Authors:G. Liptay, A. Borbély- Kuszmann, T. Wadsten, and J. Losonczi
The thermal decomposition of theα, β andγ- picoline complexes of cadmium were studied by means of TG-DTG-DTA. In connection with the preparation of the complex compounds, it was established that the ligand number was influenced by the reaction medium. The thermal decomposition took place stepwise, and intermediates were formed which could be isolated with a derivatograph by the “freezing-in” method. The structures and properties of these previously unknown compounds were investigated by far-IR spectroscopy and X-ray powder diffraction.
Authors:J. H. Levy, W. I. Stuart, and R. N. Whittem
TG, DTG, DTA and DSC methods were used to study the curing reaction of diglycidyl ether of bisphenol A and nadic methyl anhydride in the presence of a reactive diluent. DTG plots were used to identify the various stages of weight loss arising from volatilization of components from the resin formulation and pyrolysis of cured resin. DTA and DSC results established the temperatures at which catalysed and thermally activated cure occurred.
The simultaneous TG-DTG-DTA thermoanalytical curves of 13 rare earth (4f) element oxides, namely, CeO2, Dy2O3, Er2O3, Gd2O3, HfO2, Ho2O3, Nd2O3, Pr6O11, Sm2O3, Tb4O7, Tm2O3, Yb2O3 and Y2O3, were recorded with a MOM derivatograph under static air atmosphere over the temperature range from ambient to 1050°C. Only
HfO2, Nd2O3, Pr6O11, Sm2O3 and Tb4O7 showed appreciable weight losses due to the liberation of small amounts of oxygen. X-ray diffractometry was used to identify
the thermal degradation products and their precursors.
Authors:Titus Vlase, Constantin Bolcu, Gabriela Vlase, Alin Mogoş, and Nicolae Doca
Samples of flexible PU foam were prepared from a polyol (Elastoflex W 5516/115) and an isocyanate prepolymer (Iso 145/8),
both commercial Elastogram products. For the thermooxidative stabilization, two phenolic compounds were used, separately or
in mixture. These compounds were: 2,6-di-t-butyl-4-methyl-phenol (non-reactive) (AO-1), 3,5-di-t-butyl-4-hydroxy-benzyl alcohol
(reactive, AO-2), used in total mass% of 0.3/1.5. The TG/DTG/DTA curves were drawn up in dynamic air, with a heating rate
of 10 °C min−1, until 500 °C. For the unstabilized sample a single thermodegradative TG step, with a maximum rate at 268–270 °C was observed,
whereas for the stabilized samples, supplementary steps at higher temperature were observed. The changes in the TG/DTG/DTA
parameters are not in a single relationship with the mass% of the stabilizator, due to the following: AO-1 is easily migrated
out from PV, especially, at higher concentrations. AO-2 had positive effect at all studied concentrations. But the most remarkable
effect is the synergetic effect of a 1:1 mixture of AO-1 and AO-2.
The thermal decomposition of some new primary aliphatic amine RNH2 (R=methyl-, ethyl-,n-propyl,i-propyl,n-butyl-,i-butyl-,n-amyl-,i-amyl-, cyclohexyl-andi-allyl-) complexes with cadmium(II) chloride, prepared by solid-gas phase chemisorption, have been investigated by simultaneous
TG-DTG-DTA. The enthalpy changes during the degradation were followed by DSC. The course of the thermal decomposition is described
in detail. The thermal properties observed were compared to the more recently reported nickel(II) analogues. The changes in
thermal parameters in the series of cadmium(II) chloride aliphatic amine complexes are discussed on the basis of the inductive
releasing effect of the aliphatic chain and the steric hindrance of the ligands.
Formation of nitrogen ligated complexes of types NiL6X2, NiL4X2, NiL2X2 and NiL1X2 (whereL=pyridine, 2-, 3- and 4-methyl-pyridine andX=F, Cl, Br, I) have been studied by traditional preparative methods, i.e. from solutions and by solid-gas phase chemisorption.
Quaternary mixed complexes were obtained by chemisorption from heated intermediates. The complexes thus formed were further
analysed by simultaneous TG-DTG-DTA. Effects of the ligands on stoichiometry and thermal properties of the complexes are discussed.
The method of a stepwise differential isothermal analysis (SDIA) has been designed for studies of reduction processes in metallurgical
systems. The basis of the method is in multi-parameter control of reaction rate and its use for monitoring temperature, heating
rate, and gas-phase composition. In this study hydrogen reduction of MoO3 and its mix with 30% Fe have been carried out using the SDIA technique. During the measurements, TG, DTG, DTA, EGA, and temperature
control are carried out. Kinetics parameters were determined and possible reduction mechanism was suggested. The SDIA technique
is well suited for these studies.
The thermolysis of strontium and barium tris(maleato)ferrates(III), M3 [Fe(C2 H2 C2 O4 )3 ]2 ·x H2 O has been investigated from ambient temperature to 800 °C using simultaneous TG-DTG-DTA, XRD, Mössbauer and IR spectroscopic techniques. After dehydration the anhydrous complexes undergo decomposition to yield an iron(II)maleate/oxalate intermediate in the temperature range of 240-280 °C. An oxidative decomposition of iron(II) species leads to the formation of -Fe2 O3 and respective alkaline earth metal carbonate in the successive stages. Finally at 540-590 °C, a solid state reaction occurs between -Fe2 O3 and strontium/barium carbonate resulting in the formation of SrFeO2.5 and BaFe2 O4 , respectively.
Authors:Anca Mocanu, Lucia Odochian, N. Apostolescu, and C. Moldoveanu
The study on the thermal behavior of some new diazoaminoderivatives was aimed to follow the structure-thermal stability-degradation
mechanism correlation by means of the TG-FTIR technique and formation enthalpies. The TG-DTG-DTA curves reveal the thermal
degradation in air (30–900 °C) to show two ranges as a function of temperature (time), where the gaseous species resulting
by degradation are eliminated: the first, an endothermic one which is identical to that under nitrogen atmosphere and the
second, an exothermal one. As made evident by the identification of the individual gaseous species by their characteristic
absorbances as well as those obtained by TG-FTIR the compounds C2H2, H2C = NH, SO2, NH3, CO2, H2O, HCl are eliminated in the first domain while CO2, SO2, H2O in the second, which afforded the advancement of the most probable degradation mechanism.
Thermal decomposition of some alkali tris (malonato) ferrate (III) tetrahydrates, i. e. M3 [Fe(CH2C2O4)3]·4H2O (M=Na, K) has been studied in the temperature range of 433–973 K in static air atmosphere using Mössbauer, IR and TG-DTG-DTA techniques. Mössbauer spectra are reported at different stages to study the mechanism of decomposition. The anhydrous complex decomposed into -Fe2O3 of varying particle sizes and alkali metal malonate/carbonate in successive stages. In the final stage of remixing of cations, a solid state reaction between -Fe2O3 and alkali metal carbonate/oxide gives fine particles of the respective ferrites at temperatures lower than for oxalate precursor or even for ceramic method. Thermal stability obeys the order: sodium > potassium > lithium tris(malonato) ferrate (III).