Asian Transactions on Science & Technology
Volume: 01, Issue: 04, September 2011
Title: Electrical Characterization of Polyvinyl Alcohol Films Doped with Sodium Iodide
Authors: Omed Gh. Abdullah, Sarkawt A. Hussen, and Ahmad Alani
Paper ID: ATST-40106045
Abstract: Polyvinyl alcohol (PVA) films doped with sodium iodide up to (30 wt%) were prepared in order to investigate the effect of sodium iodide additions on the electrical properties of PVA host. The dielectric permittivity, dielectric loss, electric modulus and ac conductivity were studied in the frequency range 20 KHz-1 MHz and in temperature range 300-350 K. Upon increasing the contents of sodium iodide an increase in the dielectric permittivity, dielectric loss and ac conductivity of PVA host are observed. The ac conductivity is 0 ac found to obey the power law Bws. The frequency exponential factor s was estimated and it was found to vary between 0.92 and 0.34, dependant on the sodium iodide content. From the temperature dependence of the ac conductivity, an increase of activation energy was observed with dopant concentration.
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Title: Effect of aging and load on the dry sliding wear behavior of Ni3Al particles reinforced 2124Al matrix composites
Authors: Mehtap Demirel, Mehtap
Paper ID: ATST-70129048
Abstract: Interest in aluminium alloy composites as wear resistant materials continues to grow. So, this study reports the influence of load on dry sliding wear behaviour of the 2124 Al alloys reinforced with Ni3Al intermetallic. 2124 Al alloy and the composites was produced by powder metallurgy. All materials were mixed and cold compacted, the specimens were sintered and heat-treated (T6 treatment). The experiments were performed both as sintered and heat-treated conditions using pin-on-ring test machine. The wear properties of 2124 Al alloy- Ni3Al composites and the unreinforced 2124 Al alloy were examined at a constant speed of 0,4 m\s and at a constant sliding distance of 1500 m within a load in the range 83-150N. The friction coefficient was measured for all test materials. A complete micro-structural study were done by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). With increasing load, the sintered materials offered superior wear resistance to the heat treated materials (although the heat-treated materials offered superior wear resistance to the sintered materials at lower loads). A mechanically mixed layer (MML) was observed for 2124 Al-5-15 wt. % Ni3Al composites, and it was found that the thickness of MML increased with the increasing weight percentage of reinforcement.
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Title: Effect of Kaolin light concentration on optical characteristic of PVA films
Authors: Omed Gh. Abdullah, Bakhtyar K. Aziz
Paper ID: ATST-90111040
Abstract: The solution cast technique was used to prepare composite films of polyvinyl alcohol with different Kaolin light concentrations. The optical absorption measurements were carried out for all samples at room temperature across the (190 -1100 nm) wavelength regions. The optical parameters including the energy band gaps and band tail width for the samples are investigated; it was found that the optical absorption is due to direct transition, and the optical energy gaps values shifted to lower energies on kaolin light concentration from 5.53 eV for pure PVA to 5 eV for 20% kaolin addition, whereas the magnitudes of the Urbach energy tends to increase with increasing kaolin light concentration from 0.69 eV for pure PVA to 2.51 eV for 20% kaolin addition. In general the kaolin content in polymer matrix caused an increase of extinction coefficient values, which is a result of increasing the number of atomic refractions due to the increase of the linear polarizability. Thermal study of the composite films was investigated. From thermogravimetric analysis it was found that the thermal stability of the PVA sample is decreased with increasing kaolin content.
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