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Polyvinylidene fluoride (PVDF)/[(Ba0.85Ca0.15)0.995Sm0.005](Ti0.9Hf0.1)O3 (BCTH-0.005Sm3+) composite films with different BCTH-0.005Sm3+ filling amount were prepared via hydrothermal method and solution tape scraping process. The effects of BCTH:0.005Sm3+ filling amount were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectrum (FTIR), ultraviolet-visible (UV-vis) transmission spectrum and photoluminescence spectrum. XRD confirms appropriate amount filling of BCTH:0.005Sm3+ promoting formation of β-phase, and FTIR reveals coupling between PVDF matrix and BCTH:0.005Sm3+ filler in the composite films. BCTH:0.005Sm3+ nanopowder filling increases optical transmittance, widens visible light region, and induces redshift of maximum absorption of pure PVDF. Emission intensity and fluorescence lifetime increase first and then decrease with increasing BCTH:0.005Sm3+ filling amount, and one-photon assisted down-conversion process dominates fluorescence emission in the PVDF/BCTH:0.005Sm3+ composite films. Overall, filling 2 wt% BCTH:0.005Sm3+ nanopowder is more helpful to improve comprehensive performance of the composite films, broadening prospect application in electrical and optical multifunctional fields. [ABSTRACT FROM AUTHOR]

In defense and military applications, the growing use of radar technology necessitated the development of effective stealth solutions for military equipment like drones and fighter jets. This paper explored a new approach that glass fiber mat coated with various concentrations of grapheme embedded polyvinylidene fluoride (PVDF) nanofibers using electrospinning technique and stacked the Graphene/PVDF/Glass fiber mat layers by epoxy resin and hardener to form the glass fiber laminate composite by hand layup technique to enhance the electromagnetic wave absorption. These research findings demonstrated that composite materials were more successful than metals at absorbing electromagnetic waves. The tailored composite showed above 80% increase in electromagnetic absorption over conventional metal in the X-band (8–12 GHz), although having a minimum thickness of 3 mm. According to X-ray diffraction, PVDF/Graphene nanofibers had improved electroactive β-phase behavior when compared to pure PVDF nanofibers. The PVDF/graphene nanofibers which have an average diameter of 80–160 nm, were seen using scanning electron microscopy. The tailored composites also had simple configuration and mechanical characteristics that were improved when compared to plain glass fiber laminate composite. In comparison to all other configurations, experimental findings showed that the composite with 0.5 wt% Gp/PVDF had a wide band absorption of above 90% in all the frequencies. This innovative method of fabrication of the tailored Gp/PVDF nanofibers coated glass fiber laminate composite provided a promising strategy in the manufacture of military equipment and stealth fighters. [ABSTRACT FROM AUTHOR]

To investigate the damage characteristics of spacecraft structures caused by external impacts and propose protective measures, this study utilizes two-stage light gas gun launcher with detonation capability. Hypervelocity impact experiments are conducted on composite laminates that incorporate varying proportions of shear stiffening gel (SSG). Polyvinylidene fluoride (PVDF) sensors are employed to collect response signals from the front corners, rear corners, and rear edges of the laminate, enabling an assessment of its behavior under impact conditions. By analyzing the signals acquired from the Polyvinylidene fluoride sensor, the study obtains the time-frequency response characteristics of the signals at various positions with different proportions of shear stiffening gel. The correlation between these response characteristics and the damage of the laminate is investigated. The analysis reveals that the vibration response at various positions of the laminate provides a comprehensive indication of internal delamination and surface damage. Moreover, this response is linked to the level of fragmentation of the projectile. The incorporation of shear stiffening gel in the laminate enhances its impact resistance and helps mitigate damage at the connection between the laminate and other components. Interestingly, the impact resistance does not follow a monotonic trend with respect to the proportion of shear stiffening gel. Based on the experimental results discussed in this article, the optimal proportion of shear stiffening gel is determined to be 5 %. • Impact experiments were conducted on laminates containing varying proportions of shear stiffening gel. • The addition of shear stiffening gel effectively suppresses vibrations within the specified range. • Following impact, the corners of the laminate experience more pronounced vibrations compared to the edges. • Excessive proportion of shear stiffening gel may alter the internal phase and interface morphology. [ABSTRACT FROM AUTHOR]

