Abstract: The electrospun poly(vinylidene fluoride-co-hexafluoropropylene)/montmorillonite nanofibrous composite membranes (esCPMs) were prepared by electrospinning technique using a mixture of different amounts of montmorillonite (0, 3, 5, 7 and 10 wt%) into 16 wt% of PVDF-HFP polymer solution in 7:3 wt% of acetone and dimethylacetamide as the solvent. The effect of montmorillonite (MMT) on electrospun PVdF-HFP membrane has been studied by XRD, DSC, TGA and tensile strength analysis. It is found that electrospun PVDF-HFP/MMT nanofibrous composite membrane obtained using 5wt% MMT has a higher porosity, electrolyte uptake, ionic conductivity, electrochemical stability window and showed higher specific capacitance and good compatibility with electrode materials.
Abstract: Although graphene has been produced by various methods at lab scale, however, its cost effective mass production method is still a challenge. Graphene has been produced by liquid phase exfoliation, which is the most probable method for commercial production of graphene for various industrial applications.This paper reports high concentration production of few-layer graphene in DMSO (dimethyl sulfoxide) as solvent through liquid phase exfoliation assisted with sonication. The temperature was kept below 30oC. SEM, AFM, and XRD were used to characterize the produced graphene. SEM results confirm the production of few-layer graphene. EDX analysis shows that the graphene surface is free from oxides and impurities. AFM results also confirm the production of few-layer graphene. The UV-visible spectrophotometer was used to determine the concentration of the produced graphene, and the investigations demonstrate that the graphene production was increased by increasing the sonication time. There exist a linear relationship between the amount of produced graphene and sonication time for supplying energy during sonication.
Abstract: In this study, we fabricated poly vinyl alcohol/polyamide 6 (PVA/PA6) hybrid nanofiber yarns and examined the influence of PA6 content on tensile properties of hybrid nanofiber yarns. The surface morphology of nanofiber yarns was studied by scanning electron microscope (SEM). The average diameters of nanofibers in pure PA6 and pure PVA nanofibers yarns were 83±12 nm and 187±21 nm, respectively. The results showed that the strength of hybrid yarns was descending for PA6 contents below 16.5 % and ascending for higher contents. Also, by increasing the PA6 ratio in the hybrid yarn, the elongation at break was decreased. Three various models including: Hamburger, simple rule of mixtures (ROM) and hybrid models were applied to predict the tensile behavior of hybrid yarns. This study showed that neither ROM nor Hamburger’s models were capable of predicting the tensile properties of hybrid yarns. Whiles, hybrid model can predict properties with the lowest error (6.44 % error in strength values and 13.06 % error in elongation values prediction). Moreover, this model was modified further for higher performance. Our results demonstrate that the hybrid model can be applied in engineered tensile properties of nanofibrous yarns.
Abstract: Poly(lactic acid) (PLA) is blended with Poly(ethylene glycol) (PEG) and magnetic nanoparticles (MNPs). A series of mixtures are converted to fibers via electrospinning at room temperature. The fiber diameter of PLA decreases on blending with PEG from 6 down to 3 micrometers and with PEG + MNPs down ca. 1 micrometer. The thermogravimetric study confirms the effect of blending, enhancing the stability on adding PEG to PLA. The magnetic properties of polymer fibers containing different concentrations of MNPs are studied by vibrating sample magnetometer. The fiber blends shows proportionally reduced saturation magnetization compared to pure magnetic nanoparticles. The MNPs –incorporated PLA-PEG nanocomposite mat show magnetization and therefore promise the possibility for temperature effects, such as hyperthermia treatment.
Abstract: Quantum dots (QDs) of zinc sulfide (ZnS) was prepared by chemical reaction with different potential of hydrogen (pH) and used to fabricate organic quantum dot hybrid junction device. The optical properties of QDs were characterized by ultraviolet-visible (UV-Vis.) and photoluminescence (PL) spectrometer. The results show that the prepared QDs were nanocrystalline with defects formation. The energy gap (Eg) calculated from PL were 3.64, 3.53 and 3.35 eV for pH=8, 10 and 12 respectively. This decreasing of energy gaps is results of the effect the pH solution increases, which in turn leads to the shifted of the PL spectrum toward red shifted, which makes the energy bands at surface states are shallow bands. Fabrication of EL-device from ZnS QDs with different pH value was effective in efficient white light generation and can be the color of emerged light with different intensities.