Showing papers on "Thermal decomposition published in 1968"
TL;DR: In this article, the authors used a modified thermo-balance to measure the diffusion coefficient and thermal conductivity of the porous lime layer, and the mass and heat transfer coefficients to the surface of the compact.
149 citations
TL;DR: In this paper, a series of vanadium dioxide single crystals containing small concentrations of different impurity ions were grown by a thermal decomposition technique, and it was expected that these ions would produce a systematic change in the semiconductormetallic transition exhibited by the VO 2 phase.
143 citations
TL;DR: In this article, the thermal decomposition of rare earth acetates as well as lead and copper acetates have been investigated in detail by employing thermogravimetric analysis and differential thermal analysis.
Abstract: The infrared spectra of rare earth acetates have been studied to examine the metal-acetate bonding. The thermal decomposition of rare earth acetates as well as lead and copper acetates have been investigated in detail by employing thermogravimetric analysis and differential thermal analysis. Thermal decomposition of calcium dicarboxylates (malonate to sebacate) have been studied employing t.g.a. and d.t.a. Infrared spectra of the dicarboxylates have also been studied. Preliminary results on the products of decomposition of dicarboxylates have been reported.
133 citations
129 citations
TL;DR: In this paper, the decomposition of ammonium perchlorate and copper chromite mixtures has been studied in the temperature range from 250°C to 325°C and the products of decomposition were identified and the yield of each was established.
124 citations
TL;DR: In this article, rare earth orthoferrites and the analogous cobalt compounds can be prepared by the thermal decomposition of the appropriate rare earth ferricyanide or cobalticyanide compound, e.g., LaFe(CN)6·XH2O.
88 citations
TL;DR: In this paper, a comprehensive analysis of the volatile thermal decomposition products of high-density polyethylene has been made with the latest techniques in gas chromatography, and the formation of products is explained on the basis of free-radical mechanism.
Abstract: Decomposition products of polymers have been determined by many investigators, but the results are often conflicting because of difficulties in analyzing a large number of products. A comprehensive analysis of the volatile thermal decomposition products of high-density polyethylene has been made with the latest techniques in gas chromatography. The formation of products is explained on the basis of free-radical mechanism. The predominant process in the formation of volatiles appears to be intramolecular transfer of radicals, in which isomerization by a coiling mechanism plays an important role in determining the relative quantities of each product.
79 citations
TL;DR: The decomposition of rhodium, indium, and ruthenium chloride hydrates in air and in hydrogen has been studied by means of thermogravimetric analysis; additional studies have been made of their reduction when dispersed on low and high-area substrates as discussed by the authors.
78 citations
TL;DR: The thermal decomposition of polypropylene hydroperoxide (PPH) consists of two consecutive reactions as mentioned in this paper, and the initial, faster reaction has rates up to 60 times that of the slower process.
Abstract: The thermal decomposition of polypropylene hydroperoxide (PPH) consists of two consecutive reactions. The initial, faster reaction has rates up to 60 times that of the slower process. The former is largely suppressed by the addition of an excess of 2,6-di-tert-butyl-p-cresol. The course of reaction is the same in either solid state or in solution. The results are consistent with an intramolecular radical-induced mechanism for the initial reaction. This faster reaction consumes about 70–95% of the total hydroperoxides. The decomposition of PPH yields a maximum of about 1.8 radicals. Samples prepared from crystalline and amorphous polypropylenes have identical decomposition kinetics.
65 citations
65 citations
TL;DR: The thermal decomposition of manganese, cobalt and nickel oxalate dihydrates in air and nitrogen atmospheres has been studied by TGA and DTA in this paper.
TL;DR: In this article, literature data on the thermal decomposition reactions of aliphatic nitro-compounds are surveyed and described systematically, and the influence of molecular structure on the rates and mechanisms of the gas phase reactions is presented and the structures of the transition states in the C-N dissociation and HNO2 elimination processes are examined.
Abstract: Literature data on the thermal decomposition reactions of aliphatic nitro-compounds are surveyed and described systematically. Information concerning the influence of molecular structure on the rates and mechanisms of the gas-phase reactions is presented and the structures of the transition states in the C-N dissociation and HNO2 elimination processes are examined. The characteristic features of the decomposition of nitro-compounds in the condensed phase are desctibed. Data are presented on the C-N bond dissociation energy and the influence on the latter of electronic, steric, and conformational effects. The bibliography includes 86 references.
TL;DR: In this article, the homogeneous gas-phase thermal decomposition of acetic acid has been studied in a static system between 460 and 595°C and at pressures up to 1 atmosphere.
Abstract: The homogeneous gas-phase thermal decomposition of acetic acid has been studied in a static system between 460 and 595°C and at pressures up to 1 atmosphere. A second-order decomposition to keten and water occurs simultaneously with a first-order process yielding methane and carbon dioxide, the respective Arrhenius equations being k= 108·45exp(–34,200/RT) l.mole–1 sec.–1 and k= 1011·12exp(–58,500/RT) sec.–1. The decarboxylation is similar to that previously reported in flow work at 770–920° but the dehydration processes are quite different. In the static system it closely resembles dehydration in formic and propionic acids.
