Poly Vinylidene Fluoride Composites Research Articles

The effect of core-shell BaTiO3@SiO2 on the mechanical and dielectric properties of PVDF composites

ABSTRACT In this study, polymer composite films were prepared by the solution casting method using ceramic filler barium titanate (BT) to enhance the mechanical and dielectric properties of polyvinylidene fluoride (PVDF). A silicon dioxide (SiO2) shell was coated on BT surface by hydrolysis reaction of tetraethyl orthosilicate (TEOS) at different concentrations in order to provide a strong interface between PVDF and BT. The influence of SiO2 coating on morphology, structure, thermal, tensile and dielectric properties of composites were investigated compared to neat PVDF. The results of analyses show that SiO2 is successfully coated on BT and that the ceramic filler enhances the tensile and dielectric properties of the composites. At low BT concentrations (5 and 10 vol.%) the tensile strength and Young modulus are improved compared to neat PVDF. For films having a high content of SiO2, in particular, coated BT high values, such as 24.8 at 102 Hz are found for the dielectric constant, which is greatly improved by almost 2.3 times compared to neat PVDF. Properties, such as flexibility and thermal stability, are well retained in the prepared composites.

Design and durability of PZT/PVDF composites based on pavement perception

Highway pavement perception devices made from conventional piezoelectric materials are unsuitable for use in a complex road traffic environment because they lack durability. In this study, the design and durability performance of piezoelectric materials based on pavement perception were assessed. First, lead zirconate titanate (PZT)/polyvinylidene fluoride (PVDF) composites with various volume ratios were prepared with PZT and PVDF as raw materials. Then, their piezoelectric and dielectric properties were tested, and the change mechanism of electrical properties of the materials was analysed by examining their crystal structures. Their compressive and flexural strengths were tested, and the change mechanism of mechanical properties was analysed with the use of a scanning electron microscope. The optimal volume ratio of the PZT/PVDF composite was determined by combining test results with the stress characteristics of a pavement structure. Finally, PZT/PVDF composites with the best volume ratio were used to prepare piezoelectric perception devices. The devices were placed in an asphalt mixture, and the output of their perception signals was tested by simulating vehicle loads. The results show that with an increase in PZT content, the dielectric property of the composite piezoelectric material first increased and then decreased, the piezoelectric property gradually increased, and the compressive and flexural strengths both gradually decreased. The comprehensive properties of PZT/PVDF composites with a PZT volume ratio of 50% were superior; after 150,000 repeated loads, the perception signal output was stable, and the sensor had good durability.

α–β Phase transition induced by self-assembly process of BaTiO3 aggregates in polyvinylidene fluoride composites

Polyvinylidene fluoride (PVDF) exhibits favorable piezoelectric properties for energy storage applications. However, their application has been hindered owing to their low dielectric constant. To overcome this, studies have reported the incorporation of BaTiO3 fillers to induce a phase transition in PVDF to a piezoelectric phase, i.e., the β phase. In this study, the effect of self-assembled BaTiO3 filler aggregates on the α–β phase transition of BaTiO3/PVDF composites was investigated. Through scanning electron microscopy and Fourier transform infrared spectroscopy, we observed that the α–β phase transition of the composites increased as the average secondary particle area of the BaTiO3 aggregates increased. This suggested that dielectric polarization exhibited by the presence of filler/polymer/filler heterointerfaces in the aggregates was significant in the α–β phase transition of the composites.

All-organic non-aqueous redox flow batteries with advanced composite polymer-ceramic Li-conductive membrane

Composite membranes based on polyvinylidene fluoride (PVdF) binder and Li1.4Al0.4Ge0.2Ti1.4(PO4)3 (LAGTP) ceramic filler as prospective solid electrolytes for non-aqueous redox flow batteries were investigated. Membrane fabrication details and thorough material characterization is provided to show improved performance. Studied membranes possess high Li-ion conductivity of (2.7 ± 0.6)•10−4 S cm−1, uniform microstructure, and excellent stability towards acetonitrile. Moreover, a new redox flow battery configuration is demonstrated with designed composite membranes in all-organic non-aqueous redox flow batteries. For the comparison, commercial Neosepta AHA anion-exchange membranes were evaluated. Triarylamine-based catholyte and viologen-based anolyte materials, which were recently designed in our laboratory, were used as redox couples. The comparison revealed lower resistance, but faster crossover of composite PVdF + LAGTP membrane (permeability rates < 10-5 cm2 min-1); still, this is considered as acceptable for application in flow batteries. H-cells assembled with novel composite membrane exhibit Coulombic efficiency of over 97% and high charge-discharge cycling stability: after the initial 15 cycles, the capacity stabilized at 37 mA h L−1 corresponding to 70% utilization of active materials. The membrane proposed exhibits a beneficial combination of functional characteristics that allows considering it as a credible alternative to the contemporary available polymeric commercial membranes for all-organic redox flow batteries.

