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Observation and analysis of carbon black agglomerates dispersion in simple shear flows

Rwei, Syang-Peng
http://rave.ohiolink.edu/etdc/view?acc_num=case1055357306

Abstract Details

1991, Doctor of Philosophy, Case Western Reserve University, Macromolecular Science.
The purpose of this study was to investigate the mechanism of agglomerate breakup in simple shear flows and correlate the various parameters affecting the dispersion process. Specifically, the dispersion of carbon black agglomerates in various low viscosity media and polymeric melts was studied. Experiments were performed in two devices: (1) A rotating concentric cylinder device mounted in a light scattering monophotometer was used to detect the critical breakup conditions. (2) A transparent cone-and-plate device enabled observation of mechanisms of particle breakup in simple shear flows. Two distinct breakup mechanisms, denoted as "rupture" and "erosion," were observed. The rupture process is characterized by an abrupt breakage of the agglomerate into a small number of relatively large pieces. The erosion process is more gradual and initiates at lower applied shear stresses than rupture. The erosion process is characterized by the detachment of small fragments from the outer surface of the agglomerate. From the analysis of rupture, the dimensionless group α = (η cdot acuteγ/K'φ4), which is the ratio of applied stress to cohesive strength, was found to be a useful parameter in correlating material properties and flow conditions to the final particle size distribution. It was found that the erosion kinetics follows a first order rate equation. The strength of the flow field does affect the kinetics of the dispersion process, and the same parameter α is characteristic for the erosion process. The dispersion of carbon black within melts of polystyrene has also been investigated. Analysis of the evolution of the fragment size distribution indicates that rupture conditions and erosion kinetics determined from studies in low viscosity media can be applied to polymeric systems. The influence of dispersion quality on certain physical properties, namely UV absorption characteristics and tensile strength properties, can also be quantified in terms of parameters describing the quality of dispersion.
Ica Manas-Zloczower (Advisor)
116 p.
carbon black agglomerates dispersion

Recommended Citations

Citations

  • Rwei, S.-P. (1991). Observation and analysis of carbon black agglomerates dispersion in simple shear flows [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1055357306

    APA Style (7th edition)

  • Rwei, Syang-Peng. Observation and analysis of carbon black agglomerates dispersion in simple shear flows. 1991. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1055357306.

    MLA Style (8th edition)

  • Rwei, Syang-Peng. "Observation and analysis of carbon black agglomerates dispersion in simple shear flows." Doctoral dissertation, Case Western Reserve University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=case1055357306

    Chicago Manual of Style (17th edition)

case1055357306
793
© 1991, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.