Synergistic effect of multiwalled carbon nanotubes and carbon black on rheological behaviors and electrical conductivity of hybrid polypropylene nanocomposites

The monograph, electrical conductivity, and rheological behaviors of isotactic polypropylene /carbon black (CB)/multiwalled carbon nanotubes (MWCNTs) composites were studied. Ternary composites including MWCNTs and CB revealed an electrical property similar to the binary MWCNTs composites. This work showed that a synergistic effect result in preserved electrical behavior with a simultaneous effective reduced of the MWCNTs amount. Moreover, the combination of conductive fillers also resulted in a decreased rheological percolation threshold, an accelerated formation of rheological network and a delay in the destruction of the filler network. The similar value of the activation energy for CB/MWCNTs and MWCNTs verified the existence of a co-supporting networked formed by MWCNTs and CB. Two strain-softening processes are found in a strain sweep for the ternary composite melt with high filler loading. The low-strain-softening process may be an indication that the MWCNTs filler network is broken into separated aggregated structures, while the high-strain-softening process should be related to the breakdown of the temporary network structure. POLYM. COMPOS., 39:E723-E732, 2018. (c) 2016 Society of Plastics Engineers