TG/DTA curves

Figure 9.1. TG-DTA curves for Bisphenol A-derived poly(formal) (A) and Bisphenol AF-derived poly(formal) (AF).

Fig. 65. Simultaneous TG-DTA curves of o-acetophenetitide measured at various pressures. A start of vaporization, B boiling point, C end of vaporization...

FIGURE 6.2 TG/DTA curves for the precipitate obtained from [Nb(02)4] and Na solutions used as a precursor for synthesis of NaNbOj powder. 

Correlation among the pattern of the TG-DTA curve of a self-heating powdery chemical, the two types of self-heating behaviors, Le., the TD type and the quasi-AC type, and the two equations of the thermal explosion theory... 

The type of the self-healing behavior of a self-healing powdery chemical is closely related to the pattern of the thermogravimctry-diffcrcntial thermal analysis (TG-DTA) curve which the chemical affords. In other words, it is possible, in principle, to infer the self-healing behavior of a self-healing powdery chemical to be either of the TD type or of the quasi-AC type by glancing over the TG-DTA cuiwe of the chemical, so that it is also possible to infer the equation of the thermal explosion theory applied to calculate the of the chemical to be either the Semenov equation, i.e., Eq. (17) presented in Section 1.2, or the F-K equation, i.e., Eq. (29) presented in Section 1.3, or neither equation. 

Figure 8, Individual TG-DTA curves of the four powdery chemicals of the TD type.

Individual TG-DTA curves, which are each recorded with a glass open-cup cell, 5 mm in diameter, 2,5 mm in depth, at a value of Zf of 2,5 IGmin in air at... 

Figure 12. Ilic TG-DTA curve of 98 % At-mcthyl-At-nitroso-p-toluenesulfonamide (MNTS, Diazald").

After all, it follows that, when the behavior of a powdery chemical which is shown in the TG-DTA curve is some one of the following three, i.e.,... 

To begin with, the TG-DTA measurements were performed in air at atmospheric pressure with the aluminium open-cup cell, 5 mm in diameter, 2.5 mm in depth, at the value of of 2.5 K/min for the sawdusts of fifteen wood species, to see the individual oxidatively-heating properties as a whole, respectively. The TG-DTA curve of the sawdust of an average wood species is presented in Fig. 84. 

The exothermic onset temperature or EOT of the sawdust of each wood species is determined by comparing the TG-DTA curve recorded in air with the curve recorded in nitrogen gas. The EOT of the sawdust of every wood species is, however, one of the data of poor reproducibility, so that it is rather difficult to determine distinctly the value by means of TG-DTA. As an example, when DTA is performed for the sawdust of Japanese cypress, which is one of wood species relatively hard to heat oxidatively, in air and in nitrogen gas, respectively, it is almost impossible to distinguish the enthalpy change of the sawdust recorded in air from the change recorded in nitrogen gas at... 

Figure 84, The TG-DTA curve of the sawdust of an average wood species.

It is seen in Fig. 131 that guncotton begins to decompose exothermically at about 166 °C and then decomposes explosively at about 182 °C. It appears, at first glance, that the TG-DTA curve of nitrocellulose, which is composed of collodion cotton and guncotton, shows that nitrocellulose is a typical and perfect powdery chemical of the TD type, because it begins to self-heat without melting and then decomposes explosively. 

Figure 8-55. EGA-TG-DTA curves of CaC204 H20 in argon (75). Dashed line indicates absorption of evolved water.

Figure 1. TG-DTA curves of precursor Figure 2. TG-DTA curves of dry gel and precursor...

Figure 3 shows the TG-DTA curves of the dried precipitate precursor obtained from ammonia co-precipitation processing. It was observed at the TG curve that there are three stages of weight loss in the temperature ranges from 90 to 250 T, from 250 to 380 T and 400 to 620 T. Respectively, these three stages can be corresponded to three relevant endothermic peaks at 112, 308, and 530 T in DTA curve. The mass loss in total 3 steps was about 38%. It can be seen that... 

For both samples, the anatase—rutile structural transition, associated with a well-defined exothermic peak, occurs at 485°C. Such fact suggests that the temperature of the structural transition is associated with the mean crystaUite sizes, which have, for both samples, the same value. From 600°C to 800°C, an endothermic peak is observed for both samples, associated with a minor mass loss step, probably due to the sublimation of a minor amount of powder or the thermal degradation of the last alkoxide molecules, trapped into the three dimensional oxide structure. As an example, the TG—DTA curve for the DMF-synthesized powder is shown in Fig. 4.11. 

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