Investigation of β phase formation in piezoelectric response of electrospun polyvinylidene fluoride nanofibers: LiCl additive and increasing fibers tension

Abstract

As a piezoelectric polymer, poly (vinylidene fluoride) (PVDF) is attractive in energy conversion applications between electrical and mechanical forms because of its low cost, high flexibility, and biocompatibility. The piezoelectricity of electrospun PVDF polymer is due to changes in the crystalline structure (e.g., creating the β‐phase) during the electrospinning process. This research focuses on two approaches for investigation of β Phase formation: (1) addition of LiCl in different concentrations (0.001, 0.00133, 0.002, 0.004 wt%) as inorganic salt to the polymer solution, (2) increasing tension along the fiber axis by increasing the collector drum speed during the aligning process. Performances of these structures were evaluated by using X‐ray diffraction (XRD), Fourier Transform Infrared (FTIR), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). A one‐step nano‐generator and cost‐effective package based on electrospun nanofibers was presented to measure output voltages as a performance factor. Results show that the addition of LiCl leads to β Phase formation in the crystalline structure, decreasing fiber diameter to 65 nm, and increment in the work of rupture and piezoelectric output. Moreover, the results show that increasing collector drum speed causes the alignment of β‐crystallites along the fiber axis and subsequently no considerable effect on the formation of β‐phases and output voltage. POLYM. ENG. SCI., 56:61–70, 2016. © 2015 Society of Plastics Engineers

Multiscale-structuring of polyvinylidene fluoride for energy harvesting: the impact of molecular-, micro- and macro-structure

“…Additives can aid the electrospinning process, and also improve the piezoelectric performance of the composites bers. The presence of inorganic salt LiCl of 0.00133 wt% in PVDF DMF/acetone (4/6) solution in 16 wt% concentration, 211 decreased the ber diameter from 340 nm to 65 nm due to the increased charge carried by the jet, and increased the b-phase formation to 93.6%. The voltage response of PVDF was increased from 1.89 V to 8 V for composite bers with 0.00133 wt% of LiCl, which is of interest for harvesting.…”

Electrospinning Piezoelectric Fibers for Biocompatible Devices

“…[213][214][215][216][217][218][219] It has indeed been demonstrated that aligned PVDF nanofiber arrays possess superior piezoelectric properties compared to random nanofibers meshes. [220][221][222][223] Hence, a very promising research topic is how the molecular configuration of piezoelectric polymers and their polymorphic states relate to the nanofiber geometry and how piezoelectric properties can be induced by electrospinning.…”

Enhancement of β‐Phase Crystalline Structure and Piezoelectric Properties of Flexible PVDF/Ionic Liquid Surfactant Composite Nanofibers for Potential Application in Sensing and Self‐Powering

“…It should be noted that the fiber diameter is a factor that has an influence on the piezo‐response of fabricated samples as it was investigated before. Within the context of the efficacy of nanofiber's diameter on the piezoelectric response of PVDF nanofibers, Mokhtari et al [ 26 ] applied two approaches to achieve more content of the β crystalline phase and higher output voltage. In both of those methods, the addition of different concentrations of LiCl salt and applying tension on fiber by high‐speed drum collector, the smaller nanofibers were obtained that enhanced the piezo‐response.…”

“…To evaluate the potential of the prepared nanofibers for sensor and energy harvesting applications, the direct piezoelectric properties were characterized under the pressure mode using dropping ball test as described by Mokhtari et al [ 26 ] First, the samples were placed on a rectangular metal plane. To apply a uniform force on the external surface of the sensor, and also exploit all the exterior parts of the sensor for the voltage creation and avoid from any damage due to successive impacts, a squared plate with the dimension of 2 × 2 cm 2 was used on the samples.…”