Differential thermal analysis curve

Differential thermal analysis curves of iUite show three endothermic peaks in the ranges 100—150, 500—650, and at about 900°C, and an exothermic peak at about 940°C, or immediately following the highest endothermic peak. Minerals formed from iUite at high temperature vary somewhat with the... 

The hydrated alumina minerals usually occur in ooUtic stmctures (small spherical to eUipsoidal bodies the size of BB shot, about 2 mm in diameter) and also in larger and smaller stmctures. They impart harshness and resist fusion or fuse with difficulty in sodium carbonate, and may be suspected if the raw clay analyzes at more than 40% AI2O2. Optical properties are radically different from those of common clay minerals, and x-ray diffraction patterns and differential thermal analysis curves are distinctive. 

The only thermal event in the differential thermal analysis curve of (/))-penicillamine is the melting endotherm at 185 °C. Either polymorph of (z>)-penicillamine gives the same endotherm [2]. 

Figure 7 Differential Thermal Analysis Curve of Hydralazine Hydrochloride.

FIGURE 10 - DIFFERENTIAL THERMAL ANALYSIS CURVE OF SODIUM VALPROATE... 

Fig Differential thermal analysis curve for amorphous poly (ethylene terephthalate). 

Figure shows the Differential thermal analysis curve for poly (ethylene terephthalate). The lower crystalline melting range in the specimen of figure below can be attributed to impurities present in the polymer. 

Fig. 4.4.8 TGA and DTA result of sample 1. (a) Mass loss curve (b) Derivative curve of (a) (c) Differential thermal analysis curve. (From Ref. 10.)...

White (1955) believes that differential thermal analysis curves obtained by him on heating drawn fibers of 6, 6-6 and 6-10 nylons as well as polyethylene terephthalate, indicate that at first crystallites disorient and then melt. He found two peaks in what would correspond to a specific heat-temperature curve. However, it is difficult to understand why the disorientation of oriented crystals would involve the absorption of energy. 

Quantitative estimation of the sulphate content by the fusion method was found to be difficult because of the low percentage of the impurity. The anatase, thus prepared, was amorphous. The surface area of this anatase sample (B.E.T.) was 54 m2/g and the differential thermal analysis curve of the anatase sample is shown in fig. 2a. Although no exothermic peak due to crystallization was observed, the endothermic peak shows a definite splitting around... 

Fig. 5.3 Thermogravimetric and differential thermal analysis curves for reacted C3S paste experimental conditions as for Fig. 5.2. After Taylor and (T14).

Fig. 10 shows the thermograms of cellulose in atmospheres of helium and of oxygen, obtained by Tang and Neill. In the helium atmosphere, there is an endothermic dip in the differential thermal analysis curve and a sharp loss of weight in the thermogravimetric analysis curve beginning at about 300°, which denote the pyrolytic reactions. In the oxygen atmosphere, instead of the endothermic dip, there is an exotherm due to oxidation of the pyrolysis products. 

The heat of pyrolysis (in an inert atmosphere) can be calculated by integrating the area under the differential thermal analysis curve and comparing it with the value obtained for a reference substance according to the following equation... 

For the treated cellulose, the differential thermal analysis curve starts to rise rapidly at about 220°, with no indication of an endotherm, and the thermogravimetric analysis curve shows a continuous weight-loss, which is accelerated at this temperature, and a relatively large residue is left. 

MgCOj decomposes at substantially lower temperatures the dissociation pressure reaches atmospheric pressure at 400—480 C. The reaction enthalpy is 121 kJ (28.9 kcal) per mole at 25 °C. MgC03 bound in dolomite decomposes at a temperature somewhat higher than pure MgC03. The dissociation pressures are plotted in Fig. 27. The decomposition of dolomite proceeds in two stages as illustrated by differential thermal analysis curves, showing two distinctly separate endothermal peaks for MgCOa and CaCOj respectively. The DTA curves for various minerals are shown in Fig. 28 (Ivanova et al., 1974). 

All the displacive inversions of silica exhibit well discernible enthalpic effects on DTA (differential thermal analysis) curves. Pure quartz produces a minor but... 

