Differential thermal analysis apparatus

Notice that two thermocouples can be differentially connected, for instance in a differential thermal analysis apparatus (see Fig. 2.39), in order to be able to measure at the same time the specimen temperature and the temperature difference in comparison to a reference sample. Several thermocouples, moreover, may be connected in series to form a thermopile, which is a device with an increased sensitivity relative to a simple couple. 

The apparatus used are mostly stirred-tank-, tubular-, and differential recycle reactors. Also, optical cells are used for spectroscopic measurements, and differential thermal-analysis apparatus and stopped flow devices are applied at high pressures. 

In a differential thermal analysis apparatus, a sample and reference material are placed in the same large metal heat sink. Changes in the heat capacity of the sample are measured by changes in temperature between the sample and reference materials as they are heated at the same rate. 

Barshad, L, 1952. Temperature and heat of reaction calibration of the differential thermal analysis apparatus. Am, Mineral 37 667-694. 

J.M. Pakulak G.W. Leonard, A Thermis-torized Apparatus for Differential Thermal Analysis , NOTS 1920 (June 1958), 14 6) A. Schrage, USP 3058994 (1962) ... 

Pacor, P. Applicability of the DuPont 900 DTA apparatus in quantitative differential thermal analysis. Anal. Chim. Acta, 37 200-208, 1967. 

The following Refs give some of the more important studies made with DTA apparatus Refs 1) S. Gordon C. Campbell, "Differential Thermal Analysis of Inorganic Compounds. Nitrates and perchlorates of the Alkali and Alkaline Earth Groups and their Subgroups1, AnalChem 27, 1102-09(1955) (Based on PATR 2079 (Nov 1954) PATR 2200(July 1955)1 2) S. Gordon C. Campbell "Pre-... 

One of the simpler ways to obtain such information is called differential thermal analysis (DTA), and a typical apparatus is described in Figure 2.37. Basically, the polymer sample P and an inert reference material R are heated from the same source. Thermocouples measure the temperature of the polymer and that of the reference, and the temperature difference AT =TP- TR is then plotted as a function of the temperature of the polymer. 

In many cases, high-temperature modifications of sulfidic compounds cannot be quenched for room temperature examination. Inversion twinnings, crystal morphology, or other crystallographic features may indicate the appearance of polymorphism. Under these circumstances differential thermal analysis (DTA) can be suitable for the determination of the exact phase transition temperatures. DTA determinations are practically valuable if used in conjunction with high-temperature X-ray diffraction methods. DTA apparatus can operate up to 1100 °C and can be specially designed for sulfides2-4) individual experimental techniques are included in these references. 

Kocherzhinsky Yu.A., Shilkin E.A., Vasilenko V.I. Apparatus for differential thermal analysis with thermovapour sensor up to 2200°C. // Diagrammy sostoyaniya metallicheskikh system. - M. Nauka, 1971. - P. 245-249. 

Spectroscopically pure peroxy titanium oxide was prepared by the method described in the literature, using spectrographically standardized titanium powder supplied by Johnson and Matthey, London, England. Anatase was then obtained by the thermal decomposition of the peroxy compound. Differential thermal analysis of the peroxy compound was carried out using an apparatus described by Pask and Warner 13 (fig. a). 

Use a differential scanning colorimeter (DSC) or differential thermal analysis (DTA) apparatus 1 with aluminium oxide ( a - alumina) as the reference substance. 

Mitchell, B. D., and R. C. Mackenzie An Apparatus for Differential-Thermal Analysis under controlled-atmosph. conditions. Clay Minerals Bull. 4, 31/43 (1959). 

With the present arrangement, I can interchange the several furnace assemblies I use with the differential thermal analysis I can move a data acquisition system from apparatus to apparatus I can put reaction apparatus in position for direct monitoring by mass spectrometry and I can use the exhaust facilities effectively. In addition, I saved money which can be put to better use. 

Figure 11.10. Differential thermal analysis (DTA). (a) Oassical apparatus (S = sample R = reference), (b) Calorimetric...

Fig. 42. Block diagram of an apparatus for differential thermal analysis. Area inside the circle is enlarged to show details of the thermocouples and sample block. B, sample block F, fUrnace ...

Differential Thermal Analysis (DTA) experiments were carried out in dry air (Air Liquide, < 5 ppm impurities) between 25 and 500°C using a Thermal Analyst 2100 TA apparatus. Samples previously dried at 120°C were heated at 5°C.min . Preliminary experiments showed that no DTA peak was observed above 500°C. 

Implementing differential thermal analysis requires the following components (a) a circuit for measuring differences in temperature, (b) a heating device and temperature-control unit, (c) an amplifying and recording apparatus, and (d) an atmospheric-control device. 

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. 

Very often thermogravimetry alone cannot give enough information about the reactions being studied. Other measurements often add to the knowledge gained. These ancillary techniques may be applied at the same time as the TG measurement is being applied and are then referred to as simultaneous and are discussed in Chapter 6. Alternatively other measurements may take place in separate experiments in separate apparatus. This is referred to as combined measurements. Simultaneous measurements include differential thermal analysis (DTA) and evolved gas analysis (EGA). These are explained in later chapters. 

Murphy CB. Differential thermal analysis. Anal Chem. May. 1960 32 168R-71R. Murphy CB. Differential thermal analysis. Anal Chem. Apr. 1962 34 298R-301R. Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded Hot-Plate Apparatus, ASTM C177, Am Soc. For Testing and Materials. Jan. 11, 2004. 

THERMAL EXPANSION APPARATUS FOR USE WITH DIFFERENTIAL THERMAL ANALYSIS EQUIPMENT. 

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