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Adamantan-2-one is an adamantane derivative used as a precursor for different adamantane-based pharmacologically active compounds. Adamantan-2-one and memantine hydrochloride were investigated in other of our previous published papers, as pure compounds and in binary mixtures with various excipients. The aim of our study is to determine the thermal behavior of adamantan-2-one, as well as the kinetic parameters that characterize the degradation process of this precursor. The employed analytical techniques were thermal analysis (TG/DTG/HF) and FTIR spectroscopy. The TG/DTG/HF curves were recorded in air at different heating rates: β = 5, 7, 10, 12 and 15 °C min, in respect of the ICTAC 2000 protocol regarding the kinetic analysis. The methods used for kinetic analysis of the thermal degradation process were isoconversional methods: Friedman and Flynn-Wall-Ozawa. Modified NPK method was used for determination of kinetic parameters. [ABSTRACT FROM AUTHOR]

Two samples of poly(lactic acid) (PLA) with distinct molar masses were evaluated regarding thermal stability, glass transition temperature, morphology and mass loss, due to exposure to three media normally found in the petroleum industry: neutral (distilled water), saline (brine) and organic (toluene). PLA microparticles were produced using the emulsion/solvent evaporation technique. The system had an organic phase (based on PLA) and an aqueous phase (based on polyvinyl alcohol), with variation not only of the polymer's molar mass, but also the emulsifier's concentration. The greatest mass loss percentage in function of time was observed in the organic medium (65 %), followed by the neutral (35 %) and saline medium (20 %). The morphological analysis revealed that only the samples exposed to the neutral and saline media showed signs of erosion, while the sample exposed to the organic medium swelled. This was related to the fact that organic media act only to dissolve the material, while aqueous media degrade the chains, reducing the molar mass by up to 50 %. The morphology, size and size distribution of the microparticles with low molar mass were found to be more susceptible to the preparation method than those with high molar mass. Therefore, these microparticles have potential for use in controlled release of chemical additives in the oil industry, and the timing of this release can be controlled by varying the molar mass of the polymer and/or the conditions for preparing the microparticles. [ABSTRACT FROM AUTHOR]

The study describes the thermal properties of porous microspheres synthesized with functional monomer 4-vinylpyridine (4VP) and crosslinking agent trimethylolpropane trimethacrylate (TRIM). Polymeric 4VP-TRIM microspheres were prepared via seed polymerization, using polystyrene microbeads as a shape template. The resulting 4VP-TRIM microspheres were in the range of 9-12 μm, with specific surface area of about 200 m g. The thermal properties of 4VP-TRIM materials were evaluated by thermogravimetry and differential scanning calorimetry. By TG/FTIR/MS, it was observed that new porous materials exhibited multi-staged decomposition patterns, different from poly(TRIM) microspheres. DSC and TG experiments showed that water molecules were absorbed on the materials' surface. The synthesized 4VP-TRIM microspheres exhibited rather high thermal stability. Their initial decomposition temperature was about 300 °C. During the microspheres' decomposition, an evolution of carbon dioxide, water, and carbon monoxide as main gases, as well as of pyridine and aliphatic compounds, was observed. It was confirmed that the evolved pyridine accelerated the degradation of copolymeric network. [ABSTRACT FROM AUTHOR]

Five new dumbbell-shaped polyhedral oligomeric silsesquioxanes (POSSs), in which two identical silicon cages R(SiO) (with R = isobutyl), linked to various aromatic bridges (Ar, Ar-Ar, Ar-O-Ar, Ar-S-Ar and Ar-SO-Ar, where Ar = p-CH) were prepared through a literature method opportunely modified by us to make easier preparation and increase yield, which was higher than 70 % in all cases. The obtained products were the expected ones, as supported by the results of elemental analysis and H NMR spectra. Their resistance to the thermal degradation in both flowing nitrogen and static air atmosphere was checked by degrading samples at 10 °C min and determining temperatures at 5 % mass loss ( T) and residues at 700 °C. The T values in air were lower than the corresponding ones in nitrogen, but the trend among the various POSSs investigated was the same in both used atmospheres, with the most high value for the compound having the Ar-O-Ar aromatic bridge. The residues at 700 °C in air of the compounds having not hetero-atoms (O or S) in the aromatic bridge were higher than those in nitrogen, whilst no substantial difference was observed for the other ones. [ABSTRACT FROM AUTHOR]

Inclusion compounds (intercalates) of fluorinated graphite matrix with acetone (CFBr· y(CH)CO, x = 0.49, 0.69, 0.87, 0.92, z ≈ 0.01) were prepared by guest substitution from acetonitrile to acetone. The kinetics of the thermal decomposition (the first stage of filling → the second stage of filling) was studied under isothermal conditions at 292-313 K. The relationship of the host matrices structure with inclusion compounds thermal properties and kinetic parameters is discussed. [ABSTRACT FROM AUTHOR]

In this paper, the thermal behaviours of two organophosphorous compounds, N, N-dimethyl- N′, N′-diphenylphosphorodihydrazidic (NDD) and diphenyl amidophosphate (DPA), were studied by thermogravimetery (TG), differential thermal analysis (DTA) and differential scanning calorimetery (DSC) techniques under non-isothermal conditions. The results showed that NDD melts about 185 °C before it decomposes. NDD decomposition occurs in two continuous steps, in the 190–410 °C temperature range. First thermal degradation stage for NDD results a broad exothermic peak in the DTA curve that is continued with a small exothermic peak at the end of decomposition process. On the other hand, applying TG-DTA techniques indicates that DPA melts about 150 °C before it decomposes. This compound decomposes in the temperature range of 230 to 330 °C in two steps. These steps are endothermic and exothermic, respectively. Activation energy and pre-exponential factor for the first step of decomposition of each compound were found by means of Kissinger method and were verified by Ozawa–Flynn–Wall method. Activation energy obtained by Kissinger method for the first stage of NDD and DPA decompositions are 138 and 170 KJ mol−1, respectively. Finally, the thermodynamic parameters (Δ G#, Δ H# and Δ S#) for first step decomposition of investigated organophosphorous were determined. [ABSTRACT FROM AUTHOR]

This paper deals with the investigation concerning the thermal stability of two new azo-derivatives and their Cu(II) complexes of type [Cu(L1)2] and, respectively, ((C4H9)4N)2[Cu(L2)2]. The thermal decomposition steps have been put in evidence. For the kinetically workable ones, the values of the activation energy vs. conversion degree were determined. [ABSTRACT FROM AUTHOR]