Advanced Branched Carbon Nanotube/Carbon Black Hybrid Technologies: Cost-Effective Fabrication of High-Performance Conductive Polyamide 6 Filaments for Next-Generation Smart Textile Applications

Abstract

Smart textiles require conductive polymer filaments that balance electrical performance with industrial processability. This study presents a hybrid nanofiller approach combining branched carbon nanotubes (bCNTs) and carbon black (CB) in polyamide 6 (PA6), enabling scalable melt spinning of high-performance conductive filaments. Comparative analysis of PA6/bCNT, PA6/CB, and PA6/bCNT/CB systems established structure-property-processing relationships essential for smart textile applications. Rheological characterization reveals that the hybrid system merges the strong conductive network of bCNTs with the improved spinnability provided by CB, ensuring industrial-scale processability. The optimized PA6/3 wt.% bCNT/3 wt.% CB composite achieved low resistivity (approximate to 50 Omegacm) while maintaining stable spinning at winding speeds up to 1000 m min-1. A structural evolution model is proposed, showing how CB particles act as bridging agents between aligned bCNTs, stabilizing conductive pathways under high draw ratios. Complementary microscopy, thermal, and mechanical analyses validated this mechanism and confirmed the balance of conductivity, thermal stability, and mechanical performance. By integrating material design, process optimization, and functional validation, this work overcomes key barriers limiting commercial conductive filaments. The developed hybrid technology offers cost-effective, scalable solutions for next-generation smart textiles in wearable electronics, strain sensing, and electromagnetic shielding.