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1.
V. V. Nedel'ko A. V. Shastin B. L. Korsunskii N. V. Chukanov T. S. Larikova A. I. Kazakov 《Russian Chemical Bulletin》2005,54(7):1710-1714
Ditetrazol-5-ylamine (DTA) was synthesized from cyanuric chloride in four steps. The thermal decomposition of DTA in the solid
state was studied by thermogravimetry, volumetry, mass spectrometry, IR spectroscopy, and calorimetry. Under isothermal conditions
at 200–242 °C, thermal decomposition obeys the first order autocatalytic kinetics. The kinetic and activation parameters of
DTA decomposition were determined. The composition of gaseous reaction products and the structure of condensed residue were
studied. The thermal effect of thermal DTA decomposition is 281.4 kJ mol−1. The nitrogen content in a mixture of gaseous products formed by the reaction in a temperature interval of 200–242 °C exceeds
97 vol.%.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1660–1664, July, 2005. 相似文献
2.
M. R. Sovizi 《Journal of Thermal Analysis and Calorimetry》2010,102(1):285-289
Data on the thermal stability of drugs was required to obtain information for handling, storage, shelf life and usage. In
this study, the thermal stability of two nonsteroidal anti-inflammatory drugs (NSAIDs) was determined by differential scanning
calorimetry (DSC) and simultaneous thermogravimetery/differential thermal analysis (TG/DTA) techniques. The results of TG
analysis revealed that the main thermal degradation for the naproxen and celecoxib occurs in the temperature ranges of 196–300
and 245–359 °C, respectively. The TG/DTA analysis of compounds indicates that naproxen melts (at about 158.1 °C) before it
decomposes. However, the thermal decomposition of the celecoxib started about 185 °C after its melting. The influence of the
heating rate (5, 10, 15, and 20 °C min−1) on the DSC behavior of the both drug samples was verified. The results showed that, as the heating rate was increased, decomposition
temperatures of the compounds were increased. Also, the kinetic parameters such as activation energy and frequency factor
for the compounds were obtained from the DSC data by non-isothermal methods proposed by ASTM E696 and Ozawa. Based on the
values of activation energy obtained by various methods, the following order for the thermal stability was noticed: naproxen
> celecoxib. Finally, the values of ΔS
#, ΔH
#, and ΔG
# of their decomposition reaction were calculated. 相似文献
3.
Özlem Özen Karakuş Gülbanu Koyundereli Çilgi Hasalettin Deligöz 《Journal of Thermal Analysis and Calorimetry》2011,105(1):341-347
In the present study, thermal decomposition of mono- and di-azocalix[4]arene derivatives (A1–A8 and B1–B8) was investigated by means of thermogravimetry (TG), differential thermal analysis (DTA) and derivative thermogravimetry
(DTG). The exclusion of methanol, hydrolysis of benzoyl ester and methyl ketone groups in lower rim, and decomposition of azo groups in upper rim have occurred during thermal analysis, consecutively. The thermal decomposition degrees amount of volatile pyrolysis products
were determined in air atmosphere using TG, DTA and DTG curves. In conclusion, the thermal analyses of azocalix[4]arenes demonstrated
that its stability depends on the substituted groups and their positions in the calix[4]arene structure. 相似文献
4.
Beata Podkościelna 《Journal of Thermal Analysis and Calorimetry》2011,104(2):725-730
The thermal stability of the ionic liquids (ILs) 1-n-butyl-3-methylimidazolium bromide, [BMIM]Br, and 1-n-octyl-3-methylimidazolium bromide, [OMIM]Br, was evaluated through thermogravimetry (TG). Long-term isothermal TG studies
revealed that both of these ILs exhibit appreciable decomposition even at temperatures significantly lower than the onset
decomposition temperature, previously determined from fast scan TG experiments. The long-term TG studies of both the ILs showed
linear mass loss as a function of time at each temperature of 10 °C interval in the range 533–573 K over a period of 10 h.
The kinetics of isothermal decomposition of ILs was analyzed using pseudo-zero-order rate expression. The activation energies
for the isothermal decomposition of [BMIM]Br and [OMIM]Br under nitrogen atmosphere are 219.86 and 212.50 kJ mol−1, respectively. The moisture absorption kinetics of these ILs at 25 °C and 30% relative humidity (RH) and at 85 °C and 85%
RH were also studied. Water uptake of ILs exposed at 25 °C/30%RH follows a simple saturation behavior in agreement with Weibull
model while that at 85 °C/85%RH fortuitously fit into the Henderson–Pabis model. 相似文献
5.
