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.
The cefadroxil (Cef) complexes with transition divalent metals of the formula MCefnH2O (where n=2 for M=Cu2+, Ni2+, Zn2+ and n=3 for Co2+) and CdCef1.54H2O were prepared and characterized by elemental and infrared spectra. The thermal analysis of the investigated complexes in
air atmosphere was carried out by means of simultaneous TG-DSC technique. During heating in air they lose bound water molecules
and then decompose to oxides: Co3O4, NiO, CuO, ZnO and CdO. The CdCef1.54H2O complex forms probably an intermediate product Cd2OSO4. The combined TG-FTIR technique was employed to study of decomposition pathway of the investigated complexes. The first mass
loss step is the water loss of the complexes. Next, decomposition of cefadroxil ligand occurs with evolution of CO2 and NH3. At slightly higher temperature COS is observed according to decomposition of cephem ring. Additionally, as decomposition
gaseous products: HCN, HNCO (HOCN), H2CNH, CO, SO2, hydrocarbons and carbonyl compounds were observed. The formation of metal sulfates is postulated as solid intermediate product
of decomposition in the argon atmosphere.
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.
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: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.
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.
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.
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.
-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