Rheology, electrical conductivity, and the phase behavior of cocontinuous PA6/ABS blends with MWNT: Correlating the aspect ratio of MWNT with the percolation threshold

Abstract

Multiwalled carbon nanotubes (purified, p-MWNT and $ NH 2 functionalized, f-MWNT) were melt-mixed with 50/50 cocontinuous blends of polyamide 6 (PA6) and acrylonitrile-butadiene-styrene in a conical twin-screw microcompounder to obtain conductive polymer blends utilizing the conceptual approach of double-percolation. The state of dispersion of the tubes was assessed using AC electrical conductivity measurements and melt-rheology. The rheological and the electrical percolation threshold was observed to be $ 1-2 wt % and $ 3-4 wt %, respectively, for blends with p-MWNT. In case of blends with f-MWNT, the rheological percolation threshold was observed to be higher (2-3 wt %) than p-MWNT but the electrical percolation threshold remained almost same. However, the absolute values were significantly lower than blends with p-MWNT. In addition, significant refinement in the cocontinuous morphology of the blends with increasing concentration of MWNT was observed in both the cases. Further, an attempt was made to understand the underlying concepts in relation to cocontinuous morphologies that how the geometrical percolation threshold which adversely suffered because of the attrition of tubes under prolonged shear contributed further in retaining the rheological percolation threshold.

Thermoplastic Nanocomposites with Carbon Nanotubes

“…But, covalent functionalization tends to negatively affect the physical and chemical integrity of CNTs. Strong acid treatments affects the geometry of the CNTs resulting in increased filler percolation thresholds [47]. Covalent treatments could also negatively affect the intrinsic electrical properties of the CNTs and have a profounding effect on the metallic characteristics of metallic CNTs [48].…”

Studies on the selective localization of multi-walled carbon nanotubes in blends of poly(vinylidene fluoride) and polycaprolactone

“…Many studies were carried out to deal with the problem [11][12][13][14]. The design of double percolation structure in composites is one of the methods to reduce the percolation threshold of conductive fillers [15][16][17][18][19][20][21].The concept of double percolation was first proposed by Sumita et al [21] in immiscible blends that were filled with carbon black. Two requirements are needed to realize the double percolation structure in composites.…”

Injection‐molded parts of polypropylene/multi‐wall carbon nanotubes composites with an electrically conductive tridimensional network

“…length to width relation, is thought to play a large role in percolation threshold as it appears that conductive percolation paths are, in general, more easily set up when homogeneous dispersion of long and thin nanotubes is achieved. Several research studies have demonstrated that aspect ratio of MWCNTs is the main parameter in determining the conductive properties of polymer composites [32][33][34]. This has been fully supported by other studies, in which it was concluded that an increase in the aspect ratio of CNTs consistently implies an exponential decrease in percolation threshold of the composite [35,36].…”