Regensburg 2004 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 8: Physics of Polymers II

CPP 8.3: Vortrag

Montag, 8. März 2004, 16:15–16:30, H 37

Breakup of droplets in PS/PMMA blends after equibiaxial elongation — •Ulrich A. Handge — Institute of Polymers, Department of Materials, ETH Zürich, Switzerland

The breakup of liquid droplets in emulsions and molten blends of immiscible polymers has attracted much attention since many decades. The intensive research is motivated by the fundamentally oriented interest in understanding the deformation of drops in definable fields of flow and the technological relevance of dispersion processes. In this study, we investigated the breakup of equibiaxially deformed PS droplets in molten polystyrene (PS)/poly(methyl methacrylate) (PMMA) blends using a multiaxial elongational rheometer [1]. In equibiaxial deformation, the PS drop is deformed into a flat circular disc. During subsequent relaxation, the PS drop can retract to one single drop or breakup into many smaller drops. The driving force for this phenomenon is the interfacial tension at the interphase between the PS phase and the PMMA phase. During relaxation, the interfacial tension attempts to minimize the surface area of the PS drop. Using light microscopy, we observed the formation of fingers and holes in the elongated PS drop which finally results in a breakup of the extended drop into many smaller drops.

[1] P. Hachmann and J. Meissner, Rheometer for equibiaxial and planar elongations of polymer melts, J. Rheol. 47, 989 (2003).