Positive Temperature Coefficient Effect of Polypropylene/Carbon Nanotube/Montmorillonite Hybrid Nanocomposites

Ternary polypropylene/multiwalled carbon nanotube/montmorillonite (PP/MWNT/MMT) nanocomposites were prepared by melt compounding of a ball-milled MWNT and MMT mixture in a Haake mixer at a screw rotation rate of 200 r/min. The electrical conducting behavior of such hybrid composites was examined. The results showed that the conducting behaviors of PP/MWNT/MMT nanocomposites were strongly dependent on the MWNT and MMT contents. The percolation concentration of such hybrid nanocomposites was 1.0 wt% MWNT. Furthermore, percolating PP/1.0 wt% MWNT/MMT nanocomposites exhibited a positive temperature coefficient (PTC) effect. The PTC transition temperature can be regulated over a broader temperature range by varying the MMT contents. Hybridization of nanofillers provides a facile methodology to fabricate conducting polymer nanocomposites with tunable PTC transition temperatures.