Bonding, interparticle

It has been discovered that starch adsorbs onto graphite, a phenomenon that is employed in processing sulfide ores containing graphite.460 The adsorption of starch on quartz and hematite has been studied in more detail.461 In this case, adsorption is related to the balance between electrostatic interactions and hydrogen bonding. Interparticle bridging is also observed as a result of the adsorption of starch molecules at the interface (flocculation). 

The development of flaws and the loss of interparticle bonding during decompression substantially weaken compacts (see breakage subsection). Delamination during load removal involves the fracture of the compact into layers, and it is induced by strain recovery in excess of the elastic limit of the material which cannot be accommodated by... 

The success of compression agglomeration depends on the effective utilization and transmission ofthe applied external force and on the ability of the material to form and maintain interparticle bonds during pressure compaction (or consolidation) and decompression. Both these aspects are controlled in turn by the geometiy of the confined space, the nature of the apphed loads and the physical properties of the particulate material and of the confining walls. (See the section on Powder Mechanics and Powder Compaction.)... 

Floes possess two important settling features. The first is their complicated structure. The aggregates are lax, the interparticle bond in them is weak, and they hold a large amount of water in their structures, which is retained with the floes when they settle. The second feature of the flocculated pulp is the complexity of its settling mechanism. 

In this category, among the molecular, electrostatic and magnetic interparticle bonds, interest is primarily centered on the van der Waals-type attractive forces that may predominate in the absence of liquid and solid bonds. The force of the van der Waals attraction between two spheres of equal size is (R4)... 

The presence of an immobile adsorbed film or layer on the particle surface may lead to the formation of still stronger interparticle van der Waals bonds (R6). First, surface roughness is smoothed out, increasing the apparent particle size and contact area, and second, the separation distance is effectively... 

H(D,) Interparticle bonding force Fraction of void space filled by... 

In a second hypothesis, one can consider that the adsorption is mainly due to hydrogen bonds and that electrostatic attraction between polymer and particles only brings them together. In such case, the influence of c and r on the stability should be related to the number of amide groups available for hydrogen bounds and the increase of salinity should lead to the collapse of the chain and reduce the probability of interparticles bridging. 

Figure 1 Two basic types of ordering typically found in liquids, (a) Bond-orientational order describes the tendency of molecules to form well-defined angles between the fictitious bonds that can be drawn between the molecule of interest and two of its nearest neighbors, (b) Translational order describes the tendency of molecules to adopt preferential interparticle separations. (Adapted from Ref. 30.)...

Ben-Naim (1980) has recently reviewed the work in this field. The results obtained so far are not very satisfying because there does not seem to be a single method that can provide direct information on the properties of the hydrophobic interactions between two simple solutes in water at a realistic interparticle distance. Most studies have been concerned with the volume difference between a dimer 2A and a monomer A, for example, ethane and methane. However, such comparisons are not realistic because there is a covalent bond between the two monomers in the dimer, and also two hydrogen atoms are missing in the dimer. The volume of these two hydrogens seems to account for the resulting volume difference. 

The mechanism of densification begins with individnal particle motion at low pressnre before interparticle bonding becomes extensive. At higher pressures, the compact... 

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