Poly Vinylidene Fluoride Composites Research Articles

Designing of the green γ-AlOOH@Naringin thin film composite PVDF based nanofiltration membrane and application for pharmaceutical wastewater treatment

Herein, the green naringin functionalized boehmite (γ-AlOOH@Nar) bionanocomposite was used to fabricate the high-performance thin film composite (TFC) polyvinylidene fluoride (PVDF) based nanofiltration (NF) membrane with enhanced antifouling properties and pharmaceutical rejection. For this aim, the PVDF NF membrane was first activated by triazinyl groups. Then the membrane surface was subsequently functionalized by the γ-AlOOH@Nar nanocomposite at different concentrations (0.2, 0.4, and 0.6 wt%). The γ-AlOOH@Nar TFC NF membranes were characterized by means of Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscope (AFM), zeta potential, and thermogravimetric analysis (TGA). Moreover, the mean pore radius, porosity, surface hydrophilicity, salt rejection, pure water flux, and antifouling properties of the membranes were investigated. The 0.4 wt% γ-AlOOH@Nar TFC (TFC-0.4) membrane showed a pure water flux of 53.6 L/m2h and FRR of 95.4%, which were about 2.3 and 2.4 times that of the blank membrane. The TFC-0.4 membrane not only provided the highest permeability and surface hydrophilicity but also lowered the irreversible fouling ratio while keeping high pharmaceuticals rejection (99.8% for both Ceftriaxone (CTX) and cephalexin (CEX)). The pharmaceutical wastewater filtration showed that the γ-AlOOH@Nar TFC membranes achieved high normalized flux and also provided 89.8% COD removal, 100% turbidity removal, and moderate TDS removal (53.0%). Overall, the γ-AlOOH@Nar TFC membranes exhibited high separation performance and excellent antifouling properties showing their great potential for use in pharmacutical wastewater treatment facilities.

On PVDF composite as partially absorbable smart implants.

For various orthopedic needs, several studies have been testified on non-absorbable implants, prepared with different metals/alloys, and composites. But yet little has been stated on the partially absorbable smart implants of thermoplastic composites for online health monitoring of veterinary patients. This article highlights the in-house development of affordable, polyvinylidene fluoride (PVDF) composite-based partially absorbable smart implants (with online sensing capability) for orthopedic needs in canines. Hydroxyapatite (HAp) and chitosan (CS) nanoparticles were reinforced in the PVDF matrix by a melt processing route with various weight proportions (wt.%) to fabricate a partially absorbable smart implant for the canine. The study suggests that the 8.0 wt.% HAp and 2.0 wt.% CS in PVDF is the superlative composition/proportion of reinforcement for preparing feedstock stock filaments (for 3D printing of partially absorbable smart implants), based on rheological, mechanical, thermal, dielectric, and voltage-current-resistance (V-I-R) characteristics. For the selected composition/proportion of PVDF composite, acceptable mechanical properties (such as modulus of toughness (MoT) 2.0 MPa, Young's modulus (E) 889 MPa), and dielectric properties (dielectric constant (εr) 9.6 at room temperature (30°C) and 20 MHz) for online sensing capabilities (for health monitoring) was observed. The results are braced by attenuated total reflection Fourier transform infrared (ATR-FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) analysis.

Synthesis of functionalized ZnO nanoflake loaded polyvinylidene fluoride composites with enhanced energy storage properties

AbstractPolymer composite films are ideal materials for advanced energy storage capacitor in electrical systems. Therefore herein, we fabricated a novel series of polyvinylidene fluoride (PVDF) based composites embedded with well dispersed ZnO@APTES {surface modified zinc oxide with (3‐Aminopropyl) triethoxysilane (APTES)} nanoflake (0, 20, 30, 40, 50) vol% through solution casting method. Hydrothermally synthesized two‐dimensional ZnO was pre‐treated with H2O2 and surface modified with APTES for perfect distribution of nanoflake into PVDF matrix. Surface modification and high aspect ratio morphology of ZnO@APTES enhanced the interfacial interaction between organic PVDF and inorganic ZnO through reduction in heterogeneity between them. Surface functionalization reduced the dielectric loss and improved the overall energy storage performance. Investigation of electrical properties proclaimed incorporating 30 Vol% ZnO@APTES in PVDF as optimized loading due to its appreciable Wrec (recoverable energy density) about 3.2 J/cm3. Relative comparison of the energy storage density (Wrec) of PVDF/ZnO@APTES (30) vol% with recent published works established its enhanced capacitive response and its future application in energy storing portable device.

