Pitch characteristic data

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. 

The last of these methods has been applied particularly to chemical reaction vessels. It is covered in detail in Chapter 17. In most cases, however, the RTDs have not been correlated with impeller characteristics or other mixing parameters. Largely this also is true of most mixing investigations, but Figure 10.3 is an uncommon example of correlation of blend time in terms of Reynolds number for the popular pitched blade turbine impeller. As expected, the blend time levels off beyond a certain mixing intensity, in this case beyond Reynolds numbers of 30,000 or so. The acid-base indicator technique was used. Other details of the test work and the scatter of the data are not revealed in the published information. Another practical solution of the problem is typified by Table 10.1 which relates blend time to power input to... 

In Figs. 7.6 and 7.7, the measured data and regression lines are shown for the pressure and energy characteristics of the example screw with 40 mm pitch presented in Section 7.5 [4]. 

The feed section takes the product from the feeding system and conveys it to the plastification section. At the same time, there must be sufficient free volume to allow gas reflux, e. g., air or nitrogen, to escape from the process section upstream. If the throughput rate of the extruder is less than the input product flow, the product will back up in the feed hopper, indicating that the intake limit has been reached. Along with the known extruder data, such as the screw speed, the screw pitch, and the available volume in the screw channel, other influencing factors, such as the fill rate of the screw channel, the conveying efficiency, the bulk density, and other bulk characteristics of the product sometimes affect the... 

Coal Tar Products. An excess of breast cancer cases in St. Louis Park, Minnesota, was tentatively associated with coal tar contamination of the water supply (Dean et al. 1988). However, in a subsequent analysis of these data, the Minnesota Department of Health (1985) concluded that this study did not provide adequate evidence to associate breast-cancer with coal tar creosote-contaminated water (for a detailed discussion of these data, see Section 3.2.2.7 Cancer). No adverse effects on sperm characteristics were reported in male workers exposed to coal tar pitch volatiles in an industrial setting (Ward 1988). In addition, no adverse reproductive outcomes were detected in a survey of inhabitants of a housing development built on an abandoned creosote factory site, which was known to be contaminated with creosote (Agency for Toxic Substances and Disease Registry 1994). A retrospective study of dermal exposure to coal tar found no increased risk of spontaneous abortion associated with exposure to coal tar during pregnancy, but this was a small study and was unlikely to have sufficient resolution to detect a modest increase in risk (Franssen et al. 1999). 

Studies of the nuclear characteristics of DjQHiO- moderated lattices have recently been extended to include measurements of reactivity and flux perturbations. These experiments provided nuclear data on relatively simple configurations for testing theoretical methods. The basic lattices consisted of 1.206-cm-diameter aluminum-clad 2.46%-enrlched UOi fuel rods on a square pitch of 1.511 cm. Moderator compositions varied from 0 to 72% B,0.to provide a wide range of neutron spectrum. Boric acid was added to keep the core radius constant (61.11 cm). 

The phase diagram of the HPC-water system, which has a lower critical temperature of mixing, is shown in Fig. 7.7 [34]. When is reached, the system passes into the LC state, which is initially two-phase, and the system then becomes totally liquid crystalline when the concentration of polymer increases above 50% and exhibits the optical properties of the cholesteric mesophase selective reflection of visible light Characteristic alternation of the chromaticity of the preparation—from red to violet— is observed, i.e., the pitch of the cholesteric helix decreases with an increase in the concentration of the polymer, as observed for solutions of polypeptides (cf. curves 1 and 2 in Fig. 7.4). However, in contrast to polypeptides, Ae exponent n in Eq. (7.8) can have values of 0.3 to 3.0 and even up to 6.92 according to the data in the literature [32]. Like Cgp the pitch is a function of the nature of the solvent and decreases with an increase in the acidity of the solvent. 

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