Exploration of unusual electrical properties in carbon black/binary-polymer nanocomposites

Ultralow percolation threshold, strong positive temperature coefficient (PTC) effect, and abnormal alternating current electrical behaviors were obtained in ternary nanocomposites consisting of polypropylene (PP) and polyvinylidene fluoride (PVDF) (volume ratio: 1∕1) loaded with different amounts of nanosized carbon black (CB). These unusual properties could be assigned mainly to the special formation of electrically double-percolation network, the consecutive volume expansion of (PP-PVDF) cocontinuous phase, and the tunnel conduction between CB clusters. Both the low percolation threshold and the strong PTC effect should make the (CB-PP)/PVDF nanocomposites one of the most promising functional dielectric materials.