TL;DR: In this paper, the thermal decomposition of di-tert-butyl peroxide in the presence of carbon dioxide at total pressures from 0.05 to 15'atm and temperatures from 90-130 °C was studied.
Abstract: The thermal decomposition of di-tert-butyl peroxide has been studied in the presence of carbon dioxide at total pressures from 0.05 to 15 atm and temperatures from 90–130 °C. The first-order rate c...
TL;DR: The thermal decomposition of ammonium perchlorate has usually been described in terms of chemical reactions with the point defect structure of the solid ignored as mentioned in this paper, however, the authors of this paper have shown that charge carriers play a significant role in the decomposition.
Abstract: The thermal decomposition of ammonium perchlorate has usually been described in terms of chemical reactions with the point defect structure of the solid ignored. Both the isothermal and adiabatic decompositions have been reinvestigated over the temperature range 200 to 450°C. There is a good correlation between the isothermal d. c. electrical conductance of single crystals, and of conductance as a function of temperature with the extent of decomposition, indicating that charge carriers play a significant role in the thermal decomposition. The study of the electrical conductivity as a function of temperature has resulted in the assignment of a probable defect structure to ammonium perchlorate: cationic Frenkel type below 250°C and Schottky disorder at higher temperatures. This suggests an explanation for the phenomenon of only 30% decomposition below 250°C and 100% above this temperature.
TL;DR: In this paper, the reaction of CuBr with methyl-and methoxyphenyllithium derivatives and the isolation of the o-tolyl-, m-to-lyl, p-toinglyl, and o-anisylcopper are described.
TL;DR: In this article, the thermal decomposition of 9 2,5-diaryltetrazoles at 165.8° has been determined manometrically and the pertinence of these results to the mechanism of cycloadditions of 1,3diarylnitrile imines is discussed.
TL;DR: In this article, the authors investigated the deflagration of RDX propellant at pressures up to 5000 psi under the influence of burning-rate modifiers and concluded that for the burning rate of nitramine propellants the physical conditions at the burning surface and its decomposition characteristics are of importance.
Abstract: The deflagration of RDX propellant has been investigated at pressures up to 5000 psi with various particle sizes of RDX and under the influence of burning-rate modifiers. The transition point for change in slope of the burning-rate curve is shifted to lower pressure by burning-rate retarders or by decreasing the particle size of the explosive. This effect is related to changes in the burning surface of the propellant. An increase in RDX particle size and/or burning-rate catalysts enhances the formation of surface depressions during burning. Burning-rate accelerators lower the decomposition temperature and the activation energy of the thermal decomposition of the propellant, whereas a burning retarder raises the decomposition temperature. It is concluded that for the burning rate of nitramine propellants the physical conditions at the burning surface and its decomposition characteristics are of importance.
TL;DR: In this article, the structure and thermal decomposition products of diethyl ether adsorbed on alumina have been studied by infrared spectroscopy and mass spectrometry, and two kinds of surface compounds were formed at different temperature ranges, when dehydrated alumina was exposed to dietyl ether vapor: a coordination complex, (C2H5)2OAl
TL;DR: Schuyler et al. as mentioned in this paper proposed a mechanism for the pyrolysis of nitrocellulose that is essentially the same as that presented earlier by Shafizadeh and Wolf rom.
Abstract: T derivation of a realistic theory of combustion and the understanding of the aging of nitrocellulose depend upon an adequate knowledge of the kinetic mechanism of thermal decomposition. This paper is directed towards understanding the initial bond-breaking step and how this results in the distribution of products observed under different experimental conditions. Schuyler has proposed a mechanism for the pyrolysis of nitrocellulose that is essentially the same as that presented earlier by Shafizadeh and Wolf rom and by Gelernter et al. It was assumed that the initial step involved the scission of the CO—N02 bond as "it is the weakest bond in nitrocellulose." If N02 split off from a nitrate ester group attached to a secondary carbon atom, then glyoxal and N02 were assumed to be the primary products. If scission of a nitrate ester group attached to a primary carbon atom occurred, then the primary products were assumed to be formaldehyde and N02. This scheme is the same as that advanced by Wolf rom. Consistent with the experimental findings of Phillips, Orlich, and Steinberg, it was assumed that loss of N02 led to the intermediate formation of a carbonyl group on the nitrocellulose residue. However, formic acid, C02, CO, and NO were also isolated as products in addition to glyoxal and formaldehyde. It was assumed that these products resulted from oxidation of formaldehyde and glyoxal by N02 in the vapor phase. A number of independent investigators have derived values for the parameters of the Arrhenius equation. The reported values of A and Ef the pre-exponential factor and activation energy, respectively, for the first-order thermal decomposition, are tabulated in Table 1. The agreement among the values determined by the different experimental techniques is very good. It is noteworthy that activation energy lies within the range of 43-46 kcal. The dissociation energy of the CO—NO2 bond is 36.4 to 39.5 kcal determined experimentally from the kinetics of thermal decomposition of simple nitrate esters in the vapor phase. Smith thought that the difference between the activation energies for the pyrolysis of nitrocellulose and that of the simple nitrate esters might be because the former was pyrolyzed in the solid state. He measured the rate of py-
TL;DR: In this paper, the thermal decomposition of 1,1-dimethyl-1-silacyclobutane has been investigated between 400 and 460° and the rate equation is given by k1(sec−1)= 1015·80 ± 0·20 exp(−63,800 ± 500/RT).
