Physical properties thermally treated

A large number of techniques have been used to investigate the thermodynamic properties of solids, and in this section an overview is given that covers all the major experimental methods. Most of these techniques have been treated in specialized reviews and references to these are given. This section will focus on the main principles of the different techniques, the main precautions to be taken and the main sources of possible systematic errors. The experimental methods are rather well developed and the main problem is to apply the different techniques to systems with various chemical and physical properties. For example, the thermal stability of the material to be studied may restrict the experimental approach to be used. 

Thermal desorption technologies have several potential limitations. Inorganic contaminants or metals that are not particularly volatile will not be effectively removed by the process. If chlorine or another chlorinated compound is present, some volatilization of inorganic constituents in the waste may also occur. Caution should also be taken regarding the disposition of the material treated by thermal desorption because the treatment process may alter the physical properties of the material. 

The ultimate composition of ceria was established many years after its isolation by C, G, Mosander, a Swedish surgeon, chemist and mineralogist, who was for a time assistant to Berzelius, During the period 1839-1841, Mosander thermally decomposed a nitrate obtained from ceria and treated the product with dilute nitric acid. From the resulting solution, he then isolated first a new earth, "lanthana", and then another new earth, "didymia" (the twin brother of lanthana), of similar chemical but slightly different physical properties, (Figure 1)... 

It is my contention that the optical and physical properties and the optical structure produced during the destructive distillation or thermal decomposition of vitrinite is closely related to mode of carbonization and, in the case of pitch, is intimately related to the method of pitch preparation. For instance, a pitch may be produced from a high or low temperature tar, from a primary cooler tar, or from a flushing liquor tar. In addition, it may be air blown, thermally or chemically treated, straight distilled, or cut back, just to mention a few. Under similar carbonization conditions almost any one of these pitches will produce a coke which has certain characteristics that are related to the parent pitch. Even pitches similarly processed from the tar can differ in the content of quinoline- and benzene-insoluble material and P-resin, and can contain more than one distinct liquid phase. None of these points of difference has been discussed by Dr. Taylor or even recognized in the preparation. To interpret the structure of pitch coke divorced from a knowledge of the pitch source and/or carbonization conditions can lead to erroneous conclusions. These are pertinent data omitted by the authors. 

Moulded articles can be thermally treated to improve the physical properties, particularly the notched Izod impact strength, but removal of the volatile by-products of the solid-phase polymerisation is a greater problem than for fibres and films 112). Use of internal dielectric heating has been suggested as a means of avoiding limitation of further polymerisation to the surface. 

Petroleum coke calcining is a process whereby green or raw petroleum coke is thermally upgraded to remove associated moisture and volatile combustible matter (VCM) and to otherwise improve critical physical properties, e.g., electrical conductivity and real density (JL ) The calcining process is essentially a time-temperature function the most important variables to control are heating rate, VCM to air ratio and final temperature. To attain the calcined coke properties necessary for its end use by the amorphous carbon or graphite industries, the coke must be heat treated to temperatures of 1200-1350°C (2200-2500°F), or higher, to refine its crystalline structure. 

The AlPOt molecular sieves show excellent physical properties. Many are thermally stable and resist loss of structure at 1000°C. Those studied for hydrothermal stability, including AlP0i,-5, -11, and -17, show no structure loss when treated with 16% steam at 600°C. The layer structures undergo structural collapse when the organic interlayer propant is removed thermally at 200-400°C. 

The thermal analysis techniques treated in this book are used to study the physical properties of polymeric systems in relation to their chemical structure. These thermal analysis techniques are however also well suited for short case studies. Many of such case studies are performed in several technical service laboratories all over the world. The results of such (short) case studies are rarely reported although they often contain interesting information. 

Chapters 2, 3, 5, 9 and 10 concern the synthesis, the structure and the physical properties of numerous anionic and cationic clathrates with light or heavier elements as host lattices and various other ones as guest species. Some of them exhibit very interesting thermal properties and are promising thermoelectric materials, a point which is treated in details in Chap. 6 ... 

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