Evaluation of Electrical Characteristics for PMMA-TiO2 Nanocomposites Used in Dentistry

2018 ◽  
Vol 69 (1) ◽  
pp. 155-159 ◽  
Author(s):  
Eugenia Eftimie Totu ◽  
Elena Voicila ◽  
Vlad Pistritu ◽  
Gheorghe Nechifor ◽  
Corina Marilena Cristache
Keyword(s):  
Electrical Conductivity ◽  
Impedance Analysis ◽  
Dielectric Constants ◽  
Uv Exposure ◽  
Electrical Characteristics ◽  
Casting Method ◽  
Nano Tio2 ◽  
Electrical Conductivity Increase ◽  
Conductivity Increase ◽  
Electrical Conductivities

In this paper, it is studied the influence of TiO2 nanoparticles content (0.2-5% wt:wt) on the electrical conductivities and the dielectric constants of poly (methyl methacrylate) (PMMA) nanocomposites used for 3D printing in dentistry. The nanocomposites films, which have been obtained applying the casting method followed by UV exposure, were mounted in a four electrodes cell for the electrochemical a.c. impedance analysis. The experimental data showed that both the dielectric constant and the electrical conductivity increase with increasing amounts of nano-TiO2 in nanocomposites. However, the change in the electrical conductivity is not significant for less 1% nano-titania added.

Structural, Optical and D.C Electrical Properties of (PVA-PVP-Y2O3) Films and Their Application for Humidity Sensor

2017 ◽  
Vol 6 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Majeed Ali Habeeb ◽  
Leal Abdullah Hamza
Keyword(s):  
Yttrium Oxide ◽  
Humidity Sensor ◽  
Optical Microscope ◽  
Peak Position ◽  
Dielectric Constants ◽  
Energy Band Gap ◽  
Casting Method ◽  
Electrical Conductivity Increase ◽  
Conductivity Increase ◽  
Yttrium Oxide Nanoparticles

The films prepared by casting method with different percentages of nano yttrium oxide (0, 3, 6, 9 and 12) wt%, where optical microscope images show the yttrium nanoparticles form a continuous network inside the polymers when the proportion of (12 wt%). FTIR spectra shows shift in peak position as well as change in shape and intensity, comparing with pure (PVA-PVP) films, this indicates decoupling between the corresponding vibrations of two polymers and yttrium nanoparticles, and we noted that there is a decrease in transmittance at increasing the proportion of yttrium oxide nanoparticles. Scanning electron microscopy shows the surface morphology of the (PVA-PVP-Y2O3) films many aggregates or chunks randomly distributed on the top surface, homogeneous and coherent. The absorbance increases with increase the weight percentages of nano yttrium oxide. The absorption coefficient, extinction coefficient, refractive index, real and imaginary parts of dielectric constants and optical conductivity are increasing with increase the weight percentages of yttrium oxide. The energy band gap decreases with increasing the weight percentages of yttrium oxide. The D.C electrical conductivity increase by increasing yttrium oxide concentrations and temperature. The activation energy decreases by increasing yttrium oxide concentrations. The resistance of the sensor decreased as humidity increased.

The Measurement of Dielectric Constant and Electrical Conductivity of ER Fluids

2013 ◽  
Vol 711 ◽  
pp. 51-55
Author(s):  
Nan Hui Yu ◽  
Ji Jun Fan
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Constant ◽  
Dielectric Constants ◽  
Ion Concentration ◽  
Frequency Method ◽  
Electrical Field Strength ◽  
Electrical Fields ◽  
Electrical Conductivities ◽  
Er Fluids ◽  
Er Fluid

In this paper, the dielectric constants of ER fluids with different particle concentration were measured by frequency method, and their electrical conductivities under different external electrical fields were also measured by method of conductivity cell constant. The results obtained from above measurements are as follows: the dielectric constant of ER fluid increases with the increasing of concentration; its electrical conductivity of the same concentration increases with the increasing of electrical field strength; for gradually increasing concentration, the conductivity first increases, then decreases. From analysis, it is suggested that the change of effective ion concentration of ER fluid is an important reason for its variation of conductivity.