F. Yakuphanoglu A. Karadağ M. Şekerci 《Journal of Thermal Analysis and Calorimetry》2006,86(3):727-731
Thermal properties of the single crystals have been investigated by
thermogravimetry (TG) and differential scanning calorimetry (DSC) techniques.
The thermodynamic parameters such as activation energy and enthalpy and thermal
stability temperature of the samples were calculated from the differential
thermal analysis (DTA) and TG data. The activation energies for first peak
of DTA curves were found as 496.65 (for Cd–Pd) and 419.37 kJ mol–1
(for Zn–Pd). For second peak, activation energies were calculated 116.56
(for Cd–Pd) and 173.96 kJ mol–1 (for
Zn–Pd). The thermal stability temperature values of the Cd–Pd
and Zn–Pd compounds at 10°C min–1
heating rate are determined as approximately 220.7 and 203°C, respectively.
The TG results suggest that thermal stability of the Cd–Pd complex is
higher than that of the Zn–Pd complex. 相似文献
6.
E. Jóna L’. Lajdová L’. Kvasnicová S. Lendvayová M. Pajtášová D. Ondrušová P. Lizák S. C. Mojumdar 《Journal of Thermal Analysis and Calorimetry》2011,104(3):817-821
The thermal decomposition of the complexes Mg(SCN)2(2-OHpy)4·H2O(I), Mg(SCN)2(quin)4·2H2O(II) and Mg(SCN)(quinox)4·5H2O(III) (2-OHpy–2-hydroxypyridine, quin–quinoline, quinox–quinoxaline) has been investigated in static air atmosphere at 20–1000 °C
by means of thermogravimetry (TG), differential thermal analysis (DTA), and infrared (IR) spectroscopy. The composition of
the complexes had been identified by means of elemental analysis and complexometric titration. The possible scheme of destruction
of the complexes is suggested. The final product of the thermal decomposition was MgS. IR data suggest that heterocyclic ligands
were coordinated to Mg(II) through the nitrogen atom of their heterocyclic ring. Thiocyanate group is also coordinated through
the nitrogen atom. 相似文献
7.
Zou Hantao Yi Changhai Wang Luoxin Liu Hongtao Xu Weilin 《Journal of Thermal Analysis and Calorimetry》2009,97(3):929-935
Thermogravimetric (TG), differential thermal analysis (DTA) and thermal degradation kinetics, FTIR and X-ray diffraction (XRD)
analysis of synthesized glycine–montmorillonite (Gly–MMT) and montmorillonite bound dipeptide (Gly–Gly–MMT) along with pure
Na–MMT samples have been performed. TG analysis at the temperature range 25–250 °C showed a mass loss for pure Na–MMT, Gly–MMT
and Gly–Gly–MMT of about 8.0%, 4.0% and 2.0%, respectively. DTA curves show the endothermic reaction at 136, 211 and 678 °C
in pure Na–MMT whereas Gly–MMT shows the exothermic reaction at 322 and 404 °C and that of Gly–Gly–MMT at 371 °C. The activation
energies of the first order thermal degradation reaction were found to be 1.64 and 9.78 kJ mol−1 for Gly–MMT and Gly–Gly–MMT, respectively. FTIR analyses indicate that the intercalated compounds decomposed at the temperature
more than 250 °C in Gly–MMT and at 250 °C in Gly–Gly–MMT. 相似文献
8.
The thermal decomposition of copper(II) acetate monohydrate (CuAc2·H2O) under 500 °C in air was studied by TG/DTG, DTA, in situ FTIR and XRD experiments. The experimental results showed that
the thermal decomposition of CuAc2·H2O under 500 °C in air included three main steps. CuAc2·H2O was dehydrated under 168 °C; CuAc2 decomposed to initial solid products and volatile products at 168–302 °C; the initial solid products Cu and Cu2O were oxidized to CuO in air at 302–500 °C. The copper acetate peroxides were found to form between 100 and 150 °C, and the
dehydration of these peroxides resulted in the presence of CuAc2·H2O above 168 °C. The initial solid products were found to be the admixture of Cu, Cu2O, and CuO, not simply the single Cu2O as reported before. Detailed reactions involved in these three steps were proposed to describe the complete mechanism and
course of the thermal decomposition of CuAc2·H2O in air. 相似文献
9.