Composite PVDF ultrafiltration membrane tailored by sandwich-like GO@UiO-66 nanoparticles for breaking the trade-off between permeability and selectivity

It remains a great challenge to design and prepare polymeric membranes with excellent permeability while maintaining high rejection and better antifouling. However, emerging materials that are capable of minimizing membrane fouling and breaking the trade-off between permeability and selectivity are urgently needed. In this study, by combining UiO-66 with graphene oxide (GO) nanosheets, sandwich-like [email protected] was assembled using the solvothermal process, which was later blended with the bulk polyvinylidene fluoride (PVDF) membrane to produce nanocomposite membranes (NCMs) via non-solvent induce phase separation method. With the incorporation of only 1.0 w.t% [email protected] nanocomposites, the water flux of NCM reached 263.3 Lm-2h−1 from 142.8 Lm-2h−1 and BSA rejection ratio improved to 93.0% from 68.0% compared to the original PVDF membrane, respectively. Meanwhile, [email protected] NCM displayed impressive antifouling features with an 81.8 % water flux recovery ratio (FRR), which is significantly higher than that of pure PVDF membranes (51.4 %). Sandwich-like [email protected] nanomaterials increase membrane porosity and open the water molecular permeability channel. At the same time, higher-hydrophilic performance of NCM resulted from more hydrophilic functional groups of the [email protected] exposure and PVDF phase transformation from α-to-β contributed to the formation of a dense hydration layer on the surface of the membrane and Zeta potential on membrane surface decreased, thus improving organic interception and alleviating membrane fouling. Furthermore, NCMs enhance membrane mechanical strength and chemical stability. Overall results suggest that the inclusion of sandwich-like [email protected] is a competent modification technique that significantly improves membrane performance and has a great potential for practical application.

Comparison and characterization of polyacrylonitrile, polyvinylidene fluoride, and polyvinyl chloride composites functionalized with ferric hydroxide for removing arsenic from water

At present, common methods for preparing adsorbents for arsenic removal include electrospinning, tape-casting, and the powder method, but there is still a lack of research on the differences in the adsorption properties of arsenic-removal adsorbents prepared by these three methods. In this study, nine composite adsorbents were prepared by electrospinning, tape-casting, and the powder method with ferric hydroxide as the dopant, and their properties were examined. Scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction confirmed the existence of ferric hydroxide on the surfaces and insides of the composite adsorbents. Differential scanning calorimetry and mechanical performance tests showed that the addition of FeOOH changed the thermal and mechanical properties of the adsorbents. The arsenic(III) adsorption capacity of each composite adsorbent was also determined as well as the effects of pH and temperature. The results showed that polyacrylonitrile/ferric hydroxide (fiber) had the highest arsenic(III) adsorption capacity (11.31 mg/g) under the baseline conditions. When the pH was adjusted to approximately 9, the maximum adsorption capacity increased to 12.41 mg/g. When the control temperature was 15 °C, the maximum adsorption capacity was 12.07 mg/g. After three adsorption cycles, the arsenic(III) removal rate of each composite membrane reached 90%. Overall, the electrospun membranes had the highest adsorption efficiencies among the three types of adsorbents with respect to arsenic removal, and polyacrylonitrile proved to be the best base material. In comparison, polyvinylidene fluoride proved more suitable for tape-casting films and powder adsorbents. • The adsorption properties of different composite adsorbents for arsenic (As) were evaluated. • Compared the performance of three polymers and methods in the adsorption of As(III). • The effects of pH and temperature on the adsorption properties were assessed. • PAN and electrospun membranes achieved the best absorption performance.

