A constitutive model for dispersive mixtures

S.G. Hansen, G.W.M. Peters, H.E.H. Meijer

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review


Dispersion of liquids are often encountered in industrial applications. For instance, plastics manufacturers frequently blend immiscible polymers to achieve desired mechanical properties. There are two problems central to the engineering of dispersions. One considers the influence of dispersed phase microstructure, or morphology, on material properties--in many applications, the smallest dispersed phase morphology is best. The other addresses achieving a particular morphology. The morphology in a blend results from the interaction between a frequently complex or chaotic flow, and coalescence and breakup. The mixing is crucial, and, in some cases, it is possible to tailor a morphology with a flow. However, the modeling of this process is incomplete. Presently, no model can predict the spatial statistics of dispersed phase morphology. A further complication is that the dispersed phase influences the macroscopic rheology of the blend. Einstein first demonstrated this behavior by showing that the effective viscosity of a system increased with dispersed phase volume fraction of solids. Later, Taylor extended Einstein's results to allow for a dispersed phase of spherical liquid droplets. Other researchers have improved upon Taylor's work, accounting for small deformations of the droplets, and shown that droplet deformation gives the dispersion an elasticity, resulting from surface tension. More recent developments in this area, allow for larger deformations, and coal escence and breakup. However, this area is relatively new with many inconsistencies in the literature. Furthermore, these newer phenomenological models contain a variety of adjustable parameters. The two inter-related goals of our work are a model for the spatial evolution of dispersed phase microstructure, and a rheological description of liquidliquid systems. The former is accomplished by coupling pre-existing models of coalescence and breakup with the kinematics of mixing processes. We develop the latter by unifying the theory of the present phenomenological models for rheology, and by applying the description of the dispersed phase microstructure provided by our model to remove the adjustable parameters presently in the rheology models.
Original languageEnglish
Title of host publicationPolymer Processing Society : annual meeting, 15th, 's-Hertogenbosch, The Netherlands, May 31 - June 4, 1999 : proceedings
EditorsP.D. Anderson, P.G.M. Kruit
Publication statusPublished - 1999
Event15th Annual Meeting of the Polymer Processing Society (PPS-15) - 's-Hertogenbosch, Netherlands
Duration: 31 May 19994 Jun 1999
Conference number: 15


Conference15th Annual Meeting of the Polymer Processing Society (PPS-15)
Abbreviated titlePPS


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