Yazar "Unal, Halil Ibrahim" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • Küçük Resim Yok
    Öğe
    Effect of surfactant on the dielectric and electrorheological properties of zinc borate/silicone oil dispersions
    (Springer, 2019) Gümüş, Ömer Yunus; Unal, Halil Ibrahim
    Zinc borate (ZB) particles dispersed in silicone oil (SO) at concentrations of phi = 5vol%-20vol% were subjected to dielectric analysis to elucidate their polarization strength, time, and mechanism. Results revealed that all virgin dispersions lacked polarization. Triton X-100, a non-ionic surfactant, was added to ZB/SO dispersions to enhance the polarizability of ZB particles. The addition of 1vol% Triton X-100 enhanced the polarizability of ZB/SO dispersions, and the 15vol%ZB/SO system provided the highest dielectric difference Delta epsilon ' (the difference in epsilon ' values at zero and infinite frequency, Delta epsilon ' = epsilon(0) - epsilon(221D)) of 3.64. The electrorheological (ER) activities of the ZB/SO/Triton-X dispersion system were determined through the ER response test, and viscoelastic behaviors were investigated via oscillation tests. A recoverable deformation of 36% under an applied electrical field strength of 1.5 kV/mm was detected through creep and creep recovery tests.
  • Küçük Resim Yok
    Öğe
    One-Pot Preparation of Electroactive Shape Memory Polyurethane/Carbon Black Blend
    (Springer, 2021) Uranbey, Leyla; Unal, Halil Ibrahim; Calis, Gokce; Gümüş, Ömer Yunus; Katmer, Sukran; Karatas, Cetin
    Shape memory polymers are the materials that can recover their original shape after a large deformation when exposed to an external stimulus such as electric field, pH, temperature, light, magnetism or humidity. With these properties, it is possible to use them in many areas in the industry. In this study, a shape-memory polymer compound was developed which is capable of changing its shape when subjected to an external voltage. Electroactive shape memory polymer compound was prepared by mixing commercially available and economically viable thermoplastic shape memory polyurethane (SMPU) with carbon black (CB), which has low cost and high electrical conductivity, by adding at various proportions. Conductivity, structural, morphological, homogeneity, thermal, rheological and shape memory characterizations of the SMPU/CB blend were carried out by four-probe measurements, ATR-FTIR spectroscopy, x-ray diffraction analysis, scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analyses, melt flow index (MFI), and a thermal camera imaging methods, respectively. The effects of CB loading ratios on these characteristics of SMPU/CB blends were investigated. It was concluded that SMPU/20CB blend can be used as a commercial material having shape memory characteristics.
  • Küçük Resim Yok
    Öğe
    Synergistic Effects of Surfactant on Dielectric and Electrorheological Properties of Boronic Acid Derivative Polymer Dispersions
    (Wiley-V C H Verlag Gmbh, 2016) Ozkan, Seyma; Gümüş, Ömer Yunus; Unal, Halil Ibrahim
    Electric field stimulus fluids are prepared by dispersing poly(3-aminophenylboronic acid, PABA) and poly(thiophene-3-boronic acid, PTBA) nanoparticles in silicone oil (SO). Upon addition of a nonionic surfactant, Triton X-100, to the fluids, enhanced polarizabilities are detected on dielectric analysis which is driven by the increased number of dipole centers in their structures. Very high colloidal stability is observed for PABA/SO/Triton-X dispersion system since it has zeta(zeta)-potential value in colloidally stable region, whereas PTBA/SO/Triton-X dispersion system exhibits some degree of sedimentation due to low zeta-potential value. When electric field strengths are applied, increased yield stresses of the dispersions are detected. Storage and loss moduli values of PABA/SO/Triton-X and PTBA/SO/Triton-X dispersions suggest that the suspensions have vibration damping capabilities. Further, reversible non-Newtonian viscoelastic deformations are observed from the creep-recovery tests of the systems and they are classified as smart materials. Furthermore, the results show that PABA based colloidal system has better dielectric and rheological properties than that of PTBA and these results are also discussed in terms of particle conductivity and molecular structure.