Compatibilized polylactide/polyamide 11 blends containing multiwall carbon nanotubes: Morphology, rheology, electrical and mechanical properties

The effect of adding multiwall carbon nanotubes (CNTs) on the morphology and properties of reactively compatibilized polylactide/polyamide 11 (PLA/PA11) blends with a 75/25 wt% composition was evaluated. The PLA/PA11 blends were compatibilized using an epoxy-based chain extender. The blends and nanocomposites were prepared using an internal mixer. The effects of the chain extender concentration, mixing strategy, PLA molecular weight and CNT concentration on the morphology were evaluated in light of rheological, electrical and mechanical characterization. Upon pre-mixing CNTs with PLA the morphology of the dispersed phase evolved to connected non-spherical, non-coalescing PA11 domains bridged by CNTs at the interface. A network-like structure was formed in the nanocomposites containing 2–3 wt% of nanoparticles characterized by a transition from liquid-to solid-like behavior. The electrical conductivity remained in the insulating range, largely due to inadequate interconnectivity of PA11-CNT domains. The nanocomposites based on the lower molecular weight PLA displayed larger relative increase of the electrical conductivity and Young modulus, compared to the neat blend, indicative of a better CNT dispersion and formation of a more interconnected PA11-CNT network.