Influence of Noncovalent Modification on Dispersion State of Multiwalled Carbon Nanotubes in Melt-Mixed Immiscible Polymer Blends

Abstract

Multiwalled carbon nanotubes (MWNTs) were melt-mixed with polyamide6 (PA6) and acrylonitrile butadiene styrene copolymer (ABS) to obtain electrically conducting composites. MWNTs were noncovalently modified with sodium salt of 6-aminocaproic acid (MWNTs-m1) and 3-pyrenealdehyde (MWNTs-m2) to 'deagglomerate' MWNTs. Raman spectroscopic analysis indicated a G-band shift from ∼1581.9 cm(-1) for pristine MWNTs to ∼1590.2 cm(-1) for MWNTs-m1 and ∼1588.8 cm(-1) for MWNTs-m2, indicating the interaction between MWNTs and the respective modifier molecules. Blends showed 'co-continuous' morphology on the addition of MWNTs. TEM observations showed that a higher population of pristine MWNTs exhibited a 'nanoagglomerated' state in PA6 and ABS phases in the case of a 40/60 PA6/ABS blend, unlike a 60/40 blend, which depicted a higher population of 'individualized' MWNTs. Further, the corresponding blends with MWNTs-m1 and MWNTs-m2 showed 'nanoagglomerated' and 'individualized' MWNTs. Blends with pristine MWNTs showed an increase in DC electrical conductivity with an increase in PA6 concentration in the blend. Moreover, the corresponding blends with MWNTs-m1 and MWNTs-m2 exhibited an increased DC electrical conductivity value as compared to the corresponding blend with pristine MWNTs. Ratio of the intensity (H1/H2) of the crystallization peak at lower temperature (H1) to the intensity of the crystallization peak at higher temperature (H2) depicted lower values for blends with pristine MWNTs as compared to the corresponding blends with MWNTs-m1 and MWNTs-m2. TGA studies indicated the formation of a thicker 'interphase' involving MWNTs and the interacting polymer chains.

Conducting melt blending of polystyrene and EVA copolymer with carbon nanotube assisted by phosphonium‐based ionic liquid

“…The increase in viscosity of the loaded phase requires higher shear forces for melt processing, which account for the refinement of the co‐continuous structure, as observed by SEM micrographs. Similar behavior was also observed in similar blend loaded with carbon black, and in other CNT‐loaded heterogeneous blends …”

“…By using a blend composition with co‐continuous phase structure, it is possible to achieve percolated CNT network at lower filler concentration, thanks to the confinement of CNT in one phase. This principle is known as double percolation and has been used to develop several CNT‐based conducting composites based on polycarbonate, polyvinylidene fluoride (PVDF), polyamide (PA6), and polypropylene, among others.…”

Multiwalled carbon nanotubes-based polypropylene composites: Influence of interfacial interaction on the crystallization behavior of polypropylene

“…Furthermore, the corresponding FEG-SEM micrographs of Li-AHA modified MWCNTs show the adsorption of Li-AHA on MWCNTs surface, which is found to be consistent with the earlier reported results [30]. The mechanism of "debundling" of MWCNTs by using a non-covalent modifier (Li-AHA like molecules) has been earlier proposed via electrostatic charge repulsion in the aqueous medium [12,29,30]. The improvement of dispersion extent of MWCNTs was achieved earlier by using sodium salt of 6-aminohexanoic acid (Na-AHA), wherein the extent of "debundling" of MWCNTs was significantly enhanced with increased concentration of Na-AHA [35].…”

Electrical and melt rheological characterization of PC and co‐continuous PC/SAN blends filled with CNTs: Relationship between melt‐mixing parameters, filler dispersion, and filler aspect ratio

“…These depend on the nanofiller localization and reduced coalescence. In the few cases discussed in literature, a refinement of blend morphology was found …”