Dujreutai Pongkao Kashima

Effects of Surface Treatment on Adhesion of Silver Film on Glass Substrate Fabricated by Electroless Plating

Silver film was fabricated on a glass substrate by electroless plating technique. Plating solution, which also known as Tollen’s reagent, consisted of three main solutions: silver nitrate solution as a silver source, ammonia and sodium hydroxide as pH controllers and D-glucose as a reducing agent. Glass surface was treated by three different methods: HF etching, SnCl2 activation and SiC paper grinding. After that, a glass slide was immersed in plating solution for 90 minutes at a room temperature. The purpose of this work was to study the effects of different surface treatments on adhesion between substrate and film. X-ray diffraction (XRD) pattern confirmed that the obtained film was a silver phase. Surface morphology of glass slides, before and after plating was investigated by scanning electron microscope (SEM). Moreover, the adhesion of silver film to glass substrate was performed by crosscut test and it was indicated that combined treatment by SiC paper grinding and HF etching was the best surface treatment which provided a good adhesion of film to substrate.

Poly(Lactic Acid)/Poly(Butylene Succinate) Blends Filled with Epoxy Functionalised Polymeric Chain Extender

In this work, biodegradable plastics were produced from different poly(lactic acid) (PLA)/ poly(butylene succinate) (PBS) blend ratios in the presence of a fix loading (1 phr) of a commercial epoxy functionalised polymeric chain extender (Joncryl ADR-4300-S). The effects of blend ratio and chain extender on the tensile properties, thermal stability and morphology were investigated by the tensile testing, thermogravimetric analysis (TGA) and scanning electron microscopy, respectively. The results show that the incorporation of PBS and Joncryl into PLA apparently reduced the tensile strength and tensile modulus, but increased the elongation at break of the blends in a dose-dependent manner. However, their blends provide interesting materials for industrial packaging applications, due to their enhanced ductility by decreasing the tensile modulus and increasing the elongation at break. TGA analysis showed that thermal stability of the blends was lower than that of the pure PLA and PBS. Moreover, the chain-extended products exhibit two stages of thermal decomposition, the first was due to the degradation of PBS, and the second was due to the degradation of PLA.

Effects of Surface Roughness and Chemical Species on Hydrophilicity of Anodized Film on Ti-6Al-4V Formed at a Low Current Density

Anodization of Ti-6Al-4V is crucial for dental implants because it promotes the roughness, chemical species and hydrophilicity of the surface that leads to its biocompatibility. The anodized film was prepared by the galvanostatic method at a low current density in either 1 M H3PO4 or 1 M NaOH as the electrolyte. The as-anodized film showed a significant decrease in the water contact angle, likely to be due to an increased surface roughness (as revealed by scanning electron and atomic force microcopy) and change in the surface species (as revealed by X-ray photoelectron spectroscopy, XPS). XPS analyses confirmed that the Ti2p spectra scarcely changed while the O1s spectra significantly changed due to Ti-OH bonding. Moreover, the O/Ti ratio of the as-anodized film was increased. The results suggest that anodization by the galvanostatic method at a low current density in 1 M H3PO4 or 1 M NaOH could enhance the surface roughness and chemical surface species, and that both are likely to be important factors for enhancing the hydrophilicity of the anodized films.

Enhancing the Phase Conversion of Hydroxyapatite from Calcium Sulphate Hemihydrate by Hydrothermal Reaction

Hydroxyapatite (HA) is a well-known biocompatible material which is widely used in orthopedic and dental applications. Because its chemical structure is similar to the human bone so it is compatible to use as a based materials in drug delivery system for treatment of bone infection diseases. In this research we focused on fabrication of HA sphere shape by three dimension printing using calcium sulphate hemihydrate (CaSO4·0.5H2O) as a starting material, then the as-three dimension printed CaSO4·0.5H2O spheres were hydrothermally treated in 1M disodium hydrogenphosphate (Na2HPO4) at 100°C-180°C for 2-8 hr. The reaction was taken place and the conversion of CaSO4·0.5H2O was gradually changed to Ca10(PO4)6(OH)2. Phase analysis by X-ray diffraction indicated that monetite (CaHPO4) was coexisted with HA when hydrothermally treated at pH 9 at low reaction temperature (<180°C). When the pH of 1M Na2HPO4 was adjusted to pH 11, 180°C for 6 hr, the as-three dimension printed calcium sulphate hemihydrate spheres were completely converted to HA spheres without any destruction of the sphere shape. This is confirmed that hydrothermal reaction could enhance the phase conversion of HA and the conversion time was four times faster than the normal conversion.

