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products of pyrolysis. Thermogravimetric analyser coupled with Fourier transform infrared spectrometer (TG-FTIR) is a useful tool in dynamic analysis as it monitors continuously both the weight of the non-volatile materials (residue) and the time
Abstract
Thermal degradation behaviour of alcoholysis lignin-based polycaprolactones (ALPCL's) with various molar ratios of β-caprolactone monomer to each hydroxyl group of lignin (CL/OH ratios) was studied by TG-FTIR. The temperature was varied from 20 to 800C. Thermal degradation temperatures (Td's) of alcoholysis lignin (AL) and ALPCL's were determined using TG curves. Td increased with increasing CL/OH ratio, suggesting that AL becomes thermally stable after the derivatization with PCL chains. Mass residue (MR) at 500C was also determined using TG curves. MR values decreased with increasing CL/OH ratios. The evolved gases formed by thermal degradation of ALPCL's at various temperatures were simultaneously analyzed by FTIR. The main peaks observed for the samples are as follows: wavenumber (assignment): 1160 cm-1 (vC-O-), 1260 cm-1(-C(=O)-O-C-), 1517 and 1617 cm-1 (vC=C), 1770 cm-1 (vC=O), 2345 cm-1 (vCO2), 2945 cm-1 (vC-H) and 3700 cm-1 (vOH). It was found that the peak intensities for C=O, CH, C-O-C, OH peaks, which were observed for evolved gases at 430C, increased with increasing CL/OH ratios, suggesting that the evolved gases at 430C are mainly formed by thermal degradation of PCL chains in ALPCL's.
Abstract
Thermogravimetry (TG), thermogravimetry coupled with mass spectroscopy (TG-MS) and thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) were used to characterise the thermo-oxidative behaviour of two intumescent coating materials. The temperature dependence, the corresponding volatile products and the amount of residue of the different processes were determined. Using both TG-MS and TG-FTIR results in an unambiguous interpretation of the volatile products. Characteristics such as the influence of endothermic reactions, the release of non-flammable gases, the dehydrogenation enhancing the char formation and the stability of the cellular char were discussed in detail. It was demonstrated, that TG, TG-MS and TG-FTIR are powerful methods to investigate mechanisms in intumescent coatings and that they are suitable methods in respect to quality assurance and unambiguous identification of such materials.
Abstract
Thermogravimetry has been widely used for the characterization of several biomasses but the most useful information given by this technique has been normally concerned to the relative amounts of humidity, hemi-cellulose, cellulose and lignin present in the biomass. TG-FTIR has been used to yield qualitative data about the pyrolysis products, in an exploratory way, by some authors. In the present paper, this technique was employed to reach comparative data about the products of pyrolysis of biomasses that are potentially available at economic bases for the production of biofuels. Agricultural residues such as coconut shell, sugarcane bagasse, corn stalks and peanut shell were chosen to be investigated. For all samples, the thermogravimetric curves showed a mass loss between 35 and 400 °C changed up to 73%, while that the loss between 400 and 800 °C changed up to 26%. TG-FTIR indicated tendencies in the rate of the formation of important species during the pyrolysis process of the four biomasses studied. The interpretation of the spectra allowed the proposition of characteristic absorbance ratios and the comparison of these values allowed inferences about the relative abundances of components formed in the pyrolysis of the biomasses. As an example of the possible inferences reached, among the species formed in the pyrolysis condensate, called bio-oil, the formation of carboxylic acids has to be specially considered due to their corrosivity. Thus, the data produced indicated that a bio-oil derived from peanut shell should be a little less acidic while the one derived from sugarcane bagasse should be showed more acidic among the biomasses studied.
Abstract
The study on the thermal behavior of some new diazoaminoderivatives was aimed to follow the structure-thermal stability-degradation mechanism correlation by means of the TG-FTIR technique and formation enthalpies. The TG-DTG-DTA curves reveal the thermal degradation in air (30–900 °C) to show two ranges as a function of temperature (time), where the gaseous species resulting by degradation are eliminated: the first, an endothermic one which is identical to that under nitrogen atmosphere and the second, an exothermal one. As made evident by the identification of the individual gaseous species by their characteristic absorbances as well as those obtained by TG-FTIR the compounds C2H2, H2C = NH, SO2, NH3, CO2, H2O, HCl are eliminated in the first domain while CO2, SO2, H2O in the second, which afforded the advancement of the most probable degradation mechanism.
Abstract
Thermogravimetry (TG/DTG) coupled with evolved gas analysis (MS detection) of volatiles was used to characterize the thermal behavior of commercial PVC cable insulation material during heating in the range 20-800C in air and nitrogen, respectively. In addition, simultaneous TG/FTIR was used to elucidate chemical processes that caused the thermal degradation of the sample. A good agreement between results of the methods was found. The thermal degradation of the sample took place in three temperature ranges, namely 200-340, 360-530 and 530-770C. The degradation of PVC backbone started in the range 200-340C accompanied by the release of HCl, H2O, CO2 and benzene. The non-isothermal kinetics of thermal degradation of the PVC cable insulation in the temperature range 200-340C was determined from TG results measured at heating rates of 1.5, 5, 10, 15 and 20 K min-1 in nitrogen and air, respectively. The activation energy values of the thermal degradation process in the range 200-340C of the PVC cable insulation sample were determined from TG results by ASTM method.
small flow rates through the TG instrument in order to increase the gas exchange rates and to prevent peak broadening. In the present article, we report about the development and test of a TG-FTIR system for the thermal analysis of substances
Abstract
The TG-FTIR technique was used in the present study to investigate the thermal degradation behaviour of materials containing brominated flame retardants under fire conditions. Time-temperature profiles and oxygen concentrations typical of selected fire scenarios were reproduced in the thermogravimetric analyzer, while the characterization of the gaseous products generated was performed by the simultaneous FTIR analysis. FTIR analysis combined with the use of specific calibration procedures allowed the quantitative estimation of the gaseous products evolved as a function of experimental conditions. The results obtained allowed the straightforward assessment and the comparison of the quantities of hydrogen bromide formed in the oxidation and thermal degradation of pure brominated flame retardants and of flame retarded materials of industrial interest. Hydrogen bromide yields resulted dependent on the experimental conditions used, such as oxygen concentration and heating rate. Although TG-FTIR experiments only provide a representation of the actual heterogeneous combustion products in real fire conditions, the coupled TG-FTIR technique proved to be a straightforward experimental methodology allowing one to obtain reference data on the nature and quantities of the macropollutants generated in a fire.
(conservation, culinary preparations, etc.) and since the failed cultures might be capitalized by burning, this study is completely justified. By taking into account the fact that the coupled TG–FTIR analysis has lately been proved to be very efficient
stability and thermal degradation of aramid fibers, but there are few publications on the comparison in their thermal stability and analysis of thermal degradation process by TG/FTIR and Py-GC/MS. In this article, the thermal degradation of Kevlar 49
