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Showing papers on "Thermogravimetric analysis published in 1974"


Journal ArticleDOI
TL;DR: In this article, thermogravimetric curves of the thermal decomposition of CaCO3 reported in the literature have been analyzed and kinetic parameters have been derived by means of Coats and Redfern's method.
Abstract: Fifteen thermogravimetric curves of the thermal decomposition of CaCO3 reported in the literature have been analysed and kinetic parameters have been derived by means of Coats and Redfern's method. The activation energy varies between 26 and 377 kcal/mole, and the pre-exponential factors between 102 and 1069, as functions of the working conditions. The kinetic compensation effect has been observed, and the results are well described by the following empirical compensation law: logZ=0.195E− 1.86.RésuméOn a calculé les paramètres cinétiques de la décomposition thermique de CaCO3 en suivant la méthode de Coats et Redfern et en utilisant 15 courbes thermogravimétriques publiées dans la littérature. L'énergie d'activation varie entre 26 et 377 kcal/mol, les fac teurs préexponentiels entre 102 et 1069, suivant les conditions opératoires. On a observé l'effet de compensation cinétique et les résultats peuvent être décrits par la loi empirique suivante: logZ=0.195E − 1.86.ZusammenfassungFünfzehn, in der Literatur veröffentlichte thermogravimetrische Kurven der thermischen Zersetzung des CaCO3 wurden analysiert und kinetische Parameter unter Anwendung der Methode von Coats und Redfern abgeleitet. Die Aktivierungsenergie schwankt zwischen 26 und 377 kcal/Mol, die prä-exponentiellen Faktoren zwischen 102 und 1069, je nach den Arbeitsbedingungen. Der kinetische Kompensationseffekt wurde beobachtet und die Ergebnisse lassen sich mit dem folgenden empirischen Kompensationsgesetz gut beschreiben: logZ=0.195E− 1.86.РезюмеПроанализированы 15 те рмогравиметрически х кривых термораспада СаСО3, опубликованных в литературе, и по мето ду Котса и Редферна рассчитан ы кинетические параметры в зависимо сти от условий экспер имента. Энергия активации ко леблется между 26 и 377 ккал/мол, преэ кспоненциальные фак торы —между 102 и 1069. Наблю дается эффект кинетической компенсации и резуль таты удовлетворительно о писываются следующим эмпиричес ким законом компенса ции: logZ=0,195E − 1,86.

105 citations


Journal ArticleDOI
TL;DR: In this paper, the thermogravimetric measurements combined with mass-spectrometric analysis were used to analyze the thermal behavior of polystyrene polymers with pendent phosphonate groups in the presence of etheral solvents.
Abstract: Soluble chloromethylated polystyrene and its copolymers with vinylidene chloride as well as poly(phenyl oxides) brominated in the side chains and in the ring were synthesized and characterized in detail by NMR. The halogenated polymers were phosphonylated with alkyl phosphites. Uncrosslinked polymers with pendent phosphonate groups were prepared in the presence of etheral solvents, which solvate the ionic intermediates of the Arbuzov reaction. These polyphosphonates are highly hygroscopic and are soluble in a variety of solvents. Their Tg's are in the range of 50–175°C. Their thermal behavior was analyzed on the basis of thermogravimetric measurements combined with mass-spectrometric analysis. Poly(styrene phosphonate) seems to be the most stable, and its thermal decomposition starts at ∼330°C. The polymeric phosphonates are compatible with an unusually large number of polymeric systems and seem to form “true” polymeric alloys with acetylcellulose.

71 citations


Journal ArticleDOI
TL;DR: In this paper, two-component interpenetrating polymer networks (IPN) of the SIN type were prepared from three different polyurethanes and two epoxies, which showed significant improvement in thermal resistance, as measured by thermogravimetric analysis.
Abstract: Two-component interpenetrating polymer networks (IPN) of the SIN type (simultaneous interpenetrating networks) were prepared from three different polyurethanes and two epoxies. The linear prepolymers were combined in solution, together with crosslinking agents and catalysts, films cast, and subsequently chain extended and crosslinked in situ. Two of the IPN's showed significant improvement in thermal resistance, as measured by thermogravimetric analysis (TGA). All of the IPN's showed maxima in tensile strength significantly higher than the tensile strengths of the component networks at 25% polyurethane and minima at 75% polyurethane. The minima were explained by an initial dilution of the strong polyurethane hydrogen bonds by the epoxies, and the maxima, by an increase in crosslink density due to interpenetration.

