a) b - École Polytechnique de Montréal

Omonov et al. found double percolated structures for ternary 40PA6/30PP/30PS (Figure 2-8a)
and 40PA6/(25/5)(PP/PP–MA2)/(25/5)(PS/SMA2) (Figure 2-8b) blends. In this work, the
observed results were opposite to the prediction of spreading theory, which is partial wetting.
They found that despite the negative values of spreading coefficients, a complete wetting case
with PA6 phase at the interface is observed. The gravimetric measurements for all phases
showed that for 40PA6/30PP/30PS, all phases have more than 97% continuity while PA6
separates the PP and PS phases. Figure 2-8b shows that addition of a compatibilizing agent to the
sample does not change the location of phases. It only reduces phase sizes, but PA6 still remains
at the interface of the two other phases.
a) b)
Figure 2-8. Scanning electron micrograph of a) 40PA6/30PP/30PS; formic acid extracted
surfaces, and b) 40PA6/(25/5)(PP/PP–MA2)/(25/5)(PS/SMA2); formic acid extracted surfaces
(Harrats, et al., 2005)
One of the most important applications of double-percolated structures is the preparation of
conductive polymer blends. Since locating the conductive phase at the interface decreases the
percolation threshold of continuity of the middle phase, it is predicted that the percolation
threshold of conductivity of the blend is reduced significantly. Narkis et al.(Narkis et al., 2000b;
Zilberman, Siegmann, & Narkis, 1998, 2000a, 2000b) studied various polymer blends consisting
of two immiscible thermoplastic polymers and PANI and tried to locate PANI at the interface of
two other polymers, but they were not successful. They showed that for CoPA/LLDPE/PANI
(Figure 2-9) and (PS/DOP)/LLDPE/PANI (Figure 2-10), changing the concentration of the
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