Person: ÇAKIR, MUSTAFA
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ÇAKIR
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MUSTAFA
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Publication Metadata only Synthesis and Characterization of Flexible Butadien Containing Resin for 3D SLA Printers(2022-10-15) AKIN, EMRE; ÇAKIR, MUSTAFA; Akın E., Çakır M., Berberoğlu B.As well known, epoxy acrylate resins have been widely used in 3D SLA printers applications. Epoxy acrylate system consisted of bisphenol-A glycerolate diacrylate (epoxy acrylate resin) and 1,6-Hexanediol diacrylate (HDDA, reactive diluent resin) were used in this study. The weight ratio of epoxy acrylate and HDDA was determined as 1/1. The purpose of this study is to develop a novel epoxy acrylate system for 3D SLA printers and observe its properties. For this reason, a novel urethane acrylate was synthesized as reactive resin and was added into epoxy acrylate system with various weight percents. In order to obtain this novel urethane acrylate resin, hydroxyl terminated butadien oligomer was used as backbone of the chain while isophorone diisocyanate (IPDI) and 2-Hydroxyethyl methacrylate (HEMA) were used for synthesizing urethane acrylate functional groups. The addition of this novel reactive resin was carried out up to 1.5 %. Mechanical and physical tests were applied to the produced samples such as tensile, Shore-D hardness, abrasive and density tests. Considering of the results, substantial increases were observed in terms of tensile modulus. As expected, tensile strain values presented large decreases. Shore-D hardness and densities presented slight increases. Moreover, taber abrasive resistances of the produced novel samples presented considerable increases.Publication Metadata only Characterization of carbon fiber-reinforced thermoplastic and thermosetting polyimide matrix composites manufactured by using various synthesized PI precursor resins(Elsevier Ltd, 2022) AKIN, EMRE; Çakir M., Akin E.Currently, it is important to manufacture thermoplastic advanced composites with high mechanical and thermal properties because of their higher impact resistance than thermoset composites. In this study, carbon fiber (CF)-reinforced thermoplastic and thermosetting polyimide (PI) matrix composites were manufactured by vacuum bagging followed by compression molding. Before the manufacturing process, prepregs were also prepared with various PI precursor resins by using two-step impregnation. These precursors were synthesized as poly (amic acid) (PAA), polyester amine salts (PEAS) and poly (amic acid) ammonium salts (PAAS). The PAAS precursor resin was applied as a novel method for manufacturing CF-reinforced PI matrix advanced composites. The advanced thermoplastic composite obtained from the PAAS precursor (PAAS-T) exhibited superior mechanical properties and enhanced thermal properties (near the thermal properties of thermoset advanced composites) in comparison to the other advanced composites in this study and those in the literature. However, the NA-terminated PAAS precursor (thermosetting PI precursor) did not exhibit a similar effect in terms of mechanical properties. On the other hand, the thermosetting composites exhibited highly enhanced storage modulus values up to 400 °C and outstanding thermal stability at TGA. The thermosetting composite that was obtained from the NA-terminated PAA precursor resin exhibited high mechanical properties besides its thermal properties. © 2021Publication Metadata only Urethane acrylate and silicon acrylate containing novel epoxy acrylate systems for sla 3d printers(2022-10-03) AKIN, EMRE; ÇAKIR, MUSTAFA; Çakır M., Akın E., Berberoğlu B.As well known, epoxy acrylate resins have been widely used in 3D SLA printer applications. Epoxy acrylate systems have generally consisted of bisphenol-A glycerolate diacrylate (epoxy acrylate resin) and 1,6-Hexanediol diacrylate (HDDA, reactive diluent resin) in various weight percents. The purpose of this study is to develop novel epoxy acrylate systems without HDDA and investigate their properties. For this reason, two different reactive resins were used instead of HDDA in epoxy acrylate systems with various weight percents. One of these resins was urethane acrylate resin that was synthesized in our laboratory. Urethane acrylate resin was synthesized using monomeric aliphatic diisocyanate (commercial name; Desmodur H) and 2-Hydroxymethyl methacrylate (HEMA). The other reactive resin was