In the last two decades, several studies have been conducted for the process parametric optimization of fused filament fabrication (FFF) with a variety of thermoplastic composites, especially for mechanical properties. But hitherto less has been conveyed, on the development of dynamic reduced order models (ROMs) for digital twining (DT) of tensile properties (of 3D printed implants/scaffolds) with novel thermoplastic-based composites. In this study, for the generation of dynamic ROM (for hybrid analytics), the signal-to-noise (S/N) ratio was used to ascertain the best settings of parameters for tensile properties of polyvinylidene fluoride (PVDF) composite. The study suggests that the best setting of the FFF process, for the 3D printing of PVDF composite (90% PVDF, 8% hydroxyapatite (HAp), and 2% Chitosan (CS) (for maximizing the tensile properties as per ASTM-D638-Type-V) are nozzle temperature (NT) of 235°C, raster angle (RA) 45°, printing speed (PS) of 60 mm/s respectively resulting in peak load (PL) 394.87 N, peak stress (PSt) 33.92 MPa, Young's modulus (E) 2.606 MPa. For a modulus of toughness (MOT) of 0.484 MPa, the best settings are NT 230°C, RA 90°, and PS 50 mm/s. The results are supported by the morphological analysis. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) is one of the established thermoplastics with inherent piezoelectric characteristics. In the past two decades, a lot of work has been reported on the use of virgin Polyvinylidene fluoride thermoplastics for sensing applications. But hitherto little has been reported on 3D printing of secondary (2°) recycled Polyvinylidene fluoride as a smart energy storage device (ESD). This work is focused on exploring the possibilities for 3D printing of smart energy storage device comprising of Polyvinylidene fluoride having (melt flow index (MFI) 30 g /(10 min) as per ASTM D 1238) reinforced with MnO2, graphite, ZnCl2, and N H 4 Cl in different weight proportions to form a feedstock filament for fused deposition modeling (FDM) in the first stage. The MFI of Polyvinylidene fluoride composites reinforced with MnO2, graphite, ZnCl2, and N H 4 Cl (34.095, 8.480, 42.982, 11.807 g /(10 min) respectively) was ascertained for possible 3D printing on FDM. The results suggest that even with an acceptable MFI of prepared 2° recycled Polyvinylidene fluoride, the same was not printable. Further for possible 3D printing on FDM, low-density polyethylene (LDPE) was blended in a Polyvinylidene fluoride matrix, and successful 3D printing-based energy storage device was prepared in the second stage. The study also highlights the mechanical, and morphological properties of Polyvinylidene fluoride composites have been improved after processing with a twin-screw extruder (TSE) by using different input parameters (screw temperature (T), screw speed (S), and load (L)). Overall, the study suggests that the proportion of LDPE, MnO2, graphite, ZnCl2, and N H 4 Cl has a significant effect on the rheological, mechanical, and morphological properties. The results have been supported with scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Fourier-transformed infrared spectroscopy (FTIR) analysis. [ABSTRACT FROM AUTHOR]

• Phase field fracture model capable of finite deformation simulation for flexible piezoelectric. • The coupled governing equations are solved via SPSA and RCSA-EO strategies. • Can predict the fracture behavior of flexible piezoelectrics under electromechanical environments. Fracture failure is a major concern in mechanical engineering, particularly for piezoelectric materials. In contrast to other numerical methods, phase field method has significant advantages in addressing fracture progress. It can automatically track crack surfaces through ordered parameter evolution, which is versatile for modeling complex fracture behaviors. However, previous studies on phase field fracture in piezoelectric solids have primarily focused on brittle ceramics with small deformation. In recent years, flexible piezoelectrics with high stretchability have already been achieved in industrial production. These materials exhibit obvious nonlinear characteristics during deformation, which renders the traditional assumption of small deformations inadequate for predicting their fracture behaviors. In this work, we propose a finite deformation phase field fracture model for flexible piezoelectric materials, building upon the established nonlinear electromechanical material model. The numerical framework is carried out in the commercial software ABAQUS via a user element subroutine. Both single–pass staggered algorithm (SPSA) and residual-controlled staggered algorithm with even-odd iteration split (RCSA-EO) are employed to solve coupled electro-mechanical-phase field governing equations. The proposed model is validated through comparisons with analytical solutions and existing literature. Moreover, the developed numerical framework effectively explains the nonlinear fracture behavior observed in experiments conducted on Polyvinylidene fluoride (PVDF), a flexible piezoelectric material with a large failure strain. Numerical simulations are also performed to demonstrate the influence of the applied electric field on electromechanical fracture behavior. The results highlight that the specific impact of electric fields depends on material parameters, geometric parameters, and boundary conditions. The developed model is capable of making accurate and realistic predictions of fracture in flexible piezoelectric materials. This is particularly important for evaluating the reliability and safety of flexible piezoelectric devices. [ABSTRACT FROM AUTHOR]

Composite membranes based on a polymer mixture solution of quaternized polysulfone (PSFQ), cellulose acetate phthalate (CAP), and polyvinylidene fluoride (PVDF) for biomedical applications were successfully obtained through the electrospinning technique. To ensure the polysulfone membranes' functionality in targeted applications, the selection of electrospinning conditions was essential. Moreover, understanding the geometric characteristics and morphology of fibrous membranes is crucial in designing them to meet the performance standards necessary for future biomedical applications. Thus, the viscosity of the solutions used in the electrospinning process was determined, and the morphology of the electrospun membranes was examined using scanning electron microscopy (SEM). Investigations on the surfaces of electrospun membranes based on water vapor sorption data have demonstrated that their surface properties dictate their biological ability more than their specific surfaces. Furthermore, in order to understand the different macromolecular rearrangements of membrane structures caused by physical interactions between the polymeric chains as well as by the orientation of functional groups during the electrospinning process, Fourier transform infrared (FTIR) spectroscopy was used. The applicability of composite membranes in the biomedical field was established by bacterial adhesion testing on the surface of electrospun membranes using Escherichia coli and Staphylococcus aureus microorganisms. The biological experiments conducted establish a foundation for future applications of these membranes and validate their effectiveness in specific fields. [ABSTRACT FROM AUTHOR]

The quest for efficient and sustainable methods to mitigate carbon dioxide (CO2) emissions is a pressing global challenge. This study delves into the crucial role of polymers in tailoring the performance of titanium dioxide (TiO2) nanofibers for CO2 conversion reactions. By systematically comparing the influence of different polymers, specifically polyvinyl pyrrolidone (PVP) and polyvinylidene fluoride (PVDF), on the CO2 conversion activity of TiO2-NFs, we shed light on the remarkable potential of polymeric selection to fine-tune catalyst properties. The paper uses advanced experimental techniques to analyze the structural and morphological properties of PVP-TiO2-NFs and PVDF- TiO2-NFs demonstrating their various morphologies. The investigation involves SEM, XRD, BET, Raman, and UV-Vis spectroscopy to better understand the charge separation and recombination processes involved in both materials' CO2 conversion. The results show considerable differences, the choice of polymer significantly impacts the CO2 conversion performance of TiO2-NFs. PVP-based NFs exhibit enhanced surface area and porosity, resulting in superior catalytic activity, while PVDF-based NFs demonstrate remarkable stability. These findings pave the way for innovative approaches to tackle climate change and develop a more environmentally friendly future by advancing energy-efficient and long-lasting photocatalytic technology. [ABSTRACT FROM AUTHOR]

