共查询到20条相似文献,搜索用时 31 毫秒
1.
A. B. Siqueira C. T. de Carvalho E. C. Rodrigues E. Y. Ionashiro G. Bannach M. Ionashiro 《Journal of Thermal Analysis and Calorimetry》2010,100(1):95-100
Solid-state Ln–L compounds, where Ln stands for heavy trivalent lanthanides or yttrium (III) (Tb–Lu, Y) and where L is pyruvate,
have been synthesized. Thermogravimetry and derivative thermogravimetry (TG/DTG), differential scanning calorimetry (DSC),
X-Ray powder diffractometry, infrared spectroscopy, elemental analysis and complexometry were used to characterize and to
study the thermal behaviour of these compounds. The results led to information about the composition, dehydration, thermal
behaviour, ligand denticity of the isolated complexes. 相似文献
2.
M. L. S. De Melo N. A. Santos R. Rosenhaim A. G. Souza P. F. Athayde Filho 《Journal of Thermal Analysis and Calorimetry》2011,105(3):831-836
Solid state Ln2–L3 compounds, where Ln stands for light trivalent lanthanides (lanthanum to gadolinium), except promethium, and L is folate
(C19H17N7O6), have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning
calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy (FTIR), TG coupled to FTIR, elemental analysis and complexometry
were used to characterize and to study the thermal behaviour of these compounds. The results provided information concerning
the stoichiometry, crystallinity, ligand’s denticity, thermal stability, thermal behaviour and identification of the gaseous
products evolved during the thermal decomposition of these compounds. 相似文献
3.
Patrícia R. Dametto Beatriz Ambrozini Adriano B. Siqueira Cláudio T. Carvalho Massao Ionashiro 《Journal of Thermal Analysis and Calorimetry》2009,97(2):765-768
Solid-state Ln–C8H7O3 compounds, where Ln stands for Eu(III) and Gd(III) and C8H7O3 is 3-methoxybenzoate, have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential
scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy, elemental analysis and complexometry were
used to characterize and to study the thermal behaviour of these compounds. The results led to information about the composition,
dehydration, thermal stability and decomposition of the isolated compounds. 相似文献
4.
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
5.
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
6.
G. Bannach R. Arcaro D. C. Ferroni A. B. Siqueira O. Treu-Filho M. Ionashiro E. Schnitzler 《Journal of Thermal Analysis and Calorimetry》2010,102(1):163-170
Thermogravimetry (TG), differential thermal analysis (DTA), differential scanning calorimetry (DSC) as well as X-ray diffraction
powder (DRX) patterns and Fourier transformed infrared spectroscopy (FTIR) were used to study ketoprofen, ibuprofen, and naproxen.
The chemical or physical properties of the studied compounds were established and when possible by X-ray powder diffractometry
and/or infrared spectroscopy were used. In this investigation, quantum chemical approach was used to determine the molecular
structures using Becke three-parameter hybrid method and the Lee–Yang–Par (LYP) correlation functional. The performed molecular
calculations in this work were done using the Gaussian 03 routine. Theoretical calculations help in interpretations of FTIR
spectra supplying structural and physicochemical parameters. 相似文献
7.
1,2,4-triazole-3-one (TO) and guanidine nitrate (GN) have the potential to be used as alternative gas-generating agents. To
obtain a better understanding of thermal decomposition properties of TO/GN mixtures, sealed cell differential scanning calorimetry,
thermogravimetry–differential thermal analysis–infrared spectroscopy (TG–DTA–IR), and thermogravimetry–differential thermal
analysis–mass spectrometry (TG–DTA–MS) were carried out. The endothermic peak and onset temperatures of TO/GN mixtures were
lower than those of individual TO and GN. TG–DTA–IR and TG–DTA–MS showed that the mass of TO/GN mixtures decreased with heat
generation and N2 evolved as the major gas during thermal decomposition. The interaction between TO and nitric acid from the dissociation of
GN is proposed for the thermal decomposition of TO/GN mixtures. 相似文献
8.
Thermal
degradation of wood treated with flame retardants 总被引:2,自引:0,他引:2
Wood,
one of the most flammable materials, was treated with various compounds containing
nitrogen, phosphorus, halogens, and boron. For a study of flame retardance
from the standpoint of thermal degradation, the samples were subjected to
thermogravimetry (TG), differential thermal analysis (DTA) and differential
thermogravimetry (DTG) in nitrogen to determine if there were any characteristic
correlations between thermal degradation behaviors and the level of flame
retardance. From the resulting data, kinetic parameters for different stages
of thermal degradation are obtained using the method of Broido. The energies
of activation for the decomposition of samples are found to be from 72 to
109 kJ mol–1. For wood and modified wood,
the char yields are found to increase from 10.2 to 30.2%, LOI from 18 to 36.5,
which indicates that the flame retardance of wood treated with compounds is
improved. The flame retardant mechanism of different compounds has also been
proposed. 相似文献
9.
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
10.