Study of CNT Intercalated Bi2O3/PVDF Composite for Super Capacitors Applications

AbstractCarbon nanotube (CNT) intercalated‐bismuth oxide (CNT‐Bi2O3)/polyvinylidenefluoride (PVDF) composites are synthesized via sonication and roasting process. The phase structure, bonding, and morphology of CNT‐Bi2O3/PVDF composite are characterized using X‐ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), and scanning electron microscopy (SEM). The capacitance and dielectric constant of the composite electrodes are studied by impedance analyzer. The capacitance and stability of CNT‐Bi2O3/PVDF composite are found to be increased on increasing concentration of Bi2O3 in PVDF composite. These results show that CNT‐Bi2O3/PVDF composite is a very promising electrode material for high‐performance super capacitors.

Improved dielectric properties of PVDF polymer composites filled with Ag nanomaterial deposited reduced graphene oxide (rGO) hybrid particles

We report a method to improve the dielectric constant (ε′) of polyvinylidene fluoride (PVDF) composites by using a low content of Ag nanomaterials deposited reduced Graphene Oxide (rGO) Hybrid Particles (Ag-rGO HPs). The Ag-rGO HPs are prepared by a reaction between silver nitrate and ethylene glycol in a seed-mediated growing process. The dispersion of Ag nanomaterials was completely homogeneous on the surface of rGO nanosheets with particle sizes of 5.765 ± 0.189 nm. The Ag-rGO HPs/PVDF composites were produced by a liquid–phase assisted dispersion and hot-pressing methods. The high ε′ at 103 Hz for Ag-rGO/PVDF composites with fAg-rGO 7.8, and 11.9 vol% was 153 and 683, respectively. The best-fitting curve was completely achieved in percolation theory by adjusting fc = 14 vol%. The high ε′ (683 at 1 kHz) of Ag-rGO/PVDF could be explained by Maxwell Wagnare Sillars interfacial polarization and micro-capacitor due to the formation of a sandwich between Ag-rGO and PVDF.

Enhanced dielectric and piezoelectric properties in potassium sodium niobate/polyvinylidene fluoride composites using nano-silicon carbide as an additive

Piezoelectric materials are an indispensable part of modern life. Yet the existing environmental issues with conventional lead-based piezoelectrics has motivated scientist to develop novel substitutes including lead-free piezoelectric polymer composites. Following this path, the present research has focused on the fabrication of ternary composites of Polyvinylidene fluoride (PVDF)/Potassium Sodium Niobate (KNN)/nano-Silicon carbide (SiC) via hot compression molding and studying the effect of additives on the PVDF structure and the electrical properties of the composite. The obtained scanning electron micrographs and density measurements showed that the fabrication method provided dense samples. The activated polarization phenomena in the prepared samples enhanced dielectric permittivity and dielectric loss at a constant frequency with increasing KNN and SiC contents. Besides the expected dipole polarization, the presence of interfaces in the composites gave rise to the Maxwell–Wagner–Sillars effect and its corresponding polarization phenomenon. The semiconductive nature of SiC also promoted space charge polarization. However, these properties were frequency-dependent because the first two polarization mechanisms are deactivated at high frequencies. XRD patterns showed that SiC addition can alter the primary crystalline structure of PVDF and promote β-phase formation in the poled samples. Piezoelectric measurements confirmed the significant role of SiC addition to PVDF-KNN composites. The most significant increase in the piezoelectric properties was observed in PVDF-60KNN-1SiC, with a 183% increase in d33 value. The PVDF-80KNN-1SiC had the highest d33 value of 30.5 pC/N. It also had the best piezoelectric voltage coefficient and hence the highest figure of merit. Higher SiC contents restrict the efficiency of poling by forming a conductive path across the sample which would deteriorate the piezoelectric performance of the material. The present findings show that PVDF-KNN-SiC composites can be considered as a potential flexible piezoelectric material for future applications.

Construction of a Three-Dimensional BaTiO3 Network for Enhanced Permittivity and Energy Storage of PVDF Composites.