The modification of BT ceramic particles was achieved using hydrogen peroxide and vinyltriethoxysilane, resulting in the production of core–shell-structured nano-materials (VTS@BT). Upon initiation, moderately cross-linked XL-VTS@BT/PVDF composites were prepared by reacting them with modified polyvinylidene fluoride (MDPVDF). As the amount of VTS@BT increased, the dielectric constant of the composite material increased from 7.89 to 19.1, while the dielectric loss increased only slightly from 0.058 to 0.075. Furthermore, as the filling amount of VTS@BT increased, the grain size gradually increased, the nucleation rate decreased, and the addition of crosslinking agents caused a minor transformation of the β-crystalline phase to the α-crystalline phase. The moderate cross-linking improved the breakdown strength and energy storage density of the composite material, with a cross-linked structure composite material at 10wt% addition achieving an energy storage density of 10.36 J/cm3 at an electric field strength of 340MV/m, which was nearly a 57% increase in energy storage density compared to PVDF. [ABSTRACT FROM AUTHOR]

[Display omitted] The commercialization of lithium metal batteries (LMBs) is encountering significant challenges due to the electrolyte incompatibility and poor mechanical properties of polyolefin separators, as well as the hazardous growth of lithium dendrites at the anode. Simultaneously, the development of safe and environmentally-friendly separators has become a central focus in rechargeable battery technology. In this study, we introduce a novel Janus separator (CP@SiO 2), featuring a composite structure with cellulose paper (CP) as the base layer and electrospun polyvinylidene fluoride (PVDF) nanofibers as the top layer. The nanofibers are uniformly coated with mesoporous SiO 2 nanoparticles through hydrogen bonding. The CP@SiO 2 separator leverages its three-dimensional lithium-ion channels and rigid ceramic particles to enhance electrolyte retention and stabilize lithium metal anodes (LMA). Shielded by this separator, LMA exhibits an impressive cycling performance, enduring a current density of 2 mA cm−2 for 350 h without short-circuiting, effectively doubling the cycle life compared to conventional PP separators. Furthermore, the Li/LiFePO 4 cell utilizing the CP@SiO 2 separator demonstrates a high capacity of 101 mAh·g−1 at 5C, with 90 % capacity retention after 1000 cycles. This outstanding electrochemical performance is attributed to the compatible anode/separator interface and the effective inhibition of lithium dendrite growth. The research presented in this work capitalizes on a synergistic configuration design, offering a promising pathway towards the development of high-safety and advanced lithium-ion separators. [ABSTRACT FROM AUTHOR]

Poly(S-bioallethrin) (PSBA) was grafted onto the polyvinylidene fluoride (PVDF) molecular chain through a gamma-ray irradiation method to prepare the PVDF-g-PSBA membrane. Fourier transform infrared spectroscopy (FTIR) of different membranes confirmed the effective progress of the grafting reaction. The microstructure of the membrane before and after irradiation was analyzed by scanning electron microscope (SEM), illustrating that gamma-ray irradiation did not cause damage to the membrane structure. The original PVDF membrane and the modified PVDF-g-PSBA membrane were immersed in an Escherichia coli culture medium, and the antibacterial effects of membranes were tested, confirming the positive effect of the PVDF-g-PSBA membrane on inhibiting bacterial growth. This research could have market application value in terms of altering membrane materials and enhancing membrane performance. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) membranes were created utilizing the non-solvent-induced phase separation (NIPS) approach in this study, then gamma-ray irradiation was applied to form the PVDF-g-PMAM membrane. FTIR and XPS were used to examine the chemical structure of the membrane before and after irradiation. The DSC curves of membranes showed that grafting poly methylacrylamide (PMAM) caused a drop in the melting point of the modified PVDF-g-PMAM membrane. The SEM characterization showed that gamma-ray irradiation did not damage the microstructure of the membrane cross-section, and the distribution of micropores on the membrane surface was more dense and uniform. The insertion of hydrophilic PMAM greatly accelerates the initial contact angle and contact angle decline rate of the PVDF-g-PMAM membrane, illustrating that the membrane's hydrophilicity has been effectively improved. Finally, after testing of permeability and rejection of different membranes, the result demonstrated good anti-fouling performance. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Donghua University (English Edition) is the property of Journal of Donghua University Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polyvinylidene fluoride/graphene oxide (PVDF/GO) composite nanofibers were fabricated by electrospinning technology, to enhance the output performance of triboelectric nanogenerators (TENG) based on PVDF. These nanofibers were assembled into vertically contact-separate TENG to investigate the influence of GO mass fraction on the output performance of TENG. By utilizing the COMSOL software, the output performance of the TENG was simulated and analyzed, and the variations of electric potential and electric energy density at different electrode distances were observed. This study provides theoretical support for the working principle of TENG. Moreover, the morphology and structure of the PVDF/GO composite nanofibers were characterized using scanning electron microscopy, while the output performance of the TENG based on PVDF/GO composite nanofibers was characterized using a digital oscilloscope. The results indicate that the TENG based on PVDF/GO composite nanofibers exhibits excellent output efficiency when the GO mass fraction is 0.06%. The output voltage is approximately 350 V, and the short-circuit current is around 28 µA, and under impedance matching conditions, the maximum peak power is approximately 9.66 mW, with a power density of approximately 3.86 W/m². The TENG prepared by PVDF/GO composite nanofibers exhibits excellent output performance, capable of powering 120 LEDs, hereby demonstrating potential application prospects in the field of energy harvesting. [ABSTRACT FROM AUTHOR]

