Authors:B. Ambrozini, P. Dametto, A. Siqueira, C. Carvalho, and M. Ionashiro
Solid state Ln–L compounds, where Ln stands for light trivalent lanthanides (L–Gd) and L is tartrate, have been synthesized.
Thermogravimetry and differential thermal analysis (TG/DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry,
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 and thermal decomposition of the isolated compounds.
Authors:Konstantin Gavrichev, Mikhail Ryumin, Alexander Tyurin, Andrey Khoroshilov, Larisa Mezentseva, Alexander Osipov, Valeriy Ugolkov, and Viktor Gusarov
Thermal behavior of LaPO4·nH2O and NdPO4·nH2O nanopowders from room temperature to 973 K was investigated by DSC, TA/DTG, ESM, and X-ray study. Mass loss due to the release
of adsorbed and hydrate water was found in the range from 323 to 623 K. Phase transitions from hexagonal structure nanopowders
to monoclinic one for bulk specimens were found above 873 K.
Authors:R. Olar, M. Badea, N. Stanica, E. Cristurean, and D. Marinescu
The investigations concerning the thermal behaviour of a series of Ni(II) and Cu(II) complexes of type [MLCln]·mH2O ((1) M:Ni, L:L(1), n=1, m=2; (2) M:Cu, L:L(2), n=1, m=2; (3) M:Ni, L:L(3), n=2, m=0; (4) M:Cu, L:L(3), n=1, m=2) are presented in this paper. The ligands L(1)-L(3) have been synthesised by template condensation of 1,2-diaminoethane with formaldehyde and 2-amino-1,3,4-thiadiazole-5-thiole or 2-acetamino-1,3,4-thiadiazole-5-sulfonamide. The bonding and stereochemistry of the complexes have been characterised by IR, electronic and magnetic studies at room temperature. The thermal behaviour provided confirmation of the complex composition as well as the number and the nature of water molecules and the intervals of thermal stability. The different nature of the ligands and/or the metallic ions generates a different thermal behaviour for complexes. The complexes do not show biological activity against HIV virus.
In order to obtain a better understanding of thermal substituent effects in 1,2,4-triazole-3-one (TO), the thermal behavior
of 1,2,4-triazole, TO, as well as urazole and the decomposition mechanism of TO were investigated. Thermal substituent effects
were considered using thermogravimetry/differential thermal analysis, sealed cell differential scanning calorimetry, and molecular
orbital calculations. The onset temperature of 1,2,4-triazole was higher than that of TO and urazole. Analyses of evolved
decomposition gases were carried out using thermogravimetry–infrared spectroscopy and thermogravimetry–mass spectrometry.
The gases evolved from TO were determined as HNCO, HCN, N2, NH3, CO2, and N2O.
The thermal behaviour
of 2- and 4-biphenylmethanol were studied by differential scanning calorimetry
(DSC). It was found that the 2-isomer shows a relatively strong resistance
to crystallisation, and that it easily vitrifies on cooling. Oppositely, 4-biphenylmethanol
readily crystallizes on cooling. The slow molecular mobility of 2-biphenylmethanol
in the amorphous solid state was studied by DSC and by thermally stimulated
depolarisation currents (TSDC). Both techniques indicate that 2-biphenylmethanol
is a relatively strong glass-former, with a fragility index of ~50 in
the Angell's scale.
Authors:D. Malferrari, Maria Franca Brigatti, Angela Laurora, L. Medici, and S. Pini
The thermal behavior
of montmorillonite and organically modified montmorillonite, both treated
with heavy metal cations [Cu(II), Cd(II) and Hg(II)], was characterized via
thermal analyses (TG, DTG and DTA) combined with evolved species gas mass
spectrometry (MS-EGA), and X-ray diffraction at in situ controlled temperature
(HTXRD). The reactions involving Cu(II)- and Cd(II)-montmorillonite samples
are mostly related to H2O and OH loss, unlike Hg(II)-montmorillonite,
where effects associated to Hg(II) loss are also present. Finally reactions
related to dehydration, dehydroxylation and to organic matter decomposition
can be observed in montmorillonite samples treated with cysteine.
The mono- and di-imines of some diaminonaphthalenes were prepared using a solid solid reaction technique. Their structures were studied using elemental analysis, infrared and electronic spectra. The thermal behaviour of the obtained compounds and their solid solid preparation reactions have also been studied. The energies of activation as well as the reaction orders of those reactions were determined.
Authors:N. Lotti, V. Siracusa, L. Finelli, A. Munari, and P. Manaresi
Poly(2-hydroxyethoxybenzoate), poly(ε-caprolactone), and random poly(2-hydroxyethoxybenzoate/e-caprolactone) copolymers were
synthesized and characterized in terms of chemical structure and molecular mass. The thermal behavior was examined by DSC.
All the samples appear as semicrystalline materials; the main effect of copolymerization was lowering in the amount of crystallinity
and a decrease of melting temperature with respect to homopolymers. Flory's equation described well the Tm-composition data. Amorphous samples (in the 20–100%2-hydroxyethoxybenzoate unit concentration range) obtained by quenching
showed amonotonic decrease of the glass transition temperature Tg as the content of caprolactone units is increased. The Wood's equation described the Tg-composition data well.
Thermal investigation has allowed us to show the changes undergone by a sort of nitrile-butadiene rubber (NBR) as a consequence ofγ-radiation-induced ageing. The parameters of the processes, which occur at progressive heating of the
investigated samples, were determined. It was shown that for γ-irradiated samples the activation parameters corresponding
to the thermo-oxidative process leading to solid products are correlated through the relation of compensation effect. Also,
it was shown that, by γ-irradiation, NBR undergoes a relatively rapid change of its thermal behaviour which can be due to
Authors:A. Adorno, M. Guerreiro, C. Ribeiro, and C. Guerreiro
The influence of additions of 2, 4, 6, 8, 10 and 12 mass% Ag on the thermal behavior of the Cu–8 mass% Al alloy was studied
using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX)
and X-ray diffractometry (XRD). The results indicate that the presence of silver introduces new thermal events, due to the
formation of a silver-rich phase and, for additions of 10 and 12 mass% Ag, it is possible to verify the formation of the γ1 phase (Cu9Al4) and the metastable transitions which are only observed in alloys with a minimum of 9 mass% Al.