Vibration Sensing Systems Based on Poly(Vinylidene Fluoride) and Microwave-Assisted Synthesized ZnO Star-Like Particles with Controllable Structural and Physical Properties

Abstract

This study deals with the effect of zinc oxide (ZnO) star-like filler addition to the poly(vinylidene fluoride) (PVDF) matrix, and its effect on the structural and physical properties and consequences to the vibration sensing performance. Microwave-assisted synthesis in open vessel setup was optimized for the preparation of the star-like shape of ZnO crystalline particles. The crystalline and star-like structure was confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDX). Furthermore, the PVDF-based composites were prepared using a spin-coating technique from solution. An investigation of the transformation of the α crystalline phase to the β crystalline phase of the neat PVDF matrix and with various filler concentrations was performed using Fourier-Transform infrared (FTIR) spectroscopy, which shows an enhanced β-phase from 44.1% to 66.4% for neat PVDF and PVDF with 10 wt.% of particles, respectively. Differential scanning calorimetry (DSC) measurements and investigation showed enhanced crystallinity and melting enthalpy of the composite systems in comparison to neat PVDF, since ZnO star-like particles act as nucleating agents. The impact of the filler content on the physical properties, such as thermal and dynamic mechanical properties, which are critical for the intended applications, were investigated as well, and showed that fabricated composites exhibit enhanced thermal stability. Because of its dynamic mechanical properties, the composites can still be utilized as flexible sensors. Finally, the vibration sensing capability was systematically investigated, and it was shown that the addition of ZnO star-like filler enhanced the value of the thickness mode d33 piezoelectric constant from 16.3 pC/N to 29.2 pC/N for neat PVDF and PVDF with 10 wt.% of ZnO star-like particles.

Comparative Study of PVDF Sheets and Their Sensitivity to Mechanical Vibrations: The Role of Dimensions, Molecular Weight, Stretching and Poling

“…The data were collected in the wavenumber range from 4000 to 500 cm −1 . Moreover, the β-phase content, F(β), was calculated according to the following Equation (1) as also shown elsewhere [ 20 , 23 ]: where A α and A β are the absorbance values corresponding to the wavenumber of 762 cm −1 and 840 cm −1 , respectively. The κ α and κ β are the absorption coefficients for the α-crystalline phase and β-crystalline phase, having values of 6.1 × 10 4 cm 2 mol −1 and 7.7 × 10 4 cm 2 mol −1 , respectively.…”

“…The piezoelectricity of this material is not intrinsic; however, it can be induced by various modifications such as stretching [ 16 ], poling [ 17 ] or acombination of both [ 18 ]. In addition, there are various processing techniques to transform the initial α-phase to its electro-active β-phase analogue, such as the addition of particles [ 19 , 20 ], electrospinning [ 21 , 22 ] or melt-electrowriting [ 23 ]. There were several studies performed, not specifically on the PVDF, but also on the composite systems which independently and in various conditions showed the piezoelectric activity of the films with various molecular weights: low [ 24 ], medium [ 25 , 26 ] and high [ 27 ].…”

CONTROLLABLE MODIFICATION OF THE BaTiO3 NANOPARTICLES USING SI-ATRP APPROACH AND IMPACT ON THE VIBRATION SENSING CAPABILITIES OF THEIR PVDF-BASED COMPOSITES

“…The dielectric spectroscopy in temperature range from -150 °C to 100 °C and in range from 10-1 to 107 Hz was employed to investigate the polymer chains dynamics. Investigation of the d33 coefficient to prove the vibration sensing capabilities was performed in the similar way as was published elsewhere [19].…”

PVDF/PVDF-TrFE BLENDS LOADED WITH BATIO3: From processing to performance testing

“…The samples were pressed using a single-point bar; the applied mass equaled 400 grams and frequency of its oscillation was set to 1 Hz. The output signal was collected using NI-4331 resistance substitution box (National Instruments, USA) and the final d33 coefficients were calculated according to the equations described elsewhere [4,10].…”

“…For this purpose, piezoelectric materials are well-suited since they spontaneously polarize when subjected to a mechanical stress [1,3]. Although the energy nanogenerators based on various inorganic materials (BaTiO3, ZnO, InN, GaN, CdS) or ceramics (NaNbO3, KNbO3) have shown high piezoelectric coefficients, they are brittle, heavy and difficult to process [4]. These drawbacks can be eliminated/reduced by using ferroelectric polymers, mainly poly(vinylidene fluoride) (PVDF) and its copolymers with trifluoroethylene (PVDF-TrFE) [5] or hexafluoropropylene (PVDF-HFP) [6].…”