Applied Mechanics and Materials Vol. 749

Abstract: Silica (SiO₂) nanoparticles have found applications in many advanced areas. This research work is concerned with the preparation of silica nanoparticles by wet alkali chemical etching technique of commercial silicon powder using (KOH, n-propanol and water). The synthesized nanoparticles were systematically characterized by XRD, FTIR and PL spectroscopy. The XRD results revealed the amorphous nature of silica nanoparticles. FTIR spectroscopy confirmed the presence of Si-O in all the samples. PL spectra have shown emission band at around 516 nm. Then, nanosilica is promise material for the realization of light-emitting silica-based optoelectronic devices.

Abstract: Cables are an integral part of the power transmission and distribution network. As the voltage level increases, amount of insulation used in the cable increases. Therefore a need arises for a material with better insulation characteristics to be used in cables. The dielectric strength of cable insulation depends on many factors such as the existence of filler material in the insulation. In this work, laboratory studies on a new filler material for cable insulation have been conducted. The influence of Silicon dioxide (SiO₂) filler on the dielectric and mechanical properties of polyvinyl chloride (PVC) cable were analyzed. Comparison is made between the result of measurement and the actual value of the pure specimen. From the results, it is shown that the filler material has improved the dielectric and mechanical properties of the cable insulation.

Abstract: In this study, CuO was synthesized via precipitation method by using Cu (CH₃COO)₂.H₂O as precursor. KOH+NH₃, KOH and NaOH were used as reactants and zwitterionic 3-(N,N-dimethyldodecylammonio) propane-sulfonate (SB12) as surfactant in the synthesis procedure. The samples were calcined at 500°C. All prepared CuO structures were characterized by X-ray diffraction (XRD), thermal gravimetric analysis (TGA), Fourier Transform Infrared (FTIR) spectra, and scanning electron microscopy (SEM) techniques. Electrochemical characterization was performed by cyclic voltammetry (CV). CuO showed different nanostructures according to the characterization results. Furthermore, electrochemical properties of the resulting structures were investigated. The specific capacitances of the CuO structures in different environments were determined by using CV technique in the order of: KOH+NH₃>KOH>NaOH.

Abstract: 2ZnO.3B₂O₃.nH₂O (Zinc borate) having the industrially important composite and used as flame retardant, anti-smoke and semiconductor in the electronic circuits was examined different crystal structures. In this study, nanofibers of PVA /zinc nitrate/ boric acid composite were prepared by using sol-gel processing and electrospinning technique. By high temperature calcinations of the above precursor fibers, nanofibers of 2ZnO.3B₂O₃.5H₂O composite with diameters of 110 nm could be successfully obtained. The products have been characterized by X-ray powder diffraction (XRD), thermogravimetry (TG) and differential thermal analysis (DTA), scanning electron microscopy (SEM) and FT-IR (Fourier transform-infrared spectroscopy). The effects of experimental conditions on the products were investigated.

Abstract: This study uses graphene nanosheets (GNs) as filling materialand PP as base materialto preparePP/GNsnanocomposites using melt compounding. In order to compensate tensile property of PP/GNs nanocomposites,carbon-fiber woven fabrics (CFW) were stacked with the PP/GNsnanocompositesusing compression molding forming PP/GNs/CFWnanocomposites. DSC, Tensile, SEMand EMI shielding effectiveness (SE) of nanocomposites are evaluated afterwards.Result displays that, after addition of carbon fabric intoPP/GNsnanocomposites, tensile strength were reinforced significantly, and EMI shielding frequency became wider.The resulting nanocomposites successfully applied in high temperature at around 160°C.

Abstract: This study combines polyvinyl alcohol (PVA) and gelatin with various ratios and administers different voltages to make PVA/gelatin electrospinning nanofiber membranes. The PVA/gelatin mixtures are measured for their viscosity and conductivity, followed by being electrospun into nanofiber membranes. The scanning electron microscope and an FT-IR are used to evaluate the membranes. The test results show that the nanofiber membranes have a complete fiber formation with the voltage being 20 kV and the PVA/gelatin ratio being 8/2. In addition, an increase in the viscosity of the PVA/gelatin mixture leads to the formation of beads.

Abstract: This study presents polyvinyl alcohol (PVA)/multi-walled carbon nanotubes (MWCNTs) composites, and examines the influence of the content of MWCNTs on the tensile and thermal properties of the PVA matrices. The test results show that an increase of 1.5 wt% of MWCNTs results in greater tensile properties of the PVA matrices, while decreasing their toughness. The interaction between MWCNTs and PVA pertains to the thermal properties of PVA matrices, which is exemplified by a significant increase in their glass transition temperature (Tg).

Abstract: We report structural, optical and magnetic behavior of polyvinylpyrrolidone (PVP) capped iron containing tin dioxide (SnO₂) nanoparticles synthesized via facile cost effective, environmentally benign, low temperature hydrothermal process. X-ray diffraction pattern of pristine SnO₂ revealed the formation of tetragonal rutile phase with lattice parameter, a = 0.479 nm, c = 0.323 nm; crystallite size being about 3 nm. The incorporation of iron resulted in progressive increase of unit cell parameters and average crystallite size, despite the fact that Fe³⁺ ion has lower ionic radius than Sn⁴⁺. The high resolution electron micrographs revealed the [110] preferred crystal orientation.

Abstract: Pure and doped Titania nanotubes (TiO2 NTs) photoanodes were fabricated by means of anodization method. The anodization was carried out in electrolytes prepared by mixing ethylene glycol (EG), ammonium fluoride (0.3 wt % NH4F) and deionized water (2 Vol % H2O) with different concentrations of dopant Fe (NO3)3∙9H2O. A constant dc power supply of 50 V was used as anodic voltage. The samples were annealed at 450 °C for 2 hours. The resultant products were characterized by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) to determine their microstructures when TiO2 NTs were doped with different amounts of Fe atoms. The diameters of TiO2 NTs were about 60-120 nm. The highest density of TiO2 NTs was obtained when the nanotubes were doped with 0.01 M of Fe. The photocatalytic activity was examined without external applied potential. The maximum photocurrent density was 3.0 mA/cm² under illumination of 100 mW/cm².

Abstract: This paper presents an investigation on titanium dioxide (TiO₂) thin film, which is used as sensing membrane for Extended-Gate Field Effect Transistor (EGFET) for pH sensing application. TiO₂ thin films were deposited using sol-gel spin coating method on indium tin oxide (ITO) substrates. After the deposition, the thin films were annealed at 300 °C for 10 and 15 min, while another sample was annealed at 400 °C for 15 min. The sensitivity measurement was taken using the EGFET setup equipment with constant-current (100 μA) and constant-voltage (0.5 V) biasing interfacing circuit. TiO₂ thin film as the pH-sensitive membrane and the working electrode was connected to a commercial metal-oxide semiconductor FET (MOSFET). The MOSFET then was connected to the interfacing circuit. The sensitivity of the TiO₂ thin film towards pH buffer solution was measured by dipping the sensing membrane in pH4, pH7 and pH10 buffer solution. For comparison, a sample of bare-ITO was also tested to see its sensitivity. We found that the TiO₂ thin film annealed at 400 °C for 15 min gave the highest sensitivity compared to other annealing conditions and also compared to the bare ITO substrate with the value of 44.30 mV/pH. This showed that TiO₂ thin film can be used for pH sensing and the post-deposition treatment of the thin film can influence the sensing ability. We also measured the TiO₂ thin films’ current – voltage (I-V) characteristics. Relating the I-V characteristic of the thin films and sensitivity, the sensing membrane with higher conductivity gave better sensitivity.