mixture of silicone acrylate and photoinitiator (commercial name; TEGO RC 1002). These resins were added into epoxy acrylate resin in various weight percent such as 20%, 40%, 60% and 80%. Tensile, izod impact, shore-D hardness, taber abrasive, density and DSC tests were applied to these produced samples. Considering of the results, urethane acrylate containing epoxy acrylate system exhibited much more improved results compared to pure epoxy acrylate system and silicon acrylate containing epoxy acrylate systems. It also exhibited more enhanced properties than epoxy acrylate systems with HDDA. It exhibited substantial increases in terms of tensile strength, modulus and izod impact resistance. Moreover, they presented more enhanced abrasive resistance. Shore-D hardness values and densities showed almost no change. This synthesized urethane acrylate reactive resin can be used in applications that required higher mechanical and abrasive properties for epoxy acrylate systems of 3D SLA printers.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 Metadata only Synthesis and characterization of flexible polydimethylsiloxane containing resin for 3D SLA printers(2021-10-15) ÇAKIR, MUSTAFA; AKIN, EMRE; Akın E., Çakır M., Berberoğlu B.As well known, epoxy acrylate resins has been widely used in 3D SLA printers applications. Epoxy acrylate system that consisted of bisphenol-A glycerolate diacrylate (epoxy acrylate resin) and 1,6-Hexanediol diacrylate ( HDDA, reactive diluent resin) were used in this study. The weight ratio of Bisphenol-A glycerolate diacrylate and HDDA was determined as 1/1. The purpose of this study is to develop a novel epoxy acrylate system for 3D SLA printers and observe its properties. For this reason, a novel polydimethylsiloxane containing urethane acrylate was synthesized as reactive resin and added into epoxy acrylate system with various weight percents. It is also well known that polydimethylsiloxanes increase thermal properties of polymer materials. In order to obtain this novel reactice urethane acrylate resin, hydroxyl terminated polydimethylsiloxane was used as backbone of the chain while isophorone diisocyanate (IPDI) and 2-Hydroxyethyl methacrylate (HEMA) were used for synthesizing urethane acrylate functional groups. The addition of this novel reactive resin was carried out up to 1.5 % into epoxy acrylate system. Mechanical and physical tests were applied to the produced samples such as tensile, Shore-D hardness, abrasive and density tests. Considering of the results, tensile strength and modulus exhibited substantial increases while tensile strain presented large decreases. Taber abrasive resistance showed considerable increases. While Shore-D hardness of the produced novel materials presented slight decreases, the densities showed almost no changePublication Metadata only Magnetic and microwave absorption properties of PVB/Fe3O4 and PVB/NiFe2O4 composites(WILEY, 2018) AKIN, EMRE; Akinay, Yuksel; Hayat, Fatih; Cakir, Mustafa; Akin, EmreElectromagnetic and microwave absorbing properties of Polyvinylbutyral (PVB)/Fe3O4 and PVB/NiFe2O4 composites were investigated in the 1-14 GHz. PVB/filler particles (Fe3O4 and NiFe2O4) composites were prepared with 90/10 mixture ratios via Ultrasonic Probe Sonicator method in solution. The complex permittivity (epsilon-j epsilon) and permeability (- j) of the composites have been measured at different microwave frequencies in 1-14 GHz employing vector network analyzer (Keysight N9926A). The reflection loss (R-L) of composites was calculated and evaluated using theory of the absorbing wall. It was found that, both composites exhibit the large reflection loss and broadband within the frequency range from 1 to 14 GHz for 3, 5, and 7 mm. However, the R-L results show that, when the thickness is 7 mm, the minimum R-L was found to be -22.9 dB (99% power absorption) at the frequency of 13.93 GHz. The Fe3O4/PVB and NiFe2O4/PVB composites have potential application for microwave and radar absorptions. POLYM. COMPOS., 39:3418-3423, 2018. (c) 2017 Society of Plastics EngineersPublication 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 Metadata only Mechanical properties of low-density heat-resistant polyimide-based advanced composite sandwich panels(WILEY) AKIN, EMRE; Cakir, Mustafa; Akin, EmreThis study presents low-density heat-resistant polyimide (PI)-based advanced composite sandwich panels (HRACS) consisting of carbon fiber-reinforced PI matrix thermoset and thermoplastic advanced composite laminates (outer faces) and PI foams (core materials). For the outer faces, thermoplastic composite laminates were prepared from poly (amic acid) ammonium salt precursor resin, and the thermoset was prepared from nadic anhydride (NA)-terminated poly (amic acid) precursor resin. 