Three-dimensional BaTiO3 (3D BT)/polyvinylidene fluoride (PVDF) composite dielectrics were fabricated by inversely introducing PVDF solution into a continuous 3D BT network, which was simply constructed via the sol-gel method using a cleanroom wiper as a template. The effect of the 3D BT microstructure and content on the dielectric and energy storage properties of the composites were explored. The results showed that 3D BT with a well-connected continuous network and moderate grain sizes could be easily obtained by calcining a barium source containing a wiper template at 1100 °C for 3 h. The as-fabricated 3D BT/PVDF composites with 21.1 wt% content of 3D BT (3DBT–2) exhibited the best comprehensive dielectric and energy storage performances. An enhanced dielectric constant of 25.3 at 100 Hz, which was 2.8 times higher than that of pure PVDF and 1.4 times superior to the conventional nano–BT/PVDF 25 wt% system, was achieved in addition with a low dielectric loss of 0.057 and a moderate dielectric breakdown strength of 73.8 kV·mm−1. In addition, the composite of 3DBT–2 exhibited the highest discharge energy density of 1.6 × 10−3 J·cm−3 under 3 kV·mm−1, which was nearly 4.5 times higher than that of neat PVDF.

Effect of BaTiO3 nanowire on effective permittivity of the PVDF composites

With the increasing application of barium titanate (BaTiO3) in polyvinylidene fluoride (PVDF), the evaluation of its dielectric properties has attracted the attention of many frontier scholars. In this paper, from the theoretical point of view, the effects of the aspect ratio and the concentrations of BaTiO3 nanowires on macroscopic dielectric properties were studied by the finite element method. Depending on the calculation results, some conclusions had been obtained: First, it was found that the effect of higher aspect ratios of nanowires on the effective permittivity of the composites was not significant when the aspect ratio of the nanowire filler exceeded 20. Second, when the permittivity of the BaTiO3 nanowires reaches about 3000, as the permittivity of the filler increases, the rate of change of the effective permittivity of the composite material gradually slows down, which indicates that nanowires with higher permittivity have little influence on the effective permittivity of the composites. Finally, by comparing with permittivity data of BT/PVDF composites in the literature, it was found that the simulation results have good consistency with the experimentally measured values. The above-mentioned results have shown that the composite may exhibit good dielectric properties at a low concentration (&amp;lt;30 vol. %) and low permittivity filler. Moreover, the electrostatic field can roughly represent the electric field of a low-concentration composite under a certain electric field strength.

Three-dimensional composite electrospun nanofibrous membrane by multi-jet electrospinning with sheath gas for high-efficiency antibiosis air filtration

Three-dimensional (3D) composite polyvinylidene fluoride (PVDF)/polyacrylonitrile (PAN) electrospun nanofibrous membranes combining both thick and thin nanofibers have been fabricated by the method of multi-jet electrospinning with sheath gas to realize high-efficiency air filtration under a low pressure drop. The thin PAN nanofibers form a dense membrane, with a strong capturing ability on the ultra-fine particles, while the thick PVDF nanofibers play a 3D supporting effect on the thin PAN nanofibers. In this case, the combination results in a fluffy membrane with higher porosity, which could achieve the airflow passing through the membrane without the air pressure drop. The effects of the composite manner of thick nanofibers and thin nanofibers are investigated, in order to optimize the air filtration performance of the 3D composite nanofibrous membrane. As a result, the maximum quality factor for air filtration could reach up to 0.398 Pa−1. The particle-fiber interaction model was used to simulate the air filtration process as well, and the simulation results were fairly consistent with the experimental results, providing a guidance method for the optimization of composite nanofibrous membrane for high-efficiency air filtration. More interestingly, a cationic poly[2-(N,N-dimethyl amino) ethyl methacrylate] (PDMAEMA) was added in the PVDF solution to obtain a composite air filtration membrane with excellent antibiosis performance, which achieved the highest inhibition rate of approximately 90%. In short, this work provides an effective way to promote antibiosis air filtration performance by using an electrospun nanofibrous membrane, and might also effectively accelerate the biological protection application of current air filtration membranes.