61 citations


Journal ArticleDOI
TL;DR: In this article, the thermal decomposition of ferrous oxalate dihydrate FeC2O4.2H2O has been investigated using thermogravimetric (TG), DTG, differential thermal analysis (DTA), X-ray diffraction and infra-red spectroscopic techniques.
Abstract: The thermal decomposition of ferrous oxalate dihydrate FeC2O4.2H2O, has been investigated using thermogravimetric (TG), differential thermogravimetric (DTG), differential thermal analysis (DTA), X-ray diffraction and infra-red spectroscopic techniques. The DTA data obtained in air consist of an endothermic dehydration peak at ∼ 190‡ C and two exothermic peaks at ∼ 245 and ∼ 360‡ C. The first exotherm corresponds to the primary oxidative decomposition while the second one seems to be due to a structural transformation from a disordered or non-crystalline to a crystalline state ofα-Fe2O3. Similar experiments carried out using a nitrogen atmosphere show an endothermic peak ∼ 190‡ C followed immediately by an exothermic peak at 240‡ C. The final product of this decomposition has been identified as Fe3O4. The oxalate dihydrate containing traces of moisture decomposes in air under the ambient of its own gaseous products at ∼ 300‡ C to giveγ-Fe2O3. This compound has been characterized by X-ray diffraction and magnetic hysteresis measurements.

58 citations


Journal ArticleDOI
TL;DR: In this paper, structural and thermal properties have been examined as a function of composition throughout the glass forming region of the AsTe binary system, and evidence is presented to support the conclusion that a new face-centered cubic crystalline structure has the binary stoichiometry AsTe.

54 citations


Journal ArticleDOI
TL;DR: The kinetic parameters associated with the thermal decomposition of native collagen have been obtained by thermogravimetric techniques and it is believed that the first and the second peaks are results of: dissociation of water from collagen, and of breaking of the collagen molecule itself.
Abstract: The kinetic parameters associated with the thermal decomposition of native collagen have been obtained by thermogravimetric techniques. In order to achieve this a thermogravimetric analysis was carried out in the temperature range of 25°C to about 1000°C. In this temperature range, it had been found that the differential primary weight loss curve had yielded three distinct peaks for the tendon collagen. The thermal decomposition corresponding to each peak was analyzed to retrieve its kinetic parameters. The peak temperature associated with the first peak decreased as the water content in a sample increased, while that of the second peak was independent of its hydration condition. It is believed that the first and the second peaks are, respectively, results of: (1) dissociation of water from collagen, and (2) of breaking of the collagen molecule itself. The third peak has not been easily identified so far. The activation energy and the order of water decomposition are obtained by various known methods. The results obtained by these different approaches agree reasonably well. The kinetic parameters of second and third peak are also obtained and reported here.

41 citations



Journal ArticleDOI
TL;DR: An oxide phase which is isostructural with PdO has been obtained as a thin film by reactive dc diode sputtering of Pt in argonoxygen mixtures as discussed by the authors.
Abstract: An oxide phase which is isostructural with PdO has been obtained as a thin film by reactive dc diode sputtering of Pt in argon‐oxygen mixtures. Films in which this is the only crystalline phase observed have been prepared; they have a density of 13.5±1.0 g/cm3. The oxide phase is unstable at temperatures above 500 °C, and the film is converted to platinum. Thermogravimetric analysis of the films indicates that the original composition is close to PtO. Mixtures of PtO and Pt can also be obtained and the temperature coefficient of resistance of the films becomes more negative with increasing PtO content; values between +1800 and −25 000 ppm/°C have been measured.

38 citations


Journal ArticleDOI
TL;DR: In this paper, the first estimated PtC bond strength for platinum-trimethylene complexes has been reported, where the authors used differential scanning calorimetry and thermogravimetric analysis.

36 citations


Journal ArticleDOI
TL;DR: A thermogravimetric apparatus for the determination of vapour pressures by means of the Knudseneffusion method, between room temperature and 1750 K, is described in this paper.

32 citations


Journal ArticleDOI
TL;DR: In this paper, a high temperature thermogravimetric study of physicochemical equilibria between a gaseous oxidoreducing phase and oxide sample has been performed.

Journal ArticleDOI
TL;DR: In this paper, the thermal decomposition of polystyrene, polyoxyethylene glycol and mixtures of the two have been studied by thermogravimetry and gel permeation chromatography.


