Papers by Keyword: Polyvinylidene Fluoride

Abstract: In this work, the effect of peat clay particles (PCP) was investigated as pore former of polysulfone (PSf) hollow fiber membrane properties. Preparation of polysulfone membrane dope solution conducted by phase inversion technique using wet spinning method. A homogeneous dope solution is added with peat clay from four composition variations of 0-6 wt%. Followed by mixed dope until homogeneous for an hour at room temperature (~29 °C). The preparation of peat clay before used is by having it calcinated at 600 °C for 1 hour, then sifted to a size of 120 mesh. The hollow fiber membrane is casted using the wet spinning method with the dope solution flow rate set at 4 mL/min and the bore fluid flow rate at 4 mL/min. The hollow fiber membrane that has been formed is analyzed by FTIR, contact angle, water absorption, and porosity. The characteristics of the membrane show that the functional group in the addition of peat clay in the absorption of Si-OH and Si-O-Si. The specific spectrum of PSf-PEG/PC is indicated by peak wavenumbers 872 – 874 cm^-1. Polysulfone hollow fiber membrane mixed with peat clay shows the contact angle on the membrane surface shows hydrophobic characteristics without addiction of peat clay particles and become slightly hydrophilic with peat clay addiction of 71.28°. In addition, water absorption in each sample increases with the addition of peat clay from 0 to 4 wt%. The ability of water absorption increased to 32.51%, and membrane porosity increased from 23.66% to 38.87%. It is concluded that polysulfone hollow fiber membranes are enhanced by adding peat clay as a pore builder and hydrophilic additives and become less fouling in future application for water/wastewater treatment.Keywords: Peat clay, hollow fiber membrane, polysulfone, wet spinning, montmorillonite

Abstract: South Kalimantan-Indonesia is known to have extensive peatlands reaching 15% of a total peatland in Kalimantan. Due to that peat land water is mostly found and claim as abundant water sources. However, based on quality, peat land water has poor characteristic with high natural organic matter content. Therefore, peat water treatment is necessary to treat using effective method such as hybrid conventional filter and membrane using hollow fibre PVDF-TiO₂/SBE. This study aims to investigate the variation of media filter thickness and filtration pressure of hollow fibre (HF) PVDF-TiO₂/SBE membrane peat water treatment by filtration pre-treatment and HF membrane ultrafiltration. HF PVDF-TiO₂/SBE membrane was prepared by wet spinning method using spinneret set up. Hybrid process was divided into two steps: 1) conventional filter as pre-treatment and 2) HF ultrafiltration membrane under cross flow system. The filter media was used in this work is silica sand and activated carbon with varied thickness 30:10 and 10:30 cm. The HF membrane structure was analysed via scanning electron microscopy (SEM) to investigate the membrane morphology. The results show the fabricated HF membrane has a finger like-sponge sandwich structure morphology. In addition, 30:10 cm (silica sand: activated carbon) thickness exhibits TDS and turbidity removal of 92.18 and 61.37%, respectively as conventional filter pre-treatment. In other hand, HF membrane successfully removed TDS and turbidity of peat water up to 98.68% and 92.41% at 2 bar of filtration pressure. The highest permeate flux of HF membrane conducted of 13.055 Kg.m^-2.h^-1 at 3 bar. Conclusion of this work is the peat water treatment using activated carbon: silica filtration pre-treatment and HF membrane ultrafiltration can provide clean water with maximum turbidity and TDS removal.

Abstract: Polyvinylidene fluoride (PVDF) reveals outstanding properties such as lightweight, high flexibility and temperature independence material compared to other polymers. In this study, PVDF as a function of molecular weight was prepared by using an electrospinning method in order to study the influences of the molecular weight of the PVDF membrane on the morphology. Analytical techniques such as field emission scanning electron microscope (FESEM), Fourier transform infrared (FTIR) and X-ray diffraction (XRD) were used to characterize the electrospun PVDF membranes. FESEM was used for morphology characterization and also to measure the diameter of fibers while XRD and FTIR were employed to examine crystalline phase membranes. The lowest molecular weight has the smallest average diameter of fibers. Besides, a combination of both α-phase and β-phase crystalline was showed by XRD and FTIR results. This is because the crystalline phases and membrane morphology depend on the polymer molecular weight. In this research, it was found that the largest β-phase fraction for the electrospun PVDF membrane is 80.25 % with a molecular weight at 180,000 g/mol.

Abstract: Conductive polymers are promising for application in the medical and sport sectors, e.g. for thin wearable health monitoring systems. While many today’s electrodes contain either carbon or metals as electrically conductive filler materials, product design manufacturing has an increasing interest in the development of metal free and carbon free, purely polymer based electrode materials. While conducting polymers have generally rather low electrical conductivities compared to metals or carbon, they offer broad options for industrial processing, as well as for dedicated adjustments of final product properties and design aspect, such as colour, water repellence, or mechanical flexibility in addition to their electrical properties. The development of electrically conducting polymer blends, based on conductive polymers is thus timely and of high importance for the design of new attractive flexible electrodes. We have developed material formulation and processing techniques for the fabrication of self-supporting thin film electrodes based on polyaniline (PANI) and polyvinylidene fluoride (PVDF) blends. Electrical four-point probing was used to evaluate the electrode conductivity for different processing and fabrication techniques. Optical microscopy and atomic force microscopy measurements corroborate the observed electrical conductivity obtained even at low PANI concentrations revealing the nanoscale material distribution within the blends. Our self-supporting thin film electrodes are flexible, smooth, and water repellent and were furthermore successfully tested under bending and upon storage over a period of several months. This opens new perspectives for the design of metal free and carbon free flexible electrodes for medical, health, and sports applications.

