Electrical and Thermal Characterization of Electrospun PVP Nanocomposite Fibers

Polyvinylpyrrolidone (PVP) solutions incorporated with multiwall carbon nanotubes (MWCNTs) were electrospun at various weight percentages, and then the electrical resistance and some thermal properties of these nanocomposite fibers were determined using a high-accuracy electrical resistance measurement device. During the electrospinning process, system and process parameters, such as concentrations, applied voltage, tip-to-collector distance, and pump speeds, were optimized to receive the consistent nanocomposite fibers. When polymers are used in many industrial applications, they require high electrical and thermal conductivities. Most polymers exhibit low electrical conductivity values; however, in the presence of conductive inclusions, the electrical resistance of the MWCNT fibers was reduced from 50 MΩ to below 5 MΩ, which may be attributed to the higher electrical conductivities of these nanoscale inclusions and fewer voids under the applied loads. This study may open up new possibilities in the field for developing electrically conductive novel nanomaterials and devices for various scientific and technological applications

Drug-Carrying Magnetic Nanocomposite Particles for Potential Drug Delivery Systems

Drug-carrying magnetic nanocomposite spheres were synthesized using magnetite nanoparticles and poly (D,L-lactide-co-glycolide) (PLGA) for the purpose of magnetic targeted drug delivery. Magnetic nanoparticles (∼13 nm on average) of magnetite were prepared by a chemical coprecipitation of ferric and ferrous chloride salts in the presence of a strong basic solution (ammonium hydroxide). An oil-in-oil emulsion/solvent evaporation technique was conducted at 7000 rpm and 1.5–2 hours agitation for the synthesis of nanocomposite spheres. Specifically, PLGA and drug were first dissolved in acetonitrile (oily phase I) and combined with magnetic nanoparticles, then added dropwise into viscous paraffin oil combined with Span 80 (oily phase II). With different contents (0%, 10%, 20%, and 25%) of magnetite, the nanocomposite spheres were evaluated in terms of particle size, morphology, and magnetic properties by using dynamic laser light scattering (DLLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and a superconducting quantum interference device (SQUID). The results indicate that nanocomposite spheres (200 nm to 1.1 μm in diameter) are superparamagnetic above the blocking temperature near 40 K and their magnetization saturates above 5 000 Oe at room temperature

Improvement of the magnetic properties for Mn–Ni–Zn ferrites by rare earth Nd3+ ion substitution

Single spinel phases of Mn0.5Ni0.1Zn0.4NdxFe2−xO4 ferrite samples (x = 0.0, 0.01, 0.02, 0.05, 0.075, and 0.1) have been prepared by ceramic method and the composition dependence of the physical and magnetic properties has been investigated. SEM micrographs and EDX analysis revealed that there is no considerable effect for the Nd3+ ion substitution on the average grain size or porosity, whereas its concentration in the grain boundaries is higher than that in the grains. Saturation magnetization (MS) increased with the Nd3+ ion concentration (x) and reached a maximum value at x = 0.05. In addition, both the initial permeability and the magnetic homogeneity increased by increasing the Nd3+ ion content. The value of Curie temperature increased due to the substitution by Nd3+ ions to record about 170 K, for the sample with x = 0.05, higher than that of the un-substituted one

Microstructure and Superparamagnetic Properties of Mg-Ni-Cd Ferrites Nanoparticles

Magnesium substituted nickel cadmium ferrite nanoparticles MgxNi0.6−xCd0.4Fe2O4 (from x = 0 to 0.6 with step 0.1) have been synthesized by the chemical coprecipitation route. X-ray diffraction (XRD) and infrared spectroscopy (FTIR) revealed that the obtained powders have a single phase of cubic spinel structure. The crystallite sizes calculated from XRD data have been confirmed using transmission electron microscopy (TEM) showing that the powders are consisting of nanosized grains with an average size range 5–1.5 nm. Magnetic hysteresis loops were traced at 6.5 K as well as at room temperature using VSM. It was found that, due to the Mg2+-ions substitution, the values of saturation magnetization Ms for the investigated samples were decreased, whereas the coercive field Hc increased. Both zero field cooling (ZFC) and field cooling (FC) curves are measured in the temperature range (6.5–350 K) and the values of blocking temperature TB were determined. No considerable variation in the values of TB was observed with increasing Mg-content, whereas the values of the effective anisotropy constant Keff were increased

Electrical and thermal characterization of electrospun PVP nanocomposite fibers

Polyvinylpyrrolidone (PVP) solutions incorporated with multiwall carbon nanotubes (MWCNTs) were electrospun at various weight percentages, and then the electrical resistance and some thermal properties of these nanocomposite fibers were determined using a high-accuracy electrical resistance measurement device. During the electrospinning process, system and process parameters, such as concentrations, applied voltage, tip-to-collector distance, and pump speeds, were optimized to receive the consistent nanocomposite fibers. When polymers are used in many industrial applications, they require high electrical and thermal conductivities. Most polymers exhibit low electrical conductivity values; however, in the presence of conductive inclusions, the electrical resistance of the MWCNT fibers was reduced from 50 MΩ to below 5 MΩ, which may be attributed to the higher electrical conductivities of these nanoscale inclusions and fewer voids under the applied loads. This study may open up new possibilities in the field for developing electrically conductive novel nanomaterials and devices for various scientific and technological applications