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1.
The thermal decomposition of some Ni(II)-carboxylate-imidazole complexes in a nitrogen atmosphere was studied non-isothermally.
From the non-isothermal thermoanalytical data, it was found that these complexes decompose through a stepwise release of imidazole
molecules and/or CO ones forming unstable intermediates which produce metal oxide or the metal as a final decomposition product.
TG in conjunction with DTG were used to evaluate the kinetic and thermodynamic parameters of the decomposition reaction. The
kinetic studies were performed employing a computer-oriented kinetic analysis of each set of W-T data obtained under constant heating rate. The diffusion processes are the decisive mechanisms for the decomposition. The
values of ΔE, A, ΔH, ΔS and ΔG for activation were calculated for the complexes and correlated to variation in their structure.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
ZnAc2·2H2O在空气中的热分解动力学研究 总被引:2,自引:0,他引:2
用TG/DTA,DSC和XRD技术研究了固态物质ZnAc2.2H2O在空气中的热分解过程.结果表明,ZnAc2.2H2O在空气中发生两步分解,其失重率与理论计算失重率相符.XRD结果表明,ZnAc2.2H2O分解的最终产物为ZnO.用Friedman法和Flynn-Wall-Ozawa(FWO)法求得分解过程的活化能E,并通过多元线性回归方法给出了可能的机理函数.ZnAc2.2H2O在空气中两步分解的活化能分别为119.82和66.82kJ/mol. 相似文献
3.
Analysis of the thermal decomposition of commercial vegetable oils in air by simultaneous TG/DTA 总被引:2,自引:0,他引:2
This work presents a study of the thermal decomposition of commercial vegetable oils and of some of their thermal properties
by termogravimetry (TG), derivative termogravimetry (DTG) and by differential thermal analysis (DTA). Canola, sunflower, corn,
olive and soybean oils were studied. A simultaneous SDT 2960 TG/DTA from TA Instruments was used, with a heating rate of 10
K min-1 from 30 to 700°C. A flow of 100 mL min-1 of air as the purge gas was used in order to burnout the oils during analysis to estimate their heat of combustion. From
the extrapolated decomposition onset temperatures obtained from TG curves, it can be seen that corn oil presents the highest
thermal stability (306°C), followed by the sunflower one (304°C). Olive oil presents the lowest one (288°C). The heat of combustion
of each oil was estimated from DTA curves, showing the highest value for the olive oil. Except for corn oil, which presents
a significantly different thermal decomposition behavior than the other oils, a perfect linear correlation is observed, with
negative slope, between the heat of combustion of an oil and its respective extrapolated onset temperature of decomposition
in air.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
4.
Thermal analysis of barium titanyl oxalate reveals that the decomposition proceeds through four distinct rate processes. Among
them, the decomposition of oxalate occurs in the temperature range 230–350°C, and has been studied by TG and gas pressure
measurements, supplemented by IR spectroscopy, electron microscopy and chemical analysis. Oxalate decomposition proceeds differently
in vacuum and in flowing gas atmospheres. Analytical results indicate the formation of a complex carbonate together with CO,
CO2 and water vapour below 400°C. Schemes for each type of decomposition are proposed and discussed. For decomposition in vacuum,
kinetic observations fitted the three-dimensional, diffusion controlled, rate equation for almost the entire α-range (0.028≤α≤0.92).
The activation energy is calculated to be3 189±6 kJ mol−1.
In celebration of the 60th birthday of Dr. Andrew K. Galwey 相似文献
5.
Six isomeric dimethyl anilinium bromides (DMABr) have been prepared and characterized by elemental and spectroscopic studies.
Thermal decomposition of these salts has been studied by TG and simultaneous TG-DTA techniques. Kinetic parameters have been
evaluated from isothermal TG data using contracting area and contracting cube equations. The decomposition pathways have also
been suggested which involves simultaneous sublimation (at lower temperature) and dissociative vaporization/decomposition
(at higher temperature).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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7.
