Authors:Amanda dos Santos, G. Chierice, A. Riga, K. Alexander, and Ellen Matthews
Eugenol is an allyl chain-substituted guaiacol in the biosynthesized phenylpropanoid compound class derived from Syzygium aromaticum L. and widely used in folk medicine. Nonetheless, its pharmacological use is limited by some problems, such as instability
when exposed to light and high temperature. In order to enhance stability, the eugenol molecule was structurally modified,
resulting in eugenyl acetate. The eugenyl acetate’s thermal behavior and crystal structure was then characterized by differential
scanning calorimetry (DSC) and X-ray diffraction (XRD) and compared to a commercial sample.
Authors:S. Tarulli, O. Quinzani, J. Dristas, and E. Baran
Complexes of Cu(II) with substituted o-acetoxy benzoic acids (5-haloaspirines, X-asp) with and without pyridine (py), of composition
[Cu2(X-asp)4] and [Cu(X-asp)2(py)2 ] have been synthesized and characterized. Electronic and vibrational spectroscopic data of these complexes are reported.
Its thermal behaviour was investigated by thermogravimetry and differential thermal analysis. In all complexes, the haloaspirinate
ligands decompose in two or three steps, starting with the break up of the coordinated acetoxy groups. CuO is obtained as
the final pyrolysis residue in all cases.
Authors:V. Manríquez, C. Díaz, G. González, and I. Brito
Benzenesulfenamides with the formula R-S-N-(R′)2 (R=C6H5 andR′=NC4H8O, C7H7 and C6H11) and their chromium carbonyl complexes were studied by means of TG and mass spectrometric methods. The thermal behaviour of the compounds the stabilities of free sulfenamides are lower than those observed for the corresponding chromium carbonyl complexes. Combined thermogravimetry — mass spectrometry results suggest that the fragmentation mechanism of the carbonyl complexes involves cleavage of the Cr-S and Cr-CO bonds while that of sulfenamide depends mainly on the dissociation rates of the NR2 groups.
Authors:Kadri Siimer, Tiit Kaljuvee, Tõnis Pehk, and Ilmar Lasn
Thermal behaviour of industrial UF resins modified by low level of melamine was followed by TG-DTA technique on the labsysTM instrument Setaram together with the 13C NMR analysis of resin structure and testing boards in current production at Estonian particleboard factory Pärnu Plaaditehas
AS. DTA curve of UF resin which has been cocondensed during synthesis with even low level of melamine shows the shift of condensation
exotherm and water evaporation endotherm to considerable higher temperatures. The effect of melamine monomer introduced to
UF resin just before curing was compared. The effect of addition of urea as formaldehyde scavenger was studied.
Authors:P. Espeau, B. Nicolaï, R. Céolin, M. Perrin, L. Zaske, J. Giovannini, and F. Leveiller
Investigation into the thermal behavior of orthorhombic Forms I and II of spironolactone, by means of differential scanning
calorimetry and high-resolution X-ray powder diffraction, showed that Form I melts then recrystallizes into Form II at 373–393
K, i.e. in the temperature range within which high resolution X-ray powder diffration showed that Form I transforms into Form II.
Refinements of the lattice parameters of the two forms indicated that Form I is denser than Form II in the range from 298
K up to the temperature at which it melts.
The Mössbauer spectra of Sm2Fe17Nx, prepared by the nitrogenation of Sm2Fe17 powders in an ammonia and hydrogen atmosphere, were observed at elevated temperatures to shed light on the thermal behavior
of nitrogen in the compounds Sm2Fe17Nx. It was found that there were large differences in thermal behavior between the starting Sm2Fe17, crystalline Sm2Fe17Nx (x≈1.7) and amorphous Sm2Fe17Nx(x∼7).
The thermal decomposition behavior of Sm2Fe17N3.2, developed as one of the most promising hard magnetic materials, was found to be different under different atmospheres.
Authors:Rodica Olar, Mihaela Badea, Dana Marinescu, and Ramona Mardale
derivatives, new complexes with such units incorporated in Schiff bases ligands have been synthesized and characterized. The complexes have been characterized by different analytical and spectral methods.
The thermalbehaviour of these derivatives was
Authors:X. Han, Y. Hu, Z. Lin, S. Li, F. Zhao, Z. Liu, J. Yi, L. Zhang, and X. Ren
Effects of fullerenes including FS, EFS and pure C60 on thermal behaviors of polyethylene glycol (PEG) have been studied by employing thermogravimetry-differential thermogravimetry
(TG-DTG), differential scanning calorimeter (DSC) and off-line furnace-type pyrolysis-gas chromatography/mass spectrometry
(Py-GC/MS). The products were collected by Cambridge filter pad which was widely used in analyzing the combustion products
of cigarette. The results showed that the addition of fullerenes obviously restrained the thermal decomposition of PEG. The
initial decomposition temperatures (IDT) and maximum decomposition peak temperatures (MDT) were evidently postponed by the
addition of fullerenes. Pyrolysis products with one or two hydroxyl end groups obviously increased with the addition of 10%
C60. The reasons of the changes were discussed from the aspects of reaction mechanisms.
Authors:K. Siimer, P. Christjanson, T. Kaljuvee, T. Pehk, and I. Saks
Urea–formaldehyde (UF) and phenol–formaldehyde (PF) resins are the most widely used wood adhesives. The first stage in resin
manufacturing is the formation of methylol derivatives which polycondensation leads to building the tridimensional network.
Understanding the behaviour of methylol compounds in curing provides useful information for developing appropriate resin structures.
Thermal behaviour of N,N′-dihydroxymethylurea, 2- and 4-hydroxymethylphenols, urea and phenol as model compounds for UF, PF and phenol–urea–formaldehyde
(PUF) resins was followed by TG-DTA method. The measurements were carried out by the labsys instrument Setaram at 30–450 °C in nitrogen flow. The characteristic signals for model compounds and for some reaction mixtures
were measured by high resolution 13C NMR spectroscopy.
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.