Mechanical Engineering / Makina Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/4129

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  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Determination of Activation Energy for Carbon/Epoxy Prepregs Containing Carbon Nanotubes by Differential Scanning Calorimetry
    (SAGE Publications, 2022) Uz, Yusuf Can; Tanoğlu, Metin
    The aim of the present study is the thermal characterization of laboratory-scale carbon fiber/epoxy-based prepregs by incorporating single-wall carbon nanotubes (SWCNTs). Investigation of the cure behavior of a prepreg system is crucial for the characterization and optimization of the fiber reinforced polymeric (FRP) composite. To affect dispersion characteristics, SWCNTs were functionalized by oxidizing their surface with carboxyl (-COOH) group using an acid treatment. The modified resin system contained 0.05, 0.1, and 0.2 wt. % functionalized SWCNTs (F-SWCNTs). Carbon fiber (CF) reinforced prepregs containing various amount of F-SWCNTs were prepared using drum-type winding technique. FTIR was performed to identify new bonding groups formed after the functionalization of SWCNTs. Cure kinetics of prepregs prepared with/without F-SWCNTs were investigated using isoconversional methods.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Enhancement of Filament Wound Glass Fiber/Epoxy-based Cylindrical Composites by Toughening With Single-Walled Carbon Nanotubes
    (SAGE Publications, 2022) Ay Solak, Zeynep; Kartav, Osman; Tanoğlu, Metin
    In this study, the effect of incorporating nano-sized fillers (noncovalently functionalized with ethoxylated alcohol chemical-vapor-deposition-grown SWCNTs) within an epoxy resin on the performance of filament wound glass fiber (GF)-based cylindrical composites (GFCCs) was investigated. For this purpose, SWCNTs were dispersed with the concentration of 0.05 and 0.1 weight percent (wt.%) within an epoxy resin using mechanical stirring and calendaring (3-roll-milling) techniques. The rheological behavior of the SWCNT incorporated epoxy mixture was characterized to determine the suitability of blends for the filament winding process. It was revealed that the viscosity value of the resin was not significantly affected by the addition of SWCNTs in given concentrations. Moreover, contact angle measurements were also performed on the SWCNT/epoxy blends dropped on the GF for the evaluation of the wettability behavior of the GF in the presence of the SWCNTs in relevant concentrations. Eventually, it was observed that the wettability behavior of GF was not reasonably affected by the presence of the SWCNTs. The double cantilever beam (DCB), flexural, and short beam shear (SBS) tests were performed on the reference and SWCNT-modified GFCC specimens to evaluate the effects of the SWCNT presence on the interlaminar fracture toughness and out-of-plane properties of GFCCs. The fractured surfaces after the DCB and SBS tests were analyzed under the scanning electron microscopy to reveal the toughening mechanisms and the filler morphologies. Consequently, although SWCNT incorporation was on the outermost layer of GFCCs, it was found that the interlaminar shear strength (ILSS) values and Mode I interlaminar fracture toughness values of the curved composite samples were improved up to 22 and 216%, respectively, due to the presence of the SWCNTs.