With the increasing demand for flexible piezoelectric sensor components, research on polyvinylidene fluoride (PVDF) based piezoelectric polymers is mounting up. However, the low dipole polarization and disordered polarization direction presented in PVDF hinder further improvement of piezoelectric properties. Here, we constructed an oriented tertiary structure, consisting of molecular chains, crystalline region, and MXene sheets, in MXene/PVDF nanocomposite via a temperature-pressure dual-field regulation method. The highly oriented PVDF molecular chains form approximately 90% of the β phase. In addition, the crystalline region structure with long-range orientation achieves out of plane polarization orientation. The parallel orientation arrangement of MXene effectively enhances the piezoelectric performances of the nanocomposite, and the current output of the device increases by nearly 23 times. This high output device is used to monitor exercise action, exploring the potential applications in wearable electronics. [ABSTRACT FROM AUTHOR]

In this research, the CuFeS2/MXene-modified polyvinylidene fluoride (PVDF) membrane was prepared to activate peroxymonosulfate (PMS) to remove moxifloxacin (MOX) and its morphology; surface functional groups and hydrophilicity were also studied. The parameters of the catalytic membrane/PMS system were optimized, with an optimal loading of 4 mg/cm2 and a PMS dosage of 0.20 mM. High filtration pressure, alkaline conditions, and impurities in water could inhibit MOX removal. After continuous filtration, the removal efficiency of MOX using the catalytic membrane/PMS system and PVDF membrane was 68.2% and 9.9%, respectively. Batch filtration could remove 87.8% MOX by the extra 10 min contact time between the catalytic membrane and solution. During the filtration process, CuFeS2/MXene on the surface of the catalytic membrane activated PMS to produce SO4•−, HO•, and 1O2, and MOX was removed through adsorption and degradation. Taking humic acid (HA) as the model foulant, reversible fouling resistance in the catalytic membrane/PMS system was 22.8% of the PVDF membrane. The catalytic membrane/PMS system weakened the formation of the cake layer by oxidizing HA into smaller pollutants and followed the intermediate blocking cake filtration model. The novelty of this research was to develop a CuFeS2/MXene–PVDF membrane-activated PMS system and explore its application in antibiotics removal. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) and its copolymers present extensive application prospects, especially in the field of wearable electronics. However, utilizing nanofillers for enhanced β‐phase and piezoelectric properties faces challenges like noncontinuous interfaces, poor compatibility between nanofillers and PVDF matrix, and the requirement of high‐voltage polarization, hindering extensive domain alignment on a large scale. Herein, a method is proposed to synthesize high‐performance PVDF composites by introducing hydroxylated barium titanate (H@BTO) nanoparticles and a directional freeze‐drying method to enhance β‐phase content and piezoelectric properties without polarization. Molecular dynamics simulations reveal robust binding interactions between Ba and F atoms along with OH surface terminations on H@BTO, facilitating hydrogen bonding within the PVDF matrix, resulting in dipole alignment and increased spontaneous polarization. The composite film achieves an 86.69% β phase content and a piezoelectric coefficient of ≈14.49 pm V−1 without electric polarization. The freeze‐drying PVDF‐H@BTO composite film paired with a PA6 membrane is used to fabricate triboelectric nanogenerator, demonstrating a current density of ≈107.5 mA m−2 and an output voltage of ≈832 V. Results demonstrate that the utilization of strong binding interactions between various atoms, the hydroxyl anchoring effect, and directional freeze‐drying method as a strategy holds promising prospects for synthesizing high‐performance piezoelectric composites. [ABSTRACT FROM AUTHOR]

Acrylated epoxidized soybean oil (AESO) is a soybean oil derivative recently utilized as a green raw material in biopolymer synthesis. However, its potential as a photo-polymerizable feedstock in multifunctional tissue engineering scaffolds remains underexplored. While AESO exhibits strong biocompatibility, its rapid biodegradation and limited mechanical properties constrain its biomedical applications. Here, we present antibacterial scaffolds using polyvinylidene fluoride (PVDF), AESO, curcumin, and graphene oxide (GO) with high potential for tissue engineering applications. Our results showed that the scaffolds possess a semi-crystalline structure and the presence of PVDF could effectively support the mechanical integrity of the AESO phase. Fabricated scaffolds presented Young's modulus, ultimate tensile strength, and elongation at break of 105–250 MPa, 8–10 MPa, and 17–25%, respectively, that could fulfill the requirements for supporting a range of stiff tissues. Curcumin-containing scaffolds demonstrated desirable antibacterial activity against both E. coli and S. aureus bacteria. As well the capacity of the PVDF/AESO matrix for drug release was studied. As expected, hydrophilicity and biodegradation rates were influenced noticeably by incorporating GO nanosheets. Finally, the fabricated scaffold showed in-vitro biocompatibility with desirable attachment and proliferation of MG-63 cells. Our findings indicate the potential of AESO for tissue engineering and regenerative medicine applications. The employing of AESO in this study inspires the investigation of other plant oils and their derivatives as resins for fabricating biomedical scaffolds. [ABSTRACT FROM AUTHOR]

