Authors:M. Beneš, V. Pla?ek, G. Matuschek, A. A. Kettrup, K. Györyová, W. D. Emmerich, and V. Balek
Thermal behavior of commercial PVC cable insulation both before and after extraction of plasticizers, fillers and other agents
were tested by TG/DTG and DSC during heating in the range 20-800C in air. The ultrasound enhanced hexane extraction and dissolution
in THF with subsequent precipitation of PVC were used to prepare 'extracted' and 'precipitated' samples. The total mass loss
measured for the 'non-treated', 'extracted' and 'precipitated' PVC samples was 71.6, 66.6 and 97%, respectively. In the temperature
range 200-340C the release of dioctylphthalate, HCl and CO2was observed by simultaneous TG/FTIR. From TG results measured at different heating rates (1.5, 5, 10, 15 K min-1) in the range 200-340C the non-isothermal kinetics of the PVC samples degradation was determined. Activation energy values
of the thermal degradation processes calculated by ASTM E 698 method, for 'non-treated', 'extracted' and 'precipitated' PVC
samples were 174.617 kJ min-1, 192.819 kJ min-1, 217.120 kJ min-1, respectively. These kinetic parameters were used for the lifetime simulation of the materials.
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.
Triprolidine hydrochloride (C19H22N2·HCl·H2O) (TPH) is a well-known antihistamine drug which is reported as being photosensitive. The thermal stabilities of TPH and
of 1:1 molar and 1:1 mass ratio physical mixtures of TPH with β-cyclodextrin (BCD) and with glucose have been examined using
DSC, TG and TG-FTIR, complemented by X-ray powder diffraction (XRD) and infrared spectroscopic (IR) studies. Thermal studies
of the solid TPH/BCD mixtures indicated that interaction between the components occurs and it is possible that the TPH molecule
may be least partially accommodated in the cavity of the BCD host molecule. XRD results support this indication of inclusion.
The results of molecular modelling suggest that TPH is most likely to be accommodated in the BCD cavity as a neutral triprolidine
molecule with the toluene portion of the molecule preferentially included in the cavity. The results obtained illustrate the
general stability of TPH. The study has also shown TPH to be compatible with both glucose and BCD, which are potential excipients
both in solid and liquid dosage forms. The presence of these excipients in dosage forms will thus not adversely affect the
stability and the therapeutic efficacy of TPH.
Authors:Y. Duan, J. Li, X. Yang, X. Cao, L. Hu, Z. Wang, Y. Liu, and C. Wang
The thermal decomposition of strontium acetate hemihydrate has been studied by TG-DTA/DSC and TG coupled with Fourier transform
infrared spectroscopy (FTIR) under non-isothermal conditions in nitrogen gas from ambient temperature to 600°C. The TG-DTA/DSC
experiments indicate the decomposition goes mainly through two steps: the dehydration and the subsequent decomposition of
anhydrous strontium acetate into strontium carbonate. TG-FTIR analysis of the evolved products from the non-oxidative thermal
degradation indicates mainly the release of water, acetone and carbon dioxide. The model-free isoconversional methods are
employed to calculate the Ea of both steps at different conversion α from 0.1 to 0.9 with increment of 0.05. The relative constant apparent Ea values during dehydration (0.5<α<0.9) of strontium acetate hemihydrate and decomposition of anhydrous strontium acetate (0.5<α<0.9)
suggest that the simplex reactions involved in the corresponding thermal events. The most probable kinetic models during dehydration
and decomposition have been estimated by means of the master plots method.
