a) b - École Polytechnique de Montréal

carried out by comparing minimization of interfacial area and a driving force (gravitational,
centrifugal, shearing force, etc).
Bashforth and Adams(Bashforth & Adams, 1883) related the surface tension to the difference of
density between two liquids and the geometrical profile of a drop. The pendant drop method
determines the profile of a drop of one denser liquid suspended in a less dense liquid at
mechanical equilibrium.
A similar method to pendant drop method is the sessile drop method. In this technique,
interfacial tension is calculated for a liquid surrounded by another liquid with smaller density on
a flat surface based on the balance between gravity and surface forces. It implies that from the
shape of the drop at mechanical equilibrium, interfacial tension can be calculated.
The breaking thread technique is a well-known method in which interfacial tension is calculated
based on the evolution of the shape of a thread imbedded in a second phase. Small distortions
with certain wavelengths are generated at the interface of the phases due to Brownian motion.
These small distortions are expanded based on the interfacial tension and the viscosity of the
polymers. Two theories relate the evolution of the thread to interfacial tension: the theory of
Tomotika(Tomotika, 1935b) and the theory of Tjahjadi(Tjahjadi, Ottino, & Stone, 1994).
Different morphologies can be obtained for melt processing of immiscible polymer blends.
Simple morphologies such as matrix/dispersed particles structures, matrix-fiber structures,
lamellar structures and complex morphologies such as co-continuous structures, composite
droplet structures, and multiple percolated structures can be generated(Favis, 2000; Potschke &
Paul, 2003). These kinds of morphologies can easily be transformed by changing effective
parameters such as applied shear, elongation stress, interfacial tension between phases, and
coalescence and breakup of the phases during processing. For instance, the dispersed phase can
be distorted into long fibrils by applying further shear stress. Breakup mechanism can occur due
to lowering interfacial tension between components dispersing fibrils into droplets. Broken
droplets can be coalesced and form fibrils or larger droplets by coalescence mechanisms. All
other mentioned parameters affect the size and shape of droplets, fibrils, or continuous structure
of phases. The combination of these processes can potentially provide us many kinds of phase
morphologies suitable for various applications.
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