a) b - École Polytechnique de Montréal

composite droplet formation constituted of a well-segregated PMMA core and PS shell (Figure
2-4Ia, 2-4Ib, and 2-4Ic).
I) II)
a)
b) c)
Figure 2-4. SEM micrographs of the 80 (HDPE) /20 (PS/PMMA) I) a) fracture surface etched
with acetic acid for 2 min, 14%PS/86%H-PMMA; b) microtomed surface etched 24 h with
cyclohexane, 9%PS/91%H-PMMA; and c) microtomed surface etched 24 h with cyclohexane,
9%PS/91%L-PMMA, II) Evolution of the shell formation process with increasing PS content
(vol. % based on the dispersed phase) for the 80(HDPE)/20(PS/L-PMMA)(cryofractured
samples after being etched for 10 s with acetic acid).
It was explained that the thickness of the PS shell can be controlled by changing the relative
amount of PS and PMMA. They also showed the evolution of the shell formation process with
increasing PS content in a ternary HDPE/PS/PMMA blend(Reignier & Favis, 2003a) (Figure 2-
4IIa, 2-4IIb, and 2-4IIc). They also found(Reignier & Favis, 2000) that after two minutes of
mixing, approximately all of the PMMA is encapsulated within the PS dispersed phase and
morphology becomes stabilized after that.
Harrats et al.(Harrats, Omonov, & Groeninckx, 2005) reported encapsulation of the PP phase
between the PS and PA6 phases (Figures 2-5a and 2-5b). They found this against the prediction
of the Harkins equation, whereas the interfacial tension values of γPA6/PS=13.72 mN/m,
γPA6/PP=13.64 mN/m, and γPP/PS=2.26 mN/m demonstrated partial wetting case. They did not
a)
b)
c)
26