Systematic Optimization of Conductive PA6/Carbon Black Nanocomposites Through Integrated Rheological–Electrical Characterization and Melt Spinning Analysis

Abstract This study investigates the development of electrically conductive polyamide 6 (PA6) composite filaments incorporating carbon black (CB) for smart textile applications. The effects of CB content (5–10 wt%) and processing parameters on electrical, rheological, and mechanical properties were systematically evaluated. While bulk composites achieved percolation at ~ 2.5 wt% CB, fiber formation required higher loadings to maintain conductivity due to processing-induced network disruption. Rheological analysis revealed that increasing CB content enhanced shear-thinning behavior, with viscosity ranging from 10 2 Pa s (5 wt% CB) to 10 4 Pa s (10 wt% CB). Processing parameters significantly influenced CB distribution and network formation, particularly winding speed (up to 250 m/min) and throughput (0.80–0.95 cm 3 /min). The 7.5 wt% CB composition emerged as optimal, providing sufficient conductivity while maintaining acceptable processability. This systematic correlation between rheological behavior and electrical performance establishes fundamental design principles for conductive polymer fiber production with tunable properties. These findings provide a comprehensive framework for developing conductive PA6/CB filaments with tunable properties for smart textile applications and scalable industrial production.