Thermogravi metric analysis

Volatilization gravimetric methods are time- and labor-intensive. Equipment needs are few except when combustion gases must be trapped or for a thermogravi-metric analysis, which requires specialized equipment. 

Thermoanalytical techniques such as differential scanning calorimetry (DSC) and thermogravi-metric analysis (TGA) have also been widely used to study rubber oxidation [24—27]. The oxidative stability of mbbers and the effectiveness of various antioxidants can be evaluated with DSC based on the heat change (oxidation exotherm) during oxidation, the activation energy of oxidation, the isothermal induction time, the onset temperamre of oxidation, and the oxidation peak temperature. 

The thermal properties of tyrosine-derived poly(iminocarbonates) were also investigated. Based on analysis by DSC and thermogravi-metric analysis, all poly(iminocarbonates) decompose between 140 and 220 C. The thermal decomposition is due to the inherent instability of the iminocarbonate bond above 150°C and is not related to the presence of tyrosine derivatives in the polymer backbone. The molecular structure of the monomer has no significant influence on the degradation temperature as indicated by the fact that poly(BPA.-iminocarbonate) also decomposed at about 170 C, while the structurally analogous poly(BPA-carbonate) is thermally stable up to 350 C. 

The thermal decomposition of PPC has been studied in the past using several methods, including the time-dependent viscosity of hot PPC, thermogravi-metric analysis (TGA), and pyrolysis gas chromatography/mass spectrometry... 

Water of crystallization in hydrated salt can be measured by thermogravi-metric analysis. Zinc can be measured in an aqueous solution by flame- or furnace- AA or ICP-AES (See Zinc). Nitrate anion can be measured in a diluted solution by ion-selective electrode or by ion chromatography. 

Adsorbed amounts can easily be measured with high accuracy by means of the conventional volumetric (49, 50) and gravimetric (50) techniques. For static measurements the desorption temperature is increased by certain increments and the desorption carried out at constant temperature. Thermogravi-metric analysis (TGA) is a dynamic method by which the weight loss is detected by a balance while heating the catalyst continuously. The same type of information can be obtained as with the static methods, provided the heating rate is sufficiently low to attain the characteristic irreversibly adsorbed amount at any temperature. 

Powder XRD patterns of the products were recorded using Cu Ka radiation (Rich-Seifert, 3000TT). The patterns agreed with those calculated for single-crystal structure determination. Thermogravi-metric analysis (TGA) was carried out (Metler-Toledo) in an oxygen... 

Thermogravi metric analysis (TGA) of CCA treated wood and the major arsenic compound in CCA treated wood (chromium arsenate (CrAs04)),... 

Class I includes isolated lattice sites, and represents the structures with water molecules that are isolated and kept from contacting other water molecules directly in the lattice structure. Therefore, water molecules exposed to the surface of crystals may be easily lost. However, the creation of holes that were occupied by the water molecules on the surface of the crystals does not provide access for water molecules inside the crystal lattice. The thermogravi-metric analysis (TGA) and differential scanning calorimetry (DSC) for the hydrates in this class show sharp endotherms. Cephradine dihydrate is an example of this class of hydrates. 

This can be seen in Figure 2, which shows the thermogravi-metric analysis (TGA) curves of the several polymers. The differential of the TGA losses (DTG) show (Table III) no differences within experimental error, except for the copolymer containing 50 mole percent N-methyl substitution. 

Since most of the physical properties of the asphaltenes did not show any major differences, thermal reactivity was investigated to discern any differences which might exist in chemical reactivity. Differential scanning calorimetry and thermogravi-metric analysis as well as rapid pyrolysis were employed. The only notable features of the DSC analyses were what appeared to be glass transitions occurring at 175°C and 172°C for the crude and residuum asphaltenes, respectively. The TGA curves for the two materials were also virtually identical, differing by less than one percent volatile matter at any temperature. Both of these techniques thus indicate essentially no discemable differences in the two asphaltenes. 

Dhawan and Trivedi [127] studied the thermal stability of conducting polypyrrole film, grown on the FeCU spray-coated polyvinylacetate film, exposed to pyrrole vapours under mild vacuum. The thermogravi-metric analysis data for the conductive polypyrrole composite showed its stability up to I50°C and after that a continuous weight loss was observed up to 450°C implying the breakdown of the host polymer, polyvinylacetate matrix. The differential thermal analysi.s of the composite also showed first inflection at 205°C followed by a major transformation at 296°C. 

Thermogravimetry (thermogravi metric analysis) TG (TGA) Mass changes Desolvations, decomposition, oxidation, sublimation... 

Characterization Tools for Pyrolysis Oils. It wasn t too many years ago that the only tools available to the scientist interested in pyrolysis oil composition were gas chromatography and thermogravi-metric analysis. The complexity of the pyrolysis oils demands high performance equipment, and a list of such equipment mentioned during the symposium would include proton and carbon nuclear magnetic resonance spectroscopy, free-jet molecular beam/mass spectrometry (16.25), diffuse reflectEuice Fourier transform infrared spectrometry ( ), photoelectron spectroscopy ( ), as well as procedures such as computerized multivariate analysis methods (32) - truly a display of the some of the most sophisticated analytical tools known to man, and a reflection of the difficulty of the oil composition problem. 

Studies on these hydrates by differential thermal analysis (DTA), thermogravi-metric analysis (TGA) and differential scanning calorimetry (DSC) showed that the initial decomposition involved elimination of all water molecules via a multi-step process with the formation of the dihydrate and monohydrate intermediates. Further heating led to formation of the stable oxysulfates and, subsequently to the sesqui-oxides (Wendlandt 1958, Wendlandt and George 1961, Niinisto et al. 1982) ... 

A variety of advanced techniques exists for determining the species composition of the fuel, which is vital to improved predictive methods for coal, and especially ash behavior, in boilers. X-ray diffraction, performed on low-temperature ash, is the most widely used technique for qirahtatively identifying the presence of minerals in their crystalline form in concentrations of a few weight percent or greater. Thermal analytical techniques such as differential thermal analysis (DTA) and thermogravi-metric analysis (TGA) have been used as a signature analysis based on changes in physical properties with temperature. 

The thermal resistcuice of polyaminobismaleimides may be evaluated by three criteria — thermogravi-metric analysis, thermophysical profile, and thermooxidative resistance. 

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