Thermogravimetric analysis Volatiles

Typical characterization of the thermal conversion process for a given molecular precursor involves the use of thermogravimetric analysis (TGA) to obtain ceramic yields, and solution NMR spectroscopy to identify soluble decomposition products. Analyses of the volatile species given off during solid phase decompositions have also been employed. The thermal conversions of complexes containing M - 0Si(0 Bu)3 and M - 02P(0 Bu)2 moieties invariably proceed via ehmination of isobutylene and the formation of M - O - Si - OH and M - O - P - OH linkages that immediately imdergo condensation processes (via ehmination of H2O), with subsequent formation of insoluble multi-component oxide materials. For example, thermolysis of Zr[OSi(O Bu)3]4 in toluene at 413 K results in ehmination of 12 equiv of isobutylene and formation of a transparent gel [67,68]. 

Thermogravimetry (TG) is a measure of the thermally induced weight loss of a material as a function of the applied temperature [45]. Thermogravimetric analysis is restricted to studies that involve either a mass gain or loss, and it is most commonly used to study desolvation processes and compound decomposition. The major use of TG analysis is in the quantitative determination of the total volatile content of a solid. When a solid can decompose by means of several... 

Three flame retardants were compared in this study, namely, a brominated polycarbonate oligomer (58% bromine), a brominated polystyrene (68% bromine), and a brominated triaryl phosphate ester (60% bromine plus 4% phosphorus). These are described in Table I. Figures 1 and 2 compare the thermal stability of the brominated phosphate with commercial bromine-containing flame retardants by thermogravimetric analysis (TGA) and by differential scanning calorimetry (DSC). The brominated phosphate melts at 110°C and shows a 1% weight loss at 300°C. Brominated polycarbonate and brominated polystyrene are polymeric and are not as volatile at elevated temperatures as the monomeric flame retardants. 

Another type of calorimetric technique is called thermogravimetric analysis (TGA). It is the study of the weight of a material as a function of temperature. The method is used to evaluate the thermal stability from the weight loss caused by loss of volatile species. A final example, thermomechanical analysis (TMA), focuses on mechanical properties such as modulus or impact strength as a function of temperature. Both types of analysis are essential for the evaluation of polymers that to be used at high temperatures. 

As an extension of the proximate analysis or coal assay, it is worthy of note that new methods continued to be developed. For example, thermogravimetric analysis has been extended to cover determinations of volatile matter (as well as determination of moisture and ash) in coal and coke. These constituents can be measured by pyrolyzing the samples in oxygen and air, and the weight loss at prescribed temperatures was measured by using a thermobalance. 

We used thermal analysis to determine the thermogravimetric analysis (TGA) and the differential thermogravimetric analysis (DTG) of SCT pitches to obtain information on volatility and coke yield at various temperatures up to 1000°C, DTG was found very useful in defining process modifications to reduce volatiles in the pitch and increase pitch coke yield. Figure 3 gives the DTG (in nitrogen) of several SCT pitches prepared by distillation, thermal and catalytic process, in comparison with petroleum and coal tar pitches,... 

Thermogravimetric analysis (TGA) A widely used method to determine weight change upon heating, such as decomposition and amount of volatile components, including moisture. 

Although polar materials constitute the major portion of the pentane solubles, saturates and aromatics are also found in appreciable concentrations (Table V). The relatively low H/C ratio of the saturate fraction suggests a high concentration of saturated cyclics or olefins. Thermogravimetric analysis indicated that only about 40% of the pentane solubles is volatile under typical gas chromatographic conditions. 

Thermogravimetric analysis (TGA) measures the change in mass of a sample as a function of temperature. It therefore provides information on the presence of volatile components, in the present context particularly solvents or water, which form the basis of solvates or hydrates respectively, as well as processes such as decomposition and sublimation. 

Thermogravimetric analysis of the polymer was carried out under very nearly the same conditions as previously reported for permethylpolysilane and polysilastyrene (17, 18) (Figure 5). Unfractionated polymer 2 lost 35% of its weight upon heating under nitrogen at a 10 °C/min rise in temperature, up to 800 C. The theoretical loss according to equation 4 or 5 is 27 or 40%, respectively, and the results indicate that practically no volatile silicon compounds have been driven off. 

Perhaps the be.st known method of endpoint determination is thermogravimetric analysis or loss on drying analysis. This method requires an operator to stop the process and gather a representative sample for analysis. The drying process resumes while the sample is analyzed po.sing the po.ssibility that the material may exceed the acceptable endpoint while the analysis is made. Loss on drying is not specific to a particular component as all volatile components are driven off in the analysis. 

The thermogravimetric analysis of the three vendor lots of talc resulted in a total volatile content less than 1% for all samples at 300°C. 

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