Breakage mechanisms

TABLE 20-39 Growth and Breakage Mechanisms in Granulation Processes... 

A further complication in the breakage process is that depending on the breakage mechanism a breakage event can lead to... 

Mechanical Breakage. Mechanical breakage of packages can occur for several reasons. The materials may not have sufficient strength (heavy enough paper or film), puncture resistance may be insufficient, or one part of the structure may be too weak (or too strong) for the particular application. 

Product particle size distributions of impact ground thermoplastics (specifically PETP and PVC) are interpreted and models describing these distributions developed. Results from multiple and single particle breakage in a hammer mill are used. The values of the model coefficients are related to the brittle-ductile transition grinding conditions and breakage mechanisms. Results are relevant to the separation of thermoplastics, as for example, is required when recycling consumer products such as bottles. 3 refs. 

Fibril drawing mechanism versus fibril breakage mechanism The most interesting point in that comparison is that the mechanisms are the same in the case of a crack-craze system propagating in air, and differ notably in the case of a toluene vapor environment for low velocities. 

One important parameter contributing to different breakage mechanisms is solids concentration or density in the mill. This directly influences the number of particle-particle or particle-wall collisions and the force of those collisions. Particle density in the mill is controlled not only by feed rate to the mill, but also by mill residence time. Depending on the type of equipment and how it is operated, solids density in the mill can impact both the milling rate and its efficiency so understanding and control of this parameter are important for scale-up. 

FIG. 21-91 Growth and breakage mechanisms in granulation processes. [Ajier Sastry and Fuerstenau, Agglomeration 77, Sastry (ed.), AIME, New York, 1977, p. 381.]... 

Figure 1. Colloidal breakage mechanisms in quiescent media...

The fluid particle breakage controls the maximum bubble size and can be greatly influenced by the continuous phase hydrodynamics and interfacial interactions. Therefore, a generalized breakage mechanism can be expressed as a balance between external stresses (dominating component), o, that attempts to disrupt the bubble and the surface stress, ai/d, that resists the particle deformation. Thus, at the point of breakage, these forces must balance, o This balance leads to the prediction of a critical Weber number, above which the fluid particle is no longer stable. It is defined by [36] ... 

Chester AK (1991) The modelling of coalescence processes in fluid-fluid dispersions A review of current understanding. Trans IchemE 69(A) 259-270 Colella D, Vinci D, Bagatin R, Masi M, Bakr EA (1999) A study on coalescence and breakage mechanisms in three different bubble columns. Chem Eng Sci 54 (21) 4767-4777... 

Brinkman, J. R. (1989, August). Separating shock waves and gas expansion breakage mechanisms. In Proceedings of the 2nd international symposium on rockfragmentation by blasting. Keystone, CO. 

Observations of the damaged morphology of the product particles after impact tests are in agreonent with the breakage mechanisms observed during nanoindentation... 

Two key pieces of historical investigation require mention, as the approach developed here stems heavily from this work. The first involves growth and breakage mechanisms, which control the evolution of the granule size distribution (14), as... 

Figure 10 Growth and breakage mechanisms in granulation processes. (From Ref. 14.)...

Breakage mechanisms will be treated in the following section. Here, we focus particularly on growth and consolidation mechanisms. 

Development of appropriate constitutive relations that define intensive properties, mass and heat transfer mechanisms, as well as particle growth and breakage mechanisms. 

Chen YM, Fan LS. Bubble breakage mechanisms due to collision with a particle in a liquid medium. Chem Eng Sci 44 117-132, 1989a. 

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