Showing papers on "Thermogravimetry published in 1977"
TL;DR: In this article, a semi-isothermal thermogravimetric method for the mineralogical examination of Portland cement paste, and for the determination of its major constituents, is described.
85 citations
TL;DR: In this article, the authors used thermogravimetry in reducing atmospheres to study the oxygen stoichiometry of several Cu-substituted lanthanum manganates.
Abstract: Thermogravimetry in reducing atmospheres was used to study the oxygen Stoichiometry of several Cu-substituted lanthanum manganates. The oxygen content of the samples at various levels of reduction (to La2O3, MnO, and Cu) was calculated from the gravimetric data. Freeze-dried samples prepared by firing at 1100°C in O2 and cooling in O2 had the following composition: LaMnO3.13, LaMn0.7Cuo.3O2.96, LaMn0.5Cu0.5O2.93, and LaMn0.3Cu0.762.71. Single-phase perovskite structure was obtained in all but the last. The lanthanum manganate LaMnO3.13 was reduced to LaMnO3.00, which shows considerable stability. A 50% substitution of Cu for Mn gave LaMn0.5 Cu0.5O2.93, indicating that the ions involved were mostly Mn4+ and Cu2+. This compound could be reduced to LaMng0.5Cu0.5 O2.26 (largely Mn2+ and Cu1+) without destroying the perovskite structure. This reduced phase could be reoxidized to the original oxygen level but subsequent reduction required considerably higher temperatures and was accompanied by the precipitation of Cu-rich phases. Samples with a Cu:Mn ratio 30:70 and 70:30 were O-deficient. The compound LaMn0.7 Cuo.3O2.96 reduced to LaMn0.7Cu0.3O2.54, a relatively stable composition. The highly Cu-rich sample LaMn0.3Cu0.7O2.71 was easily reduced.
55 citations
TL;DR: The thermal decomposition of ferric acetate,Fe(CH 3 COO) 3, has been investigated using thermogravimetry (TG), differential thermal analysis (DTA), the conventional method involving the measurement of the volume of gaseous products evolved during decomposition and the X-ray diffraction technique.
43 citations
TL;DR: The thermal decomposition of monoclinic, orthorhombic and freeze-dried ammonium paratungstate (APT) has been studied over the temperature range 100 to 500°C using thermogravimetry, evolved gas analysis and electron optical techniques as mentioned in this paper.
Abstract: The thermal decomposition of monoclinic, orthorhombic and freeze-dried ammonium paratungstate (APT) has been studied over the temperature range 100 to 500°C using thermogravimetry, evolved gas analysis. X-ray diffraction and electron optical techniques. The particle morphologies of the original APT have been related to the morphologies of the products of decomposition. A mechanism of decomposition which postulates the formation and subsequent decomposition of amorphous ammonium metatungstate is proposed and substantiated by X-ray diffraction analysis and evolved gas analysis.
32 citations
TL;DR: In this paper, the results indicate that xonotlite tends to be defective in Ca, charge balance being maintained by incorporation of additional H atoms, which are attached to the silicate anion.
31 citations
TL;DR: The state of bound water in crystalized lysozyme was studied by four techniques: electret thermal depolarization currents, thermal-stimulated pressure, isothermal polization decay, and thermogravimetry.
30 citations
TL;DR: Several ruthenium A, X, Y, L, and mordenite zeolites have been prepared and characterized as mentioned in this paper, and their catalytic activity for the hydrogenation of benzene in the range 353-433 K has been investigated.
27 citations
TL;DR: The thermal decomposition of tetrakis(diethyldithiocarbamato)tin(IV) has been studied by TG/DTA, EGA and P/GC-MS techniques as mentioned in this paper.
23 citations
TL;DR: In this paper, three dihalotin(IV) bisdiethyldithiocarbamates have been subjected to controlled pyrolysis/GC-MS analysis and the major products of the first stage of decomposition identified.
22 citations
TL;DR: In this article, the stoichiometries of the reactions, deduced by thermogravimetry and X-ray diffraction, are given, and the stochastic properties of the reaction are investigated.
18 citations
TL;DR: In this article, the P/GC-MS and TG/DTA analysis of bis(diethyldithiocarbamato)diphenyl tin (IV) indicates that the thermal decomposition proceeds in two consecutive stages.
