Effect of PA6 / PA12 Composition on the Multifunctional Behavior of PA / MWCNT Nanocomposite Films

Abstract

This study investigates the impact of PA6/PA12 ratio on the multifunctional properties of nanocomposite films based on polyamide blends and multi-walled carbon nanotubes (MWCNTs). Blends of PA6/PA12 were prepared in various weight ratios (25/75, 50/50, and 75/25) with and without 3.5 wt.% of MWCNTs (this value being the electrical percolation threshold for the 75/25 blend according to a previous investigation). Morphological analysis revealed that MWCNTs could have acted as compatibilizing agents, altering the nanocomposites´ morphology. Thermal characterization showed that MWCNTs preferentially interact with PA6, changing its crystallization behavior across all blend ratios. Rheological studies demonstrated different viscoelastic properties in nanocomposites, with a transition to more solid-like behavior at higher frequencies, indicating the formation of a MWCNT network structure. Mechanical testing revealed a trade-off between strength and ductility upon MWCNT incorporation. Young´s modulus and tensile strength generally improved, while strain at break decreased, particularly for blends with higher PA6 content. Fracture toughness, measured by Jmax showed a decreasing trend with MWCNT addition. The 50/50 PA6/PA12 blend exhibited unique behavior, displaying both ductile and semi-ductile responses in tensile and fracture tests. Electrical conductivity measurements confirmed the functional behavior of the nanocomposites, with values in the semiconductor range. These findings provide insights into the complex interplay between blend composition, MWCNT incorporation, and resulting material properties, offering potential for tailoring nanocomposites for specific applications.