Dispersion, migration, and 'network-like' structure formation of multiwall carbon nanotubes in co-continuous, binary immiscible blends of polyamide 6 and acrylonitrile-butadiene-styrene copolymer during simultaneous melt-mixing

Multiwall carbon nanotubes (MWNTs) were melt-mixed in polyamide 6 (PA6) and acrylonitrile-butadiene-styrene (ABS) copolymer blends using a simultaneous mixing protocol in order to investigate the state of dispersion of MWNTs in PA6/ABS blends. The blend composition was varied from 40/60 (wt/wt) to 60/40 (wt/wt) in PA6/ABS blends, which showed 'co-continuous' morphology in the presence of MWNTs. State of dispersion of MWNTs in these blends was assessed through bulk electrical conductivity measurements, morphological analysis, solution experiments, and UV-vis spectroscopic analysis. MWNTs were subsequently modified with a novel organic modifier, sodium salt of 6-aminohexanoic acid (Na-AHA), to improve the state of dispersion of MWNTs. Blends with unmodified MWNTs exhibited the DC electrical conductivity in the range [~10.sup.-11] to [~10.sup.-5] S/cm, whereas blends with Na-AHA-modified MWNTs exhibited DC electrical conductivity in the range [~10.sup.-7] to [~10.sup.-5] S/cm. The reduction in MWNTs 'agglomerate' size (~73.7 µm for 40/ 60 blend with unmodified MWNTs to ~59.9 µm in the corresponding blend with Na-AHA-modified MWNTs) was observed through morphological analysis. The rheological studies showed increased complex viscosity and storage moduli in lower frequency region in case of blends with Na-AHA-modified MWNTs confirming a refined 'network-like' structure of MWNTs.
INTRODUCTION Polymer blends are of immense commercial interest as high-performance alloys, due to their excellent properties, which can be suited for applications where materials with high thermal stability, good chemical [...]