Electrospinning parameters evaluation of PVDF-ZnO/Ag2CO3/Ag2O composite nanofiber affect on porosity by using response surface methodology

The electrospinning process is a very important technique for fabricating polymeric nanofibers by applying external electrostatic forces. This study reports on the modeling of the electrospinning process of polyvinylidene fluoride (PVDF) and the immobilized ZnO/Ag2CO3/Ag2O using response surface methodology (RSM) based on the central composite design (CCD). The individual and interaction effects of the most effective variables, such as applied voltage (6.5, 8 and 9.5 kV), nozzle-collector distance (10, 12.5 and 15 cm) and ZnO/Ag2CO3/Ag2O photocatalyst concentration (0.1, 0.8 and 1.5 g), have been evaluated on the porosity response of the nanofiber. The analysis of variance (ANOVA) confirmed that the spinning voltage was the main variable affecting the average porosity of the composite PVDF nanofiber. The regression coefficient between the variables and the mean porosity (R2 = 0.8321) indicates acceptable evaluation of experimental data by quadratic polynomial regression.

Fabrication and Piezoelectric Properties of Polyvinylidene Fluoride Composites with High β Phase

Fabrication and Piezoelectric Properties of Polyvinylidene Fluoride Composites with High β Phase

Preparation of a ferroelectric composite film metal–organic framework/PVDF

With increasing of the intellectualized electronics devices, new kinds of flexible ferroelectric polymer materials with high dielectric constant attracted more and more attention in recent decades. Polyvinylidene fluoride (PVDF), as one of the most studied ferroelectric polymer materials, has been studied in many published works. Among these works, lots of efforts have been employed to promote the generation of β crystal phase. We here introduced a concise and effective way for large-scale fabrication of promising ferroelectric polymer films by doping a metal–organic framework (MOF) particles via costing process. Then effects of the addition of MOF on the ferroelectric, dielectric and mechanical properties of PVDF composite film were systematic researched. By comparing the results of XRD and FTIR, we found that the addition of MOF changed the α crystal phase of PVDF to β crystal phase which helped improve the ferroelectric and dielectric properties of PVDF composites. The new PVDF composite film, with very low addition (5wt.%) of MOF, possessed the highest remanent polarization (22μC/cm2 at 80MV/m and 1 Hz electric field), and the highest dielectric constant (21 at 10 Hz). The data of mechanical properties indicated that the fine dispersion of MOF maintained the flexibility of PVDF.

Triboelectric Energy Harvesting Response of Different Polymer-Based Materials.

Energy harvesting systems for low-power devices are increasingly being a requirement within the context of the Internet of Things and, in particular, for self-powered sensors in remote or inaccessible locations. Triboelectric nanogenerators are a suitable approach for harvesting environmental mechanical energy otherwise wasted in nature. This work reports on the evaluation of the output power of different polymer and polymer composites, by using the triboelectric contact-separation systems (10 N of force followed by 5 cm of separation per cycle). Different materials were used as positive (Mica, polyamide (PA66) and styrene/ethylene-butadiene/styrene (SEBS)) and negative (polyvinylidene fluoride (PVDF), polyurethane (PU), polypropylene (PP) and Kapton) charge materials. The obtained output power ranges from 0.2 to 5.9 mW, depending on the pair of materials, for an active area of 46.4 cm2. The highest response was obtained for Mica with PVDF composites with 30 wt.% of barium titanate (BT) and PA66 with PU pairs. A simple application has been developed based on vertical contact-separation mode, able to power up light emission diodes (LEDs) with around 30 cycles to charge a capacitor. Further, the capacitor can be charged in one triboelectric cycle if an area of 0.14 m2 is used.

Welding dopamine modified graphene nanosheets onto graphene foam for high thermal conductive composites

Developing thermal management materials with high thermal conductivity (TC) is critical to the microelectronics. Herein, we fabricated high thermal conductive polyvinylidene fluoride (PVDF) composites by using graphene foam (GF) and dopamine modified graphene nanoplatelets (mGNPs) as fillers. The results indicated that mGNPs could weld onto the GF skeleton to repair the structural defects of GF, which is conducive to improving the composite's TC by forming efficient thermal conductive pathways in the matrix. The obtained GF/mGNPs/PVDF composite (GF: 0.27 vol%, mGNPs: 8.82 vol%) exhibited an in-plane TC of 6.32 W m−1 K−1, which was much higher than that of GF/GNPs/PVDF composite (4.26 W m−1 K−1) at the same GF and GNPs contents. The GF/mGNPs/PVDF composites also possessed excellent dimensional stability and mechanical property. The study revealed that welding mGNPs onto GF is an effective method to fabricate high thermal conductive composites.

