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Abstract  

When ethylene-vinyl acetate copolymer, EVA, is heated, a two-stage thermal degradation occurs following its melting. The vinyl acetate content of the copolymer was determined to be 43.8% by using TA 2950 and TA 2050 thermogravimetric instruments. TG/FTIR was used to detect the evolved gas. Acetic acid and trans-1-R-4-R'-cyclohexane were the main products evolved from EVA in the first and second stage, respectively. The apparent activation energies were determined for both stages by differential methods.

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Journal of Thermal Analysis and Calorimetry
Authors: Yu. Trach, V. Sydorchuk, O. Makota, S. Khalameida, R. Leboda, J. Skubiszewska-Zięba, and V. Zazhigalov

Abstract

Deposited catalysts composition H3PMo12O40/SiO2 and Ag/H3PMo12O40/SiO2 have been synthesized on the basis of fumed silica, including milling technique. Physical–chemical characteristics of prepared catalysts have been studied by means of XRD, DTA-TG, FTIR, UV–Vis spectroscopy, and adsorption of nitrogen. Catalysts possess meso- or meso-macroporous structure and contain deposited Keggin heteropolycompounds. Deposition of heteropolycompounds on support with high specific surface area results in increase of selectivity to epoxide in epoxidation reactions. The use of milling during catalyst synthesis leads to further growth of selectivity of epoxides formation.

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Journal of Thermal Analysis and Calorimetry
Authors: Thangamani Rajkumar, Chinnaswamy Vijayakumar, Palanichamy Sivasamy, Bojja Sreedhar, and Charles Wilkie

Abstract  

Imparting thermal stability to polymethyl methacrylate (PMMA) without affecting its optical clarity is attempted by incorporating HET acid based oligoesters. Pure PMMA and PMMA containing five and 20 wt% of four different oligoesters are separately prepared using bulk polymerization. The thermal properties of the materials studied using DSC, TG, TG–FTIR and Pyr–GC–MS are presented. The main volatile degradation products identified are CO, HCl, CO2, H2O, hexachlorocyclopentadiene, hexachloroendomethylene tetrahydrophthalic acid/anhydride and methyl methacrylate. A detailed mechanism for the influence of the degradation products of HET acid based oligoesters on the thermal degradation of PMMA is also presented.

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A precursor of Y-Ba-Cu oxides was prepared by a modified alkoxide sol-gel method and its thermal decomposition in air was studied by on-line coupled TG-FTIR and High Resolution Thermogravimetric measurements. A continuous more or less stepwise weight loss was observed between room temperature and 600°C at which all organic compounds had evolved and were progressively oxidized as the temperature increased leaving only Y and Cu oxides and bariumcarbonate. Between 700 and 800°C a final weight loss was observed due to the decomposition of bariumcarbonate into oxide.

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Abstract  

Thermal analysis is a useful tool for investigating the properties of polymer/clay nanocomposites and mechanisms of improvement of thermal properties. This review work presents examples of applications of differential scanning calorimetry (DSC), modulated temperature differential scanning calorimetry (MT-DSC), dynamic mechanical thermal analysis (DMA), thermal mechanical analysis (TMA), thermogravimeric analysis (TG) and thermoanalytical methods i.e. TG coupled with Fourier transformation infrared spectroscopy (TG-FTIR) and mass spectroscopy (TG-MS) in characterization of nanocomposite materials. Complex behavior of different polymeric matrices upon modification with montmorillonite is briefly discussed.

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Abstract  

Composition and structure of crystals of unknown origin, crystallizing spontaneously from ethylenediamine on standing, has been determined by elemental analysis, FTIR, 1H and 13C NMR spectroscopy and X-ray diffraction. The crystal with molecular formula C6H14N4 has been found to be a highly symmetric saturated imino compound with double-ring structure, and unambiguously identified as trans-1,4,5,8-tetraazodecalin by 1H NMR and powder X-ray diffraction based on both its specific AA'BB' spin coupling system and simulated XRD pattern calculated from available data of previous single crystal structure determination, respectively. Simultaneous TG/DTA measurement shows one-step degradation of this compound. The volatile decomposition products have been followed by both TG/DTA-MS and TG-FTIR. Group of the largest fragments (m/z=80, 81 and 82) observed by TG/DTA-MS corresponds to an aromatic 1,4-diazine (pyrazine). In the EGA-FTIR spectrum of released gaseous species measured at the highest evolution rate by TG-FTIR, ethylenediamine can be identified as another decomposition product.

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Abstract  

TG, FTIR-(CO absorption), and catalytic activity in the NO reduction by CO were used to characterize Cu/Al2O3-TiO2 catalysts prepared by co-gelling aluminum tri-sec-butoxide and titanium iso-propoxide at pH 9 and at pH 3 gelling conditions. Under nitrogen flow, copper oxide decomposition, oxygen storage capacity (OSC) and sample dehydroxylation (total mass loss) was followed by TG. The CuO decomposition forming Cu0, Cu+1 was observed by means of FTIR (CO absorption) spectra. In pH 9 sample the large amount of Cu0 was observed. At low total mass loss and high Cu0/Cu+1+Cu+2 ratio (pH 9 sample) a lowest light-off in the NO reduction by CO was observed.

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Abstract  

Thermal treatment of torasemide form A resulted in several effects which were divided into five steps. These were investigated and discussed applying TG-MS and TG-FTIR with additional information derived from SEM, hot-stage and FTIR microscopy. The investigated crystal form of torasemide represents a mixed solvate including ethanol and water. Its desolvation, the solid-solid transformation into the anhydrate mod. II and the melting of this anhydrate is elucidated using thermal analysis and microscopic observations (FTIR and hot-stage microscopy). The released and evaporated solvents were determined with coupled techniques. On further heating the structural identification of evolved gases allowed the analysis of the degradation pathway of torasemide up to 340C.

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Abstract  

The thermal decomposition behaviour of the manganese(II) complexes with glycine: Mn(gly)Cl2(H2O)2, Mn(gly)2Cl2, Mn(gly)Br2(H2O)2, Mn(gly)2Br2(H2O)2 was investigated by means of TG-DTG-DTA, Hi-Res-TA and DSC techniques. The evolved gas analysis was carried out by means of the coupled TG-FTIR system. Heating of the complexes results first in the release of water molecules. Next, the multi-stage decomposition process with degradation of glycine ligand occurs. Water, carbon dioxide and ammonia were detected in the gaseous products of the complexes decomposition. The temperature of NH3 evolution from the complexes is higher than from free glycine. The final residue in the air atmosphere is Mn2O3 which transforms into Mn3O4 at 930C. In a nitrogen atmosphere, the complexes decompose into MnO.

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Journal of Thermal Analysis and Calorimetry
Authors: J. Mullens, G. Reggers, M. Ruysen, R. Carleer, J. Yperman, D. Franco, and L. Van Poucke

Abstract  

The oxidative degradation of HET-acid (1,4,5,6,7,7-hexachlorobicyclo [2.2.1] hept-5-en-2, 3-dicarboxylic acid) is studied by the combination of TG, FTIR, MS and GC-MS. The gases evolved during the decomposition of this flame retardant are investigated on-line by FTIR and by MS. Simultaneously the evolved gases are collected by an adsorbent and, after the thermal experiment, desorbed to release the volatile products for identification using GC-MS. The combination of these techniques offers the unambiguous identification of the evolved products as a function of temperature. The main identified products are CO2, H2O, Cl2, HCl, C2Cl4, maleic acid anhydride, HET-acid anhydride, chlorinated cyclic hydrocarbons and chlorinated unsaturated linear hydrocarbons.

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