Showing papers on "Thermal decomposition published in 1969"
TL;DR: In this article, the formation of impermeable glasslike carbon by thermal decomposition of 3-dimensionalally crosslinked polyfurfuryl alcohol, phenolic resin, and mixtures thereof was found to be independent of the chemical structure of these resins.
198 citations
TL;DR: Two distinct products can be obtained on the thermal decomposition of ammonium zeolite Y at 760 torr and 500 °, where the geometry of the ammonium bed during calcination determines the nature of the product.
176 citations
TL;DR: Luminescence was observed during the thermal decomposition of 3,3,4trimethyl-1,2-dioxetane to acetone and acetaldehyde.
Abstract: Luminescence is observed during the thermal decomposition of 3,3,4-trimethyl-1,2-dioxetane to acetone and acetaldehyde The wavelength maximum of the luminescence is at 430–440 mμ when the decompos
171 citations
TL;DR: The thermal decomposition of polyvinyl alcohol is known to occur in two stages as mentioned in this paper, and the main products were water, aldehydes having the general formula and methyl ketones having the formula, where n = 0, 1, 2, 3, etc.
Abstract: The thermal decomposition of poly(vinyl alcohol) is known to occur in two stages. In a study of first-stage decomposition, this polymer was pyrolyzed in vacuum at 240°C for 4 hr and the products were determined by using gas chromatography. The main products were water, aldehydes having the general formula and methyl ketones having the formula , where n = 0, 1, 2, 3, etc. Mechanisms for the formation of these carbonyl compounds are discussed.
151 citations
TL;DR: In this paper, a detailed mechanism for the chemical decomposition of ammonium perchlorate is proposed, which is adaptable to a wide range of conditions; to the low-temperature decomposition, to combustion, to the catalysed decomposition and to decomposition under various reactive gases.
138 citations
75 citations
TL;DR: The transition between the random layer order of amorphous carbons and the three-dimensional layer structure of graphite, first defined by the classical work of Franklin, has stimulated interest in the preparation of perfectly crystalline graphites, especially by the thermal decomposition of gases as mentioned in this paper.
Abstract: THE transition between the “random layer order”1 of amorphous carbons and the three-dimensional layer structure of graphite, first defined by the classical work of Franklin2, has stimulated interest in the preparation of perfectly crystalline graphites, especially by the thermal decomposition of gases. These carbonaceous products, however, begin to show a significant degree of three-dimensional layer ordering only at deposition temperatures of 2,000° C to 2,500° C (refs. 3–5). For pyrolytic carbons to possess structural properties comparable with those of natural graphite, it is necessary to carry out “stress recrystallization” at about 3,000° C under 400 atmospheres pressure, followed by annealing at 3,400° C (see ref. 6).
72 citations
01 Apr 1969
TL;DR: Granular ammonium perchlorate thermal decomposition analyzed by cinemicrography as discussed by the authors, discussing sublimation role and the role of sublimations in the decomposition.
Abstract: Granular ammonium perchlorate thermal decomposition analyzed by cinemicrography, discussing sublimation role
64 citations
62 citations
59 citations
TL;DR: In this paper, rate constants for the main bond breaking step have been found for the thermal decomposition of all the hydrocarbons formed from any pair of the following radicals: methyl, t-amyl, benzyl, methylallyl, n-propyl, s-butyl, isobutyl, neopentyl, and 3-pentyl radicals.
Abstract: Several hydrocarbons have been pyrolyzed in a single pulse shock tube. Rate parameters for the main bond breaking step have been found to be
In combination with similar studies carried out earlier and through application of the well-established experimental rule (k(AB)/kr(AA)kr(BB))1/2 ∼ 2 where A and B are radicals and the rate constants are for the combination of these radicals, rate parameters for the thermal decomposition of all the hydrocarbons formed from any pair of the following radicals: methyl, ethyl, isopropyl, t-butyl, t-amyl, allyl, methylallyl, and benzyl have been calculated. The available calculated and experimental values of the decomposition rate constants are in excellent agreement. It appears that, with the possible exception of reactions involving the ejection of methyl radicals, the frequency factors per bond are nearly constant, depending only upon the type of carbon–carbon bond that is being broken. These values are all lower than those expected from the radical recombination rates.
Heats of formation of ethyl, t-amyl, benzyl, methylallyl, n-propyl, s-butyl, isobutyl, neopentyl, and 3-pentyl radicals have been derived.
