Browsing by Author "Bayramov A.A."

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    Effects of Electric Discharge Plasma Treatment on the Thermal Conductivity of Polymer–Metal Nitride/Carbide Composites
    (Springer New York LLC, 2015) Parali L.; Kurbanov M.A.; Bayramov A.A.; Tatardar F.N.; Sultanakhmedova R.I.; Xanlar H.G.
    High-density polymer composites with semiconductor or dielectric fillers such as aluminum nitride (AIN), aluminum oxide (Al2O3), titanium carbide (TiC), titanium nitride (TiN), boron nitride (BN), silicon nitride (Si3N4), and titanium carbonitride (TiCN) were prepared by the hot pressing method. Each powder phase of the composites was exposed to an electric discharge plasma process before composite formation. The effects of the electric discharge plasma process and the filler content (volume fraction) on the thermal conductivity, volt–ampere characteristics, thermally stimulated depolarization current, as well as electrical and mechanical strength were investigated. The results of the study indicate that, with increasing filler volume fraction, the thermal conductivity of the samples also increased. Furthermore, the thermal conductivity, and electrophysical and mechanical properties of the high-density polyethylene + 70% BN composite modified using the electric discharge plasma showed improvement when compared with that without electric discharge plasma treatment. © 2015, The Minerals, Metals & Materials Society.
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    Piezoresistive and posistor effects in polymer-semiconductor and polymer-ferropiezoceramic composites
    (Maik Nauka-Interperiodica Publishing, 2016) Mamedov H.A.; Parali L.; Kurbanov M.A.; Bayramov A.A.; Tatardar F.N.; Sabikoglu I.
    In this study, piezoresistive and posistor effects in polymer-semiconductor and polymer-ferropiezoceramic composites have been investigated. The results show that composites based on crystallizable polymers, such as PVDF, HDPE, and PP dispersed by semiconductors and ferropiezoelectric fillers have piezoresistive and posistor properties, respectively. At low pressure, charge carriers tunneling through the located thin polymer among filler particles into the barrier define the conductivity of the composite. When pressure value is increased from 0 to 1 MPa, the thickness of the interlayer decreases and tunnel conductivity descends exponentially depending on barrier height. The piezoresistor sensitivity of a composite based on PVDF-70 vol % + Si-30 vol % is higher than a composite based on HDPE-70 vol % + Ge-30 vol %. Furthermore, the posistor properties of polymer composites dispersed by ferropiezoceramic are determined as the maximum resistance that varies significantly with temperature. Posistor effect in composites based on polymer + ferropiezoceramic is associated with the height of the barrier layer, which changes according to properties of filler, polymer, and dielectric permittivity of two-phase composites. The highest specific resistance related to HDPE-70 vol % + BaTiO3-30 vol % composite was observed at ~403 K. © 2016, Pleiades Publishing, Ltd.