Abstract: In this research, Polyethersulfone (PES) and Polyvinylidene Fluoride (PVDF) with the addition of a Titanium Dioxide (TiO₂) blanded membrane were prepared using the DC 15000 V electric field method. The investigation of this research is the adding result of Titanium Dioxide (TiO₂) with the DC 15000 V electric field methos such as the mechanical properties of membranes and water treatment performance. The surface mixture of Polyethersulfone (PES) and Polyvinylidene Fluoride (PVDF) membranes is characterized using SEM, the membrane pore size shrinks and forms evenly with the addition of Titanium Dioxide (TiO₂) and DC electric field methods. Tensile tests were carried out to obtain the mechanical properties of Polyethersulfone (PES) and Polyvinylidene Fluoride (PVDF) by adding Titanium Dioxide (TiO₂) mixture membrane, which showed an increase in optimal tensile strength to 3.86 MPa at a concentration of 30% Polyethersulfone (PES) and also increased to 1.15 MPa at 20% Polyvinylidene Fluoride (PVDF). The membrane surface was examined using contact angle measurements, which in the mixed membrane Polyethersulfone (PES) and Polyvinylidene Fluoride (PVDF) showed a decrease in the angle between the range of 43^o - 46^o. Therefore, hydrophilicity makes it possible to suppress the permeate flux of pure water. Making membranes with the addition of Titanium Dioxide (TiO₂), and assisted by DC electric fields opens up new ways to increase membrane strength, hydrophilicity, shrink and make pore sizes evenly formed.

Abstract: Polyvinylidene fluoride (PVDF) membranes, enhanced with metal-organic framework (MOF), were fabricated on a non-woven polyethylene terephthalate (PET) support using the non-solvent induced phase inversion (NIPS) method to produce mixed matrix membrane (MMM). Polymer concentration of 10%, 15%, and 20% were used in the study whereas UiO-66(Zr) was used as a MOF filler. The resulting membranes were characterized in terms of their morphology, porosity, wettability, mechanical strength, pure water flux, and gas permeability. Results show that the presence of UiO-66(Zr) filler improved membrane morphology, mechanical strength, and hydrophobicity of MMM as compared to pristine PVDF.

Abstract: Particles of calcium phosphate were precipitated by raising the temperature and the pH of simulated body fluid (SBF) named Apatite Nuclei (AN). AN and polyvinylidene fluoride (PVDF) composites thin films with different weight percentages of AN in PVDF were fabricated by solution casting technique, using doctor blade method. In order to assess the bioactivity, the thin films were soaked in simulated body fluid (SBF). It was found that the film containing 30 wt.% of AN in PVDF actively induced hydroxyapatite formation in 3 days soaking period in SBF.

Abstract: Membrane distillation (MD) is a membrane separation process first introduced in 1963 by Bodell whereby the major driving force is by vapor pressure difference between the feed and permeate induced by temperature gradient. The MD applications mainly focus on seawater desalination and other industry application such as extraction of fruit juice. In this study, hydrophobic polyvinylidene fluoride (PVDF) hollow fiber membranes were fabricated by wet/dry phase inversion method with 1-methyl-2-pyrrolidone (NMP) as solvents and ethylene glycol (EG) as non solvent additives. The effect of the additives on the membrane formation was studied based on the results from membrane morphology investigation through scanning electron microscope (SEM) and porosity calculation based on gravitational method. The SEM image indicated the membrane morphology changed from finger like layer extending from inner to outer surface to a finger like layer separated by microvoid attributed addition of ethylene glycol which might lead to permeate flux enhancement. Furthers, results from the gravitational test reveal that the addition of ethylene glycol demonstrated a positive effect on the porosity of the membrane. Later, the membranes were tested by membrane distillation process in sodium chloride removal varying feed inlet temperature to investigate the permeate flux performance of the membrane.

Abstract: Plasma electrolytic oxidation (PEO) of commercially pure titanium VT1-0 was performed in phosphate electrolyte. High-frequency 200 kHz bipolar signal at a duty cycle D=0.1 was used to form the oxide coatings. Polymer-containing anticorrosion coatings were formed by applying polyvinylidene fluoride (PVDF) on the base PEO-coating. The results of electrochemical tests have showed a decrease of corrosion current density by 2 orders of magnitude (down to 1.5∙10^-10 А∙сm^-2) and the corresponding increase of the polarization resistance (up to 1.9∙10⁸ Оhm∙сm²) in comparison with the metallic substrate.

Abstract: The paper presents the results of the study of electrochemical and mechanical properties of PVDF/PEO-coatings formed on magnesium alloy MA8 by plasma electrolytic oxidation (PEO) and subsequent application of polyvinylidene fluoride (PVDF) on the PEO-layer. The oxide coatings were formed using a 300 Hz bipolar signal with duty cycle (D) 0.50. The analysis of electrochemical data has showed a decrease of corrosion currents by 3 orders of magnitude (down to 6.0·10^-9 А·сm^-2) and an increase of the polarization resistance by 3 orders of magnitude (up to 5.3·10⁶ Оhm·сm²) for the coatings formed by triple dipping (x3) of the PEO-layers into PVDF solution. Evaluation of the tribological properties of the (x3) PVDF/PEO-coatings has showed a significant increase of the wear resistance (the number of abrasion cycles resulting in complete destruction of the coating increased in 25 times) as compared to the base PEO-layer.