Rate parameters for the decomposition of some simple ketones and ethers have also been estimated.
TL;DR: In this article, the homogeneous thermal decomposition of acetic acid has been studied between 530 and 762° in a flow system, and the process is first-order: k= 1012·45 exp(−64,890/RT) sec.
Abstract: The homogeneous thermal decomposition of acetic acid has been studied between 530 and 762° in a flow system. Below 600° dehydration is second-order: k= 109·52 exp(–39,300/RT) l. mole–1sec.–1, but the order falls and the Arrhenius plot curves upwards above this temperature. Above 700°, the process is first-order: k= 1012·45 exp(–64,890/RT) sec.–1. Decarboxylation, however, is first-order throughout the range: k= 1013·59 exp(–69,800/RT) sec.–1. All processes are molecular.
TL;DR: In this paper, the photo-oxidation of PVC has been studied over the temperature range 30 −150°C and the contribution of atomic oxygen and singlet oxygen (1Δg) molecules to the initiation mechanism is discussed.
Abstract: The photo-oxidation of PVC has been studied over the temperature range 30–150°C. Initiation with ultraviolet (2537A) radiation has been correlated with the presence of minute amounts of ozone. The contribution of atomic oxygen and singlet oxygen (1Δg) molecules to the initiation mechanism is discussed. The β-chloroketones probably formed in the photo-oxidation of PVC, decomposed according to a Norrish type I reaction without loss of chlorine atoms. The gaseous products of the photo-oxidation of PVC at 30°C were carbon dioxide, carbon monoxide, hydrogen, and methane. Hydrogen chloride was obtained only when PVC was heated at high temperatures. When PVC was photo-oxidized and then heated at high temperature, benzene was obtained in addition to hydrogen chloride. The gaseous products from the photo-oxidations of model compounds, such as 4-chloro-2-butanone and 2,4-dichloropentane, were also compared with those from PVC. Hydrogen chloride was detected only after photo-oxidation at temperatures of 25°C or higher. Therefore, it was concluded that hydrogen chloride is mainly a product of thermal decomposition. Since unsaturation was not observed in photo-oxidized PVC films, the cause of discoloration is unclear. When PVC was modified by stabilizers or additives, the oxidative degradation was further complicated by side reactions with the additives.
TL;DR: In this paper, the thermal decomposition of D-glucose has been studied in vacuo at 175-275°C. Mechanisms for dehydration and fragmentation processes are discussed.
Abstract: The thermal decomposition of D-glucose has been studied in vacuo at 175–275°C. The products were analyzed and their origin involving the various carbon atoms was studied, using glucose samples labelled at various positions with 14C. Mechanisms for dehydration and fragmentation processes are discussed.
TL;DR: In this article, it was found that the elementary stages of the thermal decomposition of permanganate, which is a semiconductor of the n-type, are associated with electron transition from one anion site to another.
TL;DR: In this paper, the thermal decomposition of cellulose in vacuo at 250,275 and 300°C was studied and the decomposition products appearing in different fractions were analyzed and the product ratios at different stages of the reaction were determined.
Abstract: The thermal decomposition of cellulose in vacuo at 250,275 and 300°C was studied. The decomposition products appearing in different fractions were analyzed and the product ratios at different stages of the reaction were determined. A general scheme is proposed for the process.
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TL;DR: The tetra-allyl Uranium obtained from UCl4 and C3H5 Mg Br is not thermally stable above −20°C and burns spontaneously in the air as discussed by the authors.
TL;DR: Arylmercuric arenesulphinates, such as PhHg(SO2Ph), p-MeC6H4Hg (SO2-p-meC6h4hg) as discussed by the authors, have been obtained by reaction of mercuric benzenesulphinate or p-toluenesulphine with the appropriate diarylmercury compound in chloroform or methanol.
