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    Characterization of TiO2 Nanoparticle-Reinforced Polymer Nanocomposite Materials Printed by Stereolithography Method
    (Springer, 2021) Aktitiz, Ismail; Aydin, Kadir; Topcu, Alparslan
    Additive manufacturing (AM) is a novel manufacturing technology group that revolutionizes the design and production processes behind material production. This approach is used in a wide range from simple prototypes to direct parts manufacturing in different industries such as aviation, automotive, energy, biomedical, and bioengineering. Stereolithography (SLA), fused deposition modeling, selective laser sintering, laser metal deposition approaches are the most widespread AM methods. SLA method is one of the most attractive approaches in the AM field as high-dimensional sensitivity is achieved by using liquid photosensitive resin and laser light. However, although it is possible to manufacture complex-shaped three-dimensional (3D) polymer structures with the SLA approach, the mechanical, thermal, and electrical properties are not at the desired levels. To develop more functional 3D polymer materials, various additives are dispersed into polymer structures such as metal nanoparticles, inorganic particles, fibre, carbon nanotube, and nanoclay. Titanium dioxide (TiO2) nanoparticles are a very appealing type of additive among these additives owing to their superior mechanical properties. In this study, the photosensitive resin was mixed with four different TiO2 nanoparticle concentrations (pure, 0.25, 0.5, and 1% reinforced). These slurries were then placed in the SLA device, and 3D polymer structures were fabricated. Scanning electron microscope (SEM), thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), tensile tests, and Charpy impact tests were carried out to characterize mechanical, thermal, and morphological properties of developed polymer materials. It was observed that the particle size was below 1 mu m and some agglomerations occurred. The elasticity modulus of the 0.5% TiO2 nanoparticle reinforced sample was measured as 694 MPa and was found to be approximately 20% higher than the pure polymer sample. In addition, polymer structures exhibited more brittle behavior. It was noted that 5% weight loss was experienced at 337 degrees C in all samples. Besides, the existence of unreacted carbon-carbon bonds was proven by the DSC analysis.
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    Experimental investigations on metallization in the surface modified additively manufactured plastic substrates using DC sputtering
    (Sage Publications Ltd, 2024) Aktitiz, Ismail; Daricik, Fatih; Aydin, Alkim; Aydin, Kadir
    The application of copper surface coating to plastic structures offers numerous advantages, including high thermal and electrical conductivity, improved mechanical properties, good corrosion resistance, decorative applications, and enhancements in working temperatures. Besides these advantages, producing plastic structures with 3D printing and applying surface coating enables the final structures to become functional plastic structures adaptable to different fields. In this study, 3D plastic structures were produced using the fused deposition modeling method. Pristine, dichloromethane dipping, dichloromethane vapor, cold oxygen plasma, and mechanical abrasion surface treatments were applied to determine the optimal surface treatment between copper and the plastic substrate before copper coating. Subsequently, copper coating on plastic structures was completed using the DC sputtering technique. The surface topography, optical, electrical, and structural properties of the produced plastic structures were examined. According to X-ray diffraction analysis results, the (111), (200), (220), and (311) crystal planes confirm the presence of copper. The electrical conductivity values of the plastic structures reached 7.87 x 105 S/m. Contact angle measurement results indicate that the applied surface treatments increased the contact angles to 88.309 degrees, leading the coated plastic structures to exhibit a more hydrophobic behavior.
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    Failure of surface modification 3D printed polymer materials by UV/ozone irradiation
    (Pergamon-Elsevier Science Ltd, 2023) Korkut, Volkan; Daricik, Fatih; Aktitiz, Ismail; Aydin, Kadir
    In today's technology, AM processes are widely adopted in the aerospace, energy, automotive, medicine, and agriculture industries. Fused Deposition Modeling (FDM) is one of the most remarkable methods in the AM family because of its superiorities. Besides the advantages pro-vided, the mechanical strength of the printed parts is still not at a satisfactory level. Here, there are various secondary processes applied to polymer materials to improve both the mechanical properties and functionality of the printed part. Among these processes, the UV/O3 surface treatment method stands out as the most suitable one in terms of ease of application. In this study, two different infill orientation angles were applied to two standard test models. The fabrication process was initiated using suitable process parameters for filaments made of Polylactic Acid (PLA) and Thermoplastic Polyurethane (TPU) materials. The purpose of this investigation was to examine the mechanical strength of 3D printed polymer structures. For the same purpose, the UV/O3 (UV/Ozone) process was applied to the manufactured samples. The samples are then subjected to tensile and compression tests, Shore surface hardness measurements and Scanning Electron Microscopy (SEM) analyze for both the evaluation of mechanical properties and the examination of fracture surface structures. Consequently, significant increases of 28.33%, 25.21%, 27.90%, and 32.92% were observed in material surface hardness levels. This study is important in terms of presenting that the mechanical properties of 3D printed parts can be significantly improved with UV/O3 application, which is an effective and a practical process.
