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Conference Object Citation - Scopus: 2Synthesis of Tio2 Nanostructures Via Hydrothermal Method(American Ceramic Society, 2015) Bilgin,N.; Agartan,L.; Park,J.; Ozturk,A.Titania (TiO2) nanostructures were produced via hydrothermal method using amorphous TiO2 powders synthesized by the sol-gel precipitation process. The hydrothermal system was isolated from the environment and hydrothermal reactions were allowed to execute at 130 °C for 36 h at autogeneous pressure, and at a stirring rate of 250 rpm. Scanning electron microscopy (SEM) analysis revealed that TiO2 nanofibers formed instead of nanotubes upon utilization of amorphous TiO2 precursor. After hydrothermal synthesis, the powders were acid treated by HCl several times. X-ray diffraction (XRD) analysis identified that the synthesized powders were Na-titanate and remained Na-titanate even after subjecting to acidic treatments several times. The photocatalytic performance of the powders was evaluated by degradation of methylene blue (MB) solution in UV illumination. Results were compared with nanotubes which were synthesized previously using P25 commercial titania powder and have shown that TiO2 in tubular structure offers better photocatalytic performance for the degradation of MB solution under UV illumination as compared to fiber-like structure. Copyright © 2015 by The American Ceramic Society. All rights reserved.Conference Object Production of Potassium Titanate Whisker Reinforced Dental Composites(2014) Kapusuz,D.; Park,J.; Ozturk,A.Potassium titanate (K2O.nTiO2) whiskers (KTWs) were produced by sol-gel method and embedded into UDMA-TEGDMA resins to produce KTW reinforced composites that could be used for both anterior and posterior fillings. The effect Ti/K molar ratio on the chemical, structural and functional properties of the KTWs was investigated using XRD, HR-TEM, and BET analysis. Morphology and the surface properties of the KTWs rely on the Ti/K ratio. However, HR-TEM studies clarified that the KTWs grow along [110] axis regardless of Ti/K ratio. BET analysis revealed the presence of slit shaped meso-pores in the KTWs. The KTW reinforced composites were produced by mixing UDMA-TEGDMA resins at molar compositions of 30-70, 70-30, and 50-50 wt%, and by embedding 5 wt% KTW homogeneously into the mixtures. Photocatalytic activity of the KTWs and the KTW reinforced composites were evaluated through Methylene Blue degradation test. Photocatalytic activity of the composites decreased as Ti/K ratio is increased although it showed a tendency to increase in the KTWs with increasing Ti/K ratio. Meanwhile, the photocatalytic activity of the composites was superior to unreinforced resin mixtures. Mechanical properties namely, nanoindentation hardness and wear-rate of the bulk polymers enhanced significantly by KTW reinforcement.