This work reports the preparation and characterization of composite membranes with potential applications in flow battery devices. A polymer solution of polyvinylidene fluoride (PVDF), sulfonated polyether ether sulfone (SPEES), and polyether sulfone (PES) was used to prepare proton exchange membranes with low permeation of cationic species, which is a desirable feature in energy conversion devices, such as vanadium flow batteries (VRFB). Vanadyl ion (VO2+) acidic solution was selected as a model to reveal the permeation capacity through the membranes as an affordable alternative to the Nafion® 117 commercial membrane. The effects of the chemical composition and the thickness of the membranes on the morphology and proton exchange properties were evaluated. Characterization of the membranes was performed using physicochemical techniques including water uptake, swelling ratio, thermogravimetric analysis, scanning electron microscopy, Fourier transform infrared, surface charge density, atomic force microscopy, dynamic mechanical analysis, electrochemical impedance spectroscopy for proton conductivity, proton exchange rate, and the permeability of VO2+ ions. With VO2+ ion permeability of the order of 0.62 mM and H+ exchange rates of up to 498.5 × 1018 H+ cm−2*µm−1*min−1, the PVDF/PES/SPEES composite membranes emerge as an option with potential application for VRFB compared to the Nafion® 117 membrane, which presented a VO2+ ion permeation value of 2.72 mM and H+ exchange rates of 445.2 × 1018 H+ cm−2*µm−1*min−1. [ABSTRACT FROM AUTHOR]

Copyright of China Synthetic Fiber Industry is the property of Sinopec Baling Petrochemical Company and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Membrane distillation (MD) is a promising technology for treating high-salinity mine water. However, MD membranes are known to have low membrane flux and are prone to fouling. In this study, we used the cost-effective and controllable vapor-induced phase separation (VIPS) technology to prepare polyvinylidene difluoride (PVDF) membranes, replacing the traditional immersion precipitation method and optimizing the membrane structure by including LiCl and acetone as porogen in the casting solution. The results showed that the membrane prepared using the VIPS method exhibited a highly open interconnected porous surface. Unlike traditional MD membranes with a dense epidermal layer and large finger-like pores, these optimized membranes had a symmetrical and uniform internal structure, leading to a high flux of 8.62 kg·(m2·h)−1 during direct contact membrane distillation testing. Different porogens produced varied results on the VIPS process and varying effects on membrane structure. The use of LiCl promoted the formation of PVDF β-phase, resulting in a decrease in the number of spherical nodules on the membrane surface, as well as improved density and smoothness. Consequently, this reduced fouling risk during membrane distillation while slightly decreasing membrane flux. On the other hand, acetone rapidly evaporated during the VIPS process, facilitating pre-gelatinization and α-phase formation of PVDF. This concurrent effect effectively restricted excessive nodule growth on the membrane surface, endowing the membrane with antifouling capabilities while preserving high flux. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The widespread use of lithium‐ion batteries underlines the criticality of a more sustainable cell fabrication. Here, three biopolymers gelatin, pectin, and deoxyribonucleic acid (DNA) are investigated as binders for the TiNb2O7 anode material in Li cells in a temperature range between 0 and 60 ºC and compared to conventional binder polyvinylidene fluoride (PVDF). The use of biopolymers is motivated by their own environmental friendliness and the possibility to implement an aqueous electrode processing. A specific charge capacity of at least 200 mAh g−1 is found for all binders at 0 °C when testing the cycling performance of TiNb2O7 at 77.5 mA g−1 (1C rate). However, low‐rate cycling at 60 °C shows decreasing capacity for all biopolymers due to the swelling effect and continuous contact loss to the current collector, what also reflects in lowering the overall Li‐diffusion coefficient. This effect becomes less pronounced at 0 °C and high current densities, making biopolymers competitive with commercial PVDF. The electrodes with DNA binder demonstrate overall the most stable performance, arising from the biopolymer intactness and a thin solid–electrolyte interface layer. At 0 °C, the electrode with DNA provides 150 mAh g−1 at 775 mA g−1 for at least 500 discharge–charge cycles. [ABSTRACT FROM AUTHOR]

Abstract Obtaining a polymer nanocomposite with optimum viscoelastic, thermal, and biocompatibility properties is the main objective when designing nanocomposite systems with potential applications in tissue engineering. For this purpose, a blend of Polycaprolactone (PCL) and Polyvinylidene fluoride (PVDF) in an 85/15 weight ratio, along with a nanocomposite reinforced by nanohydroxyapatite (nHA) particles, is fabricated using a solution casting method in a mold. The impact of nHA content on crystallinity, viscoelastic properties, thermal stability, and the properties–structure relationship of nanocomposites is evaluated using scanning electron microscopy (SEM). Dynamic mechanical thermal (DMTA) analysis is used to determine the William–Landel–Ferry (WLF) constants and the effect of nHA on the nanocomposite's viscoelastic behavior. The PCL/15PVDF/0.5 wt% nHA exhibits the maximum thermal stability (40% residual char value) and 95% increase in storage modulus at 90 °C (rubbery region) in comparison with PCL/15PVDF blend. Water contact angle (WCA) and biocompatibility tests are conducted on the PCL/15PVDF blend and nanocomposite scaffolds to design appropriate nanocomposite systems with potential applications in tissue engineering. The high hydrophilic properties are assigned to PCL/15PVDF/0.5 wt% nHA with a WCA of 67.5°. Finally, in vitro cell culture confirmed 0.5 wt% nHA significantly improves cell adhesion and cytotoxicity with MG‐63 cells.