J. P. Gonçalves R. D. Toledo Filho E. M. R. Fairbairn 《Journal of Thermal Analysis and Calorimetry》2008,94(2):511-516
This paper reports an experimental study on the magnesium sulphate resistance of mortar specimens incorporating 0, 10 and
20% of metakaolin (MK). The evidence of the attack was evaluated through the content of calcium hydroxide (portlandite) and
formation of magnesium hydroxide (brucite) by thermal analysis (thermogravimetric and derivative thermogravimetric analysis).
The mechanical degradation of the mortar specimens was evaluated through splitting tensile tests after 200 days of exposition
to the magnesium solution. The addition of metakaolin resulted in a reduction in the content of calcium hydroxide and in a
smaller formation of brucite in comparison with reference mixture. A tensile strength loss of about 7% was observed for the
metakaolin mortars submitted to the magnesium solution attack for 200 days. 相似文献
8.
The first syntheses of the urinary isoflavone metabolites, daidzein 4′-sulfate, daidzein 7-sulfate and daidzein 4′,7-disulfate are described. These syntheses employ a key protecting group strategy, allowing regiospecific sulfation. 相似文献
9.
M. J. Cuesta F. Rubiera A. Arenillas M. J. Iglesias I. Suárez-Ruiz J. J. Pis 《Journal of Thermal Analysis and Calorimetry》2005,80(2):333-337
Summary Perhydrous coals are characterized by a high hydrogen content and exhibit a modified composition and physico-chemical properties in comparison with normal coals. These modifications affect the behaviour of perhydrous coals during pyrolysis and, therefore, may have an influence on the subsequent combustion process. In this work the combustibility behaviour of a series of perhydrous coals was evaluated in order to study the effect of hydrogen enrichment during the thermal treatment of the coals in an oxidant atmosphere. To this end temperature programmed combustion tests for the coals, and air isothermal (500°C) reactivity tests for their chars, were carried out in a thermogravimetric analyser. A clear relationship between the combustion behaviour of the perhydrous coals, and the aromatic to aliphatic hydrogen ratio was found. 相似文献
10.
P. Miranda Jr. J. Zukerman-Schpector J. R. Matos M. F. Máduar E. M. Aricó M. Linardi L. B. Zinner G. Vicentini 《Journal of Thermal Analysis and Calorimetry》2004,75(2):577-582
The complexes [Ln(pic)3(DTSO)3] (Ln=La, Lu and Y; pic=picrate; DTSO=1,3-dithiane-1-oxide) were synthesized and characterized. Indirect structural determination by far infrared
spectroscopy is presented. Results from thermal decomposition of these complexes by TG/DTG and DSC techniques are reported.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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The rate equations for the thermal decomposition of a polymer by a random scission reaction followed by rapid depolymerization of a constant number of monomer units from both fragments together with rapid evaporation of low molecular weight species are solved by using a different approach from that used by previous workers. The results obtained are more specific and differ slightly from previous treatments. 相似文献
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Kinetics of thermal decomposition of CeO2 nanocrystalline precursor prepared by precipitation method
Xiaolan Song Xi He Haiping Yang Dayu Xu Nan Jiang Guanzhou Qiu 《Frontiers of Chemistry in China》2008,3(2):182-185
The thermal decomposition of CeO2 nanocrystalline precursor prepared by chemical precipitation method was investigated using thermo-gravimetric/differential
scanning calorimetry (TG/DSC) and X-ray powder diffraction (XRD). In particular, the differential thermal analysis curves
for the decomposition of CeO2 nanocrystalline precursor were measured at different heating rates in air by a thermal analyzer (NETZSCH STA 449C, Germany).
The kinetic parameters of the thermal decomposition of CeO2 nanocrystalline precursor were calculated using the Kissinger method and the Coats-Redfern method. Results show that the
apparent active energy E of the reaction is 105.51 kJ/mol, the frequency factor lnA is 3.602 and the reaction order n is 2. This thermal decomposition process can be described by the anti-Jander equation and a three-dimensional diffusion mechanism.
Tanslated from Journal of Central South University (Science and Technology), 2007, 38(3): 428–432 [译自: 中南大学学报(自然科学版] 相似文献
17.
