Interstitial voids

For large amounts of fillers, the maximum theoretical loading with known filler particle size distributions can be estimated. This method (8) assumes efficient packing, ie, the voids between particles are occupied by smaller particles and the voids between the smaller particles are occupied by stiH smaller particles. Thus a very wide filler psd results in a minimum void volume or maximum packing. To get from maximum packing to maximum loading, it is only necessary to express the maximum loading in terms of the minimum amount of binder that fills the interstitial voids and becomes adsorbed on the surface of the filler. 

The CPVC can be readily identified in Fig. 8 as the point where the filler particles are close packed with just sufficient binder to coat the filler and substrate leaving no interstitial voids. At this point, PVC/CPVC = 1. Below the CPVC, there is excess binder and the filler particles are not close packed. Above the CPVC, interstitial voids exist due to insufficient binder. 

MW separation factor Pore size Column i.d. Interstitial void size Thermal gradient... 

Since A V is composed of interstitial voids (between the fine particles), the weight fraction of fines in the total assembly is ... 

Rp will decrease however, we see the opposite effect due to the presence of the porous matrix, indicating the hydrodynamic effects exhibited within the interstitial void regions are significantly less than those within the pores. 

Near the end of the nuclei region the constricted capillaries in the agglomerate begin to fill up with liquid. Eventually, when the interstitial void volume becomes almost equal to the liquid content, the liquid is squeezed onto the surface of the pellet, whose appearance changes from semidry to wet. This movement or demixing of liquid signals the onset of the transition region. From this point onwards, apart from some pockets of trapped air, the pellet is comprised of two phases only, solid and liquid. 

Although a number of methods are available to characterize the interstitial voids of a solid, the most useful of these is mercury intrusion porosimetry [52], This method is widely used to determine the pore-size distribution of a porous material, and the void size of tablets and compacts. The method is based on the capillary rise phenomenon, in which excess pressure is required to force a nonwetting liquid into a narrow volume. 

An unusual and complicated array of heterocycles results from the inclusion of hydroxide moieties into a similar ferf-butylaluminium oxide system to [(f-Bu)A10]8 [50]. In this context, the product which results from the hydrolysis of [(f-Bu)Al(/T3-0)]6 [24] - [(f-Bu)Al]6(/T3-0)4(/r3-0H)4 - is best viewed as comprising an octahedron of aluminium centres each face of which is /X3-capped by either an oxide or a hydroxide group (Fig. 11) [63]. This species was the first to exhibit penta-coordinate Al-centres in an alumoxane context. Moreover, the polyhedral architecture incorporated an interstitial void which, it was suggested, might facilitate the formation of inclusion complexes. The predilection for (AlO) (n = 2) metallocycles does not hold for the tetracyclic array of n = 3 rings displayed by the mixed oxide-hydroxide... 

The pentagonal dodecahedron, however, is not entirely space-filling, i.e. a close-packed array of such figures has a number of interstitial voids. On the other hand, Kelvin s tetrakaidecahedron and the P-tetrakaidecahedron are. The latter requires 4% more surface area, so a system of such figures would spontaneously rearrange to the more stable array of Kelvin cells. Thus, it would seem that Kelvin s tetrakaidecahedron is the ideal candidate nevertheless, this is not observed in real systems Pentagonal faces are shown on foam cells. These... 

In scale-up from laboratory quantities (up to 10 kg) to production batches (300 kg and up), bed depth increases significantly. The most notable consequence is an increase in finished product bulk density, typically in the range of 15% to 20%. In some instances, this is a disadvantage (if product is packed by volume and a low density is desired). However, granule strength is usually greater as a result of the decreased interstitial void space. 

Related behaviour is exhibited by the dealkylated analogue, calix[4]arene (7.63). This material can also be sublimed to give a guest-free host but in this case the empty host forms an unusual trimer motif which is almost spherical and packs in a hexagonal close packed array with just a small interstitial void... 

Biofilms enhance bacteria-DOM interactions by several means. Their spatial and chemical heterogeneity provides additional sorption sites for DOM compared with clean surfaces. Their loose architecture with interstitial voids and channels increases diffusivity and to some extent allows convective flow within biofilm structures. Because bacteria metabolize organic matter sorbed to the biofilm, a diffusion flux from the free water to the biofilm is maintained. Large proportions of organic matter sorbed to the biofilm are not instantly turned over but remain in the biofilm as a reservoir, which buffers direct effects of DOM depletion in the water column. 

Currently, intercalation of Ceo with the rare gases into octahedral and tetrahedral interstitial voids of the fullerite Ceo crystal is broadly studied (see... 

In the present paper, we report on the dynamics of He filling the fullerite C6o fee lattice octahedral and tetrahedral interstitial voids with the respective sizes of 4.12 and 2.26 A [2], both larger than the helium Van der Waals diameter of 2.14 A [3], We also present results of study of influence of He intercalation on of photoluminescence spectra of Ceo single crystal in the low temperature phase. The measurement technique as well as the experimental setup for structural [4-6] and luminescent [5, 6] studies have been reported elsewhere. 

Fig. 5.3. Plots of the skeleton size against the through-pore size of the continuous monolithic silica prepared in a capillary (O), and the larger-sized silica rod columns (7 mm x 83 mm) having constant through-pore size/skeleton size ratio ( ) [15]. Also plotted are the particle size (vertical axis) against the size of interstitial voids (25-40% of dp as indicated by the bars) found with a conventional particle-packed column.

Figure 5.4a shows the electro-driven elution of alkylbenzenes and polyaromatic hydrocarbons (PAHs) in 80% acetonitrile. Figure 5.4a shows that the 250 mm column (100 pm diameter) produced ca. 40,000 and 35,000 theoretical plates for thiourea and hexylbenzene (k value = 0.8), respectively, at 1.1 mm/s linear velocity. Because of the presence of the very large through-pores at 8-10 pm, low column efficiency would be expected in pressure-driven elution, and this was actually the case. Interstitial voids of that size would be found in a column packed with ca. 30 pm particles. Figure 5.4b shows that the same column produced 5,000 and 6,000 theoretical plates for thiourea and hexylbenzene, respectively, under the pressure-driven conditions, with a split injection HPLC system at a similar linear velocity. The monolithic silica showed much higher performance in CEC than in the pressure-driven mode. 

Electroosmotic flow is generally reported to be independent of the size of the packing, and consequently the size of the interstitial voids between the particles, unless this size is so small that the electrical double layers overlap [74]. The ability to independently control both the pore size and level of charged functionalities of the methacrylate ester monolithic capillaries enables the direct investigation of the net effect of transport channel size on flow velocity. Recent results clearly demonstrates a... 

Despite the advances in materials since Merrifield s early investigations, microporous polymers are still mechanically weak. Their volume and properties - such as apparent loading - are altered when the solvent is changed, and, furthermore, packed columns have very large void areas, as an inevitable result of the particulate nature of the packing. Even when perfectly organized 30% of the volume consists of interstitial voids and, as a result, a significant portion of the reactor is undemsed [109]. 

Table V. Interstitial Voids in Unit Cell of a-Zirconium...

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