Person: ESMER, KADİR
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ESMER
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KADİR
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Publication Metadata only Investigation of Dielectric Properties of Polyethylene-Clay Nanocomposites for Quantifying Nanofiller Dispersion(POLYMER SOC KOREA, 2018) ESMER, KADİR; Yildirim, Saffettin; Pehlivan, Kubra; Durmus, Ali; Esmer, KadirThis study examined the dielectric properties of linear low density polyethylene (LLDPE)/organo-clay nano composites including the same amount of maleic anhydride grafted polyethylene (PE-g-MA) and oxidized polyethylene (OxPE) as compatibilizer at different frequencies (10(-1)-10(+7) Hz) and temperatures (237-373 K). The dielectric constant of natural LLDPE remained constant at around 1.5, depending on the temperature rise and frequency while that of LLDPE-PE-g-MA/clay and LLDPE-OxPE/clay nanocomposites increased up to 4.8 and 2.8, respectively, linearly with increasing temperature. Especially in the low frequency region, a Maxwell-Wagner-Sillars polarization was observed in composite structures with an increase in temperature due to the dipolar effect. It has been concluded that the clay in the polymer matrix was more homogeneously dispersed than OxPE due to the compatibilizing effect of PE-g-MA and that different polarization mechanisms were at play for each compatibilizer.Publication Metadata only Effects of Solution Mixing Temperature on Dielectric Properties of PMMA/Pristine Bentonite Nanocomposites(WILEY, 2014) ESMER, KADİR; Kaya, A. Ugur; Guner, Selahaddin; Esmer, KadirWe examined the effects of mixing temperature on the dielectric properties of polymethylmethacrylate (PMMA)-pristine bentonite nanocomposites by using X-ray diffraction, FT-IR and dielectric spectroscopies. The samples were prepared during 8 hours at temperatures 265 K, 273 K, 281 K, 289 K and 298 K without any intercalative agent and the PMMA to pristine bentonite weight ratio was chosen as 1 : 10. It was observed that with decreasing the mixing temperatures, the permittivity decreases and the dielectric relaxation displaces towards the lower frequencies with the decrease of mixing temperatures. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39907.Publication Metadata only Structural and dielectrical properties of PMMA/TiO2 composites in terms of free volume defects probed by positron annihilation lifetime spectroscopy(SAGE PUBLICATIONS LTD, 2021) TAV, CUMALİ; Kaya, A. U.; Kosem, G.; Yener, M. Y.; Tav, C.; Yahsi, U.; Esmer, K.A suspension of ultrasonically agitated Titanium dioxide micrometer-sized powder has been introduced into a poly(methyl methacrylate) (PMMA) matrix by solvent (CHCl3) mixing under slow mechanical stirring, and the resulting suspension was used to cast free-standing PMMA/TiO2 composite films. Filler contents from 0 wt% to 7.5 wt% were selected, since TiO2 particles could not be previously suspended in chloroform at higher concentrations by ultrasonic agitation. Optical and dielectric properties of composites were determined by ultraviolet (UV)-visible and dielectric spectrometry. In the UV region, 450% improvement of UV absorption was achieved in the TiO2/PMMA composite compared with neat PMMA. The structural properties and hole-free volume of the composites were determined by X-ray diffractometry and positron annihilation lifetime spectroscopy, respectively. The particle size and homogeneous dispersion of the particles in the polymer matrix were related to the hole-free volume of the PMMA.Publication Metadata only Preparation, characterisation, and dielectric properties of polypyrrole-clay composites(SPRINGER INTERNATIONAL PUBLISHING AG, 2013) ÇAKMAKÇI, EMRAH; Madakbas, Seyfullah; Cakmakci, Emrah; Kahraman, Memet Vezir; Esmer, KadirIn this study, polypyrrole-clay (PPy-clay) composites were prepared by the in situ chemical oxidative polymerisation of pyrrole in the presence of clay. The chemical structures of the composites were characterised by FTIR and XRD analysis. The thermal properties of these novel composites were analysed by TGA and DSC measurements. Glass-transition temperatures and char yields increased with the increase in clay content in the nanocomposites. The interactions between PPy and clay were mainly between polypyrrole and the layers of clay. It was observed that, as the amount of clay in the composites increased, the dielectric permittivity decreased while the dielectric