TL;DR: The thermal decomposition of CaOsO3 by differential thermal analyses, thermogravimetry and X-ray powder diffraction has been studied in this paper, where the first intermediate Ca2Os2O7 is isostructural with orthorhombic Ca2Nb 2O7 and its cell parameters are: a0 = 3.745 A, b0 = 25.1 A, c0 = 5.492 A, Z = 4, space group Cmcm or Cmc2.
TL;DR: In this paper, the thermal decomposition of γ-irradiated poly(vinylidene flouride) and the copolymer of vinylidene difluoride and vinyl fluoride has been investigated by means of thermogravimetry (TG), differential thermal analysis (DTA) and mass spectral analysis of the evolved gas.
Abstract: The thermal decomposition of γ-irradiated poly(vinylidene flouride) and the copolymer of vinylidene difluoride and vinyl fluoride has been investigated by means of thermogravimetry (TG), differential thermal analysis (DTA) and mass spectral analysis of the evolved gas. Under non-isothermal conditions (heating rate = 2 K min−1), polymers were found to lose their weight in two stages. The main process of the weight loss was the splitting-off of HF. Various aromatic compounds containing F were also observed to evolve, although their contribution to the total weight loss was small. For the volatilization reaction occurring at high temperature, initiation through random chain scission was suggested. Kinetical analysis of TG traces for the volatilization showed that the apparent overall activation energy decreases with increasing dose.
TL;DR: In this article, the P/GC-MS system has been modified such that pyrolysis can be performed in an air atmosphere and several tin(IV) dithiocarbamate complexes have been prolysed in air in order to rationalise the precise role oxygen in the decomposition process.
TL;DR: In this article, the thermal stability of ring-substituted polystyrenes, containing OMe, Me, Br and Cl para substituents, was investigated using thermogravimetry, gel permeation chromatography and gc/mass spectrometry.
TL;DR: In this article, the thermal decomposition of ammonium fluoromanganates (III) has been investigated in air and argon by simultaneous thermogravimetry and differential thermal analysis.
TL;DR: In this article, the formation and nonstoichiometry of strontium uranates, especially those with the Sr/U atom ratio around unity, were examined by means of thermogravimetry and X-ray diffraction.
Abstract: The formation and nonstoichiometry of strontium uranates, especially those with the Sr/U atom ratio around unity, were examined by means of thermogravimetry and X-ray diffraction. The reaction of SrCO3 with U3O8 in air, where Sr/U=1, produced the stoichiometric β-SrUO4, which had an orthorhombic structure. The reactions in vacuum and in hydrogen yielded the products of the composition SrUO3.563 and SrUO3.175, respectively. On the other hand, the reduction of β-SrUO4 in vacuum and in hydrogen gave SrUO3.48 and SrUO3.65, respectively. Stoichiometric SrUO3 was prepared by the reaction of SrO with UO2. The reduction product of β-SrUO4, SrUC4−x, was oxidized in air below 500 °C to α-SrUO4 which was rhombohedral. During the phase transition to β-SrUO4, α-SrUO4 exhibited anomalous behavior; that is, α-SrUO4 was first reduced and then reoxidized to nearly the initial composition with the formation of β-SrUO4. Of the uranates with Sr/U\eweq1, the formations of SrU4O13, SrU2O7, and Sr2UO5 were examined; the single ...
TL;DR: In this article, the applicability of the thermogravimetric technique in the determination of the degree of conversion of two standard high alumina cement (HAC) concrete samples was evaluated.
TL;DR: In this paper, the thermal decomposition of γ-irradiated poly(vinyl fluoride) has been investigated by means of thermogravimetry (TG), differential thermal analysis (DTA), and mass spectral analysis of the evolved gas.
Abstract: The thermal decomposition of γ-irradiated poly(vinyl fluoride) has been investigated by means of thermogravimetry (TG), differential thermal analysis (DTA) and mass spectral analysis of the evolved gas. The polymer was found to lose its weight in two main steps. The first step was the elimination of hydrogen fluoride; during the second step various unsaturated hydrocarbons were evolved as a consequence of main chain scission. The kinetical analysis of TG for dehydrofluorination under N2 showed that the apparent overall activation energy decreases with increasing irradiation dose. Considerable heat release during the decomposition was observed when DTA was performed in the presence of air. This behaviour was attributed to a crosslinking reaction catalyzed by O2. The addition of potassium salts or CsCl markedly diminished dehydrofluorination. On the other hand, dehydrofluorination was accelerated by CuF2.
