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- MakaleAçık Erişim2025Scopus SJRQ2Effect of Nano Titanium Dioxide on the Electrical and Thermal Properties of Poly(2,2,2-Trifluoroethyl Methacrylate) for Dielectric Materials
Barım, Esra; Torgut, Gülben
The increasing application areas of energy storage devices in recent years make it necessary to produce materials with sufficient efficiency. In this study, composites of poly(2,2,2-trifluoroethyl methacrylate) P(TFEM) homopolymer with nano titanium dioxide (TiO2 NPs) were prepared for applications of these devices requiring thermoelectric properties, and their thermal, dielectric, and electrical properties were investigated. Thermogravimetric analysis showed that TiO2 NPs in all composites limited the thermal diffusion of TiO2 NPs in the polymer matrix and increased the thermal stability of P(TFEM) from 341°C to 361.5°C. As dielectric properties, the dielectric constant (ε′), dielectric loss (ε″), AC conductivity (σac), and real (Z′) and imaginary (Z″) components of impedance of the composites containing TiO2 NPs were evaluated as functions of frequency and different weight percentages of TiO2 NPs. Increases in ε′ and ε″ at up to 15 wt% TiO2 NPs suggested increased dipole polarization. At 100 Hz, the ε″ value of P(TFEM) increased from 3.2 × 10−2 to 1.1 × 10−2, σac increased from 4.98 × 10−10 to 1.00 × 10−8, Z′ increased from 3.67 × 1010 to 8.66 × 1010, and Z″ increased from 2.09 × 108 to 4.42 × 108. Furthermore, ε′, ε″, and impedance decreased with increasing frequency for both P(TFEM) and TiO2 NPs composites, while σac increased with increasing frequency.
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İncele - MakaleYalnız künye2025Scopus SJRQ2Response surface method (RSM) for optimization of electrical properties of polymer/CdS composites for dielectric capacitors
Torğut, Gülben; İncesu, Rabia
This paper aims to present the statistical evaluation of dielectric constant (έ) and conductivity (σ) performance of composites preparing Maleic Anhydride (MA) and Styrene (St) polymer with various amounts of Cadmium Sülfide (CdS) by analysis of variance (ANOVA) model. For this purpose, frequency, applied voltage and CdS amount at different weight percentages were selected as input factors while dielectric constant and conductivity of the composites were selected as the response. Analysis of input factors was performed, RSM method was designed and used for estimation of response factor. From the analysis results, we found that high values of dielectric constant and conductivity were strongly related to frequency and CdS amount. However, we found that applied voltage in the selected ranges did not have a significant effect on both factors. The structural properties of the composites were investigated by Fourier Transform Infrared Spectroscopy (FTIR). The surface morphology was investigated by Scanning Electron Microscopy (SEM). The presence of CdS in polymers has been proven by X-Ray Diffraction (XRD). The thermal properties of polymers were examined by thermogravimetric analysis (TGA).
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İncele - MakaleAçık Erişim2024Scopus SJRQ3Structural, Dielectric, and Electrical Properties of Chitosan Composites Doped with Silver for Electrochemical Applications
Ayhan, Nagihan Karaaslan; Torgut, Gulben
In this study, chitosan-silver (Chs-Ag) composites containing Ag in different concentrations (0.01–0.08 M) were prepared. The characterization and structure studies of the composites containing 0.01, 0.02, 0.04, and 0.08 M Ag were carried out, and then the dielectric properties of these composites were examined. The composites were characterized by Fourier transform infrared spectrophotometer (FTIR), scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS), and thermogravimetric analysis (TGA). The dielectric and electrical properties of these composites were investigated depending on the frequency at room temperature, and these properties were determined using an impedance analyzer. Spectroscopy revealed that the dielectric constant (ε′), dielectric loss (ε′′), and real (Z′) and imaginary (Z″) components of impedance are found to decrease with increased frequency for both Chs and Chs-Ag (0.01M–0.08 M) composites. On the contrary, the AC conductivity (σac) of samples increased with increasing frequency. ε′ and ε′′ values of Chs were lower than when the Ag was added. The AC conductivity was improved by the addition of silver particles. The results show that the dielectric and electrical properties of Chs-Ag samples were improved by using Ag as filler.