Fabrication and Characterization of Composite Membranes for the Concentration of Lithium Containing Solutions Using Forward Osmosis

AbstractIn this study, an energy and highly time efficient, cost effective, and scalable forward osmosis (FO) composite polyvinylidene fluoride (PVDF) membrane is developed to concentrate lithium chloride recovered from naturally occurring geothermal brine resources. Dense thin robust defect‐free Kynar‐PVDF membranes are fabricated on porous PVDF hollow fiber supports. Various membrane fabrication parameters such as membrane thickness, coating solution concentration, cross‐linker concentration, and curing temperature are studied to develop a defect‐free dense membrane. Advanced characterization tools such as FIB‐SEM, Raman, FTIR spectroscopy, and XRD are used to study the surface and cross‐sectional morphology, chemistry of crosslinking, crystallinity and chemical structure of the dense PVDF membrane. FO is utilized to concentrate LiCl in the solution from 36 to 175 g L−1 with an average water transfer rate of 0.450 L m−2 h−1 (LMH) at 85 °C. Furthermore, the membrane showed stable performance for more than 550 h while maintaining the purity of the concentrated lithium chloride solution of &gt;99.99 wt%. The results suggest that the FO‐based technology is an innovative, time and energy efficient approach compared to the conventional technologies for concentration of battery grade LiCl for application in lithium ion batteries and other clean energy technologies.

Synthesis and comprehensive study of polyvinylidene fluoride–nickel oxide–barium titanate (PVDF–NiO–BaTiO3) hybrid nanocomposite films for enhancement of the electroactive beta phase

This study includes the successful fabrication of polyvinylidene fluoride (PVDF) based hybrid nanocomposite films loaded with nickel oxide (NiO) and barium titanate (BaTiO3) fillers via simple sol–gel casting techniques to optimize the crystallinity and β-phase formation for various sensor applications. A systematic study has been performed to assess the effect of fillers (NiO and BaTiO3) on the crystal structure, morphology and electrical conduction properties of PVDF–NiO–BaTiO3 hybrid nanocomposite films using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) using energy dispersive spectroscopy and current–voltage (I–V) measurement techniques. XRD and FTIR results indicate that the incorporation of nanostructured fillers NiO and BaTiO3 leads to the formation of long stabilized planar zigzag and all-trans conformation (TTTT) inducing the growth of electroactive β-phase and crystallinity. XRD results show that the degree of crystallinity reaches a maximum value of 85% for incorporation of 2.5 wt% of NiO and 27.5 wt% of BaTiO3. FTIR results show 85% of electroactive β-phase growth achieved by incorporating 7.5 wt% of NiO and 22.5 wt% of BaTiO3. FESEM micrographs of hybrid films show that both NiO and BaTiO3 particles are well dispersed within the PVDF pattern with the porous surface resulting in enhanced electrical conductivity. Current–voltage (I–V) measurement shows the charge transport process in PVDF composites loaded with NiO and BaTiO3 fillers is mainly governed by Richardson Schottky emission. The significant increase in the electrical conductivity of PVDF–NiO–BaTiO3 hybrid nanocomposite opens a new window for possible use in miniaturization of electronics and energy harvesting devices.

Dual functionalized Janus structural PVDF nanocomposite with surface-modified dielectric and magnetic nanoparticles

Optimizing the combination of dielectric and magnetic properties has become an important issue for electrical and electronic devices. Compared to single-function materials, multifunctional materials have the advantages of increasing device response speed, reducing costs, and increasing stability while reducing the device size. In this work, Janus structure polyvinylidene fluoride (PVDF) composites filled with barium titanate (BT) and cobalt ferrite (CFO), respectively, were prepared by electrospinning and hot pressing techniques. The Janus structural composites (J-type) have higher magnetic and dielectric properties than the conventional blended fibrous composites (H-type). When the PVDF matrix was replaced by polystyrene, the effect of Janus structure on dielectric and magnetic properties was even more pronounced. An optimum dielectric constant up to 25.1 and a saturation magnetization of 7.12 emu/g were obtained, which can be attributed to the modification and Janus structure of m-BT/PVDF+m-CFO/PVDF multifunctional composite materials.