Final diameter

A very unusual characteristic of mesophase pitch is the extreme dependency of its viscosity on temperature [19,34,35]. This factor has a profound influence on the melt-spinning process (described above), as a mesophase pitch fiber will achieve its final diameter within several millimeters of the face of the spinnerette, in sharp contrast to most polymeric fibers. 

TABLE 6.4. Empirical Relationship of Duration to Final Diameter of Fireball [Constant Initial Fuel Mass mf(kg)]... 

Roberts (1982) uses a fireball s heat production to calculate its final diameter. Roberts assumes that, at the moment of maximal fireball size, the total increase in enthalpy can be related to the initial mass ratio of fuel to air. If R = mjttif for a stoichiometric mixture, the enthalpy rise (//) can be approximated by... 

Because this relationship also reflects the average of all relations from Table 6.4, its use is recommended for calculating the final diameter and duration of a spherical fireball. 

If it is necessary to dismantle a pump after the performance test for the sole purpose of machining impellers to meet the tolerances for differential head, no retest will be required unless the reduction in diameter exceeds 5 percent of the original diameter. The diameter of the impeller at the time of shop test, as well as the final diameter of the impeller, shall be recorded on a certified shop test curve that shows the operating characteristics after the diameter of the impeller has been reduced. 

The surface-averaged final diameter Dsf can be easily controlled by adjusting the amount of particles. Because the solid particles are irreversibly adsorbed at the oil-water interface, the inverse average droplet diameter varies linearly with the amount of particles according to the simple equation ... 

Figure 6.7 shows the final diameter of a pure water void at the end of the cure cycle after it has grown from voids of various initial diameters under the conditions specified. For an initial void diameter of zero, the final diameter is about 1.25 cm under the specified conditions of growth. On the other hand, relatively large initial void diameters (0.5 cm) only triple in size. 

The final diameter of a pure water void for different initial relative humidities of the resin is shown in Figure 6.8. The marked increase in the final void size illustrates the pronounced effect that initial relative humidity exposure has on the final void size. This behavior is described by Equation 6.28 in which CTO (which is fixed during the cure cycle and determines the driving force) increases with the square of the initial relative humidity exposure. Thus, increasing the initial relative humidity by a factor of 2 would result in a four-fold increase in C oo. This would in turn increase the driving force 4-fold when the other conditions of growth are kept identical and when Csat [Pg.197]

Fig. 22. Schematic description of the two-process approach that describes the kinetics of a cylinder. In the figure, V is the total volume and d is the diameter. The initial diameter is 2a, and the final diameter is 2(a -l- A). The diffusion process changes the diameter by 8u,...

The elongation measured over a fixed gage length, and the reduction of area of the section at the fracture are measures of ductility. In cylindrical specimens, the area is readily determined from the final diameter at the fracture. The percent reduction of area is then determined as original area minus final area, divided by original area. 

Pyrolysis must be carried out with careful control of atmospheric conditions. The gases formed during pyrolysis cause the fibers to undergo a weight loss of 20-40% (60-80% volume decrease), and the fibers achieve a final diameter of 10-15 (xm. This diameter is desirable for many ceramic and plastic composite applications. A more complete discussion of this fiber processing has been presented recently (20). 

The next step is to make the barrel. The top section (that was previously set aside) and the bottom section of the barrel are both planed flat, and a S/8" barrel channel is roughly gouged out to less than final diameter with a chisel. The barrel is finished by wrapping a foot long steel bar with sandpaper, and sanding both barrel sections to final diameter. 

Thus, it seems to be of interest to examine the influence of stress-induced polymorphic changes on the microhardness. While in the case of f-PP two samples comprising the a or phase were characterized, here we wish to follow the microhardness behaviour during the a-j6 polymorphic transition caused by a mechanical field. For this purpose PBT has been selected as a suitable material because of its ability to undergo stress-induced polymorphic transition from the a (relaxed) to the P (strained) form. Bristles of commercial PBT with a diameter of about 1 mm were drawn at room temperature via neck formation (final diameter about 0.5 mm and draw ratio of 3.4) and thereafter annealed in vacuum at 200°C for 6 h with fixed ends (Fakirov etal., 1998). 

Fig. 9-24 Inverse pole figures, (a) Distribution of axis of aluminum rod, extruded at 450°F to a reduction in area of 92 percent and a final diameter of 23 mm. letter, McHargue, and Williams [9.36]. (b) and (c) show the distribution of the sheet normal for the steel sheet of Fig. 9-20. Bunge and Roberts [9.18].

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