Optical differential thermal analysis

Caslavsky, J. L. (1988). Principles of the optical differential thermal analysis (ODTA). Thermochim. Acta 134,371-376. 

J. L. Caslavsky, Principles of the Optical Differential Thermal Analysis , U.S. Army Laboratory Command, MTL TR 88-11, U.S. Army Materials Technology Laboratory, Watertown, MA (1988). 

J.L. Caslavsky, and D.J. Viechnicki, Melting behavior and metastability of yttrium aluminum garnet (Yag) and YA103 determined by optical differential thermal-analysis../. Mater. Sci. 15(7), 1709-1718 (1980). 

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 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. 

Spectroscopy has become a powerful tool for the determination of polymer structures. The major part of the book is devoted to techniques that are the most frequently used for analysis of rubbery materials, i.e., various methods of nuclear magnetic resonance (NMR) and optical spectroscopy. One chapter is devoted to (multi) hyphenated thermograviometric analysis (TGA) techniques, i.e., TGA combined with Fourier transform infrared spectroscopy (FT-IR), mass spectroscopy, gas chromatography, differential scanning calorimetry and differential thermal analysis. There are already many excellent textbooks on the basic principles of these methods. Therefore, the main objective of the present book is to discuss a wide range of applications of the spectroscopic techniques for the analysis of rubbery materials. The contents of this book are of interest to chemists, physicists, material scientists and technologists who seek a better understanding of rubbery materials. 

Technical examination of objects coated with a protective covering derived from the sap of a shrubby tree produces information that can be used to determine the materials and methods of manufacture. This information sometimes indicates when and where the piece was made. This chapter is intended to present a brief review of the raw material urushi, and the history and study of its use. Analytical techniques have included atomic absorption spectroscopy, thin layer chromatography, differential thermal analysis, emission spectroscopy, x-ray radiography, and optical and scanning electron microscopy these methods and results are reviewed. In addition, new methods are reported, including the use of energy dispensive x-ray fluorescence, scanning photoacoustical microscopy, laser microprobe and nondestructive IR spectrophotometry. 

Anionic Polymerizations (15). These experiments were performed with acrylonitrile. To favor the anionic polymerization, N,N-dimethyl-formamide (DMF), triethylamine (TEA), and isopropylamine (IPA) were selected as solvents. Acrylonitrile, N,N-dimethylformamide, and isopropylamine easily crystallize on cooling. Triethylamine, on the other hand, forms a glass below —170 °C. Some of the binary mixtures investigated were partially crystalline at —196 °C., but optically clear glasses were found over limited ranges of concentrations. Glass transition temperatures (Tg) were determined by differential thermal analysis (DTA). Some of the data are listed in Table I. No phase separation could be detected in any of the vitreous mixtures. 

Hot-stage microscopy not only benefits from the features of the hot stage but also the quality and accessories of the microscope. It is obvious that this technique also needs some fundamental knowledge of chemical and optical microscopy. In this context, it should be noted that the advantage of hot stages that combine the features of differential thermal analysis (DTA) and optical microscopy are questionable since both the sensitivity of the DTA signal and the microscopic preparation features suffer much from this combination. 

Some of the optical characteristics of alite polymorphs and their correlative changes with differential thermal analysis (DTA) and X-ray diffraction (XRD) analysis have been the subjects of reports by Maki and Kato (1982) and Chromy and Carin (1980/81). 

Compatibility has been studied employing a variety of different analytical techniques, including optical and electron microscopy, differential thermal analysis (DTA), gel permeation chromatography (GPC), solubility, thermal and... 

Differential thermal analysis (DTA) has also been exploited, mainly to determine polymer crystal melting temperatures but also (less frequently) to determine crystallization kinetics. Crystallite formation also changes the optical... 

Kno] Knotek, O., Lugscheider, E., Reimann, H., Sasse, H.G., High-Temperature Differential Thermal Analysis with Optical Measurement of Temperature (in German), Metal, 35(2), 130-132 (1981) (Phase Diagram, Experimental, 9)... 

Optical Thermal Analyzers with Differential Thermal Analysis... 

A major application of dynamic hot stage microscopy is the study of polymer structure, as a function of temperature, in the optical microscope [12, 111]. Thermal analysis in the optical microscope is complementary to thermal analysis by such methods as differential scanning calorimetry (DSC) and differential thermal analysis (Section 6.4.2). It is now possible to observe the sample in the OM and simultaneously obtain the DSC trace. 

The solidus and the melting points of the alloys were determined by an optical pyrometer method. The temperature for the hep bcc transformations was determined by differential thermal analysis. Some sohdus and hquidus points were also determined by this method and were in good agreement with those observed with the optical pyrometer. 

Raman spectra were recorded with a HORIBA Raman or T-64000 spectrometer equipped with an optical alignment and monochromator with AABSPEC 2000-A. The excitation source was a 532 nm SHG of Nd YVO4 laser with a power of 20 mW at the sample point. In order to check the stability of each sample, differential thermal analysis (DTA) measurements were carried out with Rigaku Thermo Plus under CO2 gas during all the measurements. Aliquots of 10 mg of ceria oxides/carbonate salts were loaded into an Au pan ( = 5 mm). The temperature range was 573-873 K and the scanning rate was 10 K/min in all cases. 

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