Abstract: The arylmercuric arenesulphinates, PhHg(SO2Ph), p-MeC6H4Hg(SO2-p-MeC6H4), PhHg(SO2-p-MeC6H4), p-MeC6H4Hg(SO2Ph), and C6F5Hg(SO2Ph), have been prepared by reaction of mercuric benzenesulphinate or p- toluenesulphinate with the appropriate diarylmercury compound in chloroform or methanol, and the first three compounds have also been obtained by reaction of liquid sulphur dioxide with diphenylmercury, di-p-tolylmercury, or phenyl-p-tolylmercury. Linkage isomers of phenylmercuric benzenesulphinate have been prepared. Isomer A, obtained from chloroform-pentane, is considered to be a monomeric O-sulphinato complex, and isomer B, obtained from cold acetone, methyl ethyI ketone, or methanol, to be an S-sulphinato complex. The isomers are readily interconverted. In chloroform, deuterochloroform, and acetone, at room temperature, only the O-sulphinato complex can be detected. The other arylmercuric arenesulphinates have the same structure as isomer A. Linkage isomers could not be isolated for these derivatives. However, there is evidence that p-MeC6H4Hg(SO2Ph) slowly isomerizes in the solid state to give the corresponding S-sulphinato complex. Thermal decomposition of PhHg-(SO2Ph) (both isomers), p-MeC6H4Hg(SO2-p-MeC6H4), PhHg(SO2-p-MeC6H4), and p-MeC8H4Hg(SO2Ph) gives sulphur dioxide and the corresponding diarylmercurycompound.
TL;DR: In this paper, a mass spectrometric study of gas reactions in reflected shock waves is described, which has been applied to the thermal decomposition of 2% N2O in Kr at total gas co...
Abstract: Apparatus for the mass spectrometric study of rapid gas reactions in reflected shock waves is described. This apparatus has been applied to the thermal decomposition of 2% N2O in Kr at total gas co...
TL;DR: Aromatic pinacols are capable of starting the free radical polymerization of vinyl compounds as mentioned in this paper, which is initiated mainly by hydrogen atoms stemming from the diarylhydroxymethyl radicals formed through the thermal decomposition of the initiator.
Abstract: Vinylverbindungen lassen sich durch aromatische Pinakole radikalisch polymerisieren. Die Polymerisationsauslosung erfolgt hauptsachlich durch Wasserstoffatome, die aus den primar beim thermischen Zerfall des Initiators entstehenden Diarylhydroxymethyl-Radikalen gebildet werden.
Aromatic pinacols are capable of starting the free radical polymerization of vinyl compounds. The free radical polymerization is initiated mainly by hydrogen atoms stemming from the diarylhydroxymethyl radicals formed through the thermal decomposition of the initiator.
TL;DR: The thermal decomposition of sodium dithionite in aqueous solution has been followed by means of e.p.r. signal intensity measurements, and two different reactions have been identified.
Abstract: The thermal decomposition of sodium dithionite in aqueous solution has been followed by means of e.p.r. signal intensity measurements. Two different reactions have been identified. The first one, catalyzed by bisulphite ion, proceeds according to the usual second-order autocatalytic reaction mechanism. The second one, much faster than the first one, appears after an induction period and ends as soon as a sufficient amount of decomposition product has been formed. Using previously reported values for the equilibrium constant for dithionite ion dissociation, values for the rate constant of the autocatalytic reaction are reported, and a mechanism for the decomposition is proposed.
TL;DR: In this paper, the authors have studied the lubrication of heavily loaded sliding copper contacts by a low viscosity (10 cSt) dimethylsilicone fluid containing a small quantity of a fatty acid surfactant (stearic acid).
TL;DR: In this paper, the decomposition of a cured polyimide resin (Skybond 700) was studied in detail using simultaneous mass spectral and differential thermal analysis, complemented with kinetic studies of the polymer and selected model imides.
Abstract: The decomposition in vacuum of a cured polyimide resin (Skybond 700) was studied in detail using simultaneous mass spectral and differential thermal analysis. These data were complemented with kinetic studies of the polymer and selected model imides. The mechanisms involved in the decomposition of Skybond 700 at moderate temperatures were determined using the combined results. It was discovered that the major endotherm seen in the thermogram was due to three simultaneous reactions: 1) Rupture of the benzophenone carbonyl bond to yield CO, 2) rupture of the imide bond to yield CO, and 3) rupture of the imide bond to yield CO2. Reaction 3 is in conflict with previous studies where CO2 was reported to arise from impurities in the polymer. The imide linkage as a source of C02 was substantiated by studying the degradation of model imide compounds. The decomposition rate of each of the models, in the vapor phase, was found to be first order, as was the rate of formation of CO2. It was then postulated t...
TL;DR: In this paper, a brief investigation has been carried out into the nature and quantity of the toxic gases evolved during the thermal decomposition of polyurethane, urea-formaldehyde, nylon and acrylonitrile in air and in nitrogen.
