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a) b - École Polytechnique de Montréal

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Table 6-2. Interfacial Tension of Polymer Pairs from (Reignier & Favis, 2000) and Positive<br />

Spreading Coefficient of Ternary Blends<br />

6.3.2 Rheological Analysis<br />

Interfacial tension<br />

γ (mN/m)<br />

Positive Spreading Coeff.<br />

λ (mN/m)<br />

γHDPE/PMMA = 8.6 λPS/PMMA = 2.6<br />

γPS/PMMA = 2.4 λPMMA/HDPE = -5.9<br />

γPS/HDPE = 5.1 λHDPE/PS = -11.3<br />

The disc-shape samples were compression mol<strong>de</strong>d in the hot press at 200°C. A Bohlin constant<br />

stress rheometer (CSM) in the dynamic mo<strong>de</strong> equipped with 25 mm parallel disk geometry was<br />

utilized to measure the linear viscoelastic properties of homopolymers containing 0.2%<br />

antioxidant. All polymers were found to be stable at set temperature in the time sweep test for 8<br />

minutes. After the <strong>de</strong>termination of the viscoelastic region by stress sweep, a frequency sweep<br />

allowed for the measure of the zero shear viscosity of each sample. The Carreau-Yasuda mo<strong>de</strong>l<br />

and IRIS Rheo-Hub 2008 software were employed to <strong>de</strong>termine the zero shear viscosity of<br />

PEMA. The complex viscosity of pure homopolymers is plotted as a function of frequency in<br />

Figure 6-3. The average shear rate in the mixer is approximately 25 s -1 (Reignier, et al., 2003).<br />

The zero shear viscosity and the viscosity at 25 s -1 for the various homopolymers are reported in<br />

Table 6-1.<br />

178

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