N. E. Fouad 《Journal of Thermal Analysis and Calorimetry》2000,60(2):541-547
The thermal behaviour of CrO3 on heating up to 600°C in dynamic atmospheres of air, N2 and H2 was examined by thermogravimetry (TG), differential thermal analysis (DTA), IR spectroscopy and diffuse reflectance spectroscopy
(DRS). The results revealed three major thermal events, depending to different extents on the surrounding atmosphere: (i)
melting of CrO3 near 215°C (independent of the atmosphere), (ii) decomposition into Cr2(CrO4)3 at 340–360°C (insignificantly dependent), and (iii) decomposition of the chromate into Cr2O3 at 415–490°C (significantly dependent). The decomposition CrO3 → Cr2(CrO4)3 is largely thermal and involves exothermic deoxygenation and polymerization reactions, whereas the decomposition Cr2(CrO4)3 → Cr2O3 involves endothermic reductive deoxygenation reactions in air (or N2) which are greatly accelerated and rendered exothermic in the presence of H2. TG measurements as a function of heating rate (2–50°C min−1) demonstrated the acceleratory role of H2, which extended to the formation of Cr(II) species. This could sustain a mechanism whereby H2 molecules are considered to chemisorb dissociatively, and then spillover to induce the reduction. DTA measurements as a function
of the heating rate (2–50°C min−1) helped in the derivation of non-isothermal kinetic parameters strongly supportive of the mechanism envisaged.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
Adriana Fuliaş Titus Vlase Gabriela Vlase Nicolae Doca 《Journal of Thermal Analysis and Calorimetry》2010,99(3):987-992
The thermoanalytical curves (TA), i.e. TG, DTG and DTA for pure cephalexin and its mixtures with talc, magnesium stearate,
starch and microcrystalline cellulose, respectively, were drawn up in air and nitrogen at a heating rate of 10 °C min−1. The thermal degradation was discussed on the basis of EGA data obtained for a heating rate of 20 °C min−1. Until 250 °C, the TA curves are similar for all mixtures, up this some peculiarities depending on the additive appears.
These certify that between the pure cephalosporin and the excipients do not exists any interaction until 250 °C. A kinetic
analysis was performed using the TG/DTG data in air for the first step of cephalexin decomposition at four heating rates:
5, 7, 10 and 12 °C min−1. The data processing strategy was based on a differential method (Friedman), an integral method (Flynn–Wall–Ozawa) and a
nonparametric kinetic method (NPK). This last one allowed an intrinsic separation of the temperature, respective conversion
dependence on the reaction rate and less speculative discussions on the kinetic model. All there methods had furnished very
near values of the activation energy, this being an argument for a single thermooxidative degradation at the beginning (192–200 °C). 相似文献
11.
In this paper, the thermal behaviours of two organophosphorous compounds, N,N-dimethyl-N′,N′-diphenylphosphorodihydrazidic (NDD) and diphenyl amidophosphate (DPA), were studied by thermogravimetery (TG), differential
thermal analysis (DTA) and differential scanning calorimetery (DSC) techniques under non-isothermal conditions. The results
showed that NDD melts about 185 °C before it decomposes. NDD decomposition occurs in two continuous steps, in the 190–410 °C
temperature range. First thermal degradation stage for NDD results a broad exothermic peak in the DTA curve that is continued
with a small exothermic peak at the end of decomposition process. On the other hand, applying TG-DTA techniques indicates
that DPA melts about 150 °C before it decomposes. This compound decomposes in the temperature range of 230 to 330 °C in two
steps. These steps are endothermic and exothermic, respectively. Activation energy and pre-exponential factor for the first
step of decomposition of each compound were found by means of Kissinger method and were verified by Ozawa–Flynn–Wall method.
Activation energy obtained by Kissinger method for the first stage of NDD and DPA decompositions are 138 and 170 KJ mol−1, respectively. Finally, the thermodynamic parameters (ΔG
#, ΔH
# and ΔS
#) for first step decomposition of investigated organophosphorous were determined. 相似文献
12.