Journal ArticleDOI
01 Jun 1974-Polymer
TL;DR: In this paper, the thermal degradation of polyvinyl alcohol was investigated using thermogravimetric analysis, infra-red spectroscopy and gas chromatography, and the cis-β-elimination mechanism of the phosphorus ester group was proposed for the accelerated dehydration.

Journal ArticleDOI
TL;DR: In this article, Li2N2O was obtained by the reaction of Li2CeN2 and Li2O or CeN and CeO2, which was found to be isostructural with the known nitride Li2ZrN2.
Abstract: The solid-state reactions of lithium nitride with Ce, Th, Hf and CeN, ThN, and HfN have been followed by differential thermal analysis, thermogravimetric analysis, and X-ray powder diffraction methods. Reaction with the metals was found to proceed by formation of the mononitride with the ternary nitride Li2MN2 as the final product. The compound Ce2N2O was obtained by the reaction of Li2CeN2 and Li2O or CeN and CeO2. The reaction of lithium nitride with hafnium gave the ternary nitride Li2HfN2 which is found to be isostructural with the known nitride Li2ZrN2.

Journal ArticleDOI
TL;DR: In this article, some phenomena occurring during the atomization of metal tetramethylene dithiocarbamates (MeTMDTC) in the graphite-tube furnace were observed.


Journal ArticleDOI
TL;DR: In this article, the authors used chromatographic, infrared and mass spectrometric methods to identify 44 different organic compounds, besides water and ammonia, from the pyrolysis products of nickel(II) aniline nitrate hydrate.

Journal ArticleDOI
TL;DR: In this article, the thermal decomposition of (UO2)3(PO4)2 and U(HPO4) 2 ·xH2O in the temperature range 25-1600
Abstract: The thermal decomposition of (UO2)3(PO4)2 and U(HPO4)2 ·xH2O in the temperature range 25–1600‡, was investigated.

Journal ArticleDOI
01 Jan 1974
TL;DR: In this article, the thermal decomposition in vacuum of three different dolomite specimens was monitored by recording infrared spectra of the samples at various stages of decomposition, which indicated that at 500 and 600°C the dolomsites decomposed in one step to form oxides; near 700°C, an oxide mixture containing a small amount of calcite was formed.
Abstract: The thermal decomposition in vacuum of three different dolomite specimens was monitored by recording infrared spectra of the samples at various stages of decomposition. Thermogravimetric analysis showed that the dolomite decomposition in vacuum could occur near 500°C. The complex spectra, which showed the bands due to the internal modes of the carbonate ion as well as combinations of the internal modes with lattice vibrations, indicated that at 500–600°C the dolomites decomposed in one step to form oxides; near 700°C, an oxide mixture containing a small amount of calcite was formed. Spectra were also recorded after calcined specimens had been exposed to water at 25°C. The results suggest that if a sample was decomposed in vacuum at relatively low temperature, the initial product of the decomposition was a mixed (Ca, Mg)O which would then break up to form CaO and MgO microcrystals.

Journal ArticleDOI
TL;DR: In this paper, samples of powdered zeolite A (sodium form) were examined by thermogravimetric (TG), thermomechanical (TMA) and differential thermal analyses (DTA).

Journal ArticleDOI
TL;DR: In this paper, the carboxypeptidase A was crosslinked with glutaraldehyde, and samples of the enzyme and apoenzyme were examined by thermogravimetric, dif- ferential thermal and thermomechanical analyses.

Journal ArticleDOI
TL;DR: In this article, a pyrolyzer with programming capability was coupled with a thermal conductivity cell and a mass chromatograph for thermal degradation of low-density polyethylene.
Abstract: A pyrolyzer with programming capability has been coupled in series with a thermal conductivity cell and a mass chromatograph. The thermal conductivity cell gives the flexibility for selective trapping of decomposition products, and also provides data that are complementary to thermogravimetric and differential thermal analyses. The mass chromatograph is composed of two gas chromatographs that are run parallel from a common injection port. Each chromatograph uses a different carrier gas and is equipped with a gas density balance detector. The instrument simplifies identification of mixtures of unknowns in directly providing molecular weights, absolute quantities, and gas chromatographic retention times of the constituents. In this respect, the present system is analogous to pyrolysisgas chromatography-mass spectrometry. Discussion of the technique and its application to the investigation of the thermal degradation of low-density polyethylene are presented.

