Optimizing Rheological and Viscoelastic Behavior in Polypropylene–Carbon Nanotube Nanocomposites via Melt Processing: Insights Into Percolation, Shear-Thinning, and Network Formation

Abstract

This study investigates the enhancement of rheological and viscoelastic properties in polypropylene (PP) composites through multiwalled carbon nanotube (MWCNT) reinforcement, with a focus on achieving a low percolation threshold. The composites were fabricated via optimized melt mixing and extrusion processes to promote uniform CNT dispersion. A percolation threshold of approximately 2 wt% CNT was identified, beyond which the storage modulus (G') increased by over 200% compared to neat PP, indicating the formation of a robust, continuous carbon nanotube (CNT) network that effectively reinforces the polymer matrix. Furthermore, the composites exhibited a pronounced transition to solid-like behavior, as evidenced by a significant reduction in the damping factor (tan δ), reflecting restricted polymer chain mobility due to the CNT network. Compared to prior studies, the lower percolation threshold achieved highlights the critical role of processing optimization in enhancing dispersion and property performance at minimal filler content. The resulting PP/CNT composites combine mechanical reinforcement, strong shear-thinning behavior, and improved processability, making them promising candidates for high-performance applications in the automotive, aerospace, packaging, and electronics industries. Future work will focus on scaling up production, evaluating long-term durability, and exploring hybrid nanofiller strategies to further advance composite functionality.