Droplet Vorticity Alignment in Model Polymer Blends

Published

April 1, 2000

Author(s)

Kalman D. Migler

Abstract

The shear induced deformation of polymeric droplets in an immiscible polymeric matrix reveals that under conditions of high droplet elasticity, the droplets can align in the vorticity direction. We consider the case where the viscosity ratio of the two phases is near unity but the elasticity ratio of the droplet to the matrix is greater than 100. This is achieved by using a matrix phase of polydimehylsiloxane and a droplet phase of a polyisobutylene based Boger fluid. In the limit of weak shear and small droplets, the droplet alignment is along the shear direction, whereas for strong shear and large droplets, the alignment is along the vorticity direction. There is a range of conditions for which alignment can be along either axis. For droplets aligned along the vorticity axis, the distribution of aspect ratios is broad. The kinetic transformation from droplet flow alignment to vorticity alignment upon commencement of shear flow has been observed to occur on the time scale of 102 s. We infer from the kinetics experiment that the thickness in the flow gradient direction is less than that in the flow and vorticity directions.

Citation

Journal of Rheology

Volume

44

Issue

No. 2

Pub Type

Journals

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Keywords

blend, Boger, droplet, microscopy, polymer, shear, vorticity

Citation

Migler, K. (2000), Droplet Vorticity Alignment in Model Polymer Blends, Journal of Rheology, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=851603 (Accessed June 30, 2024)