Thermal analysis history

The glass transition temperature of sorbitol has also been studied using thermal analysis, and temperatures ranging from 0 to -55°C have been reported [8,20-24]. The temperature values were dependent on heating rate, history of the sample, and pressure. The extensive variation in conditions explains the wide range of temperatures reported for this parameter. 

To obtain the cure kinetic parameters K, m, and n, cure rate and cure state must be measured simultaneously. This is most commonly accomplished by thermal analysis techniques such as DSC. In isothermal DSC testing several different isothermal cures are analyzed to develop the temperature dependence of the kinetic parameters. With the temperature dependence of the kinetic parameters known, the degree of cure can be predicted for any temperature history by integration of Equation 8.5. 

Packaging Materials. As in the case of fibers, thermal analysis can easily distinguish between most polymeric films on the basis of the glass transition and the thermal history dependence of the melt and recrystallization (20, 21). From the analysis of thin films--as, for example, used in plastic bags recovered with drugs—it should be possible to identify by comparison the bag manufacturer and possibly the manufacturing lot. 

In conclusion, it can be seen that thermal analysis is able to make a considerable contribution to forensic science. Because of its capability to differentiate between manufacturing lots, it has for years been employed in quality control laboratories to monitor production of polymeric products. Its capability of differentiating between materials of identical chemical composition on the basis of differences in molecular weight distribution and thermal or mechanical history should be a capability quite unique and useful to forensic science. With the advent of second-generation instrumentation, this technique can be usefully extended to the realm of submilligram level analysis. 

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. 

The history of differential thermal analysis and differential scanning calorimetry, as well as thermal analysis, has been described in great detail by Mackenzie (10,11). 

Thermal analysis techniques have been applied to almost every science area, from archaeology to zoology, and to every type of substance, from alabaster to zeolites. Indeed, it is difficult to find an area of science and technology in which the techniques have not been applied. This truly universal use of thermal analysis is consistent with its early history in. for example, clays, mineralogy, metallurgy, and inorganic substances. 

Before considering the development of what has become known as micro-thermal analysis , it is appropriate to review the history, technology and... 

It is useful to compare the history of the development of thermal analysis with the history of the development of the quartz crystal microbalance. Scopus (www.Scopus.com) is the largest online abstract and citation database of scientific and technical research literature and quality web sources. A search using the term thermal analysis and the terms QCM or quartz crystal microbalance in Scopus, found all references dating to 1966. A Scopus literature search on the latter terms... 

The introductory discussion on thermal analysis begins with a brief outline of the history of the understanding of heat and temperature. Heat is obviously a macroscopic quantity. One can feel its effect directly with one s senses. The microscopic origin of heat, the origin on a molecular scale, rests with the motion of the molecules of matter discussed in Sect. 2.3. The translation, rotation, internal rotation, and vibration of molecules are the cause of heat. Temperature, in turn, is more difficult to comprehend. It is the intensive parameter of heat. Before we can arrive at this conclusion, several aspects of heat and temperature must be considered. A short description based on experiments is given in Sects. 2.1.5 and 2.1.4 and more details are found in Sects. 4.2 and 4.1. 

In Fig. 4.53, a brief look is taken at the history of the DSC. Both, heating curves and calorimetry had their beginning in the middle of the nineteenth century. Progress toward a DSC became possible as soon as continuous temperature monitoring with thermocouples was possible (see Fig. 4.8), and automatic temperature recording was invented (see also Sect. 4.1). These developments led to the invention of differential thermal analysis, DTA. In Sect. 2.1.3 an introduction to thermal analysis and its instrumentations is given. 

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