Yu Huimei Qi Lingjun Zhang Qinghong Jiang Danyu Lu Changwei 《Journal of Thermal Analysis and Calorimetry》2011,106(1):47-52
The thermal behavior of the anticancer drug-irinotecan was measured by Thermogravimetry–Differential thermal analysis (TG–DTA)
to explore the application of TG–DTA in nanomedicine firstly. The TG–DTA result showed that the irinotecan was oxidized completely
before 700 °C. When irinotecan was loaded onto nanosized mesoporous silica spheres, the loading capacity for irinotecan measured
by TG–DTA was about 9.11% in the irinotecan/mesoporous SiO2 composite, similar to the typical UV–Vis spectra results (10.5%), which showed that TG–DTA characterization provided an alternative
method to determine the drug loading amount on inorganic carriers. Secondly, Thermogravimetry–Differential scanning calorimetry–Mass
Spectrometry coupling techniques (TG–DSC–MS) were used to characterize the hydrogen adsorption temperature and capacity of
TiCr1.2 (V-Fe)0.6 alloy. The MS result showed that the released region of hydrogen was 250–500 °C, which was consistent with the TG–DSC results.
Lastly, TA–MS combined with pulse thermal analysis (PulseTA) were used for a simultaneous characterizing study in the changes
of mass, determination and quantitative calibration of the evolved nitrogen formed during the thermal decomposition of the
InN powder. The results showed that relative error of this method between measured value and theoretical value was 2.67% for
the quantitative calibration of evolved N2. It shows that TA–MS combined with PulseTA techniques offer a good tool for the quantification of the evolved nitrogen in
the InN powder. 相似文献
13.
Anna Kropidłowska M. Strankowski Maria Gazda Barbara Becker 《Journal of Thermal Analysis and Calorimetry》2007,88(2):463-470
The thermal behavior of Mn(II) silanethiolate series [Mn(SR)2L(MeOH)n],
where R=SSi(OBut)3, L=heterocyclic nitrogen base and n=0,
1 or 2 has been comparatively investigated using differential scanning calorimetry
(DSC), thermogravimetry (TG) and TG-infrared spectoscopy (IR) techniques.
The TG curves indicate the differences in the thermal decomposition due to
presence of distinct N-donor ligands and labile MeOH molecules coordinated
to the central atom. The first step on the TG curves (60–110°C)
corresponds to the elimination of alcohol from respective complexes. The main
step (150–350°C) can be assigned to the decomposition of the complexes
yielding Mn3O4 and silica as
the main final products, identified by X-ray diffraction patterns. 相似文献
14.
S. C. Mojumdar L. Raki N. Mathis K. Schimdt S. Lang 《Journal of Thermal Analysis and Calorimetry》2006,85(1):119-124
A non-ionic polymer (poly(vinyl
alcohol) (PVA)) has been incorporated into the inorganic layers of calcium
silicate hydrate (C–S–H) during precipitation of quasicrystalline
C–S–H from aqueous solution. C–S–H and a C–S–H-polymer
nanocomposite (C–S–HPN) material were synthesized and characterized
by X-ray fluorescence (XRF), energy dispersive spectroscopy (EDS), 29Si
magic angle spinning nuclear magnetic resonance (29Si
MAS NMR) and 13C cross-polarization nuclear magnetic
resonance (13C CP NMR) spectroscopy, atomic force
microscopy (AFM), thermal conductivity, thermogravimetric analysis (TG) and
differential thermal analysis (DTA). Thermal conductivity of PVA, C–S–H
and C–S–HPN material was studied in the temperature range 25–50°C.
C–S–HPN materials exhibited the highest thermal conductivity at
25 and 50°C. The thermal conductivity increases from 25 to 50°C are
7.03, 17.46 and 14.85% for PVA, C–S–H and C–S–HPN
material, respectively. Three significant decomposition temperature ranges
were observed on the TG curve of C–S–HPN material. 相似文献
15.
Aouad A. Bilali L. Benchanâa M. Mokhlisse A. 《Journal of Thermal Analysis and Calorimetry》2002,67(3):733-743
The natural phosphate and its demineralization products from Moroccan deposit were pyrolysed in a thermogravimetric analyser
(TG) to examine the influence of the heating rate and mineral matter on their thermal decomposition. The heating rates investigated
in the TG were 5–100°C min−1 to final temperature of 1200°C. The integral method was used in the analysis of the TG to determine the kinetic parameters.
It has been found that for the natural phosphate and corresponding kerogen analysed in the TG, the increase of the heating
rate shifts the maximum rate loss to higher temperature. A first order reaction was found to be adequate for pyrolysis in
the range 150–600°C which was attributed to kerogen decomposition. In addition, the results indicate that the removal of mineral
matter affected the kinetic parameters found for kerogen in the natural phosphate.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
16.
