Interparticle bonds

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)... 

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

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

Wax Emulsions. The final component in most particleboard is a sizing agent to reduce the absorption of liquid water. This is normally a paraffin wax emulsion which is supplied to the particleboard manufacturers at approximately a 50 percent wax solids in water. Less than 1 percent wax solids based on the ovendry wood weight is used in most particleboard levels above 1 percent tend to interfere with interparticle bonding while levels below 0.75 percent do not offer maximum water resistance. 

The blending operation is an important step in the production of quality part i cleboard--uneven distribution of the adhesive will result in regions of low interparticle bonding and weak particleboard. Strict monitoring of both the adhesive and particle streams delivered to the blender is required for optimum blending. 

In the absence of interparticle bonding material, the forces of adhesion are reasonably well understood and are orders of magnitude weaker than those discussed above. The results of many theoretical and experimental investigations of these long-range forces have been summarized by Krupp [6]. 

Kachrimanis, K., Nikolakakis, I., and Malamataris, S. (2003), Tensile strength and disintegration of tableted silicified microcrystalline cellulose Influences of interparticle bonding,/. Pharm. Sci., 92(7), 1489-1501. 

The difference between ceramics and cements, however, goes beyond this definition. From a structural viewpoint, the distinction between ceramics and cements concerns the interparticle bonds that holds them together and provides the necessary strength. Hydraulic cements are bonded by van der Waals forces, while ceramics are formed by either ionic or covalent bonds between their particles. Because covalent and ionic bonds are stronger than van der Waals bonds, ceramics have better strength than cements. 

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