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    Preparation and mechanical properties of carbon nanotube grafted glass fabric/epoxy multi-scale composites
    (Taylor & Francis Ltd, 2017) Eskizeybek, Volkan; Avci, Ahmet; Gulce, Ahmet
    In the present paper, carbon nanotubes (CNTs) were chemically grafted onto surfaces of the amino silane-treated glass fabric by a novel chemical route for the first time to create 3D network on the glass fibers. The chemical bonding process was confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy. The glass fabric/CNT/epoxy multi-scale composite laminates were fabricated with the CNT grafted fabrics using vacuum assisted resin infusion molding. Tensile tests were conducted on fabricated multi-scale composites, indicating the grafting CNTs on glass fabric resulted a decrease (11%) in ultimate tensile strength while toughness of the multi-scale composite laminates were increased up to 57%. Flexural tests revealed that the multi-scale composite laminates prepared with CNT grafted glass fabric represent recovering after first load fall. The interfacial reinforcing mechanisms were discussed based on fracture morphologies of the multi-scale composites.
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    Preparation of a New Polyaniline/CdO Nanocomposite and Investigation of Its Photocatalytic Activity: Comparative Study under UV Light and Natural Sunlight Irradiation
    (Amer Chemical Soc, 2013) Gulce, Handan; Eskizeybek, Volkan; Haspulat, Bircan; Sari, Fahriye; Gulce, Ahmet; Avci, Ahmet
    Polyaniline (PANI)/CdO nanocomposite was prepared for the first time in aqueous diethylene glycol solution medium, by chemical oxidative polymerization, and its photocatalytical activity was studied. Optical analysis of the new PANI/CdO nanocomposite revealed that electron densities and bond energies of the PANI homopolymer decreased after modifying with CdO nanoparticles, due to interactions between PANI chains and CdO nanoparticles. The prepared PANI/CdO nanocomposite exhibits excellent photocatalytic activity under both UV light and natural sunlight irradiation. The photocatalytic decolorization rate was increased up to 7 times after CdO addition, compared to the decolorization rate of PANI homopolymer under UV light irradiation. During the photocatalytic activity investigations, methylene blue and malachite green dyes were photocatalytically decolorized under natural sunlight irradiation with 99% efficiency by the use of 0.4 mg/mL PANI/CdO nanocomposite as photocatalyst. Furthermore, the PANI/CdO photocatalyst retains its efficiency with slight decreases upon being reused up to five times.
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    The Mode I interlaminar fracture toughness of chemically carbon nanotube grafted glass fabric/epoxy multi-scale composite structures
    (Elsevier Sci Ltd, 2014) Eskizeybek, Volkan; Avci, Ahmet; Gulce, Ahmet
    A novel and simple chemical route was successfully applied to graft carbon nanotubes (CNTs) onto silanized plain weave glass fabric (PWGF) mats, as confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy. The CNTs grafted PWGF mats were used to reinforce epoxy matrix for multi-scale composite production due to their potential for increasing interlaminar fracture toughness by bridging the ply interfaces. Grafting CNTs onto PWGFs improved both initial and steady-state toughness more than double as measured by Mode I interlaminar fracture testing. Failed specimens were visualized to determine the failure modes using fractography. The key findings indicated that the covalent interactions created between CNTs and fibers lead fibers bridging the interface region like barbed wires, which are mainly responsible for increased fracture toughness as a result of improved interfacial adhesion. (C) 2014 Elsevier Ltd. All rights reserved.