Waste cigarette filter (WCF) is one of the most common wastes found in the environment. Cigarette filters contain up to 96% cellulose acetate (CA), which can be used as a material for membrane fabrication. However, the CA-based membrane from WCF posed a weak mechanical property (brittle). Therefore, the objective of this work is to improve mechanical property of CA-based membrane from WCF by preparing blend membranes with polyvinylidene fluoride (PVDF) polymer and evaluate their performance for filtration of real river water containing high natural organic matter (NOM) concentrations. The variations of WCF and PVDF used were 100:0, 75:25, 50:50, 25:75, and 0:100. The membranes were then characterized to determine the morphology, pore size and pore size distribution, hydrophilicity, mechanical properties, and filtration performance of the membrane using clean water and river water. The SEM test results showed the presence of spherulites on the surface of the blend membrane, indicating that crystallization occurred during membrane formation. The spherulites resulted in smaller pore size, narrower pore size distribution, higher hydrophilicity, and mechanical properties. Meanwhile, the filtration test results showed that blend membranes produced higher permeability compared to pristine WCF, PVDF, and commercial-based CA membranes, where the result of river water permeability was in the range of 875–1062.5 L/m2.h.bar. The membrane fouling formation was aligned well with the result of permeability and is dominated by irreversible fouling formation from the dynamic cake layer built on the membrane surface, with NOM rejections of 26.6–33.8%, suggesting the need for further developments.

This work deals with enhancing piezoelectric energy harvesting by incorporating different auxetic structures and varying geometrical parameters. A bimorph consisting of polyvinylidene fluoride as a piezoelectric layer and brass auxetic substrate (re-entrant, s-shape, and elliptical holes) are considered for analysis. A finite element method-based simulation is performed to find the best auxetic systems that provide higher power output. The environmental vibration is taken for energy harvesting; thus, the first resonance frequency is below 100 Hz. The maximum power of ∼0.52, ∼0.67, and ∼0.79 mW is estimated for piezoelectric energy harvesters (PEH's) re-entrant, s-shape, and elliptical holes. The auxetic re-entrant, s-shape, and elliptical substrate-based PEHs show 200%, 300%, and 333% more power than the solid substrate (conventional design). However, the elliptical-based auxetic structure obtains a maximum power density of 0.004 66 mW/mm3. The stresses in all structures are within the permissible limit; hence, any design can be used for practical applications. All three auxetics have comparable geometrical dimensions and the same material is used; thus, auxetic behavior is independent of the material employed and depends on the structure's shape. The estimated power is higher than that reported in the literature. [ABSTRACT FROM AUTHOR]

The mode manipulation of Lamb waves plays an important role in damage detection and identification of damage types, location, and size. In this paper, we propose a composite phononic crystal (PC) plate with antisymmetric and symmetric PCs for realizing mode conversion from A0 to S0 mode of Lamb waves. The theoretical analysis, numerical simulations, and experimental validation are introduced and the mode conversion mechanism of the composite PC plate is systematically investigated. The effect of geometrical parameters on band structures of antisymmetric and symmetric PCs is first discussed. Then multi-physics field simulation models are developed and in-plane displacement fields are obtained in numerical simulations, which shows that the mode conversion is enhanced when the period number of the antisymmetric PC decreases and that of symmetric the PC increases. The composite PC plate specimens are fabricated with precision wire cutting technology for experimental measurements and the self-designed polyvinylidene fluoride (PVDF) comb transducer is used to stimulate the Lamb waves. The experimental results are consistent with the numerical simulations, which demonstrate that the proposed composite PC plate can achieve the mode conversion from A0 to S0 mode of Lamb waves. Our proposed structures have applicable values for the mode manipulation of Lamb waves in damage detection. [ABSTRACT FROM AUTHOR]

The optimization of the processing condition of polyvinylidene fluoride (PVDF) plays a pivotal role in determining the structural, dielectric, and energy storage behavior. The present work addresses the effect of annealing on the structural, dielectric, piezoelectric, and energy storage behavior of the PVDF thick film. X-ray diffractogram/Fourier transform infrared spectroscopy/RAMAN reveals the enhancement in the β crystalline phase of PVDF with annealing temperature which is highest for the film annealed at 110 °C. The film annealed at 110 °C exhibited the dielectric constant, dielectric loss, and piezoelectric coefficient as 14.02, 0.05 at 100 Hz and 24 pC/N, respectively. A systematic enhancement of 21% in dielectric constant, 46% in discharge energy density, and 87% in piezoelectric coefficient is reported for the PVDF film annealed at 110 °C as compared to the film annealed at 50 °C. The enhancement in dielectric and energy storage properties is attributed to the alignment of CH2–CF2 by virtue of molecular motion in the PVDF chain. This work suggests the adaptation of annealing for modifying the dielectric and energy storage behavior which is momentous for various electronic applications. [ABSTRACT FROM AUTHOR]

Abstract The present study aims to evaluate the performance of porous hydrophobic Polyvinylidene fluoride − Polytetrafluoroethylene (PVDF-PTFE) composite membranes for desalination by vacuum membrane distillation (VMD) technique. The effect of operating parameters such as feed NaCl concentration (10,000 to 40,000 mg/L), feed temperature (50 °C to 80 °C), and downstream pressure (80 to 120 mmHg) on water permeation rate was studied. The increase in feed temperature enhanced the water permeation rate due to a rise in driving force across the membrane. For a constant downstream pressure of 80 mmHg, feed temperature of 80 °C and feed flow rate of 80 L/h, the membrane exhibited a maximum water flux of 3 kg/m2h with 99.86% salt rejection when aqueous NaCl concentration of 10,000 mg/L was charged as feed. Membrane characterization was performed using various analytical tools to determine physico-chemical properties such as pore size, structural elucidation, thermal stability, crystallinity, and hydrophobicity of the membrane material. Further, a temperature and concentration polarization coefficient-based analysis was performed by solving the mass and heat transport model equations using MATLAB software. The proposed research study promotes the application of VMD for recovering potable water from highly saline sea/brackish water and alleviates brine disposal issues.

