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

有了这个探索性研究的早期概念拨款（EAGER），预期增强纳米纤维压电聚合物束机械性能的可行性将被探索。压电材料是一种响应材料，它对外加电场产生机械应力（反之亦然）。该概念的前提是静电相互作用可以增强纱线中压电纤维之间的负载传递，从而潜在地增加纱线的强度和韧性。这一发现可能会影响航空航天和汽车行业的应用，在这些行业中，纤维增强复合材料具有高强度和轻重量的特点。这项研究工作将作为培训未来STEM领域的劳动力的平台，重点是纳米技术和材料工程。本研究的目的是通过实验证明变形引起的压电电荷之间的内部远程静电相互作用对增强纤维合成纱的机械性能的影响程度。计划的方法是基于这样一个前提，即在分层结构中压电感应电荷之间的静电相互作用可以大大增强纱线纤维之间的负载传递。压电对机械性能的增强具有潜在的重要意义，并可能通过压电行为的系统工程影响高性能结构材料的设计。骨的韧性机制和胶原原纤维的压电效应在骨的显著力学性能中的潜在作用激发了本研究的灵感。因此，在合成材料中证明压电增强机械性能可能为自然材料的力学提供新的见解。为此，聚合（聚偏氟乙烯）压电膜和纱线将通过静电纺丝工艺制备，并通过机电处理极化。测试了纳米纤维的压电性能和纱线的力学性能随拉伸条件的变化。

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.