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The influence of agglomerate structure on the dispersive mixing process

Horwatt, Steven Wayne

Abstract Details

1991, Doctor of Philosophy, Case Western Reserve University, Macromolecular Science.
The transmission of stress in an agglomerate, and hence the stress required for breakup of the agglomerate, is strongly dependent on the agglomerate structure. The purpose of this study was to investigate the influence of agglomerate structure on the dispersion process through the use of computer simulations. A total of six agglomerate structures were simulated using various simple cubic lattice based models; the agglomerates ranged from very tenuous, highly ramified structures with a fractal dimension of 1.96 to very compact structures having a fractal dimension of 3.0. Two models of the stress required to rupture the agglomerates were formulated. The first model was based on fracture of the agglomerate along a planar surface; this model invariably predicted that rupture would occur in the outer fringes of the agglomerate, where the density of the cluster was lowest. The second model was based on fracture along an irregular surface, and accounted for the concentration of stress at the roots of branches in the agglomerate. This stress concentration was found to cause the fragments produced from the highly ramified clusters to be comparable in size to the parent cluster. The irregular fracture model also predicted much lower critical rupture stresses and a stronger dependence of the critical rupt ure stress on cluster size (for the fractal clusters) than did the planar fracture model. Simulations of agglomerate breakup at supercritical stresses were carried out, under the assumption that breakup occurs by successive fracture of the cluster at its weakest point until all fragments produced are stable at the stress applied. Using this model, the average fragment size exhibited a power law dependence on the applied stress (above the critical stress) for all of the clusters simulated. The magnitude of the exponent in this power law relationship increased as the structure went from being highly ramified to completely dense.
Ica Manas-Zloczower (Advisor)
242 p.

Recommended Citations

Citations

  • Horwatt, S. W. (1991). The influence of agglomerate structure on the dispersive mixing process [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1055778042

    APA Style (7th edition)

  • Horwatt, Steven. The influence of agglomerate structure on the dispersive mixing process. 1991. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1055778042.

    MLA Style (8th edition)

  • Horwatt, Steven. "The influence of agglomerate structure on the dispersive mixing process." Doctoral dissertation, Case Western Reserve University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=case1055778042

    Chicago Manual of Style (17th edition)