The main challenge with membrane bioreactors is fouling, which leads to decreased flux performance and a shortened membrane lifespan. This study aims to provide a solution for the flux recovery and removal of irreversible fouling on Polyvinylidene Fluoride (PVDF) membranes without damaging their structure using sulfate radicals. Sulfate radicals are formed via peroxodisulfate precursors that are activated by Fe2+. The membrane flux recovery and irreversible fouling ratio were 88.45-99.04% and 11.60-0.96%, respectively, at operating temperatures of 298-308 K. The PVDF membrane has been tested for microfiltration and washed up to 6 times per cycle. The mechanical properties, XRD, SEM-EDX, and ATR-FTIR characterization of the PVDF membrane after washing with PDS/Fe2+ did not show a negative effect on the PVDF structure. Additionally, the results of the kinetic and thermodynamic studies showed that washing with PDS/Fe2+ inhibited the formation of fouling particles on the membrane surface. Based on this study, sulfate radical oxidants with PDS precursors activated by Fe2+ can be applied as cleaning chemicals for PVDF membranes without damaging their structures.

This study evaluates the effectiveness of some commercial membranes (polytetrafluoroethylene [PTFE], polyvinylidene fluoride [PVDF], polyethersulfone [PES], and nitrocellulose [NC]) in concentrating a binary ethanol-water mixture under different conditions (volumes, temperatures, pressures, and concentrations). Then, the membrane was selected based on its performance for use in ethanol and by-product separation from OPEFB fermentation broth. The optimum result for the binary ethanol-water separation was found in the PVDF membrane with the highest separation factor of 3.03 and flux of 0.015 g.cm−2 s−1 under 10 ml permeate volume, 75 °C temperature, 60 psi pressure, and 20 % (v/v) ethanol concentration. Based on the membrane field emission-scanning electron microscope (FE-SEM) analysis, the PVDF membrane also had the lowest swelling degree. Utilization of the PVDF membrane to separate crude bioethanol resulting from OPEFB fermentation gave a separation factor of 3.66. The initial bioethanol concentration was 7.67 % (v/v), and the ethanol concentration in the permeate was 23.31 % (v/v). In addition, the separation factor of propanol from the crude mixture was 5.44, and the acetic acid rejection factor was 96.7 %. The S.cerevisiae suspension and the cellulase enzyme were also separated and recovered in the retentate phase. Hence, the PVDF membrane can be used to separate bioethanol from the yeast and enzyme suspension while pre-concentrating the bioethanol product. This could eventually help reduce the energy requirement to obtain industrial-grade bioethanol.

Fouling on hydrophobic membranes can be eliminated by modification with hydrophilic additives such as dragon blood resin (DBR: bio-polymer) and polyethylene glycol (PEG: non-bio-polymer). In this study, the surface modification of polyvinylidene fluoride (PVDF) membranes with bio/non-bio polymeric additives and their coordination reaction with Fe3+ ions was investigated. Five types of membranes with different compositions were prepared by immersion precipitation phase inversion method. The result showed that membrane M–PD (PVDF/PEG/DBR) improved the membrane hydrophilicity, resulting in high pure water flux (98.7 L.m−2.h−1) and humic acid rejection (99.08 %). However, the coordination reaction with PEG and Fe3+ as well as PEG/DBR and Fe3+ resulted in reduced water and humic acid flux. Coordination reaction successfully increased membrane stability as evidenced by FRR < 100 %. These results will be useful in the design of PVDF-based membranes with bio- or non-biopolymer additives.

Abstract The removal of phenolic compounds from the water was of great importance due to their high toxicity. In this study, the separation of phenol from an aqueous environment by pervaporation technique using (PVA) polyvinyl alcohol, (CA) cellulose acetate, and (PVDF) polyvinylidene fluoride membranes was tested. The effect of feed concentration up to 9000 ppm, operating temperature from 25 to 65 °C, and flow rate ranging from 2 to 6 L h−1 on the separation performance was investigated. It was found that the CA membrane possessed a higher water flux of 348.25 kg m−2 h−1 and a separation factor of 49 compared to PVDF, and PVA/SA membranes at 65 °C and a flow rate of 6 L h−1. The properties and morphology of membranes were observed using mechanical properties, contact angle, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results showed that CA has a lower contact angle of 48.3° indicating the hydrophilicity nature of the membrane, which enhances the separation process and explains the increases of water flux. Moreover, the mechanical properties test indicated that the mechanical strength of CA has a maximum tensile strength of 65.5 MPa and an % elongation of 48% compared to PVDF and PVA/SA which indicates lower roughness, manifesting its improved anti-fouling properties.