Lucica Viorica Ababei Angela Kriza Adina Magdalena Musuc Cristian Andronescu Elena Adina Rogozea 《Journal of Thermal Analysis and Calorimetry》2010,101(3):987-996
New complexes of 2-benzoyl-pyridil-isonicotinoylhydrazone (L) with Cu(II), Co(II), Ni(II) and Mn(II), having formula of type
[ML2] SO4·xH2O (M = Cu2+, Co2+, Ni2+, x = 2 and M = Mn2+, x = 3), have been synthesised and characterised. All complexes were characterised on the basis of elemental analyses, IR spectroscopy,
UV–VIS–NIR, EPR, as well as thermal analysis and determination of molar conductivity and magnetic moments. The thermal behaviour
of complexes was studied using thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry
(DSC). The structure of L hydrazone was established by X-ray study on single crystal. The ligand works as tridentate NNO,
being coordinated through the azomethine nitrogen, the pyridine nitrogen and carbonylic oxygen. Heats of decomposition, ΔH, associated with the exothermal effects were also determined. 相似文献
11.
Suzana Samaržija-Jovanović Vojislav Jovanović Sandra Konstantinović Gordana Marković Milena Marinović-Cincović 《Journal of Thermal Analysis and Calorimetry》2011,104(3):1159-1166
The thermal stability of pure urea–formaldehyde resin (PR) and modified urea–formaldehyde (UF) resins with hexamethylenetetramine-HMTA
(Resin 1), melamine-M (Resin 2), and ethylene urea (EU, Resin 3) including nano-SiO2 was investigated by non-isothermal thermo-gravimetric analysis (TG), differential thermal gravimetry (DTG), and differential
thermal analysis (DTA) supported by data from IR spectroscopy. Possibility of combining inorganic filler in a form of silicon
dioxide with UF resins was found investigated and percentage of free formaldehyde was determined. The shift of DTG peaks to
a high temperature indicates the increase of thermal stability of modified UF resin with EU (Resin 3) which is confirmed by
data obtained from the FTIR study. The minimum percentage (6%) of free formaldehyde was obtained in Resin 3. 相似文献
12.
I. Blanco L. Abate F. A. Bottino P. Bottino 《Journal of Thermal Analysis and Calorimetry》2012,108(2):807-815
Six polyhedral oligomeric silsesquioxanes (POSSs) with general formula R7 R′1 (SiO1.5)8, where R- was an isobutyl group and R′- a variously substituted phenyl group, namely hepta isobutyl polyhedral oligomeric
silsesquioxane (hib-POSS), were prepared and their composition was checked by elemental analysis and 1
H NMR spectroscopy. The degradation of compounds obtained was studied by simultaneous differential thermal analysis/thermogravimetry
(DTA/TG) technique, in both inert (flowing nitrogen) and oxidative (static air atmosphere) environments, in order to draw
useful information about their thermal stability. Experiments, performed in the 35–700 °C temperature range, showed different
behaviour between the two used atmospheres. The formation of volatile compounds only, with an about complete mass loss, was
observed under nitrogen, while a solid residue (≈40–50% in every case), due to the formation of SiO2, as indicated by the FTIR spectra, was obtained in static air atmosphere. The results obtained were discussed and compared,
and the classifications of resistance to thermal degradation in the studied environments were made. A comparison between the
thermal stabilities of hib-POSSs and analogous cyclopentyl POSSs previously studied was also performed. 相似文献
13.
A. T. Adorno R. A. G. Silva A. G. Magdalena 《Journal of Thermal Analysis and Calorimetry》2007,87(3):759-762
Thermal behavior of α-(Cu–Al–Ag) alloys, i.e. alloys
with composition less than about 8.5 mass% Al, was studied using differential
scanning calorimetry (DSC), differential thermal analysis (DTA), scanning
electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray
diffractometry (XRD). The results indicated that the presence of silver introduces
new thermal events ascribed to the formation of a silver-rich phase and, after
addition higher amounts than 8 mass% Ag to the Cu–8 mass% Al alloy it
is possible to observe the formation of the γ1
phase (Al4Cu9), which is only
observed in alloys containing minimum of 9 mass% Al. These results may be
attributed to some Ag characteristics and its interaction with Cu and Al. 相似文献
14.
I. Kohsari S. M. Pourmortazavi S. S. Hajimirsadeghi 《Journal of Thermal Analysis and Calorimetry》2007,89(2):543-546
Data on the thermal stability of organic materials such as diaminofurazan (DAF) and diaminoglyoxime (DAG) was required in
order to obtain safety information for handling, storage and use. These compounds have been shown to be a useful intermediate
for the preparation of energetic compounds. In the present study, the thermal stability of the DAF and DAG was determined
by differential scanning calorimetery (DSC) and simultaneous thermogravimetery-differential thermal analysis (TG-DTA) techniques.
The results of TG analysis revealed that the main thermal degradation for the DAF and DAG occurs in the temperature ranges
of 230–275°C and 180–230°C, respectively. On the other hand, the TG-DTA analysis of compounds indicates that DAF melts (at
about 182°C) before it decomposes. However, the thermal decomposition of the DAG started simultaneously with its melting.
