Authors:Yu. Trach, V. Sydorchuk, O. Makota, S. Khalameida, R. Leboda, J. Skubiszewska-Zięba, and V. Zazhigalov
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.
Authors:Thangamani Rajkumar, Chinnaswamy Vijayakumar, Palanichamy Sivasamy, Bojja Sreedhar, and Charles Wilkie
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
Authors:M. K. Van Bael, J. Mullens, R. Nouwen, J. Yperman, and L. C. Van Poucke
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.
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
Authors:Agnieszka Leszczynska and Krzysztof Pielichowski
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.
Authors:Margit Bán, J. Madarász, Petra Bombicz, G. Pokol, and S. Gál
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
Authors:R. Mrozek, Z. Rzączyńska, and M. Sikorska-Iwan
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.
Authors:J. Mullens, G. Reggers, M. Ruysen, R. Carleer, J. Yperman, D. Franco, and L. Van Poucke
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.
A novel PMR polyimides (TMBZ-15) based on substituted benzidines is examined and compared to state-of-the-art PMR-15. The
mechanism for the thermal decomposition of two specific PMR polyimides is obtained using TG/FTIR/MS techniques. In order to
verify the pathway of polyimide degradation, a pyrolysis/GC-MS technique was employed to evaluate the organic degradation
products, particularly the larger components that are destroyed in traditional TG/MS. A proposed degradation mechanism involves
two main stages of decomposition, each of which produce a variety of products. The first group includes aromatic hydrocarbons,
aromatic amines and nitriles, which correspond to partial fragments of polymer chains. The second group consists largely of
fluorene, naphthalene and phenanthrene, which are attributed to the isomerization, rearrangements and cyclizations of the
aforementioned pyrolyzates at high temperature.
Authors:M. Morán-Pineda, S. Castillo, M. Asomoza, and R. Gómez
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.