Multiphase polymer blends can provide unique morphologies which can, when they include carbon black partitioned preferentially into one phase or onto a phase boundary, reduce the percolation concentration and increase conductivity of the composites.  In this study we investigated the morphological features of a ternary blend of polypropylene (PP), poly(methyl methacrylate) (PMMA), and ethylene-acrylic acid (EAA) with carbon black (CB) to provide a fundamental morphological understanding of the changes in electrical conductivity as a function of compounding sequence and annealing time.  At short annealing times, the CB distribution was influenced by the compounding sequence where the CB was added after being premixed with one of the polymer components or directly added to the three component polymer melt, but again was thermodynamically driven at longer annealing times with the CB migrating to the EAA phase.  The resistivity was found to decrease by a statistically significant amount to similar levels for all of the composite systems with increasing annealing time.  The increase in conductivity at longer annealing times was accompanied by a coarsening of the PMMA domain size and partitioning of the EAA to the PP/PMMA interface bridging between the PMMA domains.

Morphological characterization of tri-continuous conductive PP/PMMA/EAA carbon black composites

252nd National Meeting (2016)

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