centre temperatures of the sample were obtained
under controlled heating for temperatures of up to 1000°C. Measured data was used to quantify specific and latent heats by
employing inverse numerical modelling technique. The instrument was calibrated with calorimetric calibration materials and
results were compared with the literature values. The average experimental error was estimated to be approximately 0.9% for
the reaction peak temperatures and 1.7% for the latent heats. Detailed experimental and calculation procedures as well as
measured results of specific heat and enthalpy for a number of materials are presented here.
Authors:R. Macêdo, T. Gomes do Nascimento, C. Soares Aragăo, and A. Barreto Gomes
The present work reports studies of the thermal behaviour of some anti-hypertensive drugs. Their purities were determined
by DSC and specialized pharmacopeial methods. The activation energy values suggest the following sequence of satability: nifedipine>propanolol
hydrochloride>captoril. Analysis of the DSC data indicated that the degrees of purity of nifedipine, captopril and propanolol
hydrochloride were similar to those found by pharmacopeial methods BP 93 and USP 23. The simplicity, speed and low operational
costs of thermal analysis justify its application in the quality control of pharmaceutical drugs.
Authors:Y. Li, N. Obando, F. Tschen, and R. J. Morgan
Thermal analysis of phenylethynyl end-capped imide oligomer AFR-PEPA-4
was performed to characterize cure reaction, thermal stabilities and semicrystalline
behavior of AFR-PEPA-4 oligomer and its cured polyimide. Cured AFR-PEPA-4
polyimide showed high Tgs
up to 418C. Both AFR-PEPA-4 oligomer and polyimide exhibit excellent
thermal stabilities comparable to PETI-5 polyimides. AFR-PEPA-4 imide oligomer
has a Tm of 330C
and exhibits spherulite crystalline morphology in the film. The crystallinity
in AFR-PEPA-4 films could not be regenerated under any annealing conditions
after the initial melt.
Activated carbons (AC), particularly those containing sulphur, are effective adsorbents for mercury (Hg) vapour at elevated
temperatures. Activated carbon-based technologies are expected to become a major part of the strategy for controlling mercury
emission from coal-fired power plants. Understanding the mechanism of mercury adsorption on sulphur impregnated activated
carbons (SIAC) is essential to optimizing activated carbons for better mercury removal efficiency and to developing technologies
for the handling of the spent AC.
In this work thermal analysis before and after mercury uptake was carried out for the SIAC prepared under various conditions
from oil-sand petroleum coke using a simultaneous differential thermal analyzer. Samples were heated at 20°C min−1 under nitrogen in the temperature range from ambient to 1000°C. The DSC curves suggest both endothermic and exothermic changes
during heating. The endothermic processes were attributed to evaporation of moisture and other volatile components. The exothermic
processes existed in a wide temperature range of 150–850°C likely due to the oxidation reactions between carbon and adsorbed
oxygen, oxygen-containing surface groups. The enthalpies of liquid mercury interaction with SIAC at different Hg/AC mass ratio
were also measured at 30, 40 and 50°C using a differential scanning calorimeter. The combination of thermal analysis and calorimetry
techniques enabled confirmation that the interaction of mercury with SIAC involves both physical and chemical processes.
Thermal analysis is widely used in combustion research for both fundamental and practical investigations. Efficient combustion
of coals in cement industry is very important and necessary. In this research, the effects of three coal-burning additives
on burning behaviour of bituminous coal and anthracite were studied with the help of thermogravimetry (TG) and differential
scanning calorimetric (DSC) analysis. The kinetic study was carried out and the results were presented. The results showed
that the coal-burning additives especially LSZ can reduce the ignition temperature, increase the ignition index Di, combustion ending index Df and affect the activation energy of the coal samples studied. The coal-burning additives especially LSZ can improve coal