Specific Interactions and Reactive Coupling Induced Dispersion of Multiwall Carbon Nanotubes in Co continuous Polyamide6/Ionomer Blends

Summary: An efficient strategy to achieve electrical conductivity in melt‐mixed co‐continuous blends is to restrict the conducting filler in a particular phase in the blends next to forming a percolated ‘network‐like’ structure in that particular phase. However, strong inter‐tube van der Waals' forces often lead to the aggregated structure leading to higher percolation threshold. In addition, the migration of the conducting filler during melt‐mixing and the blending sequence significantly affect the bulk conductivity of the blends. SEM observation showed fine co‐continuous structures associated with 50/50 blends of PA6/Surlyn with multiwall carbon nanotubes (MWNT). MWNT were localized in the vicinity of the ionic domains in the ionomer corresponding to a specific blending sequence when unmodified MWNT were used, however, in presence of Na‐salt of 6‐amino hexanoic acid (Na‐AHA) modified MWNT, selective clustering was not observed may be due to the confinement of MWNT in the PA6 phase. To understand these complexities the electrical conductivity of melt‐mixed blends of polyamide6/ionomer with MWNT was studied. However, it was observed that the blends with even 3 wt% unmodified MWNT showed insulating behaviour irrespective of the blending sequence adopted. In addition, the key role of a reactive modifier (Na‐AHA) in facilitating uniform dispersion and subsequent ‘network‐like’ formation by establishing specific interactions with MWNT was studied. It was found that the MWNT are selectively localized in the PA6 phase in the NA‐AHA modified blends manifesting in higher electrical conductivity (∼10 −5 S/cm at 3 wt% MWNT) when using a specific blending sequence, due to melt‐interfacial reaction between the ∼NH 2 functionality of Na‐AHA and the ∼COOH end groups of PA6. FTIR and Raman spectroscopic analysis also supported the existence of the specific interactions.