Differential thermogravimetric analysis

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. 

Major instrumentation involved with the generation of thermal property behavior of materials includes thermogravimetric analysis (TG, TGA), DSC, differential thermal analysis (DTA), torsional braid analysis (TBA), thermomechanical analysis (TMA), thermogravimetric-mass spectrometry (TG-MS) analysis, and pyrolysis gas chromatography (PGQ. Most of these analysis techniques measure the polymer response as a function of time, atmosphere, and temperature. 

Powdering, or grinding, of samples is a simple preparation method required in a number of spectrometric and spectroscopic techniques, such as x-ray diffraction (XRD), nuclear magnetic resonance (NMR), differential thermal analysis (DTA), thermogravimetric analysis (TG), or ATR-FTIR spectroscopy. Control of the particle size during grinding must be taken into account in attempting to obtain reliable results. 

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). 

Examination of the thermal stability of the polyimides synthesised, carried out using differential thermogravimetric analysis (air, AT = 4.5 °C/min), revealed that, under the conditions specified, the 10% weight loss (used as a criterion of thermal stability) is almost independent of the structure of the polyimides (Table 5.1). For all polyimides examined, the 10% weight loss temperature was 400 °C. The relatively low thermal stability of these polyimides may be related to the presence of the methoxy groups. 

Figure 6.6 Thermogram of HMX-fS using differential thermal analysis and thermogravimetric analysis...

Transparent yellow iron oxide has the a-FeO(OH) (goethite) structure on heating it is converted into transparent red iron oxide with the a-Fe203 (hematite) structure. Differential thermogravimetric analysis shows a weight loss at 275 °C. Orange hues develop after brief thermal treatment of yellow iron oxide and can also be obtained by blending directly the yellow and red iron oxide powders. 

FIGURE 9.17 Differential thermogravimetric analysis of EVA-containing alumina trihydrate (A l I I) and Firebrake ZB. 

Son and coworkers also reported the syntheses of hyperbranched poly(carbosilanes) via hydrosilylation. In one report, they prepared a series of AB3 carbosilarylene monomers (5, 6 and 7)173 which polymerized cleanly and rapidly to form soluble hyperbranched polymers in high yields. The polymers, ranging in appearance from sticky solids to oils, were characterized by NMR spectroscopy, thermogravimetric analysis, differential scanning calorimetry and vapor pressure osmometry. The polymers possessed subambient Tg... 

Two crystal modifications and an amorphous phase were found for 24 by X-ray diffraction and differential thermogravimetric analysis [91KFZ(3)78]. The structure of a complex formed from 3-[p-methylphenyl)amino]-4-[(p-methylphenyl)imino]-4//-pyrido [1,2-a]pyrazine, sodium bis(trimethylsi-lyl)amide and (norbomadiene)Mo(CO)4 in THF was characterized by single-crystal X-ray diffraction [95JPR(337)38],... 

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,... 

Figure 3. Differential thermogravimetric analysis (DTG) in nitrogen of SCT, petroleum, and coal tar pitches.

Riga, A. T., Collins, R., and Mladchak, G. 1998. Oxidative Behavior of Polymers by Thermogravimetric Analysis, Differential Thermal Analysis and Pressure Differential Scanning Calorimetry. Thermochim. Acta, 324,135-149. 

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

The compositions of the products were determined by inductively coupled plasma (ICP) with a Perkin-Elmer plasma 40 emission spectrometer. Simultaneous differential thermal analysis and thermogravimetric (DTA-TG) curves were carried out by using Perkin-Elmer DTA-7000, TGA-7 PC series thermal analysis instrument in air with a heating rate of 10 °C /min. The infrared (IR) spectra were recorded on an Impact 410 IR spectrometer on samples pelletized with KBr powder. Valence states were determined by X-ray photoelectron spectroscopy (XPS). The XPS for powder samples fixed on double sided tapes was measured on an ESCA-LAB MKII X-ray photoelectron spectrometer. The Cis signal was used to correct the charge effects. 

Comparison of several techniques (namely Fourier transform infrared spectroscopy (FTIR), simultaneous thermogravimetric analysis-differential scanning calorimetry (TGA-DSC) and ultrasonic spectroscopy) for assessing the residual physical and mechanical characteristics of polymer matrix composites (PMCs) exposed to excessive thermal loads showed the measured power spectra of ultrasonic energy to correlate with performance of graphite fibre epoxy matrix composites exposed to thermal degradation, and also that analyses with the three techniques all pointed to the same critical temperature at which thermally induced damage increased sharply [58],... 

The thermal techniques most commonly used to investigate the acid-base or redox character of soHd surfaces are differential thermal analysis (DTA), thermogravi-metric (TG) and differential thermogravimetric (DTG) methods, differential scanning calorimetry (DSG) and calorimetry. These techniques can be used either by themselves, or in conjunction with other techniques (for instance, TG-DSC, calorimetry-volumetry, DSG-chromatography, etc.) [5, 6]. 

TGA, Differential Thermal Analysis (DTA) and Differential Thermogravimetric Analysis (DTG) measurements have been employed to determine the number and nature of water molecules present in the POMs. The results of TGA show the presence of two types of water in POM compounds, namely water of crystalHza-tion and constitutional water molecules. The loss of the former usually occurs at temperatures below 443-473 K [141]. At temperatures exceeding 543 K for H3PM012O40 and 623 K for H3PW12O40, the constitutional water molecules (the acidic protons bound to the oxygens of the polyanion) are lost, according to the literature and for the acid forms [140]. For example the thermolysis of H3PM012O40 proceeds in two steps as schematized below ... 

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... 

Loss on drying Karl Fischer titration Residue on ignition Thermogravimetric analysis Differential scanning calorimetry High-performance... 

SIMULTANEOUS THERMOGRAVIMETRIC ANALYSIS-DIFFERENTIAL SCANNING CALORIMETRY... 

Figure 7. Typical differential thermal analysis and thermogravimetric analysis curves for lead azide [2]. Both run in a flowing atmosphere of 10 liters/hr of helium.

Fig.5. Thermogravimetric analysis (a), differential thermogravimetric analysis (b), and differential thermal analysis (c) of as synthesized ZGctab sample.

Several samples of YBa2Cu307 x with controlled stoichiometries, 0.04 < x < 1.00, have been prepared and characterized by thermogravimetric analysis, differential scanning calorimetry, magnetic susceptibility and Meissner effect measurements. 

New physicochemical techniques have now become available for studying thermal reactions these include differential thermal analysis and thermogravimetric analysis. These techniques have been applied in studying the pyrolysis of starch. 

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