2, Mechanical Engineering, Rowan University, Glassboro, New Jersey, United States
3, Physics, Rowan University, Glassboro, New Jersey, United States
The current surge in wearable electronics has initiated a need for alternative energy sources. Energy harvesters that employ piezoelectric materials are capable of harnessing the mechanical energy from muscular contractions to power portable devices. The present study examined the properties of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) nanofibers fabricated from conventional electrospinning, and an automated track collector system that contains a post-drawing component. The polymer solution was originally processed by means of the traditional technique, flat-plate electrospinning, which produced a fiber arrangement with random orientations. When carrying out mechano-electrical testing and analysis these fibers yielded negligible voltage. The solution was subsequently processed employing a post-drawing electrospinning procedure, exclusive to our research laboratory, that permitted fiber alignment and individual nanofiber post-drawing immediately upon collection, prior to total solvent evaporation. Fibers that endured post-drawing displayed an increase in crystal alignment in the direction of the fiber axis (verified by polarized FTIR), and resulted in higher voltages than undrawn fibers and fibers from the traditional electrospinning method. It was examined that fibers produced by means of the post-drawing technique, with varying draw ratios (DR=Final length/Initial length) including DR-2 and DR-3, exhibited improved piezoelectric characteristics. Mechanical properties of the nanofibers were also enhanced as a result of post-drawing . This investigation suggests that the post-drawing practice results in PVDF-HFP nanofibers that are more suitable for piezoelectric applications than conventionally electrospun nanofibers.