Abstract: A brief investigation has been carried out into the nature and quantity of the toxic gases evolved during the thermal decomposition of polyurethane, urea-formaldehyde, nylon and acrylonitrile in air and in nitrogen. The weight fractions of the polymers evolved as hydrogen cyanide are given, together with the lowest temperatures at which hydrogen cyanide, carbon monoxide, ammonia and nitrogen oxides are evolved. Apparent activation energies for the evolution of hydrogen cyanide and carbon monoxide have been determined. A brief discussion of the experimental data is given.
TL;DR: In this paper, a series of organic ammonium ions were exchanged onto clay minerals montmorillonite and hectorite and thermal effects on these surface modified organic-inorganic complexes were investigated by means of differential thermal analysis and heating-oscillating X-ray diffraction methods.
Abstract: A series of organic ammonium ions were exchanged onto clay minerals montmorillonite and hectorite. Thermal effects on these surface modified organic-inorganic complexes were investigated by means of differential thermal analysis and heating-oscillating X-ray diffraction methods. It was found that the organo-clay complexes were dehydrogenated at temperatures from 180 to 350°C, depending on the organic cation used. Following the dehydrogenation, hydrolysis took place leaving a layer of “carbon” on the clay surface. The “carbon” was then oxidized at a temperature of about 550°C. Investigation of possible correlations between the activation energy of dehydrogenation and basicity, boiling point, ionization potential, molecular structure, and carbon-carbon bond distances of the organic cations showed that the geometric factors outweighed the acid, chemical and electronic factors in determining the effect of montmorillonite and hectorite toward the dehydrogenation of organic ions exchanged on the surfaces of these clay minerals.
TL;DR: In this paper, the thermal dissociation of COS was investigated in shock waves with argon as carrier gas, the concentration was varied between 0.05 and 0.5% COS in argon.
Abstract: The thermal dissociation of COS was investigated in shock waves with argon as carrier gas. The concentration was varied between 0.05 and 0.5% COS in argon, the total density from 2.5 × 10−5 mole/cm3 to 2.5 × 10−3 mole/cm3. Temperatures between 1500°K and 3100°K were applied.
For the reaction
the rate constant was found to be
in the low pressure range of the unimolecular reaction and
in the high pressure range.
TL;DR: In this article, the apparent kinetic parameters of the pyrolysis reaction have been derived by means of the modified Doyle method, which do not characterize the purely chemical reaction, but the complex heterogeneous process as a whole.
Abstract: Thermal decomposition of 21 complexes of the type [Co(DH)2(amine)2]NCS has been studied under the conditions of thermogravimetric analysis, by using different heating rates. From the thermogravimetric curves apparent kinetic parameters of the pyrolysis reaction have been derived by means of the modified Doyle method. Apparent reaction order increases and apparent activation energy decreases with increasing heating rate. Thus, the obtained kinetic parameters do not characterize the purely chemical reaction, but the complex heterogeneous process as a whole. The explanation of the observed effect is discussed. Results are compared with those obtained with other analogous complexes.
01 Nov 1969
TL;DR: In this article, a calorimetric study of first order transitions in the specific heat of PVC was performed and the results showed that various types of commercial PVC exhibit a melting range which starts at about 150 °C and extends into the thermal decomposition region.
Abstract: A calorimetric study of first order transitions in the specific heat of PVC is reported. The results show that various types of commercial PVC exhibit a melting range which starts at about 150 °C and extends into the thermal decomposition region. A heat of fusion of 750 cal/mole was calculated from the melting energy and the change in density upon melting. A similar melting range starting at 180 °C was found in PVC polymerized at −30 °C. Once melted, this primary cristallinity does not reappear after annealing. It can be restored by dissolution and subsequent careful precipitation.
TL;DR: In this paper, the diamide, Yb(NH 2 ) 2, is the predominant decomposition product of liquid ammonia solutions of ytterbium metal, and the processes leading to formation of diamide and triamide are examined, and why the differences in both the decomposition of the metal solutions and the thermal decomposition products occur.
Abstract: At −50 °C, the diamide, Yb(NH 2 ) 2 , is the predominant decomposition product of liquid ammonia solutions of ytterbium metal. Europium metal solutions decompose to form the diamide exclusively at −50 °C. Thermal decomposition leads to the imide, EuNH, for europium, and the nitride, YbN, for ytterbium. The heats of solution of europium and ytterbium in liquid ammonia are calculated to be −20.9 and −19.4 kcal/g.-at., respectively. The processes leading to formation of the diamide and triamide are examined, and it is shown why the differences in both the decomposition of the metal solutions and the thermal decomposition products occur.