EAGER/Collaborative Research: Experimental Verification of Piezoelectric Augmentation of Strength and Toughness in Polymer Fiber Bundles

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With this EArly-concept Grant for Exploratory Research (EAGER) the feasibility of an anticipated enhancement of mechanical properties for piezoelectric polymeric bundles of nanofibers will be explored. Piezoelectric materials are responsive materials that generate mechanical stress in response to an applied electric field (or vice versa). The premise for the concept is that electrostatic interactions can enhance load transfer between piezoelectric fibers in a yarn, thereby potentially increasing the strength and toughness of the yarn. This finding could impact applications in aerospace and automotive industries where fiber-reinforced composites are used for their high strength and light weight features. This research effort will serve as a platform to train the future workforce for STEM fields with focus on nanotechnology and materials engineering. The objective of this research is to experimentally demonstrate the magnitude of internal long-range electrostatic interactions between deformation-induced piezoelectric charges toward enhancing the mechanical properties of fibrous synthetic yarns. The planned approach is based on the premise that the electrostatic interactions between piezoelectrically-induced charges in hierarchical structures can considerably enhance load-transfer between fibers of the yarn. The piezoelectric enhancement of mechanical properties is potentially significant, and may impact the design of high performance structural materials through systematic engineering of piezoelectric behavior. This research is inspired by toughness mechanisms in bone and potential role of piezoelectric effect of collagen fibrils in bone's remarkable mechanical properties. As such, demonstration of piezoelectric augmentation of mechanical properties in a synthetic material may provide new insight into mechanics of natural materials. Toward the goal, polymeric (polyvinylidene fluoride) piezoelectric membranes and yarns will be fabricated via electrospinning process and poled via electromechanical treatment. The piezoelectric properties of the nanofibers and the mechanical properties of the yarns will be measured as a function of poling conditions.