Recent research has shown that long, porous nanofibers are one of the safest nanomaterials due to their controllable production, high specific surface area and continuous matrix structure. In this study, following the previous study of the authors, Structural phases of More
Recent research has shown that long, porous nanofibers are one of the safest nanomaterials due to their controllable production, high specific surface area and continuous matrix structure. In this study, following the previous study of the authors, Structural phases of nanofibers were synthesized from combination of polyvinylidene fluoride (PVDF) and iron/manganese binary oxide nanoparticles (FMBO) were evaluated. Mineral adsorbents were integrated into polymer matrix in the range of zero to 0.5. The properties of nanofibers according to the structure and surface characteristics using SEM and TEM were determined. In this study, structural phases of PVDF and PVDF/FMBO electrospinning nanofibers were distinguished by examining the FTIR vibration bands and analyzing the XRD characteristics due to the different reports on the analysis of α, β and γ phases according to the measured data. The results of FTIR, specifically by examining bands 762 and 612, 1275 and 1234 cm-1 and its compliance with XRD results and reviewing published research the α, β and γ phases were distinguished, respectively.
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One of the most important factors affecting membrane formation via phase inversion method is the viscosity of the polymer solution. In this research, with the aim of providing a solution to predict the performance of polymeric membranes based on viscosity data, the infl More
One of the most important factors affecting membrane formation via phase inversion method is the viscosity of the polymer solution. In this research, with the aim of providing a solution to predict the performance of polymeric membranes based on viscosity data, the influence of dope solution temperature and casting speed on the viscosity of PVDF solution were investigated. For this purpose, the viscosity of PVDF/DMAc solution with LiCl and PEG additives was measured at the temperature range of 10-50 °C and atmospheric pressure with a precise rheometer. The performance of PVDF ultrafiltration membrane with composition of PEG 3 wt. % and LiCl 7 wt. % was evaluated and an empirical model using response surface methodology and central composite design was developed to predict membrane permeability and rejection based on viscosity data and two variables of solution temperature and casting speed. Scanning electron microscopy, pure water permeability and membrane rejection tests were used to characterize the membranes. The results show that the model is in good agreement with the experimental data and based on the results, the casting speed of 1.2 m/min and the temperature of the polymer solution at 50 °C are the optimum conditions for membrane fabrication to obtain the membrane with maximum flux and rejection.
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An extensive review of the literature showed that both graphene and Cloisite 30B nanosheets are widelyemployed to modify the crystalline structure and piezoelectic properties of polyvinylidene fluoride (PVDF).Due to the similarity in the geometry of these nanoparticles More
An extensive review of the literature showed that both graphene and Cloisite 30B nanosheets are widelyemployed to modify the crystalline structure and piezoelectic properties of polyvinylidene fluoride (PVDF).Due to the similarity in the geometry of these nanoparticles a comparative study is reported to find the stemsof difference in their effects on crystalline structure of PVDF. Scanning electron microscopy (SEM) of thesecomposites showed that large and wide graphene particles are dispersed in PVDF matrix whereas theirthickness is well below 100 nanometers. Meanwhile, a careful inspection of SEM micrographs of Cloisite 30Bloaded composites revealed existence of smaller particles with almost the same particles thicknesses. Bothtechniques of Fourier transform infrared (FT-IR) spectroscopy and wide angle X-ray diffraction (WXRD)witnessed changes in the crystalline structure of PVDF. The overall finding was that Cloisite 30B improvesthe polar beta phase of PVDF crystals, whereas a revers effect was found in the presence of graphenenanosheets. These observations were accounted for by differences in surface geometry and surface free energy(surface tension and interfacial tension). Based on the data available for surface properties of these twonanosheets it was found that surface properties of Cloisite 30B is very close to those of PVDF, whereas thesurface properties of graphene are far from those of PVDF. Also a lower interfacial tension was found to beactive in PVDF-Cloisite 30B system compared to that operative in PVDF-graphene system. An intimateinterface along with proper surface texture led to higher content of PVDF’s beta crystals in case of Cloisite30B nanocomposite.
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