DTA/TGA analysis

Synthesis and Characterization of Layered Precursors. Hydrotalcite-like materials of Mg-Al, Zn-Cr, Ca-Al, and Ni-Al were prepared from the nitrate salts. A mixed solution of the appropriate divalent and the trivalent cation salts in the required molar ratios was co-precipitated with a base, typically NaOH, at room temperature. The pH of the suspension was maintained between -8 and 10 during the addition, which required approximately 1 hour. After complete addition, the precipitate was allowed to age for 16 hours and later washed with deionized water. The purity and crystallinity of the material was verified by X-ray diffraction. DTA/TGA analysis was used to study the thermal stability as well as the accompanying weight loss of the materials. 

Figure 3. DTA-TGA analysis of (a) raw clay (b) wastewater from olive-washing stage (wet OW) (c) wastewater from oil olive-washing (wet OOW) (d) dry OW and (e) dry OOW.

The thermal characterization of the foaming process was carried out by simultaneous DTA-TGA analysis (Netzsch STA 409PC) on a small piece (10 g) of the green compacted sample. This analyse was performed, according to the foam glass preparation conditions, in the temperature range from room temperature to 850°C at heating rate of 6.5°C/min and under air atmosphere. 

Figure 12. The DTA-TGA analysis of the reaction mixture during synthesis of La2SrFe207.

When solids react, we would like to know at what temperature the solid state reaction takes place. If the solid decomposes to a different composition, or phase, we would like to have this knowledge so that we can predict and use that knowledge In preparation of desired materials. Sometimes, intermediate compounds form before the final phase. In this chapter, we will detail some of the measurements used to characterize the solid state and methods used to foUow solid state reactions. This will consist of various types of thermal analysis (TA), including differentlEd thermal analysis (DTA), thermogravimetric analysis (TGA) and measurements of optical properties. 

Apart from the qualitative observations made previously about suitable solvents for study, the subject of solvates has two important bearings on the topics of thermochemistry which form the main body of this review. The first is that measured solubilities relate to the appropriate hydrate in equilibrium with the saturated solution, rather than to the anhydrous halide. Obviously, therefore, any estimate of enthalpy of solution from temperature dependence of solubility will refer to the appropriate solvate. The second area of relevance is to halide-solvent bonding strengths. These may be gauged to some extent from differential thermal analysis (DTA), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) solvates of "aprotic solvents such as pyridine, tetrahydrofuran, and acetonitrile will give clearer pictures here than solvates of "protic solvents such as water or alcohols. 

The research papers which originated in the last couple of years in different countries in this field indicate that ED and Er are not generally reported and there is an emphasis on the study of comprehensive thermal behavior of explosives as a function of temperature or time by means of different thermal analytical techniques. Most commonly used methods of thermal analysis are differential thermal analysis (DTA), thermogravimetric analysis (TGA) or thermogravimetry and differential scanning calorimetry (DSC). 

Simultaneous Thermal Analysis (STA) A technique which combines DTA, TGA, DSC (cal.) and derivatives of DTA/TGA in a single instrument, offers advantages over the performance of each technique as a separate experiment on stand-alone instruments. By examining a single sample, one ensures no variation in sample homogeneity, atmosphere difference and other instrumental parameters. At the same time, there is a provision for detection and analysis of evolved gases (EGA) during thermal decomposition. Also, derivatives of TGA and DTA can be precisely measured (electronically). 

Closely related to DSC is the much older technique of differential thermal analysis (DTA). DTA works on the simpler principle of measurement (via thermocouple) of temperature difference between a sample and reference as the same heating power is supplied to both. The DTA trace therefore represents a temperature effect, which is related only semiquantitatively to AH. A combined DTA-TGA trace for the Werner clathrate (Section 9.4) [Ni(NCS)2(4-phenylpyridine)4] CgHg is shown in Figure 9.22. The DTA trace shows that all three thermal events observed are endothermic. The first is associated with loss of the benzene guest, while the second and third relate to loss of the coordinated 4-Phpy ligands. Note the high temperature (about 350 °C) required to remove the enclathrated benzene. This is a clear indication of the thermal stability of the Werner clathrate family.18... 

