29.06.2013 Views

a) b - École Polytechnique de Montréal

a) b - École Polytechnique de Montréal

a) b - École Polytechnique de Montréal

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

The results of resistance for PS/PEMA/PANI are plotted as a function of volume fraction of<br />

PEMA in Figure A-4.5. The plot of resistance values for PS/PEMA/PANI samples containing<br />

10% of PANI is completely different from what was observed for HDPE/PEMA/PANI,<br />

represented in Figure A-4.3. Figure A-4.5 reveals that for blends containing 10% of PANI at all<br />

concentrations of PEMA, the resistance value is significantly high, since for all concentrations of<br />

PEMA the resistance is approximately constant and the percolation threshold is not reached. The<br />

reason for not achieving the formation of PANI connected pathways in blends with a low amount<br />

of PANI (10%) is proposed to be attributed to the low value of interfacial tension between<br />

PEMA and PS. Such a low interfacial tension results in the constitution of a co-continuous<br />

network of PEMA and PS, leading to dispersion of droplets of PANI in a large volume. In the<br />

previous case (HDPE/PEMA/PANI), because of many parts of blend being occupied by HDPE,<br />

PANI was forced in geometrically restricted paths, and a few connected pathways of PANI, even<br />

at low concentration, are formed. In the PS/PEMA/PANI case, there is no force to get the PANI<br />

droplets coalesced because of the interdiffused network of PEMA and PS resulting in the<br />

distribution and dispersion of PANI in the droplet shape throughout the sample. Such<br />

morphology represents unconnected droplets of PANI, and subsequently, due to the absence of<br />

formation of a PANI connected network, a high value of resistance for all compositions of<br />

PEMA is revealed. However, for samples containing 20% PANI, due to the sufficient amount of<br />

PANI at a high content of PEMA, networks of PANI are formed, and for this plot a percolation<br />

threshold of 20% of PEMA can be consi<strong>de</strong>red. High concentrations of PS reveal a matrix-droplet<br />

morphology, as the value of resistance is high.<br />

259

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!