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.
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.
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.
Authors:F. Kovanda, V. Balek, V. Dorničák, P. Martinec, M. Mašláň, L. Bílková, D. Koloušek, and I. Bountseva
Thermal behaviour of synthetic pyroaurite-like anionic clay with molar ratio Mg/Fe=2 was studied in the range of 60-1100C
during heating in air. TG/DTA coupled with evolved gas analysis, emanation thermal analysis (ETA), surface area measurements,
XRD, IR and Mssbauer spectroscopy were used. Microstructure changes characterized by ETA were in a good agreement with the
results of surface area measurements and other methods. After the thermal decomposition of the pyroaurite-like anionic clay,
which took place mainly up to 400C, a predominantly amorphous mixture of oxides is formed. A gradual crystallization of MgO
(periclase) and Fe2O3 (maghemite) was observed at 400-700C by XRD. The MgFe2O4 spinel and periclase were detected at 800-1100C. The spinel formation was also confirmed by Mssbauer spectroscopy.
Authors:V. Sargentelli, A. Mauro, A. de Godoy Netto, M. Mattioli, V. Nogueira, and V. De Lucca Neto
Pseudohalide complexes of copper(II) with aliphatic bidentate amines, [Cu(N3)2(N,N-diEten)]21, [Cu(NCO)2(N,N-diEten)]22, [Cu(NCO)2(N,N-diMeen)]23, [Cu(N3)(NCS)(N,N'-diMeen)]24 and [Cu(N3)(NCO)(N,N-diMeen)]25 (N,N-diEten=N,N-diethylethylenediamine; N,N-diMeen=N,N- dimethyl-ethylenediamine and N,N'-diMeen = N,N'-dimethylethylenediamine), were prepared, characterized and their thermal behavior was investigated by TG curves. According to thermal analysis and X-ray diffraction patterns all compounds decomposed giving copper(II) oxide as final product. The mechanisms of decomposition were proposed and an order of thermal stability was established.
Thermal behaviour of the
glass series (100–y)[0.5ZnO0.1B2O30.4P2O5]yTiO2
(with y=0–39 mol% TiO2)
was investigated by DSC and TMA. The addition of TiO2
results in a non-linear increase of glass transition temperature. The compositional
dependences of thermal stability, evaluated by two criteria exhibit two maxima
for the glasses doped with 10.7 and 35.9 mol% TiO2.
All the glasses crystallize on heating in the temperature range of 576–670C.
The crystallization mechanism was studied at the glasses with 19.4 and 35.9
mol% TiO2 and the results showed that surface nucleation
mechanism prevails in these glasses over the internal one.
The thermal behaviors of three pentaerythritol tetranitrate (PETN) base polymer bonded explosives (PBX), Detasheet A (EL506A,
red) and Datasheet C (EL506C, yellow-green) that supply by DuPont Co., PBXN-301 were investigated using thermal techniques
in this work. The thermal properties of PETN base polymer bonded explosives, such as vacuum thermal stability (VTS), time
to ignition, auto-ignition and shelf life of PBX that calculation from Arrhenius equation by the length of time for 5% decomposition
were also examined. By comparing the thermal properties, VTS and shelf life of PETN base polymer bonded explosives, the application
and storage of Datasheet C (EL506C, yellow-green) should be considered carefully, owing to the ingredients of Datasheet C
(EL506 C, yellow-green) containing nitrocellulose. Binders that using in this study seems play no significant effect on the
decomposition for polymer bonded explosives, because the decomposition temperature of binders is always higher than that of
Authors:D. Balköse, T. Egbuchunam, and F. Okieimen
Soaps are a class of surface active compounds derived from natural oils and fats. Double decomposition reactions permit the
synthesis of metallic soaps, which are long-chain carboxylates of metal ions, from alkaline ones such as sodium, potassium
or ammonium soaps. Metallic soaps are commercially important as they find use in diverse applications such as driers in paints
or inks, components of lubricating greases, heat stabilizers for plastics (especially PVC), catalysts and water proofing agents,
fuel additives and cosmetic products amongst others. Many of these applications are related to the thermal properties of these
compounds and the thermal behaviour of metal soaps in terms of decomposition processes is of great importance. Rubber seed
oil (RSO) which is an unsaturated triglyceride abundantly available in Nigeria, India and Australia is an excellent starting
material for metal soaps. In this study rubber seed oil having 2.2% myristic acid, 7.6% palmitic acid, 10.7% stearic acid,
20.61% oleic acid, 36.62% linoleic acid, 22.5% linolenic acid was used in making barium, calcium, cadmium and zinc soaps.
The thermal behaviour of soaps (Ba, Ca, Cd and Zn) of rubber seed oil for use as additives in the processing of poly(vinyl
chloride) (PVC) was investigated by thermal gravimetry and differential scanning calorimetry. The stability of the soaps was
examined by thermogravimetry up to 873 K at a constant heating rate of 10 °C min−1. The soaps were found to be thermally stable up to 473 K as they recorded less than 5% mass loss at this temperature with
values of apparent activation energy for decomposition varying from 52 to 96 kJ mol−1. Differential scanning calorimetric studies of the soaps revealed melting and decomposition behaviour of metal soaps.
Authors:B. Yan, H. X. Ma, N. N. Zhao, T. Mai, J. R. Song, F. Q. Zhao, and R. Z. Hu
]. N -2,4-dinitrophenyl-3,3-dinitroazetidine (DNPDNAZ) is a novel insensitive high-energy explosive. Presently, there are no reports about the thermal and detonation characterizations of DNPDNAZ. In the present study, thermalbehavior, non