Thermal analysis of -Pt02 indicates that oxygen evolution begins at 575 °C. Decomposition to the metal occurs in a single step, and is complete at —600 °C. The / -form is somewhat more stable, with decomposition beginning at 600 °C. The dta-tga trace frequently gives an indication of a two-step process, but all attempts to isolate or identify an intermediate product have been unsuccessful. All x-ray powder patterns of partially decomposed samples showed only two phases Pt02 and Pt. 

Differential Thermal Analysis (DTA), Thermogravimetric Analysis (TGA), and Differential Thermogravimetric Analysis (DTG) of Potato Starch Dried by Three Methods (All Temperatures in °C)3SS... 

Differential thermal analysis (DTA)/thermogravimetric analysis (TGA) (DT-60H thermal analyzer, Shimadzu, Japan) changes for magnesium silicate are shown in Fig. 7.13. The data shows an endothermic peak with a maximum at T ax = H9 °C resulting in a mass loss of 21.5% of the total weight. This loss continues at a slow rate up to 700 °C to yield another 10.5% mass loss, followed by an intense exothermic peak at T max = 750 °C accompanied by a mass loss of 5.5%. The first peak is assigned to the dehydration of hygroscopic water. The second peak is... 

The object of this paper is the application of thermal analysis techniques, such as DTA/TGA, and sintering tests performed in a muffle furnace, in combination with SEM-EDX analysis techniques, to deepen our understanding of the high-teroperattu e of the ash of various solid biofiicls. 

Two different thermal methods were used for the analysis of the high-temperature behavior of the various ash san5>Ies, i.e., simultaneous DTA/TGA using a NETSCH STA 429 friermal analysis instrument, and sintering tests performed in a simple muffle furnace, both in combination with a SEM/EDX technique for the elemental analysis of the thermally treated ash samples, using a JEOL 6300 scaiming microscope. 

In the case of com cob, the results of the sintering tests (Table 3), in combination with those from the SEM-EDX analysis of the thermally treated ash samples, are in full agreement with the results obtained by the DTA-TGA thermal analysis method, clearly showing that mdiing/sintering effects begin at around 750 C or even at lower temperatures. 

Table 4 SEM-EDX elemental analysis of thermally treated (DTA/TGA) biomass ash,... 

All the samples were characterized using conventional methods X-ray diffraction (Rigaku, D-Max IIIB), UV-VIS (Shimadzu 240), FTIR (Perkin-Elmer 1760), EDX (JEOL-5200), SEM (Philips Model 525), Cyclic voltammetry (Rikadenki), DTA-TGA (Dupont, 951), Particle size analyzer (Galai CIS-100), BET surface areas (350-450 m /g). Chemical analysis was obtained by atomic absorption (AAS) after solubilization of the samples in HF-HCl solutions. It was ascertained that the samples were free of any phase impurity and are catalytically active. 

The catalytic activity in decomposition of H2O-HAN (79 wt-%) mixture was followed by DTA-TGA to determine the onset of the decomposition and by means of a constant volume batch reactor using increase temperature mode or isothermal mode at 90 °C. The same catalyst to propellant ratio was used lOpL propellant and 16 mg catalyst for thermal analysis, 100 pL propellant and 160 mg catalyst for batch reactor experiments the temperature ramp was 10... 

In the case of the combined DTA/TGA (theimogravimetric analysis), open DTA test crucibles are hooked on a high precision balance and then vertically inserted into the heating chamber of the DTA. This way thermal effects and loss of mass may be recorded simultaneously and quantitatively. Due to this arrangement, such effects are extremely well identifiable which show strong exothermic transitions only if a critical amount of volatile components have been evaporated thus heightening the concentration of the unstable compound. This is extremely helpful if the thermal stability of distillation or rectification residues has to be assessed. 

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