Flexural Strength and Cytotoxicity of ZCC, a Resin Modified Zinc-Calcium Liner Prototype

Objective: To investigate the flexural strength and cytotoxicity of ZCC, a resin modified zinc oxide-calcium carbonate liner prototype, compared with commercial dental liners. Materials and Methods: ZCC, Dycal, Ultra-Blend® plus (UB), and TheraCal LC® (TC) were evaluated for flexural strength. Six samples of each material were incubated in growth medium (10% fetal bovine serum supplemented DMEM) for 24 h. Primary human dental pulp cells were cultured in the conditioned medium from each sample, with growth media used as a control. Cytotoxicity was determined using an MTT assay. Data were analyzed by one-way ANOVA. The value of p<0.05 was considered significant. Results: UB had the highest flexural strength with Dycal presenting the lowest values (p<0.05). ZCC demonstrated significantly higher flexural strength values compared with those of TC and Dycal (p<0.05). The MTT assay indicated that Dycal conditioned media significantly reduced cell viability at 24 and 48 hours (p<0.05). There was no significant difference in viability between the control, ZCC, UB, and TC groups at 24 and 48 hours (p>0.05). Conclusion: ZCC met the requirements for flexural strength per ISO 9917-2:2010(E). There was no significant difference in viability between the control and ZCC group at 24 and 48 hours.

Surface Characteristics and Hydrophilicity of the as-Anodized Films Formed at High Current Density on Ti-6Al-4V in Different Electrolytes

Hydrophilicity of the as-anodized films is an important factor for improving the osseointegration of Ti implants and bone tissues. This study investigated the surface characteristics and the hydrophilicity of the as-anodized films formed on Ti-6Al-4V. The as-anodized films on Ti-6Al-4V were prepared using galvanostatic method in 1M H3PO4 or 1M MCPM as an electrolyte with different current densities (5, 20, 80 mA/cm2) and using potentiostatic method with different voltages (5, 100 and 150 V) for 30 minute at room temperature. The as-anodized films shows a significantly lower water contact angle compared to the untreated Ti-6Al-4V. The porous oxide films were fabricated on Ti-6Al-4V. Ti 2p spectra show that the as anodized films consist of TiO2 and O 1s present hydroxide (OH-) and adsorbed water (H2O) that effect to the hydrophilicity on the as-anodized film surface. These results demonstrate that the galvanostatic method at a high current density of 20 mA/cm2 and the potentiostatic at a high voltage of 150 V in MCPM could enhance both of the high surface roughness and appropriate surface species which is leading to good hydrophilicity on the as-anodized films.

Anodic Oxide Film Formed on Ti-6Al-4V at a Low Current Density in Monocalciumphosphate Monohydrate (MCPM) Electrolyte and its Biocompatibility

Anodic oxide film on titanium alloy (Ti-6Al-4V) substrate was prepared by anodization. The reaction was done by applying low current densities from 0.25 to 2 mA/cm2 for 30 minutes using monocalciumphosphate monohydrate (MCPM) solution as an electrolyte. Essential parameters which affected to the formation of anodic oxide film were studied. The properties of the anodic oxide film would be optimized when the parameters were appropriately controlled. Increasing of the current density and the concentration of MCPM electrolyte could promote hydrophilicity and surface roughness of the film. After anodization, the anodic oxide film formed at 2 mA/cm2 in 1M MCPM showed the best hydrophilicity (lowest water contact angle) and the film formed at 0.25 mA/cm2 in 0.5M MCPM showed the lowest hydrophilicity (highest water contact angle). XPS analyses confirmed that the chemical species of as-anodized film formed at 2 mA/cm2 in 1M MCPM changed. Ti2p spectra scarcely changed while the O1s spectra significantly changed due to the presence of chemisorbed water and Ti-OH formed during anodization. The SEM micrographs also revealed the biocompatibility from the growth of the cementoblast cell on anodized surface. It was indicated that anodization using MCPM as an electrolyte at 2 mA/cm2 in 1M MCPM could modify the surface roughness and chemical species and that both are likely to be crucial key factors for enhancing of hydrophilicity of as-anodized film which would enhance the biocompatibility of Ti-6Al-4V as a result.

Phase Composition and Morphology of Pottery Stone Microcrystalline Powders Synthesized by Hydrothermal Method

Pottery stone (PTS) microcrystalline powders were synthesized by a hydrothermal method using two concentrations of NaOH solution (2 M and 4 M) at 60, 80 and 120°C for 8 h in a Teflon- lined stainless steel autoclave. The phase composition and morphology of the samples were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The major phase compositions of the as-prepared PTS powders appeared in the XRD patterns are all silicate compounds such as tridymite, crystobalite, quartz, feldspar, albite, sodium silicate, analcime, hydroxyl-cancrinite and sodium aluminium silicates, depending on the NaOH concentration and the reaction temperature. Moreover, SEM micrographs showed the spherical polyhedral particles ranging from 8 to 14 µm in diameters and needle-like particles with a mean aspect ratio of 5.7 that obtained by the hydrothermal treatment operated at 120°C using 2 M and 4 M of NaOH, respectively.

Hydrothermal Synthesis of Analcime from Local Pottery Stone

In this study, local pottery stone (PTS) was hydrothermal treated with 2 M of NaOH at different reaction temperatures (60, 80 and 120°C) and times (8, 12 and 24 h) in a Teflon-lined stainless steel autoclave in order to synthesize analcime fine powders. All the as-prepared samples were characterized for their phase composition and morphology using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results showed that under the conditions investigated, pure analcime could be obtained only at 120°C for all synthesis durations. The analcime microcrystalline particles exhibit isometric trapezohedron or deltoidal icositetrahedron morphology with narrow size distribution from 8 to 14 µm.