Influence of carbon nanotube type and novel modification on dispersion, melt-rheology and electrical conductivity of polypropylene/carbon nanotube composites

Melt-mixing was employed to prepare multiwall carbon nanotubes (MWCNTs) based polypropylene (PP) composites, wherein MWCNTs vary in agglomerate size and also in terms of agglomerate structure. Morphological analysis revealed MWCNTs-D type exhibits bigger agglomerate size with compact agglomerate structure with respect to MWCNTs-N type, that show smaller agglomerate size with porous agglomerate structure in the corresponding PP/MWCNTs composites. Melt-rheological analysis showed a rheological percolation threshold of 2 to 3 wt% in PP/MWCNTs-N composites, whereas PP/MWCNTs-D composites exhibited a rheological percolation of 3 to 4 wt% of MWCNTs. AC electrical conductivity measurements exhibited an electrical percolation threshold of 0.5 to 1 wt% of MWCNTs-N, whereas MWCNTs-D type depicts an electrical percolation threshold of 2 to 3 wt% of MWCNTs in the respective composites. Further, an unique dispersant; Li salt of 6-aminohexanoic acid (Li-AHA) was utilized to deagglomerate MWCNTs. Moreover, PP-g-MA was also utilized in combination with Li-AHA encapsulated MWCNTs in the corresponding composites. An extensive morphological, rheological, and electrical conductivity measurements suggested the influence of Li-AHA encapsulated MWCNTs and PP-g-MA on the transformation of MWCNTs agglomerate into individualized and smaller MWCNTs agglomerate in PP/MWCNTs composites.

Automated summary

Melt-mixing was employed to prepare multiwall carbon nanotubes (MWCNTs) based polypropylene (PP) composites, and morphological, rheological, and electrical conductivity measurements indicated the influence of MWCNTs agglomerate structure on the properties of the composites.