Yazar "Ekrem, Muersel" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim Yok
    Öğe
    Impact resistance of composite to aluminum single lap joints reinforced with graphene doped nylon 6.6 nanofibers
    (Elsevier Sci Ltd, 2024) Yilmaz, Musa; Ekrem, Muersel; Avci, Ahmet
    In this study, the low velocity impact resistance of pure and modified epoxy adhesives for single lap joints be-tween aluminum and carbon epoxy composites was investigated. Epoxy resin was used as the adhesive, and pure epoxy resin was modified by adding graphene-doped nylon 6.6 nanofibers (1%, 3% and 5% by weight) and pure nylon 6.6 nanofibers produced by electrospinning. These nanofibers are reinforced to aluminum-composite single lap joints as a second interface according to ASTM D1002-10 standard. Thus, single lap joints were pre-pared using 5 different adhesives. To create the impact effect, some joints were subjected to impact at a low velocity (1.04 m/s). Then, all impacted and non-impacted samples were subjected to single lap shear testing at room temperature and constant load to determine the impact resistance. While the non-impact lap shear strength of the pure epoxy adhesive samples was 6.81 MPa, the non-impact shear strength of the samples using pure nanofiber reinforced epoxy adhesive increased by 71.3% to 11.67 MPa compared to the pure epoxy adhesive. When comparing the post-impact failure loads, it was determined that the addition of graphene increases the impact resistance. Furthermore, adhesive surfaces were examined by scanning electron microscopy (SEM) for damage analysis after the tensile tests and toughening mechanisms such as bridging, adhesive crack formation, nanofibers breakage was determined in epoxy adhesives reinforced nanofiber with graphene in different pro-portions by weight. In addition, the glass transition temperature, melting temperature, thermal decomposition temperature and mass loss of epoxy resin, and graphene doped/undoped N6.6 nanofiber-reinforced epoxy ad-hesives were analyzed by Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) and it was determined that the addition of 3% GNP to N6.6 nanofiber reinforcement increased the thermal stability by 12.4%, the addition of 1% GNP to N6.6 nanofiber reinforcement increased the thermal resistance (glass tran-sition temperature) by 34.9% compared pure epoxy.
  • Küçük Resim Yok
    Öğe
    Thermal stability and adhesive strength of boron nitride nano platelets and carbon nano tube modified adhesives
    (Sage Publications Ltd, 2018) Ekrem, Muersel; Sahin, Omer Sinan; Karabulut, Salim Egemen; Avci, Ahmet
    The effect of multi-walled carbon nanotube and/or boron nitride nano platelets usage on shear strength and thermal stability of epoxy based adhesives have been investigated. Commercially available diglycidyl ether of bisphenol A based epoxy was used as matrix and reinforced by using nanofillers. The resulting adhesive was tested for its shear-lap adhesion to aluminum alloy sheets (2024-T3). The nano particles modified epoxy adhesives were characterized by Fourier transform infrared, differential scanning calorimetry, and thermal gravity analyses analysis. These characterizations revealed that incorporation of nano particles can result in enhancement in chemical stability. Single lap strength joint testing was conducted in accordance with ASTM-D-1002-10 standard. Fracture morphologies and the effects of multi-walled carbon nanotubes and boron nitride nano platelets on epoxy adhesive were investigated after shear tests by means of scanning electron microscopy. Compared to neat epoxy, increases of 30% in shear strength and 57% in energy required to break joints have been obtained by multi-walled carbon nanotube/boron nitride nano platelet modification.