The gas phase thermal decomposition of triallylamine was studied in the temperature range 531 to 620 K. The major products observed in the reaction were propylene and 3-picoline. The first order rate constants for depletion of triallylamine, obtained using the internal standard technique, are found to be independent of pressure and conversion, and fit the Arrheniusrelationship The reaction appears to be homogeneous, as a 15-fold change in thc surface-to-volume ratio of the vessel left the rate constants unchanged. The Arrhenius parameters are consistent with a molecular elimination reaction involving a six-center transition state, yielding propylene and N-allyl-prop-2-enaldimine. It is proposed that the latter product undergoes a 1,5-hydrogen transfer, followed by a ring closure reaction to yield dihydropicoline, which in turn reacts forming 3-picoline via a self-initiated decomposition reaction. 相似文献
18.
A. I. Kazakov Yu. I. Rubtsov G. B. Manelis L. P. Andrienko 《Russian Chemical Bulletin》1997,46(12):2015-2020
Kinetic regularities of thermal decomposition of dinitramide in aqueous and sulfuric acid solutions were studied in a wide
temperature range. The rate of the thermal decomposition of dinitramide was established to be determined by the rates of decomposition
of different forms of dinitramide as the acidity of the medium increases: first, N(NO2)− anions, then HN(NO2)2 molecules, and finally, protonated H2N(NO2)2
+ cations. The temperature dependences of the rate constants of the decomposition of N(NO2)− (k
an) and HN(NO2)2 (k′ac) and the equilibrium constant of dissociation of HN(NO2)2 (K
a) were determined:k
an=1.7·1017 exp(−20.5·103/T), s−1,k′ac=7.9·1016 exp(−16.1·103/T), s−1, andK
a=1.4·10 exp(−2.6·103/T). The temperature dependences of the decomposition rate constant of H2N(NO2)2
+ (k
d) and the equilibrium constant of the dissociation of H2N(NO2)2
+ (K
d) were estimated:k
d=1012 exp(−7.9·103/T), s−1 andK
d=1.1 exp(6.4·103/T). The kinetic and thermodynamic constants obtained make it possible to calculate the decomposition rate of dinitramide solutions
in a wide range of temperatures and acidities of the medium.
In this series of articles, we report the results of studies of the thermal decomposition of dinitramide performed in 1974–1978
and not published previously.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2129–2133, December, 1997. 相似文献
19.
B. L. Korsounskii V. V. Nedel'ko N. V. Chukanov T. S. Larikova F. Volk 《Russian Chemical Bulletin》2000,49(5):812-818
Thermal decomposition of hexanitrohexaazaisowurtzitane (HNIW) in the solid state and in solution was studied by thermogravimetry,
manometry, optical microscopy, and IR spectroscopy. The kinetics of the reaction in the solid state is described by the first-order
equation of autocatalysis. The rate constants and activation parameters of HNIW thermal decomposition in the solid state and
solution were determined. The content of N2 amounts to approximately half of the gaseous products of HNIW thermolysis. The thermolysis of HNIW and its burning are accompanied
by the formation of a condensed residue. During these processes, five of six nitro groups of the HNIW molecule are removed,
and one NO2 group remains in the residue, which contains amino groups and no C−H bonds.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 815–821, May, 2000. 相似文献
20.
The homogeneous gas-phase decomposition kinetics of methylsilane and methylsilane-d3 have been investigated by the comparative-rate-single-pulse shock-tube technique at total pressures of 4700 torr in the 1125–1250 K temperature range. Three primary processes occur: CH3SiH3 → CH3SiH + H2 (1), CH3SiH3 → CH4 + SiH2 (2), and CH3SiH3 → CH2 = SiH2 + H2 (3). The high-pressure rate constants for the primary processes in CH3SiH3 obtained by RRKM calculations are log (k1 + k3) (s?1) = 15.2 - 64,780 Cal/θ and log k2 (s?) = 14.50 - 67,600 → 2800 Cal/θ. For CH3SiD3 these same rate constants are log k1 (s?) = 14.99 - 64,700 cal/θ log k2 (s?) = 14.68 – 66,700 → 2000 cal/θ, and log k3 (s?) = 14.3 ? 64,700 cal/θ. 相似文献