FIG. 28. Differential thermal analysis curves of various minerals. 

Most of the information about dehydration because of temperature increase has come from differential thermal analysis curves, which are deceptive with regard to the subsurface environment because of the rapid rate at which temperature is raised (water loss therefore occurs at a higher temperature than it would otherwise), and because the sample is surrounded by air at 0.101 MPa (1 atm.) pressure rather than a saline solution at elevated pressure. Nevertheless, these curves (e.g., Hendricks et at, 1940 Rowland et al., 1956) indicate a relative order of events. 

Barshad, I., 1948. Vermiculite and its relation to biotite as revealed by base exchange reactions, X-ray analyses, differential thermal analysis curves, and water contents. Am. Mineral. 33 655—678. 

FIGURE 6 Thermogravimetric and differential thermal analysis results from a granulation blend of a hydrated API. The thermogravimetric curve is dotted the differential thermal analysis curve is solid the derivative of the thermogravimetric curve is dashed. 

Figure 6. Typical differential thermal analysis curve for lead azide [25].

X-ray diffraction patterns were recorded on a Siemens D5000 diffractometer using CuKa radiation. Thermogravimetric and differential thermal analysis curves were recorded on a Setaram Setsys 12 thermal analysis station by heating in an argon atmosphere from 25 to 1200 -C at a rate of 5 min". Samples were used untreated. The Pt content was determined by the Service Central d Analyse, CNRS (Vernaison, France) and the microanalyses (C, H) were performed at Complutense University (Madrid, Spain). Na isotherms were determined on a Micromeritics ASAP 2000 analyzer. H MAS NMR, Si MAS NMR and C CP MAS NMR spectra were recorded at 400.13, 79.49 and 100.61 MHz, respectively, on a Broker ACP-400 spectrometer at room temperature. An overall 1000 free induction decays were accumulated. The excitation pulse and recycle time for H MAS NMR spectra were 5 ps and 3 s, respectively, those for Si MAS NMR spectra 6 ps and 60 s and those for C CP MAS NMR spectra 6 ps and 2 s. Chemical shifts were measured relative to a tetramethylsilane standard. Prior to measurement, if necessary, samples were dehydrated in a stove at 423 K for 24 h. 

Fig. 20. Differential thermal analysis curves for low-pressure polyethylene Hizex 5000 [41], Upper curve, in air lower curve, in a nitrogen atmosphere.

The differential thermal analysis curves do not show any exotherm (Fig. 42). Small endotherms corresponding to weight loss are visible. Monomer is the major volatile product. Since low molecular weight... 

Fig. 5A Differential thermal analysis curve of a PPX sample polymaized from the cjclic dimer at 296 K and annealed below the transition to the isotropic state, at 625 K, fm- 12 h. The shoulder at about 475 K is an annealing peak (fusion of imperfect crystals). Transition ot-P, occurs at 500 K (Tj ). Transition P,-P2, at 570 K (Tdj). The endotherm for Tj (7(X) K) is not shown (see Ref.

Fig. 5.9. Differential thermal analysis curve of a liquid crystalline polymer with flexible spacers in the main chain IPoiy(oxy-2,2 -dimethylazoxybenzene-4,4 -diyloxydodecanedioyl)]. Heating at 50 K/min after cooling at 50 K/min. LC glass transition at 290 K. Crystallization of the mesophase at T,. = 345 K. Disordering transition at = 385 K. Transition to the isotropic phase Ti = 420 K, ASi = 9.8 J/(K mol). Drawn after Ref.

List some of the factors that influence (a) thermogravimetry curves, (b) differential thermal analysis curves, and (c) differential scanning calorimetry curves, indicating which are most important for the various techniques. 

The XRD patterns were recorded with a Shimadzu apparatus using Cu Kot radiation. The TG—DTA (differential thermal analysis) curves were obtained under argon atmosphere with a heating rate of 10°C min using a DuPont instrument. 

Differential thermal analysis curve Graphical representation of data collected by a differential thermal analyser, where the difference temperature is plotted as a function of temperature (scanning mode) or time (isothermal mode). 

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