Papers by Author: Kalayanee Kooptarnond

Abstract: Tin oxide nanotubes (STs) were synthesized by the hydrothermal process using manganese dioxide nanowires (MWs) as a template and followed by oxalic acid treatment. The effect of the stannous chloride concentration on the structure and crystallite size of the product were investigated. The phase composition was determined by XRD. Morphologies were revealed by FESEM and TEM. Firstly, manganese dioxide nanowires were fabricated from KMnO₄. Then_, tin oxide nanoparticles were coated on the wall surfaces of MWs templates. The template was then leached out by oxalic acid treatment. Nanotubular structure of the final product was formed by the agglomeration of the tin oxide nanoparticles coating on the template surfaces. On increasing the stannous chloride amount, crystallite size and the electrochemical properties increased, while the specific surface area decreased.

Abstract: A simple and green method for scaffold production was introduced here. The method is based on bubbling process of PVA solution. This process is superior to other conventional techniques in the matter of controllable pore size and without using of any other organic solvents. Microstructure of the scaffold was examined by a stereo microscope. Pore size and size-distribution were determined using a scanning electron microscope. Interconnected cells with uniform pores were observed without any other impurities within the pores. Average pore size was about 220 microns which is in the range required for bone tissue engineering application.

Abstract: Natural rubber latex foam (NRF) was produced using nitrogen bubbling process. The process involved flowing of nitrogen with a constant flow rate of 80 cc/min through a bubble column, filled with latex compound, to generate a high bubble-volume inside the column. Microstructure of the finished product was examined using a scanning electron microscope (SEM), in comparison with that of the purchased Dunlop foam. The results showed characteristic of the as-produced foam that they composed of spherical pores with a uniform interconnected-cell structures. On the other hand, the Dunlop foam exhibited non-spherical pores and non-uniform cell structure with broken cells.

Abstract: In this work, titanium dioxide nanotubes (TNTs) were prepared by anodization method with carbon cathode rather than the conventional platinum electrode. The composition of electrolyte and the anodizing voltage was fixed as constant for this research. Carbon plate was used as the counter electrode and the anodizing times were varied for 5 h and 10 h. After anodization, the samples were further annealed at 450 °C to crystallize the as-produced TNTs. Phase composition and morphology were identified by XRD and FESEM, respectively. Wettability of the samples were examined using a contact angle instrument. The results showed that the annealed TNTs were anatase phase with average pore diameter and tube-length of 28.7 nm and 284.6 nm for 5 h, and 30.0 nm and 376.5 nm for 10 h, respectively. The differences in pore diameter and length of the nanotube samples were due to the effect of anodizing time. Wettability of both annealed TNTs was also affected by anodizing time. The surface modifications and wettability results suggested potential applications in biomedical fields.

Abstract: Lithium molybdate doped tungsten trioxide electrochromic films were prepared from tungsten trioxide precursor and lithium molybdate powder by sol-gel and dip coating methods on fluorine doped tin oxide glass. The films, which synthesized were flat and amorphous structure, which confirmed by x-ray diffraction patterns. From UV-vis transmittance spectra within the wavelength from 400 to 800 nm. and cyclic voltammogram at the applying a potential of 1.0 V (bleached state) to -1.0 V (colored state) in sulfuric acid 0.5 M solution. The doping lithium molybdate 10 mol% films showed good result in terms of transmittance modulation, high diffusion coefficient and optimal surface area. Therefore, doping lithium molybdate 10 mol% has better outcome when compared to undoped lithium molybdate.

Abstract: The objective of this study is to explore a method to improve hydrophilicity of the surface of formers that could be more easily dipped to produce high quality dipped rubber products. Photocatalytic TiO₂ composite films were prepared by sol-gel method. Glass formers were coated with nitrogen doped TiO₂ nanocomposite film by dipping method and annealed at 600°C for 1 h. Phase formation of TiO₂ was characterized by XRD. Morphology of the TiO₂ films was observed by using atomic force microscopy (AFM). Optical absorption of the films and degradation concentration of methylene blue had been measured employing UV-Vis spectrophotometer. The hydrophilicity of the thin films was determined in terms of the contact angles of water and NR rubber latex droplets on the coated TiO₂ composite films under visible light irradiation. It was found from the experimental study that the TiO₂ nano-composite film can improve wet-ability of the coated former surfaces.

Abstract: The objective of this study is to explore a method to improve hydrophilicity of the surface of formers that could be more easily dipped to produce high quality dipped rubber products. Photocatalytic TiO₂ composite films were prepared by sol-gel method. Glass formers were coated with the Ni/B/N/TiO₂ nanocomposite film by dipping method and annealed at 400°C for 1 h. Phase formation of TiO₂ was characterized by XRD. Morphology of the TiO₂ films was observed by using atomic force microscopy (AFM). Optical absorption of the films and degradation concentration of methylene blue had been measured employing UV-Vis spectrophotometer. The hydrophilicity of the thin films was determined in terms of the contact angles of water and NR rubber latex droplets on the coated TiO₂ composite films under visible light irradiation. It was found from the experimentally study that the Ni/B/N/TiO₂ nanocomposite film can improve wet-ability of the coated former surfaces.

Abstract: TiO₂-AgCl thin films doped with Cu were prepared by sol-gel and coated on glass slide by dip coating process. The prepared thin films were synthesized at the temperature of 400 ^◦C for 2 h with a heating rate of 10^◦C/min. The microstructures of synthesized thin films were characterized by XRD, AFM and SEM. Finally, the light absorption property was evaluated by UV-vis diffuse reflectance spectroscopy. The results show all samples have the thickness in range of 200-250 nm and surfaces are dense with a large surface area. It was found that Cu doping has an effect on light absorption and structure properties of the synthesized thin films. It can be noted that TiO₂-AgCl-5Cu thin films showed the highest light absorption (2.50%) under UV irradiation.

Abstract: The effect of 0.1-1 mol%Ag doping on crystallite size, morphology, photocatalytic and fungal growth suppression activities of TiO2/SnO2/SiO2 nano-composite powders were investigated. The powder was synthesized by sol-gel method and studied for physicochemical properties by XRD, spectrometric techniques, FTIR, SEM, EDX and BET. The anatase structure was formed after calcination at 500oC. Photocatalytic activities towards Penicillium expansum growth suppression correlated to the amount of sliver doped in TiO2/SnO2/SiO2 nano-composite powder under ultraviolet radiation. Ag 1.0mol% doped in TiO2/SiO2/SnO2 composite has a significant effect on antifungal behaviour. It could completely kill Penicillium expansum within one day of photacatalytic treatment under UV irradiation.

Abstract: TiO2-AgCl/Cu2+ thin films containing 0 to 1%Cu2+ coated on glass slides were prepared by sol gel-dip coating method. The prepared films were synthesized at the temperature range of 100-500 °C. The microstructure and properties of synthesized TiO2-AgCl/Cu2+ thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectroscopy (DRS). Finally, the hydrophilic property was evaluated by means of contact angle of water droplet on the films. The results show that both calcinations temperature and Cu2+-doping have an effect on anatase and AgCl phase formation, crystallite sizes and phase content of the films. It was found that TiO2-AgCl/1%Cu2+ thin films calcined at 500 °C exhibit the highest photochromic (darken reaction) and self–cleaning effects (small contact angle) under UV irradiation.