Shayan Farhikhteh Amir Maghsoudipour Babak Raissi Babak Mozaffari 《Journal of Sol-Gel Science and Technology》2009,49(1):60-65
In this study high specific surface area yttria-stabilized zirconia (ZrO2–8Y2O3) nanocrystalline powder have been synthesized through “modified polymerized complex (MPC) method”. Zirconium chloride, yttrium
nitrate, citric acid and ethylene glycol were polymerized at 80 °C to produce a gel-like mass in which metallic ions were
uniformly distributed. During the thermal treatment of dried gel, nanocrystalline YSZ powder was formed. Thermal reactions
and phase formation of dried gel were investigated through thermal analysis (DTA/TG) and X-ray diffraction (XRD) analysis,
respectively. Chemical bonding and thermal decomposition behavior of dried gel was investigated by FTIR analysis. During decomposition,
the nature of the bonding between carboxylate groups and the cations changed from unidentate to bridging at 370 °C and carbonate
species were detected at 470 °C. Morphology of powder calcined at 650 °C was analyzed by scanning electron microscope (SEM).
YSZ powder with high specific surface area was prepared successfully by this method. 相似文献
17.
K. Chennakesavulu M. Raviathul Basariya G. Bhaskar Raju S. Prabhakar 《Journal of Thermal Analysis and Calorimetry》2011,103(3):853-862
Thermal decomposition kinetics of calix[6]arene (C6) and calix[8]arene (C8) were studied by Thermogravimetry analysis (TG)
and Differential thermal analysis (DTA). TG was done under static air atmosphere with dynamic heating rates of 1.0, 2.5, 5.0,
and 10.0 K min−1. Model-free methods such as Friedman and Ozawa–Flynn–Wall were used to evaluate the kinetic parameters such as activation
energy (E
a) and pre-exponential factors (ln A). Model-fitting method such as linear regression was used for the evaluation of optimum kinetic triplets. The kinetic parameters
obtained are comparable with both the model-free and model-fitting methods. Within the tested models, the thermal decomposition
of C6 and C8 are best described by a three dimensional Jander’s type diffusion. The antioxidant efficiency of C6 and C8 was
tested for the decomposition of polypropylene (PP). 相似文献
18.
Lanthanum(III) tris-tartrato lanthanate(III) decahydrate, La[La(C4H4O6)3]·10H2O has been synthesized and characterized by elemental analysis, IR, electronic spectral and X-ray powder diffraction studies.
Thermal studies (TG, DTG and DTA) in air showed a complex decomposition pattern with the generation of an anhydrous species
at ~170°C. The end product was found to be mainly a mixture of La2O3 and carbides at ~970°C through the formation of several intermediates at different temperature. The residual product in DSC
study in nitrogen at 670°C is assumed to be a similar mixture generated at 500°C in TG in air. Kinetic parameters, such as,
E*, ΔH, ΔS, etc. obtained from DSC are discussed. IR and X-ray powder diffraction studies identified some of the decomposition products.
The tentative mechanism for the thermal decomposition in air of the compound is proposed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
Bhojya Naik H. S. Siddaramaiah Ramappa P. G. 《Journal of Thermal Analysis and Calorimetry》1999,55(3):841-849
The complexes of cobalt(II) with dothiepin (DOT) hydrochloride have been studied for kinetics of thermal degradation by thermogravimetric
analysis (TG) and derivative thermogravimetric studies (DTG) in a static nitrogen atmosphere at a heating rate of 10° C min−1. A general mechanism of thermal decomposition is advanced involving dehydration and decomposition process for both organic
and inorganic ligands. The thermal degradation reactions were found to proceed in three steps having an activation energy
in the range 6.75–170 kJ mol−1. Thermal decomposition kinetics parameters were computed on the basis of thermal decomposition data.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
By thermoanalytical methods TG, DTG, DTA there have been investigated the processes occurring during the formation of ceramic
materials on the basis of Al2O3, ZrO2, Si3N4, SiC,and inorganic binder. IR spectroscopy has been an additional research method. It's been determined that with the use
of H3PO4 as the binder for ceramic materials, the mechanisms of thermal decomposition are connected with the following processes:
1. removal of weakly tied and crystallized water in the temperature range of120–230°C, the removal being characterized by
the endothermic effect, 2. interaction of the initial powder components of the ceramic materials with orthophosphoric acid
conditioned by a strong exothermic effect on the DTA curve in the range of 230–530°C, 3. overlapping of endo- and exo-effects,
testifying to a complex mechanism of thermal transformations, 4.oxidizing of the non-reacted silicon at the temperature of
720(760)°C, an increase of mass is observed on the TG curve as a result of the formation of SiO2 – crystoballite.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献