Quantitative differential thermal analysis

This instrument was originally proposed for quantitative differential thermal analysis (DTA) (34) and it has proved indeed to be very suitable... 

E. S. Watson, M. J. O Neil, J. Justin,N. Brenner.X Differential Scanning Calorimeter for Quantitative Differential Thermal Analysis. Anal. Chem. 1964, 36, 1233-1238. 

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

Watson, E. S., O Neill, M. J., Justin, J. and Brenner, N. 1964. A differential scanning calorimeter for quantitative differential thermal analysis. Anal. Chem. 36, 1233— 1237. 

In many of the methods of quantitative differential thermal analysis, the calibration coefficient can be mathematically deiermined and no experimental procedures are necessary. For example, Kronig and Snoodjik ((04) calculated K for a cylindrical sample holder as... 

Quantitative differential thermal analysis Differential thermal analysis in which the equipment used is designed to produce quantitative results in terms of energy and/ or other physical parameters (ISO). Kemp RB (1999) Handbook of thermal analysis and calorimetry. Elsevier Science and Technology Books, New York. 

The main reason for using induction time data for the determination of antioxidant concentration in polymers is the frequently observed linear relationship between induction time and antioxidant concentration [131]. In view of the aforementioned considerations great caution should be exercised in quantitative estimation of antioxidant levels in polymers. Wight [181] and others [143] have used quantitative differential thermal analysis (QDTA), in particular for determining the degree of oxidative stability of polyolefins for QC purposes in the wire and cable industry in lieu of a direct antioxidant analysis. Application of the basic purpose of a QC test... 

This discussion of quantitative differential thermal analysis has shown that it is possible to do calorimetry by DTA. Whenever quantitative heat measurements are made, it is preferred, as mentioned above, to apply the term "differential scanning calorimetry" (DSC) to the description of the experiment. 

The techniques referred to above (Sects. 1—3) may be operated for a sample heated in a constant temperature environment or under conditions of programmed temperature change. Very similar equipment can often be used differences normally reside in the temperature control of the reactant cell. Non-isothermal measurements of mass loss are termed thermogravimetry (TG), absorption or evolution of heat is differential scanning calorimetry (DSC), and measurement of the temperature difference between the sample and an inert reference substance is termed differential thermal analysis (DTA). These techniques can be used singly [33,76,174] or in combination and may include provision for EGA. Applications of non-isothermal measurements have ranged from the rapid qualitative estimation of reaction temperature to the quantitative determination of kinetic parameters [175—177]. The evaluation of kinetic parameters from non-isothermal data is dealt with in detail in Chap. 3.6. 

Differential thermal analysis (DTA) is the monitoring of the difference in temperature between a sample and a reference as a function of temperature [42], Differences in temperature between the sample and reference are observed when changes occur that require a finite heat of reaction. If AH is positive (endothermic reaction), the temperature of the sample will lag behind that of the reference. If the AH is negative (exothermic reaction), the temperature of the sample will exceed that of the reference. Differential thermal analysis is not normally used for quantitative work instead it is used to deduce temperatures associated with thermal events. 

Differential thermal analysis proved to be a powerful aid in a detailed study that fully explained the polymorphism and solvates associated with several sulfonamides [19]. For instance, three solvate species and four true polymorphs were identified in the specific instance of sulfabenzamide. Quantitative analysis... 

Differential Thermal Analysis (DTA) A sample and inert reference material are heated at a controlled rate in a single heating block. This test is basically qualitative and can be used for identifying exothermic reactions. Like the DSC, it is also a screening test. Reported temperatures are not reliable enough to be able to make quantitative conclusions. If an exothermic reaction is observed, it is advisable to conduct tests in the ARC. 

Thermal analysis is a term used to cover a group of techniques in which a physical property of a substance and/or its reaction product(s) is measured as a function of temperature. This experiment is confined to the area of differential thermal analysis (DTA) and, more specifically, its quantitative development, differential scanning calorimetry (DSC) [1-15]. 

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... 

The polymers whose geometric structures have been quantitatively evaluated are polyacetylene 89), poly(ferf-butylacetylene)19), poly(isopropylacetylene)14), and poly-(phenylacetylene)88). In the case of polymers from aromatic monosubstituted acetylenes, qualitative evaluation of geometric structure is possible by means of IR spectroscopy, differential thermal analysis, and X-ray diffraction 66,90). In contrast, no information has been obtained on the geometric structure of disubstituted acetylene polymers. This is due to the fact that their main chain comprises fully substituted ethylene units, the difference between cis and trans structures being small. 

Thermo-Raman spectroscopy Raman spectroscopy is a useful technique to extract information during dynamic thermal processes and this specific application is termed as thermo-Raman spectroscopy (TRS). It is possible to investigate thermally induced changes in Raman band positions, band intensities, and bandwidths and correlate with corresponding structural changes in samples. TRS can also provide quantitative information related to the dynamics thermal processes. Unlike techniques such as thermogravimetric analysis (TGA) and differential thermal analysis (DTA) which can only provide bulk information associated with thermal properties of a solid sample, TRS can be used to study thermally induced structural transformation in solids [17]. 

Thermal analysis techniques (differential thermal analysis (DTA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and evolved gas analysis (EGA)) provide qualitative, semiquantitative, and in special cases, quantitative measurements of the energetic evolution of nanophase materials on heating. Variation of the heating rate and the atmosphere surrounding the sample provide additional information. Some examples are given below in the context of specific systems. 

Anonymous Differential Scanning Calorimetry, A Quantitative Technique for Differential Thermal Analysis. MPL-6632, Perkin-Elmer Instrument Division, Norwalk, Conn. (1964). 

Differential thermal analysis was the first major improvement developed over simple melting point analysis, and in countless studies was used to determine the characteristic temperature ranges associated with a variety of thermally induced reactions. Differential scanning calorimetry subsequently effectively replaces the DTA method, primarily because of its ability to yield quantitative information regarding the magnitude of the heat associated with the thermal reaction. For this reason, DSC has become accepted as the most widely used method of thermal analysis for the pharmaceutical industry. 

As summarized in Table 7, the yields in solid polyethylene (mp initial 132 °C, final 135 °C, by differential thermal analysis (DTA) cristallinity 85-90%) are very high. The transition metals proposed for this polymerization are Ti, V, Cr, Mn, Fe, Co, Ni, Cu. The results quoted in the patent related to the use of these metals38 are reported in Table 8 chromium and vanadium give the highest yield in solid polyethylene, nickel gives quantitative dimerization to 1-butene, as expected from the bibliographic data related to the chemical activity of these metals. 

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