The new 1,2,4-benzenetricarboxylates of lanthanide(III) of the formula Ln(btc)�nH2O, where btc is 1,2,4-benzenetricarboxylate; Ln is La-Lu, and n=2 for Ce; n=3 for La, Yb, Lu; and n=4 for Pr-Tm were prepared and characterized by elemental analysis, infrared spectra and X-ray diffraction patterns. Polycrystalline
complexes are isotructural in the two groups: La-Tm and Yb, Lu. IR spectra of the complexes show that all carboxylate groups
from 1,2,4-benzentricarboxylate ligands are engaged in coordination of lanthanide atoms.
The thermal analysis of the investigated complexes in air atmosphere was carried out by means of simultaneous TG-DTA technique.
The complexes are stable up to about 30�C but further heating leads to stepwise dehydration. Next, anhydrous complexes decompose
to corresponding oxides. The combined TG-FTIR technique was employed to study of decomposition pathway of the investigated
Authors:A. Saponar, E.-J. Popovici, I. Perhaita, G. Nemes, and A.-I. Cadis
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.
Authors:C. T. Carvalho, F. J. Caires, L. S. Lima, and M. Ionashiro
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.
Authors:B. Zapata, J. Balmaseda, E. Fregoso-Israel, and E. Torres-García
Thermal degradation of orange peel was studied in dynamic air atmosphere by means of simultaneous TG-DSC and TG-FTIR analysis.
According to the obtained thermal profiles, the orange peel degradation occurred in at least three steps associated with its
three main components (hemicellulose, cellulose and lignin). The volatiles compounds evolved out at 150–400 °C and the gas
products were mainly CO2, CO, and CH4. A mixture of acids, aldehydes or ketones C=O, alkanes C–C, ethers C–O–C and H2O was also detected. The Eα on α dependence reveled the existence of different and simultaneous processes suggesting that the combustion reaction is
controlled by oxygen accessibility, motivated by the high evolution low-molecular-mass gases and volatile organic compounds.
These results could explain the non-autocatalytic character of the reactions during the decomposition process.
The effect on the stability of the isomers of aminosalicylic acid of formation of their sodium salts has been studied by use
of differential scanning calorimetry and thermogravimetry, coupled with evolved gas analysis by Fourier transform infrared
spectroscopy. X-ray powder diffraction and infrared spectroscopy provided complementary information. The DSC curves for the
sodium salts of all of the isomers showed complex dehydration/decomposition endotherms. From the initial mass losses of the
TG curves, the amounts of water per mole of salt were estimated as 0.5, 2.4 and 1.4 moles for the sodium salts of 3-aminosalicylic
acid, 4-aminosalicylic acid and 5-aminosalicylic acid, respectively. TG-FTIR results for the sodium salt of 3-aminosalicylic
acid showed the evolution of carbon dioxide in three stages: below 150C, between 200 and 300C and continuous formation up
to 500C. This behaviour differs from that of 3-aminosalicylic acid itself, which forms CO2 between 225 and 290C. For the sodium salt of 4-aminosalicylic acid, the formation of carbon dioxide starts from 250C and
is still being formed at about 650C. 4-aminosalicylic acid decarboxylates above 150C. 5-aminosalicylic acid and its sodium
salt showed no evolution of carbon dioxide below 600C.
Authors:M. Lappalainen, I. Pitkänen, H. Heikkilä, and J. Nurmi
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.
Authors:J. Ledru, B. Youssef, J. Saiter, and J. Grenet
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.
Authors:T. Kaljuvee, M. Radin, D. Astahhov, and Y. Pelovski
TG-FTIR technique was used for identification of gaseous compounds evolved
at thermal treatment of six coal samples from different deposits (Bulgaria,
Russia, Ukraine). The experiments were carried out under dynamic heating conditions
up to 900C at heating rates of 5, 10 or 50 K min–1
in a stream of dry air. The emission of CO2, H2O,
CO, SO2, COS, methane, methanol, formic acid, formaldehyde,
acetaldehyde, chlorobenzene was clearly identified in FTIR spectra of the
samples studied. The formation of ethanol, ethane, ethylene and p-xylene, at least on the level of traces, was also
identified. At the heating rate of 5C min–1
the temperature of maximum intensities of the characteristic peaks of COS
was 270C, of formaldehyde, formic acid, ethane and methanol 330C,
of SO2, CO, acetic acid, ethylene and p-xylene
400C and of chlorobenzene 500C. At 10C min–1
and 50C min–1 these temperatures were
shifted, respectively, by 70–300C and 150–450C towards
higher temperatures and the respective absorption bands in FTIR spectra were,
as a rule, more intensive.
Authors:S. Jingyan, L. Jie, D. Yun, H. Ling, Y. Xi, W. Zhiyong, L. Yuwen, and W. Cunxin
The thermal behavior of nicotinic acid under inert conditions was investigated by TG, FTIR and TG/DSC-FTIR. The results of
TG/DSC-FTIR and FTIR indicated that the thermal behavior of nicotinic acid can be divided into four stages: a solid-solid
phase transition (176–198°C), the process of sublimation (198–232°C), melting (232–263°C) and evaporation (263–325°C) when
experiment was performed at the heating rate of 20 K min−1. The thermal analysis kinetic calculation of the second stage (sublimation) and the fourth stage (evaporation) were carried
out respectively. Heating rates of 1, 1.5, 2 and 3 K min−1 were used to determine the sublimation kinetics.
The apparent activation energy, pre-exponential factor and the most probable model function were obtained by using the master
plots method. The results indicated that sublimation process can be described by one-dimensional phase boundary reaction,
g(α)=α. And the ‘kinetic triplet’ of evaporation process was also given at higher heating rates of 15, 20, 25, 30 and 35 K min−1. Evaporation process can be described by model of nucleation and nucleus growing,