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a) b - École Polytechnique de Montréal

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5.3.4 Annealing Test<br />

For the annealing experiments a compression molding press was employed. Small pieces of<br />

samples were cut from the blend and then sandwiched between two metal plates in a disc-shaped<br />

mould. The temperature of both upper and lower plates was set at 200°C. The annealing was<br />

carried out un<strong>de</strong>r nitrogen in five steps. As a first step, both heating plates of the compression<br />

press were brought into contact with the sample pieces without imposing any pressure for 5<br />

minutes, in or<strong>de</strong>r to minimize any <strong>de</strong>formation or flow of the sample. After heating and melting<br />

the samples, pressure was applied for 15 minutes. After annealing, the samples were cooled by<br />

placing the samples in a large cold press for 3 minutes.<br />

5.3.5 Solvent Extraction<br />

Solvent extraction was used to extract various components and generate porosity in the substrate.<br />

Selective solvent extraction also allows for the <strong>de</strong>termination of the % continuity of the different<br />

components in the blend system using Equation 5-2. The volume of the components before and<br />

after extraction is measured by weighing the sample and converting the weight to volume. As a<br />

primary advantage, solvent extraction is an absolute measurement of continuity.<br />

Equation 5-2<br />

% Cocontinui ty<br />

∑V − ∑V<br />

initial<br />

n n<br />

=<br />

∑V<br />

A homogenous blend is assumed when carrying out the selective solvent extraction of the<br />

PMMA, PS, and PVDF phases in dimethylformami<strong>de</strong>(DMF). Volume loss measurements were<br />

carried out for one week at room temperature and were used to calculate the extent of continuity<br />

of the PMMA, PS, and PVDF phases altogether. Vinitial and Vfinal are the volume of one<br />

component or several components present in the sample before and after extraction calculated by<br />

weighing the sample and converting it to the volume. The % continuity represents the fraction of<br />

a phase that is continuous.<br />

n<br />

initial<br />

final<br />

144

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