Polyvinylidene fluoride (PVDF) membrane is frequently employed for filtration due to its excellent properties. The hydrophobicity of PVDF membrane causes easy fouling; therefore, hydrophilic polymer materials are required to increase hydrophilicity. This study applies cellulose and cellulose esters as fillers for PVDF membranes to solve the fouling problem. Cellulose esters, such as cellulose acetate (PSCA), cellulose benzoate (PSCB), and cellulose citrate (PSCC), were successfully synthesized from peanut shell cellulose (PSC) using Fischer and non-Fischer reactions. The phase inversion method was successfully used to fabricate PVDF membranes with cellulose or cellulose esters as fillers. The fabricated membranes have been applied for methylene blue (MB) filtration. Adding PSC fillers improved the hydrophilicity and performance of the PVDF membranes up to 23.49 ± 2.40 L m−2 h−1 for water flux and 95.75 ± 0.78 % for rejection of MB. Regarding cellulose esters, cellulose acetate gave the highest value of 77.63 L m−2 h−1 for water flux, and cellulose citrate gave the highest value of 86.88 ± 3.54 % for MB rejection. Hence, cellulose or cellulose esters from peanut shells are suitable fillers for MB filtration in PVDF membranes.

The effectiveness of polyvinylidene fluoride (PVDF) membranes in various applications is often hampered by fouling, necessitating the exploration of modification strategies to enhance their antifouling properties. This study investigates the effect of combining cellulose nanocrystal (CNC) and graphene oxide (GO) on PVDF membranes to address this issue. Six flat sheet membranes with different compositions were fabricated using a non-solvent-induced phase separation method. The resulting membrane (M5: CNC 1 % w/w and GO 0.25 % w/w) exhibited increased surface pores, a finger-like cross-sectional structure, and higher water content. The pure water flux (PWF) in the M5 membrane increased to 37 L/m2∙h, with a humic acid (HA) rejection rate of 60 % and excellent antifouling properties (98.32 %). In conclusion, this study successfully modified PVDF membranes by combining CNC and GO, resulting in membranes with improved properties and performance. The present study provides valuable insights into composite membrane design and offers potential solutions to fouling challenges.

BACKGROUND: Polyvinylidene fluoride (PVDF) with piezoelectric properties, good biocompatibility and nontoxicity make it a suitable candidate for periosteal repair. OBJECTIVE: To evaluate the cytotoxicity of PVDF bionic periosteum by electrospinning with zinc and magnesium ions in vitro. METHODS: Pure PVDF, zinc-doped PVDF, magnesium-doped PVDF and Zinc-magnesium ion PVDF piezoelectric bionic periosteum were prepared by electrospinning technology, respectively. They were named PVDF, PVDF-Zn, PVDF-Mg and PVDF-Zn-Mg, in which the mass fraction of zinc and magnesium ions were all 1%. Osteoblasts and vascular endothelial cells were co-cultured with four groups of bionic periosteum. Cell compatibility of bionic periosteum was determined by alkaline phosphatase staining, CD31 immunofluorescence staining, and scanning electron microscopy. RESULTS AND CONCLUSION: (1) Osteoblasts: Alkaline phosphatase staining after 7 days of culture showed that the PVDF-Zn group secreted more alkaline phosphatase than the other three groups. Under a scanning electron microscopy, after 1 day of culture, the cells had a certain spread on the surface of PVDF-Mg and PVDF-Zn-Mg bionic periosteum, and the pseudopod extended to all sides. On day 3, the cell edge of each group extended pseudopods to the material. By days 5 and 7, the cells were fully spread, well grown and firmly covered the surface of the fibers, and the cellular pseudopods extended around and into the interstitial space of the fibers. CCK-8 assay showed that the cell proliferation on the bionic periosteum of each group showed an increasing trend over time and the relative proliferation rate of cells at 1, 3, 5, and 7 days was ≥75%, and the cytotoxicity was ≤ grade 1. (2) Vascular endothelial cells: CD31 immunofluorescence staining for 3 days showed that the cells adhered and spread well on the bionic periosteum of each group and connected with each other, and the number of cells in the PVDF-Zn-Mg group was more than that in the other three groups. Under scanning electron microscope, the cells began to adhere to the surface of each group of fibers after 1 and 3 days of culture. On day 5, the cells were well spread on the surface of the fibers and extended obvious pseudopods. On day 7, the cells on the PVDF-Mg and PVDF-Zn-Mg bionic periosteum grew in multiple layers and extended the pseudopod into the fibrous void. CCK-8 assay showed that the cell proliferation on the bionic periosteum of each group showed a downward trend over time, and the relative proliferation rate of cells at 1, 3, 5 and 7 days was ≥125%, and the cytotoxicity was grade 0. (3) The results showed that Zn-Mg electrospun PVDF piezoelectric bionic periosteum had good cytocompatibility. [ABSTRACT FROM AUTHOR]

This study explores the utilization of metal–organic frameworks (MOFs), particularly those incorporating lanthanide-based elements for their fluorescence capabilities, to create an advanced barcode system. By exploiting the modular nature of MOFs, we have developed a material capable of dynamic information encoding and robust against counterfeiting efforts. We introduce a novel barcode prototype that exhibits visible color shifts and fluorescence modulation when exposed to a specific sequence of chemical and thermal stimuli. The barcode is composed of MOF-808, which is modified with transition metals like iron or cobalt, and europium cations. These components are embedded within polyvinylidene fluoride (PVDF) to form a composite. This embedding process ensures that the MOF particles remain reactive to specific trigger molecules, enabling a distinct read-out sequence. The decoding process, involving exposure to ammonia, heating at 120 °C, and treatment with HCl, triggers observable changes in fluorescence and color, depending on the transition metal used. Our investigations with Eu,Co-MOF-808, and Eu,Fe-MOF-808 composites have resulted in the creation of a barcode prototype that demonstrates the feasibility of using europium-modified and unmodified transition metal modified MOF-808@PVDF composites for enhanced security applications. [ABSTRACT FROM AUTHOR]