scholarly journals Влияние электронного облучения на диэлектрические характеристики монокристаллов AgGaSe-=SUB=-2-=/SUB=-

2019 ◽  
Vol 61 (10) ◽  
pp. 1743
Author(s):  
А.У. Шелег ◽  
В.Г. Гуртовой
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Electron Irradiation ◽  
Frequency Dispersion ◽  
Significant Frequency ◽  
Electrical Conductivity Increase ◽  
Conductivity Increase ◽  
Measuring Field ◽  
Dielectric Constant Decrease

The effect of various doses of electron irradiation on the dielectric constant and electrical conductivity of triple nonlinear AgGaSe2 crystals at different measuring field frequencies in the temperature range of 100-300 K has been investigated. It has been found that single-crystal irradiation leads to a dielectric constant decrease and an electrical conductivity significant increase. It is shown that the dielectric constant and electrical conductivity increase with an temperature increase. It has been established that AgGaSe2 crystals are characterized by the presence of several conductivity types. A significant frequency dispersion of the dielectric properties of the investigated crystals was found.

scholarly journals Thermal and Electrical Conductivity of Unsaturated Polyester Resin Filled with Copper Filler Composites

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Kemal Yaman ◽  
Özer Taga
Keyword(s):  
Electrical Conductivity ◽  
Polyester Resin ◽  
Unsaturated Polyester ◽  
Filler Particle ◽  
Unsaturated Polyester Resin ◽  
Electrical Conductivity Increase ◽  
Conductivity Increase ◽  
Filler Particle Size ◽  
Polyester Matrix ◽  
Composite Mixture

Thermal and electrical conductivity of unsaturated polyester resin with copper filler composite material are investigated both theoretically and experimentally. In the experiments, polyester matrix is combined with dendrite-shape copper to determine the effects of both filler size and content on thermal and electrical conductivity, respectively. It is observed that the increase in the concentration causes the thermal and electrical conductivity of composite mixture to grow up. It has also been observed that the both thermal and electrical conductivity increase with increasing filler particle size.

Electrical conductivity studies on silica phases and the effects of phase transformation

2019 ◽  
Vol 104 (12) ◽  
pp. 1800-1805
Author(s):  
George M. Amulele ◽  
Anthony W. Lanati ◽  
Simon M. Clark
Keyword(s):  
Electrical Conductivity ◽  
Activation Volume ◽  
Activation Enthalpy ◽  
Hydrogen Charge ◽  
Charge Compensation ◽  
Composition Analysis ◽  
Conductivity Measurements ◽  
Pressure System ◽  
Electrical Conductivities ◽  
Silica Phases

Abstract Starting with the same sample, the electrical conductivities of quartz and coesite have been measured at pressures of 1, 6, and 8.7 GPa, respectively, over a temperature range of 373–1273 K in a multi-anvil high-pressure system. Results indicate that the electrical conductivity in quartz increases with pressure as well as when the phase change from quartz to coesite occurs, while the activation enthalpy decreases with increasing pressure. Activation enthalpies of 0.89, 0.56, and 0.46 eV, were determined at 1, 6, and 8.7 GPa, respectively, giving an activation volume of –0.052 ± 0.006 cm3/mol. FTIR and composition analysis indicate that the electrical conductivities in silica polymorphs is controlled by substitution of silicon by aluminum with hydrogen charge compensation. Comparing with electrical conductivity measurements in stishovite, reported by Yoshino et al. (2014), our results fall within the aluminum and water content extremes measured in stishovite at 12 GPa. The resulting electrical conductivity model is mapped over the magnetotelluric profile obtained through the tectonically stable Northern Australian Craton. Given their relative abundances, these results imply potentially high electrical conductivities in the crust and mantle from contributions of silica polymorphs. The main results of this paper are as follows:The electrical conductivity of silica polymorphs is determined by impedance spectroscopy up to 8.7 GPa.The activation enthalpy decreases with increasing pressure indicating a negative activation volume across the silica polymorphs.The electrical conductivity results are consistent with measurements observed in stishovite at 12 GPa.

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