Papers by Keyword: PVDF

Abstract: The study explores the integration of additive manufacturing for the development of 4D-printed piezopolymer metamaterials, aiming to create dynamic, multifunctional structures capable of distributed sensing and energy harvesting. The focus is on Polyvinylidene fluoride (PVDF), a partially fluorinated polymer renowned for its strong electromechanical coupling, specifically within its polar β-phase. To harness these properties, three distinct experimental strategies were evaluated for integrating PVDF with conductive electrodes necessary for electrical poling: direct 3D printing with manually applied silver paste, printing directly onto pre-integrated aluminium foil substrates, and a novel chemical solvent-based deposition using a DMF/acetone mixture. While high-precision inkjet printing was initially tested for electrode deposition, it demonstrated significant limitations in scalability, throughput, and durability, particularly suffering from structural degradation during the post-poling silicon oil removal process. Consequently, the study advocates for a robust, hybrid multi-material extrusion platform. This approach will enable the simultaneous, monolithic deposition of structural PVDF thermoplastics and highly conductive thixotropic inks.

Abstract: Mechanical vibrations are abundant in human-made environments and can be harnessed using piezoelectric transduction. Among the piezo materials, piezoelectric polymers exhibit flexibility and mechanical compliance, improving resilience to shock and deformation—suited for low-frequency high strain environments. In this paper, distinct designs of piezoelectric active area were topology optimized using ANSYS. Three designs of bimorph cantilevered energy harvesters were developed to obtain the optimum material layouts of piezoelectric PVDF, maximize the voltage output, decrease the resonant frequency, and reduce the amount of material needed. Two additional designs with varying volume retainment were also simulated to investigate the effects of optimization parameters. The best topology optimized design, #2, had a resonant frequency of 16.9 Hz and a piezo voltage of 1.08E-3 V/mm³ normalized to the amount of remaining PVDF after optimization. Although the frequency is still higher than the target ambient energy sources, this study showed that topology optimization in conjunction with design can be used to define structures leading to the energy harvesting application frequency.

Abstract: Piezoelectric materials possess a special property to produce electricity from mechanical motion and are therefore it is suitable for green energy solutions. In our project, we fabricated a flexible piezoelectric device through a simple, non-vacuum process. We prepared the device by a solution casting process with a thin poly (vinylidene fluoride) (PVDF) film. Under mechanical stress, the device shows a clear electrical response, confirming its functionality. This indicates that piezoelectric materials can be fabricated to utilize as a low-cost, eco-friendly, and efficient means to harvest energy. This device can also be used as a sensor in robots and robot-related applications. This device can sense movement, which can be used in autonomous robots to sense movement, feed back, or even to harvest energy to power robotic sensors. In the future, we can improve the device performance by modifying the film thickness, using more efficient electrode materials, and making it stable to operate in different conditions.

Abstract: With the rapid advancement of global industrialization, there is an increasing year-on-year demand for oil in society. The occurrence of oil spills during the processes of development, refining, and transportation has become an urgent issue that needs to be addressed. Electrospun fiber separation using selective oil/water absorption represents a relatively new yet promising technology. However, despite the lipophilic nature of the membrane for oil absorption, the rate of oil absorption is slow. There are still challenges in meeting the needs of developing communities. The plant employs a strategy of multi-branching with narrowed pores, which serves to enhance the efficiency of water and nutrient transfer. Inspired by plant transpiration, we adjusted the parameters of electrospinning and constructed a PVDF biomimetic nanofiber membrane with gradually reduced pore size through a bottom-up layer-by-layer spinning strategy. This PVDF biomimetic nanofiber membrane conforms to Murray's law. The experimental results showed that the oil absorption of carbon tetrachloride by PVDF Murray membrane was 3.06 g/g. Significantly, the PVDF Murray membrane demonstrates rapid adsorption of the oil slick (0.3 mL, n-hexane) in just 13s, as compared to 24s without the Murray structure. Therefore, the one-step preparation of the PVDF Murray membrane indicates a promising potential for its future application as a sustainable and quick oil-absorbent membrane.

Abstract: The high difference in surface tension between the filler and the polymer often constrains membrane compatibility. To reduce the surface tension, organosilane such as GPTMS is usually used to improve miscibility. In this study, GPTMS was introduced to produce lignin-GPTMS (LG) and lignosulfonate-GPTMS (LsG). The modification was done by reacting lignin and lignosulfonate with GPTMS using ethanol as the media. The product was characterized using Fourier Transform InfraRed (FTIR), X-ray Diffraction (XRD), Particle Size Analyzer (PSA), Scanning Electron Microscope-Energy Dispersive X-ray (SEM-EDX) and microscope. The success of functionalization was shown in FTIR spectra with the vibration of Si-O at 1034 cm^-1 and 528 cm^-1. The XRD analysis presents that the filler material has an amorph and crystalline structure. The functionalization using a 2:1 ratio increases zeta potential absolute and particle size due to the silane being a bridge and making a larger macromolecule. For a ratio of 1:1, a higher organosilane compound results in breaking siloxane linkages and making smaller molecules. Mixed LG and LsG into PVDF membrane conducted to analyze filler compatibility. The sulfonation and functionalization of GPTMS increase the compatibility of lignin in PVDF membrane with the best homogeneity achieved by a membrane with the addition of LsG 1:1.