Additively Manufactured Micro‐ and Nano‐ Al/PVDF Ignition Sensitivity and Burning Characterization

AbstractAluminum (Al) and polyvinylidene fluoride (PVDF) composites can be used in many unique applications in the field of energetic materials. Due to their low melting point, many PVDF composites can be additively manufactured. However, more research is needed to better understand the ignition and combustion of these materials. Manipulating the size of aluminum (Al) particles in Al/PVDF composites can drastically alter the burning rate, ignition characteristics, and possibly flame temperatures. This study characterizes the ignition of additively manufactured micro‐ and nano‐ Al/PVDF composites through hotwire ignition tests. Both nAl and μAl particles were mixed in PVDF at 20 wt.% and additively manufactured into disks via fused filament fabrication. The nAl/PVDF printed disks ignited at a minimum ignition power (MIP) of 4.1 W compared to the 9.5 W required for ignition of μAl/PVDF disks. At identical powers, ignition delays were significantly shorter for nAl/PVDF disks. Additionally, while the nAl/PVDF disks reacted instantaneously at any power above their MIP, the μAl/PVDF disks exhibited smaller, localized flames before complete combustion, if the power was below 17.5 W. Flame temperatures were estimated through three‐color pyrometry and compared to thermochemical equilibrium calculations. While theoretical flame temperatures for nAl/PVDF and μAl/PVDF are 2023 K and 2314 K respectively, both samples burned near 2000 K when measured using pyrometry.

Enhanced piezoelectric response in BTO NWs-PVDF composite through tuning of polar phase content

We have fabricated a flexible, environment friendly piezoelectric nanogenerator (PENG) based on the ferroelectric Polyvinylidene fluoride (PVDF) composite incorporated with Barium titanate (BaTiO3) nanowires (NWs) of piezoelectric coefficient d 33 = 308 pm V−1. The single-layered PENG can deliver output power density of 10 μW cm−2 and an output voltage of 2 V with a nominal mechanical load of 1 kPa. BaTiO3 (BTO) NWs of different concentrations were incorporated into PVDF to tune the polar phase content, internal resistance, and optimize the output power. We show that there exists a critical value of BTO NWs loading of 15 wt%, beyond which the piezoelectric energy harvesting characteristics of the PVDF nanocomposites decrease. The oxygen vacancies present in the BTO NWs surface attract the fluorine ions of PVDF chain and favour the formation of β phase. The enhanced value of dielectric constant and dielectric loss of BTO-PVDF samples in the low frequency region suggest strong interfacial polarization in the composite system. The fabricated PENG can charge a super-capacitor up to 4 V within 35 s. The origin of the high power output from the BTO (15 wt%)-PVDF composite is attributed to the combined effect of enhanced polar phase content, strong interfacial polarization, and reduced internal resistance. This study provides an effective pathway in enhancing the performance of BTO-PVDF based piezoelectric energy harvesters.

Enhancing Thermal Conductivity of Polyvinylidene Fluoride Composites by Carbon Fiber: Length Effect of the Filler.

Thermally conductive polyvinylidene fluoride (PVDF) composites were prepared by incorporating carbon fibers (CFs) with different lengths (286.6 ± 7.1 and 150.0 ± 2.3 µm) via cold pressing, followed by sintering. The length effects of the CF on the thermal conductivity, polymer crystallization behaviors, and mechanical properties of the PVDF composites were studied. The through-plane thermal conductivity of the PVDF composites increased significantly with the rise in CF loadings. The highest thermal conductivity of 2.89 W/(m∙K) was achieved for the PVDF composites containing 40 wt.% shorter CFs, ~17 times higher than that of the pure PVDF (~0.17 W/(m∙K)). The shorter CFs had more pronounced thermal conductive enhancement effects than the original longer CFs at higher filler loadings. CFs increased the storage modulus and the glass transition temperature of the PVDF. This work provides a new way to develop thermally conductive, mechanically, and chemically stable polymer composites by introducing CFs with different lengths.

Nano-Sized Calcium Copper Titanate for the Fabrication of High Dielectric Constant Functional Ceramic-Polymer Composites.

A novel calcium copper titanate (CaCu3Ti4O12)–polyvinylidene fluoride composite (CCTO@PVDF) with Cu-deficiency was successfully prepared through the molten salt-assisted method. The morphology and structure of polymer composites uniformly incorporated with CCTO nanocrystals were characterized. At the same volume fraction, the CCTOs with Cu-deficiency displayed higher dielectric constants than those without post-treatment. A relatively high dielectric constant of 939 was obtained at 64% vol% CCTO@PVDF content, 78 times that of pure PVDF. The high dielectric constants of these composites were attributed to the homogeneous dispersion and interfacial polarization of the CCTO into the PVDF matrix. These composites also have prospective applications in high-frequency regions (106 Hz). The enhancement of the dielectric constant was predicted in several theoretical models, among which the EMT and Yamada models agreed well with the experimental results, indicating the excellent distribution in the polymer matrix.

