Influence of carbon nanotube type and novel modification on dispersion, melt‐rheology and electrical conductivity of polypropylene/carbon nanotube composites
J. P. Banerjee, Sreenivas Kummara, Ajay S. Panwar, Kingsuk Mukhopadhyay, Arvind K. Saxena, Arup R. Bhattacharyya
Abstract
Abstract 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.