A.C electrical conductivity and dielectric properties for poly
(vinyl alcohol) (PVA) /poly (ethylene oxide) (PEO) blends undoped
and doped with multi-walled carbon nanotube (MWCNTs) with
different concentrations (1, and 3 wt %) in the frequency range
(25x103 - 5x106 Hz) were investigated. Samples of (PVA/PEO)
blends undoped and doped with MWCNTs were prepared using
casting technique. The electrical conductivity measurements showed
that σA.C is frequency dependent and obey the relation σA.C =Aωs for
undoped and doped blends with 1% MWCNTs, while it is frequency
independent with increases of MWCNTs content to 3%. The
exponent s showed proceeding increase with the increase of PEO
ratio (≥50%) for undoped blends samples, while s value for doped
blends exhibits to change in different manner, i.e. s increases and
reach maximum value at 50/50 PVA/PEO, then decreases for
residual doped blends samples with 1% MWCNTs on the other hand
the exponent s decrease and reach minimum value at 50/50
PVA/PEO for samples doped with 3% MWCNTs, then return to
increase. The results explained in different terms.
The Rock Wool Board (RWB) is widely used in the building exterior insulation all over world. As polymer affects hardening of plate, meaning it acted as a basic binder in this work and gave a smooth texture, ease of carrying and workmanship in different sizes and shapes. PVA was studied at the rates of PVA %4, %5, %6.66, %10, %20, results showed that 6.66% is the best percentage, through tensile and bending tests, this percentage was use with polyurethane with rates of PU 1, 0.5, 0.333, 0.25, 0.2 It is found that the ratio 0.333 is the best ratio to give good mechanical properties of bending, tensile and elongation. This percentage was fixed on different percentages of polymer (PU/PVA) as %2.5, %5, %10, %15, %20 and examinations
... Show MoreEpoxy (EP) – Silica (SiO2) composites are well known composites used in microelectronic industry . So it is important to study their dielectric behavior under different conditions such as
the presence carbon black (UV absorber) and immersion in the water for 30 days .
Dielectric properties were calculated over the frequency range 102 – 106 Hz for epoxy composites with different weight % of micrometer 1.5μm SiO2 particles (60%, 65% and 70wt%) modified with 0.5wt% silane coupling agent to improve adhesion between EP and SiO2 phases .
A significant influence of temperature width found on the vanadium oxide properties, it plays a major role in highlighting the thermal limits of the three phases (metallic, semiconductor, and dielectric). Two values of the temperature width , and , had taken and studied their effect on both the dielectric constant and its two parts; refractive index, and extinction coefficient, and. It found that: as the temperature width is greater, the more the properties of the three phases for . In addition to increasing the thermal range for phases which can be reached to when , while it's at . Our results have achieved great compatibility with the published results globally. In addition to the effect of both ultraviolet, visible, and infrared
... Show MoreThe present studies are focused on the modification of the properties of epoxy resin with different additives namely aluminum, copper by preparing of composites systems with percentage (20%, 40% and 50%) of the above additives. The experimental results show that the D.C of conductivity on wt% filler content at ( 293-413 ) K electrical conductivity of all above composites increased with temperature for composites with filler contact and find the excellent electrical conductivity of copper and lie between (2.6*10-10 - 2.1*10-10)?.cm . The activation energy of the electrical conductivity is determined and found to decrease with increasing the filler concentration.
In this research prepared two composite materials , the first prepared from unsaturated polyester resin (UP) , which is a matrix , and aluminum oxide (Al2O3) , and the second prepared from unsaturated polyester resin and aluminum oxide and copper oxide (CuO) , the two composites materials (Alone and Hybrid) of percentage weight (5,10,15)% . All samples were prepared by hand layup process, and study the electrical and thermal conductivity. The results showed decrease electrical conductivity from (10 - 2.39) ×10-15 for (Up+ Al2O3) and from (10 - 2.06)×10-15 for (Up+ Al2O3+ CuO) .But increase thermal conductivity from( 0.17 - 0.505) for (Up+ Al2O3) and from (0.17 - 0.489) for (Up+ Al2O3+ CuO).
This article includes the preparation of luminescence materials from rare earth (Eu ) ion doping Yttrium Oxide (Y2O3) 70% and SiO2 25% and study the characteristics of phosphors for ultraviolet to visible conversion. The phosphor materials have been synthesized by two steps: Preparing the powder by solid state method using Y2O3, SiO2 and Eu2O3 with doping materials concentration (70%, 25% and 5%) respectively and different calcination temperature (1000, 1200 and 1400 oC).
The second step is to prepare the colloid solution by dispersing the produced powder in a polyvinyl alcohol solution (4%) .
Powde
... Show MoreOptical properties and surface morphology of pure and doped Polystyrene films with different divalent metals of Zn, Cu and Sn and one concentration percentage have been studied. Measurements of UV-Vis spectrophotometer and AFM spectroscopy were determined. The absorbance, transmittance and reflectance spectrums were used to study different optical parameters such as absorption coefficient, refractive index, extinction coefficient and energy gap in the wavelengths rang 200-800nm. These parameters have increased in the presence of the metals. The change in the calculated values of energy gaps with doping metals content has been investigated in terms of PS matrix structural modification. The value of opt
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