conductivity of the composite materials increased.Publication Open Access Structural and Dielectric Properties of Eu3+, B3+ co-doped CoNb2O6 Ceramic(2024-04-01) EKMEKÇİ, METE KAAN; ESMER, KADİR; İLHAN M., EKMEKÇİ M. K., ESMER K.The boron co-doped CoNb2O6:xEu3+, yB3+ (x=1, 3, 6, 9, 12 mol%, y=10 mol%) ceramics were obtained by the molten salt method, which has advantageous properties such as short reaction time, low sintering temperature, improved homogeneity, and crystallinity. The ceramic samples were examined by structural and dielectric analyses. In X-ray diffractions, the orthorhombic columbite type CoNb2O6 structure was obtained, and also a minor EuNbO4 phase was detected with increasing Eu3+ doping concentrations. Additionally, increasing Eu3+ concentration led to a slight increase in crystallite size, and two theta peak shifts occurred towards higher angles associated with shrinkage in the lattice or reduction in the lattice constant. In SEM examinations, a slight increase was observed in grain sizes from 1 to 9 mol% Eu3+ in the range of 1-30 m, while some decrease occurred in grain sizes at 12 mol%, and there was an evident increase in plate-shaped and elongated grains. The dielectric constant (ε') of the ceramic samples increased with increasing Eu3+ concentration and reached approximately 35 and 0.24 at 20 Hz for 9 mol% Eu3+, respectively. The increase in dielectric loss with increasing Eu3+ was associated with an increase in ionic conductivity, in which Eu3+ substitution does not suppress oxygen vacancies or make them more ordered.Publication Metadata only Investigation of Temperature, Thermodynamic Parameters and Dielectrical Properties of Poly(vinylimidazole)-Na-Bentonite Nanocomposite(WILEY, 2011) ESMER, KADİR; Kaya, A. Ugur; Esmer, Kadir; Tekin, Nalan; Beyaz, Saadet K.The adsorption of poly(vinylimidazole) (PVI) onto Na-Bentonite from aqueous solutions has been investigated as a function of temperature. According to the experimental results, the adsorption of PVI decreases with temperature from 25 to 55 degrees C. The study of temperature effect has been quantified by calculating various thermodynamic parameters such as Gibbs free energy, enthalpy and entropy changes. The electrical and dielectrical properties of PVI Na Bentonite composite have been investigated. The current-voltage studies show that conductivity was increased at T = 25 degrees C. The dc conductivity was calculated at T = 25 degrees C. The samples show typical dielectric behavior from capacitive measurements. Depending on maximum interactions at 25 degrees C, ac conductivity and loss factors are also in high values. Especially, at frequencies over 1.5 kHz, it was seen completely clay behavior. Variation of tangent loss factor-frequency shows decreasing of polarization density in structure in high frequency. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 874-879, 2011Publication Metadata only Mechanical, electrical and tribological properties of graphite filled polyamide-6 composite materials(WALTER DE GRUYTER GMBH, 2013) ESMER, KADİR; Unal, Huseyin; Esmer, Kadir; Mimaroglu, AbdullahIn this study, the influence of adding graphite filler, on the mechanical, electrical and tribological properties of nylon-6 composites, is studied. Graphite fillers with different percentages, varying between 5 and 15 wt% were added to nylon-6 polymer material. Nylon-6 composite samples were prepared by the injection molding process. Tensile, impact, electrical and tribological tests were carried out and the dielectric permittivity tangent loss factor, tensile strength, modulus of elasticity, elongation at break, impact strength, specific wear rate and coefficient of friction properties were obtained. The results showed that the tensile strength, elongation at break, impact strength, and specific wear rate of nylon-6 composites, decrease with the increase in graphite filler weight ratio, while the modulus of elasticity, hardness, real part of dielectric permittivity, imaginary part of dielectric permittivity and dielectric loss, increase with increase in the filler weight ratio. Furthermore, it is observed that a rise in the relaxation time of ionic polarization is proportional to the increase in the amount of graphite in the medium and the dielectric conductivity and loss decrease proportionally after approximately 10 KHz. Finally, the maximum improvement in properties, in total, is recorded following the addition of 5 to 10 wt% graphite filler.