Multiple Necking Coalescence in Graphene and Graphene Oxide Reinforced Electrospun PVDF Partially Hollow Nanocomposite Fibers with Superplastic Behavior

This research examines the mechanical properties of poly-vinylidene fluoride (PVDF) nanocomposite fibers produced via electrospinning and reinforced with graphene (G) and graphene oxide (GO). Using a fork-shaped copper target, individual fibers were collected and characterization through nanotensile testing. The incorporation of 0.5 wt% of GO enhanced Young's modulus by 20% and yield strength by 47%, while reducing strain at failure and toughness by 43% and 9%. No reinforcement was observed with unfunctionalized graphene. An analogy is drawn between the fibers' microscale and multiple necking observed in macroscopic polypropylene drinking straws. Their shared geometrical slenderness enables energy dissipation through stable, localized necking. Electrospun PVDF fibers reached 400% strain at break and 85 J/g toughness, comparable to the properties of straws. Based on this analogy, a new constitutive model is proposed to predict the stress-strain response of electrospun fibers, supporting their integration into engineered products such as textile, ropes, and ballistic materials.