3D printed innovative customized solution for regulating weathering effect on heritage structures

• 3D printed solution with acceptable corrosion resistance towards chemical weathering faced by heritage structures. • Effect of acid rain on 3D printed customized innovative strips of PVDF composite. • Innovative PVDF composite based smart strips for crack repair. In the recent past, some studies have been reported on applications of 3D printing processes as an innovative and cost-effective solution for the maintenance and repair of heritage structures. But hitherto little has been reported on ascertaining the weathering effect (acid rain) on such heritage structures revamped as 3D printed customized solutions. This study highlights the effect of H 2 CO 3 on 3D printed customized innovative strips with alternate layers of conducting (polyvinylidene fluoride (PVDF)-6%graphene-3%Mn-doped-ZnO) and non-conducting (PVDF-6%CaCO 3 ) composites engineered for controlled self-expansion and contraction (SEC). Based on the acceptable SEC features of the innovative 3D printed strip (as 4D characteristics), the composite structure was tested for corrosion resistance to mimic the acid rain environment. The results obtained for composite structure based on the Tafel exploration outlined that the proposed 3D printed solution possesses acceptable corrosion resistance (2.84 × 10 -7 mm/y) towards chemical weathering faced by heritage structures.

Novel high dielectric polymer composites with BaTiO3 co-doped by Nb2O5 and Co3O4

BaTiO3 (BT) and BaTiO3 modified with Nb2O5 and Co3O4 (BT@NC) were used as fillers and polyvinylidene fluoride (PVDF) as matrix to prepare BT/PVDF composites and BT@NC/PVDF composites, respectively. Microstructure, phase composition, dielectric properties and breakdown strength were investigated. 50 vol% BT@NC/PVDF composite exhibits high dielectric constant of 70.2 (at 104 Hz) and low dielectric loss of 0.02. It also possesses energy storage density of 0.7 J/cm3 at 47.2 kV/mm, which is 123.2 % higher than that of 50 vol% BT/PVDF composite. Therefore, modification of BT can be a good approach to increase dielectric response and enhance energy storage of BT@NC/PVDF composites.

Multi-material printing of PVDF composites: A customized solution for maintenance of heritage structures

In the past three decades, 3D printing technologies have emerged as a convenient tool for the repair and maintenance of heritage structures. But hitherto little has been reported on multi-material 3D printed composites with 4D properties for the repair and maintenance of heritage structures. The present study reports the investigations on multi-material 3D printing of conducting and non-conducting polyvinylidene fluoride (PVDF) composite layers with self-actuating and self-healing properties to repair non-structural cracks in heritage buildings. The non-conducting (PVDF-CaCO3) and conducting (PVDF-graphene-Mn doped ZnO) composites were 3D printed and tested for electrostriction-based strain measurement for 4D analysis. The thermo-mechanical properties of the composite solution were obtained from dynamic mechanical analysis (DMA). The electrical, bonding, and morphological properties were investigated by current-voltage (I-V), x-ray diffraction (XRD), Fourier transformed infrared (FTIR), and scanning electron microscopy (SEM)-energy dispersive spectroscopy (EDS) analysis. Results of the self-elongation and contraction by electrostriction in PVDF composite demonstrate the feasibility of 3D printing technology as a novel tool to fabricate cost-effective smart solutions for the repair and maintenance of heritage structures.

One-step fabrication of highly sensitive pressure sensor by all FDM printing

A highly sensitive pressure sensor with a sandwich structure is developed through one-step fabrication with a double nozzle FDM printer. Multiwalled carbon nanotubes (MWCNTs) and ionic liquid (IL) are introduced into polyvinylidene fluoride (PVDF) to obtain high β phase composites (named PIM), which serves as piezoelectric layer, and a conductive PVDF composites is used as electrode materials. Post-processing steps are not required because of the strong adhesion between the above layers. The 4-layer PIM sensor exhibits a high sensitivity (2.65 V kPa−1) and excellent long-term stability (10000 cycles), which is further successfully applied in gait recognition.

Fabrications and dielectric performances of novel composites: Calcium copper titanate / Polyvinylidene fluoride

CCTO (Calcium copper titanate) powder as inorganic filler was synthesized by the Sol-gel method firstly. CCTO/PVDF (Polyvinylidene fluoride) composite was fabricated by solution mixing based on high temperature resistance of PVDF and insulated property of CCTO. The composite of CCTO/PVDF were characterized by X-ray diffraction, Fourier Transform infrared spectroscopy, Scanning Electron Microscope and impedance analysis. The results showed that the addition of CCTO and increasing in its content did not affect the phase- and micro-structure of the composites,but the increase of CCTO content can induce the generation of C–F new bonds. PVDF/CCTO composites were enhanced in performance of thermal and frequency-depended stability with increasing in the fraction of CCTO. The dielectric constant of CCTO/PVDF composite materials with 50% CCTO achieved to a maximum value of 50 almost, which is 5 times higher the pure PVDF. The conductivity felled into 10−8 to 10−1 S m−1 during the frequency of 102–108 Hz. The composite material would be expected to be applied in the field of integrated circuit.

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.