13 Feb 2026

Morphology-Driven Electromagnetic Shielding Performance of Graphitic Nanoparticles in Segregated Polypropylene Nanocomposites via Electromagnetic Melt Processing

Abstract: Electromagnetic melt-processing has emerged as an innovative and energy-efficient strategy for the structuring of thermoplastic nanocomposites. In this study, polypropylene (PP)-based TPNCs were fabricated using different grades of graphitic carbon nanoparticles to yield electrical conductivity and electromagnetic interference shielding effectiveness. The applied structuring methodology consists of a multiscale processing strategy that combines high-energy ball milling of polymer micro-pellets and CNPs, formulated powder compaction into green bodies, and EM-driven localized heating to produce the TPNCs. This enables the formation of highly segregated, percolated conductive networks at ultra-low filler loadings. The percolation threshold values for green bodies were significantly dependent on CNP morphology, ranging from approximately 0.50 wt% for low-aspect-ratio graphene nanoplatelets to around 1.0 wt% for medium-aspect-ratio carbon nanotubes. Upon EM melt-processing, due to viscoelastic deformation of CNP networks, the resulting threshold values of the structured TPNCs were approximately 0.73 wt%, 0.50 wt%, and 0.74 wt% for low, medium, and high aspect ratios, respectively. High-aspect-ratio CNTs, despite exhibiting greater structural defects, achieved the highest EMI SE of 19.7 dB/mm at 10 wt%, demonstrating that morphology dominates over graphitic crystallinity in governing transport properties and electromagnetic performance. Statistical modeling via response surface methodology confirmed the predictive significance of the CNP morphology and the concentration responses. This work underscores the critical influence of filler architecture and EM-induced structuring in enabling a novel, scalable platform for multifunctional polymer nanocomposites with enhanced electromagnetic shielding capabilities, offering promise for next-generation aerospace, electronics, automotive, and defense applications.