Weight-loss curve

Fig. 7 Thermogravimetric weight loss curve (A) and subsequent IR spectra measured at the designated temperatures (B) 70°C, (C) 95°C, (D) 120°C, (E) 160°C, and (F) 180°C. A slight lag time exists between the TG weight loss and IR spectral acquisition due to the evolved gas being carried into the IR gas cell by the He carrier gas. Each IR spectrum is plotted on the same absolute intensity scale (Abs. units).

TGA. Unlike the previous two sets of molding compounds, the semiconductor grade novolacs investigated in this section do not differ solely in the presence or absence of a flame retardant. However, they are considered to be relatively equivalent. Weight loss measurements for the FR formulation, sample F, and the non-FR compound, sample G, are presented in Figure 7 for both nitrogen and air. Several differences are observed in the weight loss curves for these samples. 

Figure 2. Typical weight loss curve for rich shale...

Fig. 19. Weight loss curve for diffusion of AsF3 out of polyacetylene, showing the effect of deswelling of the surface in slowing diffusion. (Ref.515>)...

Fig. 6.2 Weight loss curves for C4AH,j (static Buttler et al. (B69)) and monosulphate and ettringite (TG IOdegCmin Taylor (TI6)).

Some kinetic models for thermal or catalytic polymer degradation have been proposed. The commonly used approach is first-order kinetics to investigate the characteristics of degradation (Equation 9.1). In this approach at first the weight loss curve of polymers during the decomposition is determined, and overall rate constants are calculated... 

The results for the TG experiments performed with the equipment shown in Figure 21.2, showed typical exponential weight-loss curves that are consistent with the use of the simple power-law model (pseudo-first-order reaction) in order to model the overall process. Figure 21.4 shows the results obtained for the degradation of three kinds of materials, when the experimental weight loss curves were averaged and transformed into conversion curves. 

Fig. 12.7 (a) Raman spectra and HRTEM images of as-received and vacuum-annealed (graphitized) MWCNTs. As-received nanotubes contain iron particles and amorphous carbon on their surface (inset), (b) Weight loss curves (TGA) of as-received, air-oxidized (0.25 h at 550°C), and graphitized MWCNTs. (c) In situ Raman spectra of nonisothermal oxidation of as-received MWCNTs. All Raman spectra were recorded using 633-nm laser excitation... 

Figures 10.8 and 10.9 are data traces showing TGS weight-loss curves for various polymers, including polyurethane foam.

An important effort in this investigation was the thermal decomposition study of the shales. Considerable effort has been made to find a simple kinetic model which will accurately describe the weight loss curves for non-isothermal pyrolysis at various heating rates. In the past, many researchers have proposed and tested theoretical kinetic models for this reaction Q-4), however, most attempts at finding a suitable model have been focused on finding a very accurate fit to experimental data. Successive studies have increasingly emphasized microscopic details (i.e., diffusion models, exact chemical composition, etc.) in an attempt to find a precise model to fit the weight loss curves. In this... 

After reaching the upper temperature set limit, the temperature was held constant (isothermal hold) for several hours. The weight-loss curves (TG) are shown in Fig. 1. The weight losses recorded on lithium and sodium fluxes alone (Spec-troflux 100 and 200) caused by thermal decomposition above i000°C were negligible. Similar results were obtained with mixtures of anhydrite and sodium tetraborate. The latter showed a weight loss of less than 0.1% when heated at lOOO C for 1 h. 

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