An improved method for the synthesis of four heterotrinuclearpolyacids of the type: Hx[EM′yM″zO40⋅nH2O (E=P, Si; M′=Mo, W; M″=V, W) was elaborated. The studied compounds were characterized by elemental analysis, IR spectra and thermal behaviour over
20–800C temperature range.
Thermal behaviour of raw fly ashes-wasted products from various Polish power plants has been investigated using X-ray diffractions
(XRD), Fourier transform infrared spectroscopic (FT-IR), differential thermal analysis (DTA) and thermogravimetry (TG). On
the basis of the DTA and TG analysis differentiation between examined ashes has been made, which could not be achieved by
XRD and FT-IR methods.
Authors:E. Plevová, A. Kožušníková, L. Vaculíková, and G. Simha Martynková
The definition as well as prediction of rock thermal behavior seems to be a quite difficult problem significantly effected
by rock composition and structure. Temperature increase causes various changes of rock material (such as decomposition, oxidation,
phase and polymorphic transformation, etc.). These changes are connected to thermal expansion with following appearance of
tensions and cracks in minerals and rock structure. After consequential temperature decrease, developed tensions and cracks
still influence the process. This study presents the application of thermogravimetric analysis, differential thermal analysis
and thermomechanical analysis in characterization of selected marble thermal behavior. The texture and morphological orientation
of calcite grains for marble samples was determined by optical microscopy. FTIR spectroscopy application along with X-ray
diffraction (XRD) extended data about mineralogical composition. According to optical microscopy, the calcite grains show
marked morphological anisotropy in one direction for some samples. Therefore, the thermal expansion had to be measured in
three different (perpendicular to each other) directions. It is evident, that the effect of temperature on the final marble
properties depends not only on mineralogical composition, but also on structure, texture and morphological orientation of
grains. All these facts significantly influence the interpretation of differences in various marble thermal behavior.
Authors:N. Laptash, E. Merkulov, and I. Maslennikova
The thermal behaviour of ammonium oxofluorotitanates (NH4)3TiOF5, (NH4)2TiOF4 and NH4TiOF3 was investigated by thermoanalytical, X-ray and IR spectroscopic methods. The first decomposition stages under quasi-isobaric conditions are characterized by the formation of (NH4)2TiF6 and ammonium oxofluorotitanate with the less content of ammonium and fluorine than in the initial compound. The decomposition process is accompanied by the Ti(IV) reducing due to ammonia evolved. The new ammonium oxofluorotitanate of high volatility was isolated and characterized. Ammonium-containing non-stoichiometric titanium oxyfluorides are the final products of thermal decomposition of ammonium oxofluorotitanates.
Authors:I. Labádi, R. Tudose, I. Fejér, Z. Jóri, and O. Costisor
Parent and mixed ligand complexes of cobalt and copper with antipyrine derivatives of 1,2-ethanediamine or piperazine and
with 2-aminobenzothiazole (TAB) were synthesized and their thermal behaviour was investigated. The complexes contain N,N′-bis(4-antipyrylmethyl)-piperazine
(BAMP) or N,N′-tetra(4-antipyrylmethyl)-1,2-diaminoethane (TAMEN) or/and TAB as ligand, and Cl−, ClO4− or SCN−. The complexes decompose with the evolution of heat. The decomposition route depends on the presence of ClO4−. If the ClO4− is not coordinated, it oxidizes the TAB and BAMP or TAMEN and the decomposition is explosive.
Authors:L. Ji-zhen, F. Xue-zhong, H. Rong-zu, Z. Xiao-dong, Z. Feng-qi, and G. Hong-Xu
The thermal behavior of copper(II) 4-nitroimidazolate (CuNI) under static and dynamic states are studied by means of high-pressure
DSC (PDSC) and TG with the different heating rates and the combination technique of in situ thermolysis cell with rapid-scan
Fourier transform infrared spectroscopy (thermolysis/RSFTIR).
The results show that the apparent activation energy and pre-exponential factor of the major exothermic decomposition reaction
of CuNI obtained by Kissinger’s method are 233.2 kJ mol−1 and 1017.95 s−1, respectively. The critical temperature of the thermal explosion and the adiabatic time-to-explosion of CuNI are 601.97 K
and 4.4∼4.6 s, respectively. The decomposition of CuNI begins with the split of the C-NO2 and C-H bonds, and the decomposition process of CuNI under dynamic states occurs less readily than those under static states
because the dynamic nitrogen removes the strong oxidative decomposition product (NO2). The above-mentioned information on thermal behavior is quite useful for analyzing and evaluating the stability and thermal
charge rule of CuNI.
Authors:S. Jingyan, L. Jie, D. Yun, H. Ling, Y. Xi, W. Zhiyong, L. Yuwen, and W. Cunxin
The thermal behavior of nicotinic acid under inert conditions was investigated by TG, FTIR and TG/DSC-FTIR. The results of
TG/DSC-FTIR and FTIR indicated that the thermal behavior of nicotinic acid can be divided into four stages: a solid-solid
phase transition (176–198°C), the process of sublimation (198–232°C), melting (232–263°C) and evaporation (263–325°C) when
experiment was performed at the heating rate of 20 K min−1. The thermal analysis kinetic calculation of the second stage (sublimation) and the fourth stage (evaporation) were carried
out respectively. Heating rates of 1, 1.5, 2 and 3 K min−1 were used to determine the sublimation kinetics.
The apparent activation energy, pre-exponential factor and the most probable model function were obtained by using the master
plots method. The results indicated that sublimation process can be described by one-dimensional phase boundary reaction,
g(α)=α. And the ‘kinetic triplet’ of evaporation process was also given at higher heating rates of 15, 20, 25, 30 and 35 K min−1. Evaporation process can be described by model of nucleation and nucleus growing,
Authors:D Apreutesei, G Lisa, N Hurduc, and D Scutaru
into account the importance of thermal stability in the liquid crystals field,
the study presents thermal behavior of some cholesteric esters, which differ
by the nature of the functional group attached to the cholesteryl unit and
the connecting position of the nitro or amino functions to the aromatic ring.
The cholesteric esters present liquid crystalline properties, with high melting
and clearing points and may be used as intermediates in the synthesis of liquid
crystals. Some other kinetic characteristics, such as reaction order (n), activation energy (Ea)
and pre-exponential factor (lnA) have been
also evaluated. The type of functional units adjacent to the aromatic unit
determines thermal stability of the cholesteryl compounds. Groups with a powerful
withdrawing effect induce a decreasing of the temperatures at which the material
starts to lose mass. An increased thermal stability for the amino esters has
been observed, probably because of some intermolecular hydrogen bonds formation.
The thermal behaviour of the intercalation complex of a dickite from Tarifa, Spain, with dimethylsulfoxide was studied by
high-temperature X-ray diffraction, differential thermal analysis and thermogravimetry, and attenuated total reflectance infrared
spectroscopy. The ATR-FTIR study indicated that the heating between room temperature and 75C produced the elimination of
adsorbed molecules. Above this temperature the elimination of intercalated molecules occurs through several stages. Loss of
6.5% of the intercalated DMSO first causes a slight contraction of the basal spacing at 90şC due to a rearrangement of the
DMSO molecules in the interlayers positions. This contraction is followed by the formation of a single layer complex and the
restoring of the dickite structure, at 300C, when the loss of intercalated species have been completed.