Journal ArticleDOI
TL;DR: In this paper, the authors used derivative thermogravimetric analysis (TGA) to estimate the degree of thermal degradation which has taken place in complex parts composed of cellulosics and polymeric insulation unless complete failure has occurred.
Abstract: It is difficult to estimate the degree of thermal degradation which has taken place in complex parts composed of cellulosics and polymeric insulation unless complete failure has occurred. There is a definite need for a parameter which can quickly and easily measure the relative degree of thermal attack on organic insulation subjected to various known environmental and processing conditions. This paper reports preliminary work using derivative thermogravimetry to perform this function. Derivative thermogravimetric analysis (TGA) was used to produce a value, TGA Index, related to the peak height of the major TGA derivative signal. This TGA Index was found to correlate with the copper number of insulating paper measured after thermal degradation. The application of TGA Index to evaluation of polymer degradation after thermal shock, water absorption, and accelerated UV attack is also discussed. Finally, preliminary studies on the use of derivative TGA to evaluate coatings exposed to various outdoor e...

Journal ArticleDOI
TL;DR: In this article, acrylic acid has been grafted to polyethylene terephthalate (PET) by mutual irradiation, and the resulting copolymers converted to their sodium, calcium and lead salts.

Journal ArticleDOI
TL;DR: The thermal stability of radiation-grafted poly(vinyl chloride) (PVC) has been investigated by thermogravimetric analysis as discussed by the authors, and it has been suggested that the retardation effect is due to the interruption of the propagation of dehydrochlorination by branch sites produced by the radiation process.
Abstract: The thermal Stability of radiation-grafted poly(vinyl chloride) (PVC) has been investigated by thermogravimetric analysis and compared with the thermal stability of the corresponding PVC polymer blends. Although both the grafting of methyl methacrylate and styrene and the blending of the corresponding homopolymers yield products of improved thermal stability as compared with unmodified PVC, the radiation grafting is somewhat more efficient for the stabilization of PVC than blending. Further, the rate of dehydrochlorination of PVC–g–styrene at relatively high temperatures exhibits a retardation, whereas that of unirradiated PVC show significant acceleration. A detailed study about a series of PVC–g–styrenes polymerized under various conditions shows that the retardation effect is more noticeable in the samples irradiated to 2.0–3.0 Mrad than in those irradiated to less than 1.0 Mrad. From the dose dependency, it has been suggested that the retardation effect is due to the interruption of the propagation of dehydrochlorination by branch sites produced by the radiation process. On the other hand, the graft copolymers of vinyl pyridines, PVC-poly(vinyl pyridine), and PVC irradiated in the presence of pyridine are much less stable than unmodified PVC. The instability is explained in terms of the substitution reaction with the bases and the base-catalyzed dehydrochlorination of PVC.


01 Jan 1974
TL;DR: In this paper, the Bureau of Mines through contract with Ultrasystems, Inc., obtained gram per gram data of products formed on thermal oxidative degradation of selected compositions, both under dynamic and static conditions.
Abstract: : The Bureau of Mines through contract with Ultrasystems, Inc., obtained gram per gram data of products formed on thermal oxidative degradation of selected compositions, both under dynamic and static conditions. Four broad classes of materials were studied: Polyvinyl chloride compositions, neoprene compositions, rigid urethane foams, and variously treated woods. Whenever possible, comparisons between pure components and composites were attempted. Thermogravimetric and differential thermal analyses were performed to gain understanding of the processes occurring and to explore the feasibility of using these analyses as a method of material identification. The toxic products detected and quantitated included HCl, H2S CO, SO2, CS2, COS, HCOOH, CH3COOH, formaldehyde, acrolein, C6H6 , chloroprene, chloroethanol, benzyl chloride, aniline, and furfural.


Book ChapterDOI
01 Jan 1974
TL;DR: In this paper, a polarizing microscope was used to study the condensed phase behavior of propellants and some of the phenomena associated with this condition for nitrocellulose, catalyzed and uncatalyzed materials were elucidated.
Abstract: Methods were devised for using a polarizing microscope to study the condensed phase behavior of propellants. Some of the phenomena associated with this condition for nitrocellulose, catalyzed nitrocellulose, and double base propellant both with and without catalysts was elucidated. At the same time techniques of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and thin layer chromatography (TLC) were brought to bear on the problem. Optically and thermally measurable differences in catalyzed and uncatalyzed materials tended to be small and were probably not as great, for instance, as is to be found with certain cases of composite propellants. Nevertheless, clues were obtained as to ways the catalysts were affecting condensed phase behavior. Unraveling these problems fully remains a formidable task.