Electrical and Rheological Behavior of Melt-Spun Polyamide 6 via Synergistic SWCNT/Carbon Black Networks

Abstract

Melt-spun electrically conductive polymer fibers often face trade-offs among conductivity, mechanical strength, and processability. This study introduces a synergistic SWCNT/carbon black (CB) hybrid strategy where spherical CB particles appear to maintain connectivity within aligned SWCNT networks. PA6 composites with optimized ratios (PA6/1% SWCNT/3% CB) were systematically characterized for electrical, rheological, thermal, and processing behavior. Percolation thresholds (?c, SWCNT ? 0.1–0.25 wt.%, ?c, CB ? 2–2.5 wt.%) confirmed the superior efficiency of SWCNTs in network formation. The hybrid system maintained resistivity of ?102–104 ?·cm despite drawing (DDR 2–4), while single-filler SWCNT systems failed (>109 ?·cm). Complex viscosity (?1400 Pa·s at 270°C) remained within processable ranges despite elevated values, exhibiting stable shear-thinning behavior. Mechanical properties showed tenacity of 4–6 cN/dtex with 100%–150% elongation. These structure-property relationships demonstrate the potential of hybrid nanofiller systems for producing conductive filaments suitable for smart textile applications, positioning hybrid SWCNT/CB systems as promising candidates for scalable smart textile manufacturing. © 2026 The Author(s). Macromolecular Materials and Engineering published by Wiley-VCH GmbH.