Abstract: The thermal decomposition of 1,1-dimethyl-1-silacyclobutane has been investigated between 400 and 460°. In this range the reaction is first order and homogeneous. Ethylene and 1,1,3,3-tetramethyl-1,3-disilacyclobutane are the only products. The rate equation is given by k1(sec.–1)= 1015·80 ± 0·20 exp(–63,800 ± 500/RT). The mechanism of the reaction is interpreted in terms of a reversible initial reaction to give an unstable intermediate containing a silicon–carbon double bond. Some reactions of this intermediate are investigated.
01 Jan 1968
TL;DR: In this article, differential thermal analysis was conducted in both helium and oxygen atmospheres on the thermal decomposition of wood, cellulose, and lignin, untreated and treated with 2 and 8 percent by weight of eight inorganic salts and an acid.
Abstract: : Differential thermal analysis was conducted in both helium and oxygen atmospheres on the thermal decomposition of wood, cellulose, and lignin, untreated and treated with 2 and 8 percent by weight of eight inorganic salts and an acid. Thermograms were obtained for the temperature ranges for endothermic and exothermic reactions, for the temperatures of maximum heat absorption or release, and for the heat intensities. These data combined with results of a previous work utilizing thermogravimetric analysis provide additional information on the characteristics of thermal decomposition. In particular, these data show that the net heat of pyrolysis for untreated and treated cellulose is endothermic. The heat of pyrolysis for both wood and lignin is initially endothermic and later becomes exothermic. However, the net exothermic heat of pyrolysis for wood is only about 2 percent of the heat of combustion. The heat of combustion from wood is released by flaming of the volatiles with a maximum release at about 310C and a glowing of the solids with a second maximum release at about 440C. The influence of the several types of effective and ineffective fire-retardant salts on the initial temperature of volatilization, rate of decomposition and heat release, transition temperatures of volatilization and heat release, and maximum heat intensities are also related by this work to theories that have been developed concerning the retarding of flaming and glowing reactions of wood and its components. (Author)
TL;DR: The influence of various soap and monomers on the rate of thermal decomposition of potassium peroxydisulphate has been investigated in this paper, and it was found that all investigated compounds, except a fully fluorinated soap, caused marked increases in the rate or peroxysulfate disappearance.
Abstract: The influence of various soaps and monomers on the rate of thermal decomposition of potassium peroxydisulphate has been investigated It was found that all investigated compounds, except a fully fluorinated soap caused marked increases in the rate or peroxydisulphate disappearance This finding should be considered in studies on the kinetics of polymerization in which peroxydisulphate is the initiator
Es warde der Einflus von verschiedene Seifen monomern auf die Geschwindigkeit des thermischen Zerfalles von Kaliumperoxydisulfat untersucht Gefonden wurde, das alle untersuchten Verbindungen, ausgrenommen eine vollsandig fluorierte Seife, eine bedeutende Zunahme in der Geschwindigkeit des Verschwindens von Peroxydisulfat verursachen Dieser Befund sollte bei allen kitnetischen Untersuchungen bei welchen das Peroxydisulfat als Initiator benutzt wird, berucksichtigt werden
TL;DR: In this article, thermal decomposition profiles and enthalpies of decomposition of lanthanide chloride hydrates were obtained using a differential scanning calorimeter, and the results were compared with those of other workers.
Abstract: Thermal decomposition profiles and enthalpies of decomposition of lanthanide chloride hydrates have been obtained using a differential scanning calorimeter. The results are compared with those of other workers.
TL;DR: In this paper, the rates of the thermal decomposition of t-butyl methyl ether have been measured in the range 433-495o and the reaction products are isobutene and methanol, and the kinetic form is first order.
Abstract: The rates of the thermal decomposition of t-butyl methyl ether have been measured in the range 433-495o. The reaction products are isobutene and methanol, and the kinetic form is first order. The Arrhenius equation K1 = 1014.38exp(-61535/RT) sec-1 describes the variation of rate with temperature. The reaction behaviour is consistent with a unimolecular mechanism. Comparison of the results with those obtained for the production of isobutene from various t-butyl compounds indicates that the reaction has some degree of heterolytic character.