Thermal behaviour and structure of glasses from the SiO2–P2O5–K2O–MgO–CaO system modified by Fe2O3 addition were studied by DSC, XRD and FTIR methods. It has been found that the replacement of MgO and CaO modifiers by Fe2O3 in the structural network of silicate–phosphate glass results in decrease of the glass transition temperature (Tg) and heat capacity change (ΔCp) accompanying the glass transformation. Simultaneously, the ability for crystallization, its course and the type of the forming
phases depend on the relative proportions between iron and phosphorus as components forming the silicate–phosphate structure.
The type of the crystal phases forming in the course of heating the considered glass has been found to be in agreement with
the character of the domains occurring in this glass, confirmed by FTIR examinations.
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.
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:L.-M. Zhang, W.-G. Xie, T.-T. Wen, and X. Zhao
The thermal behavior of five free anthraquinones (chrysophanol, emodin, physcion, aloe-emodin, and rhein) from rhubarb had
been investigated using TG, DTG and DTA technique. The results show that all the free anthraquinones have the similar TG and
DTG curve shapes, however, due to the substituted groups attached on the skeleton of 1,8-dihydroxy anthraquinone are different,
every anthraquinone has different mass loss features. Moreover, all the DTA curves of these free anthraquinones have two obviously
characteristic peaks, but with special curvilinear types, peak location and peak values. Therefore, thermal analysis (TA)
characteristics of anthraquinones above mentioned could be established, and it is possible to easily distinguish these anthraquinones
by using TA technique.
Authors:Mihaela Badea, Rodica Olar, Dana Marinescu, and Gina Vasile
A series of new complexes with mixed ligands of the type [ML(C3H3O2)2]·nH2O (((1)M=Mn, n=1; (2)M=Co(II), n=2; (3)M=Ni(II), n=4; (4)M=Cu(II), n=1.5; (5)M=Zn(II), n=0; L=3-amino-1,2,4-triazole and (C3H3O2)=acrylate anion) were synthesized and characterised by chemical analysis and IR data. In all complexes the 3-amino-1,2,4-triazole
acts as bridge while the acrylate acts as bidentate ligand except for complex (5) where it is found as unidentate. The thermal behaviour steps were investigated in nitrogen flow. The thermal transformations
are complex processes according to TG and DTG curves including dehydration, acrylate ion and 3-amino-1,2,4-triazole degradation
respectively. The final products of decomposition are the most stable metal oxides, except for complex (4) that leads to metallic copper.
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 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.
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