Authors:J. Suuronen, I. Pitkänen, H. Halttunen, and R. Moilanen
The thermochemical behaviour of betaine and betaine monohydrate was investigated under two degradation conditions. Betaine was heated up to 700°C at 10°C min–1 in air and nitrogen flows and the evolved gas was analysed with the combined TG-FTRIR system. The evolved gas from betaine pyrolysis at 350 and 400°C was analysed by gas chromatography using mass-selective detection (Py-GC/MSD). In addition, the electron impact mass spectra of betaine and betaine monohydrate were measured.Esterification is one of the most important pyrolytic processes involving beta- ines. Even glycine betaine can change to dimethylglycine methyl ester via intermolecular transalkylation by heating. Trimethylamine, CO2, and glycine esters were the main degradation products. Small amounts of ester type compounds evolved both in pyrolysis and with TG-FTIR. The monohydrate lost water between 35 and 260°C while the main decomposition took place at 245-360°C. The residual carbon burnt in air to CO2 up to a temperature 570°C.
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.
Authors:J. G. Dunn, A. C. Chamberlain, N. G. Fisher, and J. Avraamides
The thermal decomposition of SEX in a nitrogen atmosphere was studied by coupled thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR), and by pyrolysis-gas chromatography-mass spectrometry (py-GC-MS). The TG curve exhibited two discrete mass losses of 45.8% and 17.8% respectively, at 200 and 257–364°C. The evolved gases identified as a result of the first mass loss were carbonyl sulfide (COS), ethanol (C2H5OH), ethanethiol (C2H5SH), carbon disulfide (CS2), diethyl sulfide ((C2H5)2S), diethyl carbonate ((C2H5O)2CO), diethyl disulfide ((C2H5)2S2), and carbonothioic acid, O, S, diethyl ester ((C2H5S)(C2H5O)CO). The gases identified as a result of the second mass loss were carbonyl sulfide, ethanethiol, and carbon disulfide. Hydrogen sulfide was detected in both mass losses by py-GC-MS, but not detected by FTIR. The solid residue was sodium hydrogen sulfide (NaSH).
SEX was adsorbed onto activated carbon, and heated in nitrogen. Two discrete mass losses were still observed, but in the temperature ranges 100–186°C (7.8%) and 186–279°C (11.8%). Carbonyl sulfide and carbon disulfide were now the dominant gases evolved in each of the mass losses, and the other gaseous products were relatively minor. It was demonstrated that water adsorbed on the carbon hydrolysed the xanthate to cause the first mass loss, and any unhydrolysed material decomposed to give the second mass loss.
Thermal decomposition of a mixed valence copper salt, Na4[Cu(NH3)4][Cu(S2O3)2]2·0.5NH3 (1) prepared from pentahydrates of sodium thiosulfate and copper sulphate of various molar ratios in 1:1 v/v aqueous ammonia
solution, has been studied up to 1,000 °C in flowing air by simultaneous thermogravimetric and differential thermal analysis
coupled online with quadrupole mass spectrometer (TG/DTA-MS) and FTIR spectrometric gas cell (TG-FTIR), in comparison. Compound
1 releases first but very slowly some of the included ammonia till 170 °C, then simultaneously ammonia (NH3) and sulphur dioxide (SO2) from 175 to 225 °C, whilst the evolution of SO2 from thiosulfate ligands continues in several overlapping stages until 410 °C, and is escorted by explicit exothermic heat
effects at around 237, 260, 358 and 410 °C. The former two exothermic DTA-peaks correspond to the simultaneous degradation
and air oxidation processes of excess thiosulfate anions not reacted by formation of copper sulfides (both digenite, Cu1.8S and covellite, CuS, checked by XRD) and sodium sulfate, while the last two exothermic peaks are accompanied also by considerable
mass gains, as the result of two-step oxidation of copper sulfides into various oxosulfates. The mass increase continues further
on until 580 °C, when the sample mass begins to decrease slowly, as a continuous decomposition of the intermediate copper
oxosulfates, indicated also by re-evolution of SO2. At 1,000 °C, a residual mass value of 64.3% represents a stoichiometric formation of CuIIO and anhydrous Na2SO4.
-MS), TG-FTIR, and TG-DTA] in details which field is the most dynamically developing ones recently.
The following section (Chap. 4) introduces thermomechanical analysis (TMA) and thermodilatometry (TD) by Harvey E. Bair, Ali E. Akinay, Joseph D