Abstract: The implementation of water-chitosan slurry is needed to achieve better battery, in terms of enviromentally friendly and cheapest cost. In this research, sodium-ion cathode batteries based on sodium iron phosphate and the water-chitosan slurry were successfully synthesized with the sol-gel method. The result of the X-Ray Diffraction (XRD) test confirmed the two phases of sodium iron phosphate, which are Na₃Fe₂(PO₄)₃ and Na₃Fe₃(PO₄)₄, with the percentage weight of the phases of 31.19% and 68.81%, respectively. Then, this sample was examined using Scanning Electron Microscope-Energy Dispersive X-ray (SEM-EDX) test, it is known that the morphology of particles look like agglomerate thin sponges and no other elements besides Na, Fe, P, and O were found in the sample. Cyclic Voltammetry (CV) dan Electrical Impedance Spectroscopy (EIS) tests were also carried out to determine the electrochemical performance of the cathode material. The CV test was carried out to determine the specific capacity value of each sample. From the test results, it is known that sodium iron phosphate cathode with PVDF binder had a higher specific capacity value than cathode with chitosan binder, which was 44.13 mAh/g and 26.78 mAh/g, respectively. From the EIS results, it was found that sodium iron phosphate cathode with chitosan binder had better electrical conductivity and Na⁺ ion diffusion, with values of 7.44×10^-3 S.cm^-1 and 1.48×10^-11 cm² s^-1 respectively.

Abstract: Energy harvesting has been at the forefront of research due to the significant interest in green energy sources, especially for powering remote sensors in structural health monitoring of coastal and offshore facilities. This work reports the magnet-actuated piezoelectric harvesters (M-APH) that use magnetic coupling to actuate piezoelectric film-embedded silicon rubber strips for energy harvesting from fluids. The piezo-silicon strips are deflected by the tip-magnets in the actuation system, such that the M-APH can effectively be triggered to generate electrical energy from vibration. The M-APH prototypes are printed using 3D printing technology, and the experiments are conducted to determine the output electrical voltage using a rectifier. Strip properties are varied to study the geometric influence (i.e., thickness and shape) on the energy performance. The electrical performance was evaluated for each curved piezoelectric strip and straight strips according to the piezoelectric material used. The reported M-APH can be applied to various fluids for energy harvesting.

Abstract: Membranes are used in various different applications in water treatment due to the wide array of properties that can be attained from different materials and polymers. A new hybrid membrane for the purification of water by electrodialysis has been manufactured and studied in this research. The membrane consists of two different materials: A host polymer matrix and a cation selective metal organic framework, MOF. For the polymer matrix, polyvinylidene fluoride, PVDF, was selected to act as the body that is meant to be the backbone of the membrane. It was dissolved in different solvents with different concentrations to determine the most stable matrix. Using scanning electraon microscope, SEM, imaging, it was found that 10% wt in dimethylformamide (DMF) provided the most suitable conditions for this work. As for the cation selective MOF, UIO-66 was selected and then synthesized using hydrothermal method and characterized using X-ray diffraction, XRD, and found to match previous literature. UIO-66 provides the membrane with cation selectivity, which allows the membrane to function in an electrodialysis system, so it was dissolved with the PVDF matrix to provide a hybrid membrane. Different amounts of the MOF in the membrane matrix were tested to find the most suitable distribution of the MOF over the surface of the membrane and was found to be around 2%. The membrane was tested with LiCl salt, before and after UIO-66 addition, in a half cell to measure the influence of the UIO-66 as a cation selective material and its effect on ion migration.

Abstract: A high performance flexible temperature sensor for environmental and health monitoring has been fabricated using various combinations of composite blend of poly vinylidene fluoride / poly (3,4-ethylenedioxythiophene)-poly (styrenesulfonate) (PVDF/PEDOT:PSS). The response curves and working principle were investigated and sensors were then fabricated to achieve highly linear and stable response for a wide range of temperature sensing (25°C to 120°C). The film was fabricated on flexible polyethylene terephthalate (PET) substrate using spin coating. The copper electrodes were fabricated using copper tape. The sensors showed stable and close to linear response of impedance change by varying temperature in the range 25°C to 120°C. The resistance of the sensors changed from ~70MΩ to ~52MΩ for the temperature change in the range 25°C to 120°C. The sensors are aimed to replace low performance, complex and expensive sensors in the market for environmental and health monitoring applications.

Abstract: In this study, polymer electrolyte gel membranes (GPEs) as separators in Lithium-Ion battery cells were prepared using polymer blends between polyvinylidene fluoride (PVDF) and cellulose acetate (CA). The CA used was obtained from the recovery process from cigarette butts. The prepared GPEs showed increased thermal stability and membrane strength. This research consists of two stages, the CA recovery process from cigarette butts is the initial stage, then the next stage is the synthesis of GPEs membranes. In the CA recovery process from cigarette butts, using a solvent mixture of ethanol and toluene with the ratio of 1:1.0, 1:1.1, 1:1.2, and 1:1.3 respectively. Furthermore, CA was characterized using XRD, FTIR, and SEM methods. The characterization results showed that the solvent variation of 1:1.3 produced CA with the most suitable properties with commercial CA. In the synthesis stage, GPEs were made using the Non-solvent Induced Phase Separation method. Membrane solutions were prepared by mixing PVDF/CA polymers with variations of cellulose acetate (2, 4, 6, 8, and 10% wt), PVP additives, and ZnO filler. This solution is then printed on glass and then immersed in a non-solvent (water) for the solidification process of membranes. The result shows that the modified GPEs have the best porosity and electrolyte uptake properties of 79.05% and 942.105%, respectively, in the modification with the addition of 10% wt CA.