3,3,4,4-Benzophenone tetracarboxylicdianhydride and 4,4-diamino diphenylsulfone were used as monomers for the polymer backbones. For the thermosetting composite, NA was also used as an end capper and to provide crosslinking of the polymer chains. On the other hand, the HRACSs had two kinds of core materials with low densities. As core materials, isocyanate-based PI foams were used. Pyromellitic anhydride and polymeric diphenylmethane diisocyanate were used for the PI foams and the amounts of the additives such as the surfactant, water, and triethylamine. As a result of these variations, different compressive properties and densities were obtained. On the other hand, a polymerization of monomeric reactant (PMR)-type adhesive PI resin was synthesized in this study. The HRACSs were prepared with the curing and crosslinking of this synthesized PMR-type adhesive PI resin at the interfaces of the outer face and core materials. These HRACSs exhibited outstanding compressive and flexural properties. The flexural force of the HRACSs increased up to 535 N while the composite laminates exhibited values of 197 and 255 N. Additionally, the thermomechanical properties determined with dynamic mechanical analysis, especially those related to the composite faces, were promising.Publication Metadata only Wear, thermal, and physical properties of fluorine-containing polyimide/silica hybrid nanocomposite coatings(WILEY, 2019) AKIN, EMRE; Cakir, Mustafa; Akin, EmreThis study prepared fluorine and SiO2 particles containing organic-inorganic hybrid polyimide nanocomposite coatings (PISFs) with inorganic content in the range of 5-20% in pure polyimide solutions via the sol-gel process. Polyimide hybrid structures containing fluorine and SiO2 particles were synthesized by using perfluorooctyltriethoxysilane and tetraethyl orthosilicate. These formulations were applied on aluminum sheets by using a 75 mu m wire wound applicator, and the coatings were cured for 8 h at room temperature and then 24 h at 100 degrees C. Increased inorganic contents caused slight decreases in the initial decomposition temperatures, but the char yield values increased for PISF15 and PISF20. All samples exhibited hydrophobic properties. When all samples were compared, PISF5 and PISF10 exhibited hydrophobicity, high wear resistance and thermal properties. Additionally, PISF5 and PISF10 showed high adhesion, hardness, and methyl ethyl ketone solvent resistance. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47399.Publication Metadata only Coating properties of 1H,1H-perfluorooctylamine-terminated polyimides based on hexafluoroisopropylidene diphthalic anhydride and 1,4,5,8 naphthalenetetracarboxylic dianhydride(SPRINGER, 2019) AKIN, EMRE; Cakir, Mustafa; Akin, Emre; Artir, RecepThis study attempted to prepare polyimide coatings (PIs) containing 6FDA (hexafluoroisopropylidene diphthalic anhydride) and/or NTDA (1,4,5,8 naphthalenetetracarboxylic dianhydride) in various ratios. 1% of these polyimide chains were terminated with 1H,1H-perfluorooctylamine (PFOA) and PFOA, and terminated polyimide coatings (PIFs) were prepared in the same ratios as PIs. Coatings were produced on aluminum substrates by a 75-mu m wire-wound applicator and thermally imidized. Finally, thermal, wear, and physical properties of PIFs and PIs were compared to each other. PIFs exhibited higher abrasion resistance than PIs due to the presence of PFOA. The increase in 6FDA content also resulted in elevated abrasion resistance. Both NTDA and 6FDA compounds improved thermal stability. The increase in NTDA content raised the T-g values of the polyimides. PIFs exhibited higher static water contact angle values than PIs, but the existence of microcracks decreased their hydrophobicity. The gloss values of PIFs were excellent. Improved values were obtained for pencil hardness, crosscut adhesion, and MEK (methyl ethyl ketone) rubbing properties for all coatings. In addition to the pencil hardness test, a pendulum hardness test was also carried out. The presence of PFOA affected pendulum hardness values positively, and the increase in the amount of 6FDA on polymer backbone improved the pendulum hardness values despite the rigidity of NTDA.