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a) b - École Polytechnique de Montréal

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The final part of the work focuses on the complex morphological structures which can be<br />

generated from a ternary polymer blend <strong>de</strong>monstrating complete wetting behavior. This work<br />

examines the complete range of possible morphological states for such a system over the entire<br />

ternary composition diagram as prepared by melt mixing. A ternary polymer blend comprised of<br />

HDPE, PS, and PMMA is selected as a mo<strong>de</strong>l system <strong>de</strong>monstrating complete wetting. The<br />

positive spreading coefficient of λPS/PMMA=2.6 mN/m indicates that PS separates the HDPE and<br />

PMMA phases. Four thermodynamically stable sub-categories of morphologies can be<br />

i<strong>de</strong>ntified: a) matrix/core-shell dispersed phase; b) tri-continuous; c) bi-continuous/dispersed<br />

phase; and d) matrix/two separate dispersed phases. Electron microscopy as well as focused ion<br />

beam irradiation and atomic force microscopy are used to clearly illustrate and i<strong>de</strong>ntify the<br />

various phases. Solvent extraction/gravimetry is used to examine the extent of continuity of the<br />

systems so as to effectively i<strong>de</strong>ntify regions of high continuity. Triangular compositional<br />

diagrams are used to distinguish these various morphological regions and the results are<br />

interpreted in light of the interfacial tension of the various binary combinations and their<br />

subsequent spreading coefficients. The effect of the molecular weight and viscosity ratio on the<br />

phase size of the various structures is also consi<strong>de</strong>red. It is shown that the viscosity of the phases<br />

can influence the interfacial area between phases, but does not affect the morphological state<br />

classification.<br />

xii

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