Authors:F. Kovanda, V. Balek, V. Dorničák, P. Martinec, M. Mašláň, L. Bílková, D. Koloušek, and I. Bountseva
Thermal behaviour of synthetic pyroaurite-like anionic clay with molar ratio Mg/Fe=2 was studied in the range of 60-1100C
during heating in air. TG/DTA coupled with evolved gas analysis, emanation thermal analysis (ETA), surface area measurements,
XRD, IR and Mssbauer spectroscopy were used. Microstructure changes characterized by ETA were in a good agreement with the
results of surface area measurements and other methods. After the thermal decomposition of the pyroaurite-like anionic clay,
which took place mainly up to 400C, a predominantly amorphous mixture of oxides is formed. A gradual crystallization of MgO
(periclase) and Fe2O3 (maghemite) was observed at 400-700C by XRD. The MgFe2O4 spinel and periclase were detected at 800-1100C. The spinel formation was also confirmed by Mssbauer spectroscopy.
Authors:V. Sargentelli, A. Mauro, A. de Godoy Netto, M. Mattioli, V. Nogueira, and V. De Lucca Neto
Pseudohalide complexes of copper(II) with aliphatic bidentate amines, [Cu(N3)2(N,N-diEten)]21, [Cu(NCO)2(N,N-diEten)]22, [Cu(NCO)2(N,N-diMeen)]23, [Cu(N3)(NCS)(N,N'-diMeen)]24 and [Cu(N3)(NCO)(N,N-diMeen)]25 (N,N-diEten=N,N-diethylethylenediamine; N,N-diMeen=N,N- dimethyl-ethylenediamine and N,N'-diMeen = N,N'-dimethylethylenediamine), were prepared, characterized and their thermal behavior was investigated by TG curves. According to thermal analysis and X-ray diffraction patterns all compounds decomposed giving copper(II) oxide as final product. The mechanisms of decomposition were proposed and an order of thermal stability was established.
Thermal behaviour and structure of glasses from the SiO2–P2O5–K2O–MgO–CaO system modified by Fe2O3 addition were studied by DSC, XRD and FTIR methods. It has been found that the replacement of MgO and CaO modifiers by Fe2O3 in the structural network of silicate–phosphate glass results in decrease of the glass transition temperature (Tg) and heat capacity change (ΔCp) accompanying the glass transformation. Simultaneously, the ability for crystallization, its course and the type of the forming
phases depend on the relative proportions between iron and phosphorus as components forming the silicate–phosphate structure.
The type of the crystal phases forming in the course of heating the considered glass has been found to be in agreement with
the character of the domains occurring in this glass, confirmed by FTIR examinations.
Authors:L.-M. Zhang, W.-G. Xie, T.-T. Wen, and X. Zhao
The thermal behavior of five free anthraquinones (chrysophanol, emodin, physcion, aloe-emodin, and rhein) from rhubarb had
been investigated using TG, DTG and DTA technique. The results show that all the free anthraquinones have the similar TG and
DTG curve shapes, however, due to the substituted groups attached on the skeleton of 1,8-dihydroxy anthraquinone are different,
every anthraquinone has different mass loss features. Moreover, all the DTA curves of these free anthraquinones have two obviously
characteristic peaks, but with special curvilinear types, peak location and peak values. Therefore, thermal analysis (TA)
characteristics of anthraquinones above mentioned could be established, and it is possible to easily distinguish these anthraquinones
by using TA technique.
Thermal behavior of α-(Cu–Al–Ag) alloys, i.e. alloys
with composition less than about 8.5 mass% Al, was studied using differential
scanning calorimetry (DSC), differential thermal analysis (DTA), scanning
electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray
diffractometry (XRD). The results indicated that the presence of silver introduces
new thermal events ascribed to the formation of a silver-rich phase and, after
addition higher amounts than 8 mass% Ag to the Cu–8 mass% Al alloy it
is possible to observe the formation of the γ1
phase (Al4Cu9), which is only
observed in alloys containing minimum of 9 mass% Al. These results may be
attributed to some Ag characteristics and its interaction with Cu and Al.