TL;DR: In this article, a tri-arc melting technique was used to grow high purity crystals of the congruently melting compounds Ti2O3, Ti3O5 and V2O2n-1.
Journal Article•
TL;DR: In this article, a comparison of observed and calculated weight loss provided a method to determine if condensed-phase reactions occur among the materials in the blend, and definite evidence for condensed phase reactions was observed when polybutadiene (impact modifier), decabromodiphenyl oxide, and antimony trioxide were present simultaneously.
Abstract: Blends of high-impact polystyrene with decabromodiphenyl oxide and/or antimony trioxide were characterized by thermogravimetry. The observed weight loss for the blends was compared with a calculated weight loss which was determined from a weighted sum of the weight loss of the individual materials in the blend. This comparison of observed and calculated weight loss provided a method to determine if condensed-phase reactions occur among the materials in the blend. Definite evidence for condensed-phase reactions was observed when polybutadiene (impact modifier), decabromodiphenyl oxide, and antimony trioxide were present simultaneously. In that case, the observed weight loss exceeded the calculated weight loss above 330°C. When one of the three materials was absent, the observed weight loss was less than or equal to the calculated weight loss. The condensed-phase reactions involving polybutadiene, decabromodiphenyl oxide, and antimony trioxide occurred in nitrogen as well as in air.
TL;DR: In this paper, the thermal degradation of polyepichlorhydrin and copolymer of epichlor hydrin with ethylene oxide, both in uncompounded and compounded form, has been studied in air and inert atmosphere by thermogravimetry.
Abstract: The thermal degradation of polyepichlorhydrin and of the copolymer of epichlorhydrin with ethylene oxide, both in the uncompounded and compounded form, has been studied in air and inert atmosphere by thermogravimetry. A detailed examination has also been made of the evolution of hydrogen chloride from the homopolymer as a function of temperature and compounding formulation, specific attention being given to the efficiency of the acid acceptor. It is concluded that with suitable formulationohydrogen chloride evolution should not be a problem at temperatures at least up to 175°C.
TL;DR: In this article, the results of simultaneous thermogravimetric and differential scanning calorimetric measurements of PTOX have been analyzed by using a sample pan system with good thermal conductivity and good thermal contact.
Abstract: Thermally unstable poly (trioxane) (PTOX) has been studies by simultaneous thermogravimetric and differential scanning calorimetric measurement in order to clarify the melting behavior. When the sample pan system has good thermal conductivity and good thermal contact, the decomposition of poly (trioxane) takes place after melting. In this case the profile of melting endotherm does not require a correction for the thermal decomposition in obtaining the melting point and the enthalpy of melting. In order to compare the results of thermogravimetry and differential scanning calorimetry, the lid of a sample pan system must have high thermal conductivity and have space for dissipation of gases evolved. Usage of a silver net lid with good thermal contact is thus recommended.
01 Jan 1977
TL;DR: In this paper, the authors investigated the hydrogen reduction of lacunar phases with a spinel structure using thermogravimetry, electrical conductivity and X-ray analysis.
TL;DR: In this paper, the authors used thermogravimetry and EPR to identify paramagnetic species formed during the vacuum thermal decomposition of Mg- and K-sulfites and -thiosulfates.
TL;DR: In this article, the decomposition of Mg(OH) was studied by means of thermogravimetry, IR-spectroscopy, DTA, thermodesorption with GC and MS, and X-ray analysis.
Abstract: The decomposition of Mg(OH)₂ was studied by means of thermogravimetry, IR-spectroscopy, DTA, thermodesorption with GC and MS, and X-ray analysis.Water was evolved in two steps, at 230 °C (a small amount only) and 380 °C. The band at 3700 cm⁻¹, that is assigned to OH groups of Mg(OH)2, was not present above 270 °C. Assuming that only surface OH groups appear in the IR spectrum, but no bulk OH groups, the steps at 230 °C and 380 °C can be attributed to the decomposition of the surface and the bulk, resp.