Person: ÇAKIR, MUSTAFA
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ÇAKIR
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MUSTAFA
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Publication Open Access Multi-featured epoxy composites filled with surface-modified PTFE powders treated by Na-naphthalenide system(2023-01-01) AKIN, EMRE; ÇAKIR, MUSTAFA; DEMİRER, HALİL; AKIN E., ÇAKIR M., DEMİRER H.This study aimed to produce new multi-featured epoxy composites that are advanced in terms of mechanical properties, wear and impact resistance, and glass transition and heat deflection temperatures. Epoxy composites filled with chemically surface-treated poly (tetrafluoroethylene) (PTFE) powders at various ratios were prepared to obtain these improved properties. The chemical treatment was carried out via a Na-naphthalenide system. After this treatment, the x-ray photoelectron spectroscopy results presented the existence of functional groups such as OH, carbonyl groups, and C=C unsaturation points on the surface of the PTFE powders. On the PTFE surfaces, while the atomic ratios of carbon and oxygen were substantially increased, the fluorine ratio presented a significant decrease after the chemical treatment. However, the wear rates of the novel composites were highly advanced despite this large decrease in the fluorine ratio on the surface of the PTFE powders. Moreover, functional groups such as OH, carbonyl groups, and C=C unsaturation points and spongelike or network structures on the PTFE surfaces provided the opportunity to obtain strong adhesion and interfacial bonding between the surface-modified PTFE powders and the matrix. Strength and modulus values showed substantial enhancement besides the IZOD impact resistance. All glass transition and heat deflection temperatures were also substantially improved.Publication Open Access Properties of UV-Curable Bisphenol-A Glycerolate Diacrylate Coatings_x000D_ Containing 1H,1H,2H,2H-Perfluorodecyl Acrylate Monomer(2018-09-30) AKIN, EMRE; Mustafa Sefa ÇAKIR;Süleyman Emre AKIN;Perihan ULAKAbstract: In this study, fluorine chains were bonded with covalently in epoxy acrylate system via UV light.For this purpose, five different coating samples prepared. Bisphenol-A glycerolate diacrylate (epoxy acrylate)and 1,6-Hexanediol diacrylate were used as the main coating solution. The weight ratio of Bisphenol-Aglycerolate diacrylate and HDDA was determined as 7/3. As a long fluorine chain, 1H,1H,2H,2Hperfluorodecyl acrylate (PFOA) was added into the main coating solution in the ratios of 0.25 wt %, 0.50 wt%, 0.75 wt % and 1 wt %. All prepared solutions were coated on aluminum plates by 75 µm by wire woundapplicator and then cured via UV dryer. Physical properties of coatings were measured by tests such as MEKrubbing test for solvent resistance, gloss 60otest for brightness, cross-cut test for adhesion property and pencilhardness test for scratch resistance. Hydrophobicity was measured as static water contact angle test. The totalsurface energy was calculated by contact angle measurement software. In terms of mechanical properties,sheen impact test (for coating samples) and Shore - D hardness tests (for free film samples) were carried out.By examining the results of all these tests; cross-cut adhesion and gloss 60ovalues decrease with the fluorinecontent. On the other hand, by the increasing within the content of the fluorine chains, Taber abrasionresistance and hydrophobicity increase significantly but sheen impact resistance and Shore - D hardnessvalues decrease slightly. In terms of cost and overall results, the most proper and multifunctional coatingseemed at 0.25 wt %.Publication Open Access Mechanical and thermal properties of fumed silica-incorporated silane-terminated urethane/epoxy-interpenetrating polymer network nanocomposites(2024-01-01) AKIN, EMRE; ÇAKIR, MUSTAFA; KARTAL, İLYAS; AKIN E., ÇAKIR M., KARTAL İ.In this study, it was aimed to improve the mechanical and thermal properties of epoxy materials based on diglycidyl ether of bisphenol-A-based. For this purpose, three different nanocomposite materials were prepared at various ratios including a fumed silica nanoparticle-reinforced epoxy nanocomposite (FSN), an epoxy/silane-terminated urethane (STU) hybrid interpenetrating polymer network (IPN) nanocomposite (SHIN), and a fumed silica-reinforced epoxy/STU hybrid IPN nanocomposite (FSHIN). While synthesizing SHIN, 3-isocyanato propyl trimethoxy silane (ICPTMS) and poly (hexamethylene carbonate) diol were used. The synthesized STU polymer chains were crosslinked by reacting them with TEOS via the sol–gel process. Therefore, hybrid networks were obtained. Moreover, fumed silica nanoparticles were incorporated into the hybrid networks via the sol–gel process for FSHINs. The three different nanocomposite materials exhibited much more improved properties than the neat epoxy. The most prominent nanocomposite was FSHIN. In comparison with the neat epoxy, Young\"s modulus, ultimate tensile strength, and Izod impact resistance values increased at ratios of 53%, 50%, and 223%, respectively. Glass transition temperature values and char yield values increased substantially in all nanocomposites. However, thermal decomposition temperatures increased only for FSNs. Moreover, these values for FSHINs that were very close to those of the neat epoxy were considerably higher than those of SHINs. Highlights: Fumed silica-incorporated silane-terminated urethane/epoxy IPN nanocomposites. Substantially improved mechanical properties and impact resistance. Improved thermal stability.Publication Open Access Mechanical properties of carbon-aramid hybrid fiber-reinforced epoxy/poly(vinyl butyral) composites(2023-01-01) ÇAKIR, MUSTAFA; AKIN, EMRE; ÇAKIR M., AKIN E., Renda G.Currently, it is important to manufacture fiber-reinforced epoxy matrix composites with high impact resistance besides their high strength and modulus values for industries such as automotive, aerospace, and aviation due to the brittle structure of epoxy. In this regard, we found the attractive results of the 0.5 wt% poly(vinyl butyral) (PVB)-containing epoxy blend in terms of strength, Young\"s modulus, and impact resistance. These results substantially motivated us to manufacture fiber-reinforced advanced epoxy/PVB matrix composites with 30–60 vol% carbon-aramid fiber ratios. Flexural (three-point bending) and tensile tests were performed to obtain strength and modulus values by measuring the force required to break the fiber-reinforced composite specimens and elongation at break points. Interlaminar shear strength tests were performed by the short beam bending method by measuring the resistance of the composite to delamination. The Charpy impact test was used to measure the energy absorbed during crack formation and fracture propagation. The composites with PVB were generally superior to those without PVB (EPCs). Two types of findings were observed. First, PVB increased the tensile and flexural strength values substantially for the 30 and 40 vol% ratios, but the modulus values slightly decreased. Second, PVB also substantially increased the modulus values for the 50 vol% ratio besides the strength values. It was thought that this result could be attributed to the increase in the compatibility of the fiber/matrix for the 50 vol% ratio. These decreases for EPCs could be derived from the micro-cracks and weaker interface between fiber and matrix.