Void size, final

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]

Figure 6.7 Effect of initial pure water void size on the final void size for the process conditions shown...

A bifurcation cascade with micro channels feeds a wide fixed bed (channel void space for particle insertion), followed by a multitude of catalyst retainers, which act like frits, i.e. support the catalyst particles and prevent their loss [7, 77, 78]. Besides supporting the particles, these parts have a size-exclusion function to the lower size limit of about 35-40 pm. The retainers are followed by an array of elongated channels that serve to build up a uniform pressure drop along the wide retainer bed. Finally, the streams are collected in a bifurcation cascade of identical shape as the feeding cascade, but mirror-imaged in position. 

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. 

Finally, the framework formed by the boron clusters is relatively rigid and therefore, there are constraints on the size of the metal atoms/ions which can occupy the voids. That is why there are different boundaries regarding which rare earth atoms can form each particular higher boride (as will be seen in the following sections). A rare earth existence diagram for all the higher borides will be presented at the end of this review, see Section 13. 

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