AtıfScopus3WoS3OpenAlex4İncele - MakaleYalnız künye2023Scopus SJRQ1Improving dielectric properties, electrical conductivity, and thermal properties of biodegradable polymer composites prepared with lanthanum
Torgut, Gulben; Ayhan, Nagihan Karaaslan; Acikses, Aslisah
The precipitation method was adapted to synthesize the poly(ε-caprolactone-copolymer- ethylene oxide) (ε-CL-co-EO) composite with the salt of lanthanum (La), a rare earth element. This salt was incorporated into the polymer of different weight percentages to study how it affects the thermal and dielectric properties of the polymer. The resulting products were characterized by Fourier Transform Infrared Spectroscopy, X-ray diffractometry (XRD), Scanning electron microscopy (SEM) and thermogravimetric analysis. XRD and SEM data show that the polymer mixes homogeneously with the metal salt. Thermal degradation data show that the thermal stability of composites synthesized with La is lower than that of pure polymer. The dielectric properties and A.C conductivity measurements of the composites were investigated by using impedance analyzer in the frequency range (100 Hz to 20 kHz) at room temperature. The electrical property results of (ε-CL-co-EO)/La composites displayed that dielectric constant (έ), dielectric loss (ε"), tan delta (tan δ) and A.C electrical conductivity (σac) increase with increasing La content. The largest conductivity of (ε-CL-co-EO)/La composite filled with 20 wt% La was 8.80 × 10−8 S/cm, which was 162% times pure (ε-CL-co-EO). In addition, impedance (IZI) of composites was evaluated from the dielectric data. This procedure is eco-friendly and easy to handle, which provides a promising route to polymer composites in the application of the conductivity field.
AtıfScopus6WoS6OpenAlex7İncele - MakaleYalnız künye2022Scopus SJRQ2Physicomechanical, thermal and dielectric properties of eco-friendly starch-microcrystalline cellulose-clay nanocomposite films for food packaging and electrical applications
Gürler, Nedim; Torğut, Gülben
Potato starch (PS) films reinforced with microcrystalline cellulose (MCC) were prepared with casting solution, and the effect of montmorillonite (MMT) clay in different proportions (1, 3, 5 and 10 wt%) using nanofiller was established. The films were investigated by Fourier transform ınfrared (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), tensile strength, opacity, colour, water vapour permeability and solubility. Tensile strength for nanocomposite films depending on the clay content was increased significantly from 0.64 to 1.89 MPa. The water vapour permeability of nanocomposite films was improved compared to the PSMCC blend without MMT. Also, dielectric properties and electrical conductivity of films were studied. The dielectric permittivity (έ), the dielectric loss (ε˝) and the electrical conductivity (σ) increased with increasing MMT content at frequencies between 100 Hz to 10 kHz. This nanocomposite with improved functional properties could be used in potential food packaging materials and electrical applications.
AtıfScopus21WoS19İncele - MakaleYalnız künye2019Scopus SJRQ1Fabrication, characterization of poly(MA-co-NIPA)-graphene composites and optimization the dielectric properties using the response surface method (RSM)
Torğut, Gülben
Poly(Maleic anhydride-N-isopropyl acrylamide poly(MA-co-NIPA) copolymer was synthesized by Free radical polymerization method. Response surface methodology (RSM) was used for optimizing the dielectric constant (έ) and dielectric loss factor (ε՛՛). The aim of this study is to determine the quantitative relationship between selected parameters (frequency, applied voltage and graphene content) at room temperature. The importance of process parameters in the model is assessed by analysis of variance (ANOVA) investigation. Our results show that, with increasing the frequency the έ and ε՛՛ of the polymers decreases, whereas voltage has no significant effect on έ and ε՛՛ of the composites. With the incorporation of graphene into poly(MA-co-NIPA) the έ and ε՛՛ considerably increased by 244% and 387% respectively. The model predicted the maximum value of the έ (13) when the frequency was set at 4506, the voltage was set at 1.45, and the graphene content was set at 14.97 wt%. Also, the RSM indicated that maximum ε՛՛ (1969) was achieved at the frequency of 512, at the voltage of 20.44, and at the graphene content of 14.76 wt%. The morphology of composites was investigated by scanning electron microscopy (SEM). SEM results demonstrated that the poly(MA-co-NIPA)-graphene composites has interconnected and they form different morphologies with the increase of GNs content. ATR tests showed that no significant change in chemical bond and crystallization is found in composites.
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