Void final diameter

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]

The final consideration in suction piping design is the method used to reduce the pipe diameter (i.e. 1.5 or greater than the pump s inlet flange) so that it can be attached to the pump. Care must be taken to ensure that the reduction method does not cause a void where air can be trapped or a low spot that will permit buildup of solid contaminates. 

If the initial void volume fraction and average initial diameter d0 are known, the final void volume fraction vv can be calculated [34]. 

In this case, the "fine" particles and the "coarse" particles were separated so that the difference in size between individual particles was minimized. That is, most of the individual particles in each fraction were almost the same size. Both the fine and coarse particles have a sintering slope of 1/2 but it is the coarse particles which sinter to form a solid having a density closest to theoretical density. This is an excellent example of the effect of pore volume, or void formation, and its effect upon the final density of a solid formed by powder compaction and sintering techniques. Quite obviously, the fine particles give rise to many more voids than the coarser particles so that the attained density of the final sintered solid is much less than for the solid prepared using coarser particles. It is also clear that if one wishes to obtain a sintered product with a density close to the theoretical density, one needs to start with a particle size distribution having particles of varied diameters so that void volume is minimized. 

As shown in Fig. 12, a monotonous decrease in the self-diffusion coefficient was measured by PPG NMR for a series of n-alkanes in Na-X [50]. A similar trend was observed in ZSM-5 by QENS. From the NSE experiments performed in 5A, one finds that Dt drops to a minimum at Cs and has a clear maximiun at Ci2. A similar variation is obtained for Do after correcting from the thermodynamic correction factor (the number of carbon atoms per cavity is the same). Recent PEG NMR results indicate also a small minimum for Ds at Cg and a small maximum at Cm [51]. The NSE data obtained for longer n-alkanes in 5A are in contradiction with simulations which predict increasing diffusivities from C12 to Ci7 [52] whereas a decreasing trend is observed (Fig. 12). Finally, the activation energies derived from the NSE measurements show a minimum for C12, in agreement with the explanation in terms of the window effect. These results are related to similar concepts such as resonant diffusion [53] or the levitation effect, which corresponds to a maximum in self-diffusivity when the size of the diffusant is comparable to the diameter of the void [54]. 

The experiments were conducted on relatively laige cylindrical specimens of 155 mm in height and 75 mm in diameter prepared using Moist Tamping Method. Each specimen was prepared at a different final void ratio. A known weight of... 

Finally, if the percentage of voids is expected to be 10%, the specimen bulk density is determined following Procedure D of CEN EN 12697-6 (2012). During this procedure, the calculation of the specimen bulk density is conducted geometrically (diameter - surface area multiplied by height). 

Finally, the pol mer (B) and the compatibUizer (C) is extracted at least partially, from the polymer blend by dissolving (B) and (C) in a solvent that is a non-solvent of polymer (A). In this way, the article becomes essentially continuously porous. A void volume of 10-90% can be obtained. The pore diameters show a unimodal pore size distribution. 

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