The influence of the heating rate (5, 10, 15 and 20°C min−1) on the DSC behaviour of the compounds 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 E698 and Ozawa. Based on the
values of activation energy obtained by ASTM and Ozawa methods, the following order in the thermal stability was noticed:
DAF>DAG. 相似文献
15.
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
16.
Milena P. Segato É. T. G. Cavalheiro 《Journal of Thermal Analysis and Calorimetry》2007,87(3):737-741
Thermal behaviour of ammonium (NH4alg),
mono- (MEAalg), di- (DEAalg) and triethanolammonium (TEAalg) salts of alginic
acid (Halg) was investigated by thermogravimetry (TG) and differential scanning
calorimetry (DSC). Salts were prepared by the direct reaction of alginic acid
with the ammonium hydroxide and with the respective ethanolamines. After preparation
the compounds were lyophilized during 24 h and characterized by FTIR spectroscopy
and elemental analysis (C, H and N). Under air the compounds exhibited three
successive thermal decomposition steps: dehydration, decomposition of the
polymeric matrix and finally, burning of carbonaceous residue. Under nitrogen
two steps (dehydration and decomposition) were observed. The stability order
of this series of compounds was: TEAalg this series of compounds was: TEAalg<DEAalg<NH4alg<Halg≈MEAalg.
DSC curves between –50 and 150°C did not show any thermal events
suggesting that after lyophilization probably non-freezing type water is present
in the system. 相似文献
17.
S. K. Arya Tanvi Vats Shailesh N. Sharma Kulvir Singh A. K. Narula 《Journal of Thermal Analysis and Calorimetry》2012,107(2):555-560
In this study, we have studied the stability of TiO2–CdSe nanocomposites in which the individual moieties are linked using a bifunctional linker (mercaptopropionic acid). Nanoparticles
of TiO2 and CdSe are synthesized by sol–gel and one pot methods. The equimolar amount of the above particles is utilized to prepare
nanocomposites with and without linker. These samples are characterized for their structural, thermal, and optical properties
using X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis (TG), Fourier transform infra-red
spectroscopy (FTIR), and UV–Vis spectroscopy. The average particle size of TiO2 and CdSe are 16 and 23 nm, respectively. The addition of a bifunctional linker shows remarkable effect on the properties
of TiO2–CdSe nanocomposites. 相似文献
18.
M. A. S. Carvalho Filho N. S. Fernandes M. I. G. Leles R. Mendes M. Ionashiro 《Journal of Thermal Analysis and Calorimetry》2000,59(3):669-674
Some new compounds of cinnamic acid with lighter trivalent lanthanides were prepared in the solid state. The compounds have
general formula ML3 H2 O, where L is cinnamate (C6 H5 –CH=CH–COO– ) and M is La, Ce, Pr, Nd or Sm. Thermogravimetry, derivative thermogravimetry, differential scanning calorimetry, infrared absorption
spectra and X-ray diffraction powder patterns were used to characterize and to study the thermal stability and thermal decomposition
of these compounds.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
Reactions of Pentapseudohalonitrosyl ferrate(II) with Morpholinobenzyl benzamide(MBB) and Piperidinobenzyl benzamide(PBB)
formed complexes of the type, [Fe(X)3(NO)(L–L)] where X = CN−, NCO− and N
3
−
and L–L = Morpholinobenzyl benzamide(MBB) and Piperidinobenzyl benzamide(PBB). These compounds have been characterized
by various physico-chemical techniques such as elemental analysis, molar conductance, magnetic susceptibility measurements,
i.r., electronic spectra, thermal gravimetric analysis. The molecular modeling Studies have been carried out for structural
analysis for some of the complexes have been carried out using Hyperchem release 7.52 professional version. 相似文献
20.
Hengfeng Li Kaiyuan Tan Zeming Hao Guowen He 《Journal of Thermal Analysis and Calorimetry》2011,105(1):357-364
A number of solution-casted poly(vinylidenefluoride–chlorotrifluoroethylene–trifluoroethylene) [P(VDF–CTFE–TrFE)] terpolymer
films with different CTFE content have been characterized by a series of thermal analysis techniques, including thermogravimetric
analysis (TG), differential scanning calorimetry, dynamic mechanical analysis (DMA) and thermal mechanical analysis (TMA).
The work intends to provide more comprehensive information about thermal behavior of these ferroelectric polymers. TG results
suggest that the introduction of the CTFE units slightly decreases the thermal stability of the polymer due to the instability
of C–Cl bond during heating. DMA detected a relatively weak αa relaxation and a broad αc relaxation in the samples of low CTFE content. These two relaxation processes completely mixed together in the sample with
high CTFE content, revealing the crystalline structures in the polymer, become a more imperfect and diffuse state as CTFE
units increasing. The polymer with less CTFE units possesses an enhanced stiffness due to its higher degree of crystallinity.
A contraction process after a slight amount of thermal expansion upon heating is detected by TMA, due to the release of internal
tensile strain/stress generated during solidification of the films. The higher crystallinity of the polymer film generated
the greater strain/stress, leading to the larger degree of shrinkage. Also, the higher melting point of the polymer with less
CTFE units allows the film soften at a higher temperature. 相似文献