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.
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
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.
The thermal behaviour of three ester derivatives of p-tert-butyl calix[n]arene (n = 4, 6 and 8) in comparison with the parent calixarene was investigated by means of the thermogravimetric (TG) and differential thermogravimetic (DTG) analysis and differential scanning calorimetry (DSC). The thermal stability domains, the composition of the pyrolysis products and the thermal effects, were determined on the basis of TG, DTG and DSC plots registered in nitrogen flow. Attempts to analyse the evolved gases by TG-FTIR coupling were also performed. It was demonstrated that the stability of the calix[n]arene derivatives depends on both the size of the hydrophobic cavity and number of the substituting groups grafted on the calix[n]arene skeleton.
Solid-state M-2-MeO-CP compounds, where M represents bivalent Mn, Fe, Co, Ni, Cu, Zn and 2-MeO-CP is 2-methoxycinnamylidenepyruvate, were synthesized for the first time. Simultaneous thermogravimetry and differential thermal analysis, differential scanning calorimetry, X-ray powder diffractometry, infrared spectroscopy, TG-FTIR system, elemental analysis and complexometry have been used to characterize and to study the thermal behaviour of the compounds. The dehydration in all the compounds, except for iron occurs in a single step. The thermal decomposition of the anhydrous compounds occurs in two or three steps with the formation of the respective oxides, Mn3O4, Fe2O3, Co3O4, NiO, CuO and ZnO, as final residue. The results also provided information concerning the thermal behaviour and identification of the gaseous products evolved during the heating of these compounds.
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.
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.
Commercial light-cured dental composites were used in this study. Two laboratorial composites, Resilab (Wilcos/Brazil), Epricord
(Kuraray/Japan) were compared under cured and uncured conditions. Thermal analysis, infrared spectroscopy and scanning electron
microscopy were used to evaluate the dental composites. The mass change and heat flow signals (TG–DSC) were recorded simultaneously
by using STA 409 PC Luxx (NETZSCH), in the 25–800 °C temperature range at a heating rate of 10 °C/min under nitrogen atmosphere
(70 mL/min). Employing thermo-microbalance TG 209 C F1 Iris (NETZSCH) coupled to the BRUKER Optics FTIR TENSOR, the samples
were analyzed by combined thermogravimetric and spectroscopic methods (TG–FTIR). The initial sample mass was about ~12 mg,
the data collection have been done in the 35–800 °C temperature range at a heating rate of 20 K/min in nitrogen atmosphere
(flow rate: 40 mL/min). Finally, superficial topographic was analyzed by scanning electron microscopy (SEM). Dental composite
evaluation suggests a high thermal stability and inorganic content in RES D sample. Degrees of conversion (DC) values were
almost the same and there was no direct relationship between DC and amount of particles and size. Similar compositions were
found in all samples.
Two different poly(urethane acrylate) resins (one with a trimer: PUA1, the second with a dimer: PUA2) prepared  by photo
curing reaction are investigated by means of thermogravimetry and thermomechanical measurements. The lack of mass loss found
up to 300C for both systems shows their good thermal stability. Beyond this temperature, two mass losses occur consecutively.
This mass loss already studied by TG-FTIR coupled measurements for PUA1 resin has been attributed to the degradation of carbonyl
groups . The extension to PUA2 and the comparison between the mass loss magnitude and the relative contain in acrylate
of the resins leads to attribute the first degradation to the degradation of the acrylate fraction. The degradation of dimer
based resin occurs earlier and with a faster kinetic than the trimer based resin. The variations of linear expansion and penetration
coefficients measured by thermomechanical analysis (penetration probe) in the glassy state and in the glass transition temperature
domain (the onset glass transition temperatures measured by DSC at 20C min–1 are respectively equal to 111 and 107C for PUA1 and PUA2, the transitions, not well defined, extending over 30C), show
that despite of a weaker compactness, the trimer based resin is more rigid than the dimer one.
enantiomeric forms of xylose were identified as α-D-xylopyranose
and α-L-xylopyranose by powder diffraction.
Their melting behaviour was studied with conventional DSC and StepScan DSC
method, the decomposition was studied with TG and evolved gases were analyzed
with combined TG-FTIR technique. The measurements were performed at different
heating rates. The decomposition of xylose samples took place in four steps
and the main evolved gases were H2O, CO2
and furans. The initial temperature of TG measurements and the onset and peak
temperatures of DSC measurements were moved to higher temperatures as heating
rates were increased. The decomposition of L-xylose
started at slightly higher temperatures than that of D-xylose
and L-xylose melted at higher temperatures
than D-xylose. The differences were more
obvious at low heating rates. There were also differences in the melting temperatures
among different samples of the same sugar. The StepScan measurements showed
that the kinetic part of melting was considerable. The melting of xylose was
anomalous because, besides the melting, also partial thermal decomposition
and mutarotation occurred. The melting points are affected by both the method
of determination and the origin and quality of samples. Melting point analysis
with a standardized method appears to be a good measure of the quality of
crystalline xylose. However, the melting point alone cannot be used for the
identification of xylose samples in all cases.