Drop breakup mechanisms in polymer-polymer systems

Abstract

The deformation and breakup of a single viscoelastic polymer drop inside a viscoelastic polymer matrix at high temperatures under simple shear was visualized in a specially designed transparent Couette mixer. The polymer systems studied were polyethylene matrix/polycarbonate drop (PE/PC) with viscosity ratios between 2 and 8. Aside from the "erosion" mechanism, which has already been reported (1, 2), three other distinct breakup modes were observed: (a) "parallel breakup" - the drop breaks after being stretched into a thin sheet or sausage parallel to the flow direction; (b) "tip streaming" - streams of small droplets are released from the tips of a pointed drop in the flow direction; and (c) "perpendicular breakup" - the drop breaks after being elongated in the vorticity direction.