Authors:D. Balköse, T. Egbuchunam, and F. Okieimen
Soaps are a class of surface active compounds derived from natural oils and fats. Double decomposition reactions permit the
synthesis of metallic soaps, which are long-chain carboxylates of metal ions, from alkaline ones such as sodium, potassium
or ammonium soaps. Metallic soaps are commercially important as they find use in diverse applications such as driers in paints
or inks, components of lubricating greases, heat stabilizers for plastics (especially PVC), catalysts and water proofing agents,
fuel additives and cosmetic products amongst others. Many of these applications are related to the thermal properties of these
compounds and the thermal behaviour of metal soaps in terms of decomposition processes is of great importance. Rubber seed
oil (RSO) which is an unsaturated triglyceride abundantly available in Nigeria, India and Australia is an excellent starting
material for metal soaps. In this study rubber seed oil having 2.2% myristic acid, 7.6% palmitic acid, 10.7% stearic acid,
20.61% oleic acid, 36.62% linoleic acid, 22.5% linolenic acid was used in making barium, calcium, cadmium and zinc soaps.
The thermal behaviour of soaps (Ba, Ca, Cd and Zn) of rubber seed oil for use as additives in the processing of poly(vinyl
chloride) (PVC) was investigated by thermal gravimetry and differential scanning calorimetry. The stability of the soaps was
examined by thermogravimetry up to 873 K at a constant heating rate of 10 °C min−1. The soaps were found to be thermally stable up to 473 K as they recorded less than 5% mass loss at this temperature with
values of apparent activation energy for decomposition varying from 52 to 96 kJ mol−1. Differential scanning calorimetric studies of the soaps revealed melting and decomposition behaviour of metal soaps.
Authors:B. Yan, H. X. Ma, N. N. Zhao, T. Mai, J. R. Song, F. Q. Zhao, and R. Z. Hu
]. N -2,4-dinitrophenyl-3,3-dinitroazetidine (DNPDNAZ) is a novel insensitive high-energy explosive. Presently, there are no reports about the thermal and detonation characterizations of DNPDNAZ. In the present study, thermalbehavior, non
Authors:K. Gjurova, M. Michailov, B. Bogdanov, and C. Uzov
The thermal behaviour (from 20 to 500°C) of high-molecular polyoxyethylene-urea mixtures which formed a molecular complex
was investigated by means of a derivatograph. Under the conditions of the investigation, there were no indications of an interaction
between the thermal decomposition products and the initial components, or of new intermediates with a thermostabilizing effect.
A linear coorelation was obtained between the mass loss at 250°C and the urea content of the mixture, which may be used to
determine the urea content of similar mixtures.
Authors:G. Keller, F. Lavigne, C. Loisel, M. Ollivon, and C. Bourgaux
The thermal behavior of three ural fats (displaying very different composition), cocoa butter (CB)2, lard, and a stearin obtained from anhydrous milk-fat (AMF) fractionation, were studied by both DSC and X-ray diffraction as a function of temperature (XRDT). To perform temperature explorations between −30‡C and +80‡C, at rates identical to those used for DSC and ranging from 0.1 K min−1 to 10 K min−1, a new set of X-ray sample-holders, temperature-controlled by Peltier effect, has been developed. It is shown that the three more stable polymorphic forms of CB were easily characterized by either X-ray diffraction or DSC, and existence of two Β-3L forms was confirmed. On the contrary, the more complex polymorphism of lard and AMF required combined examination by DSC and XRDT and the brightness of the synchrotron source for studies at the highest heating rates. Quantitative analysis of the long spacings of XRDT recordings is invaluable for interpretation of thermal events. For instance, it was found that the simultaneous formation of two polymorphic forms, of apparent long spacing of 34 and 42 å, at the onset of lard crystallization might explain the difficulty of its fractionation.
Authors:J. Giusti, G. G. T. Guarini, L. Menabue, and G. C. Pellacani
The thermal behaviour of single-crystals of the title compound has been investigated by means of thermal methods supported by optical microscopy. A complex change takes place on heating. After the loss of the two water molecules, leading to an amorphous phase, recrystallization takes place. This results in a solid (probably an anhydrous form) which reacts further, through partial liquefaction, to yield a red crystalline product whose structure has been characterized via X-ray powder spectra and electronic and IR spectroscopy.