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    Metallization of 3D Printed Polylactic Acid Polymer Structures via Radio-Frequency Sputtering
    (Springer, 2024) Aktitiz, Ismail; Daricik, Fatih; Aydin, Alkim; Aydin, Kadir
    The metallization of polymer structures eliminates disadvantages such as low electrical conductivity, undesirable mechanical properties, degradation under different environmental conditions such as UV radiation and humidity, and poor thermal properties, thereby enabling the achievement of more functional polymer structures. 3D printing provides production flexibility by allowing the manufacture of polymer, ceramic, metal, and composite materials with any level of complexity and intricacy. This study aims to investigate the improvement of the drawbacks associated with polymers, by combining the advantages of polymers and metals through 3D printing and surface modification. The newly acquired features will offer researchers and users significant freedom in various applications. Polylactic acid was used to additively manufacture the polymer structures by using fused deposition modeling. Subsequently, the surfaces of polymer structures were subjected to surface treatment methods: as-printed, dichloromethane dipping, dichloromethane vapor, cold oxygen plasma, and sandpaper. The metallization process was completed using the RF sputtering technique with aluminum as the target material. To examine the morphological, structural, optical, and electrical properties of the metalized structures, various analyses were conducted, including scanning electron microscopy, energy-dispersive spectroscopy analysis, atomic force microscopy, x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) analysis, ultraviolet-visible-near-infrared (UV-VIS-NIR) analysis, contact angle measurement, ellipsometry analysis, and electrical resistance measurement. The results showed improvements in surface roughness due to the applied surface treatments. EDX and XRD analyses confirmed the presence of aluminum in the polymer structure. Electrical conductivity values of 0.32 x 106 S m-1 were achieved at a thickness of 1000 nm. Contact angles increased up to 91.728 degrees.
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    Morphological, mechanical, magnetic, and thermal properties of 3D printed functional polymeric structures modified with Fe2O3 nanoparticles
    (Wiley, 2021) Aktitiz, Ismail; Delibas, Hulusi; Topcu, Alparslan; Aydin, Kadir
    The Fe2O3 nanoparticle structures, which have many application areas such as electronics, marine, and aviation, have been studying extensively due to the compliance between organic polymer and inorganic Fe2O3 nanoparticles. Nanocomposite structures are successfully produced in the desired complexity with the additive manufacturing method. In the current study, Fe2O3 nanoparticles were doped into the photocurable resin at different concentrations (pristine, 0.25%, 0.5%, and 1% in wt), and the prepared 3D polymer nanocomposite mixtures were printed via stereolithography method. To investigate the morphological, mechanical, magnetic, and thermal properties of the printed nanocomposite structures, scanning electron microscopy, hardness, vibrating sample magnetometer, thermogravimetric analysis, and differential scanning calorimeter analysis were performed, respectively. It was revealed that the Fe2O3 nanoparticles improved the thermal stability of the structures. Moreover, an increase in magnetic properties has been observed up to 459%.
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    Production of different metal oxide nanoparticle embedded polymer matrix composite structures by the additive manufacturing technology and investigation of their properties
    (Wiley, 2022) Aktitiz, Ismail; Aydin, Kadir; Daricik, Fatih; Topcu, Alparslan
    Metal oxide nano additives are widely used as a second phase modifier as they improve the properties of the matrix materials. Nano additives also supply various advantages for polymers which can be employed in additive manufacturing methods. Among the additive manufacturing methods, stereolithography is one of the most remarkable to produce nano-modified polymers because of the easy nano modification of the photocurable resins. In the present study, we mixed the metal oxide particles; Fe2O3, ZnO, NiO, Al2O3, TiO2, and MgO with the photocurable epoxy and used the mixtures to print the specimens. We investigated the structural morphology, thermal and mechanical properties of the printed specimens with an optical microscope, scanning electron microscope, Fourier transform infrared spectroscopy, differential scanning calorimeter, differential thermogravimetric analysis, and microhardness, respectively. Findings proved the dilute agglomeration of the nano additives. Besides, nano additives can improve the thermal stability of the photo-cured polymer. The microhardness of the Fe2O3 added polymers reached 27.63 HV levels while it was measured as 16.16 HV for the pristine samples (similar to 70% raise was experienced). The maximum degradation temperatures of the polymer nanocomposite structures were measured in the range of 396-420 degrees C.