a) b - École Polytechnique de Montréal

Reignier & Favis, 2000, 2003a; Reignier, Favis, & Heuzey, 2003; Tchomakov, Favis, Huneault,
Champagne, & Tofan, 2004; Urashita, Kawakatsu, & Doi, 2000).
It has been observed that the rheological properties of the two minor phases can play a role in the
final morphology of ternary polymer blends, most notably through viscosity effects(Gupta, 1993;
Luzinov, Pagnoulle, & Jerome, 2000; Nemirovski, Siegmann, & Narkis, 1995; Tchomakov, et
al., 2004), and elasticity ratio effects(Legros, Carreau, Favis, & Michel, 1997; Vanoene, 1972).
The effect of the viscosity ratio is still controversial amongst the authors. Some authors did not
observe any influence of the viscosity ratio on the type of morphology(Reignier, et al., 2003;
Tchomakov, et al., 2004), while some observed encapsulation of the higher viscosity component
by the component of lower viscosity(Nemirovski, et al., 1995), and others observed a contrary
result(Gupta, 1993).
Van Oene(Vanoene, 1972) showed that under conditions of dynamic flow, the difference in
elasticity between the phases can contribute to the interfacial tension. A dynamic interfacial
tension, which can be quite different from the static interfacial tension, can have a significant
impact on the final morphology. He developed an expression for the interfacial tension in flow
and defined a term proportional to the difference between a second normal stress function in this
equation(Equation 26)
2.1.2.2.1 Composite Droplet Morphology
Another interesting morphology observed in multiphase polymer blends is the composite
droplets morphology. In this particular morphology, a dispersed phase (B), in a matrix of (A),
encapsulates a third phase (C).
There are two main causes for sub-inclusion formation: 1) Thermodynamic effect: to minimize
the surface free energy of a blend (Guo, Packirisamy, et al., 1997; Hobbs, et al., 1988) and 2)
Rheological effect: the entrapment of the sub-inclusions in a more viscous phase near the phase
inversion region(Favis & Chalifoux, 1988).
Reignier et al.(Reignier & Favis, 2000, 2003a, 2003b; Reignier, et al., 2003) showed that in a
ternary blend comprised of PMMA, PS, and HDPE, when HDPE is the matrix, the blend exhibits
25