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Author: search.filters.author.Jinawath, SupatraHas files: No

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    Preparation and characterization of hydroxyapatite/poly(ethylene glutarate) biomaterials
    (2007-05-01)
    Siriphannon, Punnama
    ;
    Monvisade, Pathavuth
    ;
    Jinawath, Supatra
    ;
    Hemachandra, Khemchai
    Hydroxyapatite/poly(ethylene glutarate) (HAp/PEG) biomaterial composites were prepared by ring-opening polymerization (ROP) of cyclic oligo(ethylene glutarate) (C-PEG) in porous HAp scaffolds. The HAp/C-PEG pre-composites were prepared by immersing the porous HAp scaffolds in the mixture solution of C-PEG and dibutyl tin-oxide catalyst overnight and polymerizing at 200°C for 24, 48, and 72 h under vacuum. The successful ROP of C-PEG in the porous HAp scaffolds was corroborated by the signals of hydroxyl end-group of PEG shown in the <sup>1</sup>H NMR spectrum of the ROP-products extracted from the composites. PEG in the composites was present as a thin layer coating on the HAp grains and was evenly distributed throughout the samples. The PEG content was about 13-16 wt % and decreased with increasing polymerization time. Its molecular weight (M̄<inf>w</inf>, weight average) measured by gel permeation chromatography was in the range of 4300-6800 g/mol. Compressive strength of the HAp/PEG composites was significantly increased from 3 MPa of the porous HAp scaffold to 11-15 MPa, depending on the PEG content in the composites. In vitro bioactivity of the HAp/ PEG composites was studied by soaking in simulated body fluid (SBF) at 36.5°C for 7-28 days. After prolonged soaking, the HAp nanocrystals precipitated from the SBF solution and formed as a layer of globular aggregates, coated on the composite surfaces. This result suggested that the HAp/PEG composite was a bioactive material. © 2006 Wiley Periodicals, Inc.
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    Ag-doped TiO2 immobilized on Al2O3 bead as oxidation catalyst
    (2007-01-01)
    Jaroenworaluck, Angkhana
    ;
    Supothina, Sitthisuntorn
    ;
    Chumnanklang, Rung Arun
    ;
    Juengsuwattananon, Kannikar
    ;
    Jinawath, Supatra
    Ag-doped TiO<inf>2</inf> catalyst employed as the oxidation catalyst candidate was prepared by two methods, co-precipitation and dip coating method. Co-precipitation method was conducted by adding AgNO<inf>3</inf> into the titanium precursor before gelation and then the obtained solution was coated on the alumna beads. Dip coating method was conducted by coating the first layer on alumina beads with titanium precursor followed by coating the second layer with AgNO<inf>3</inf>. The fired Ag-doped TiO<inf>2</inf> coated on alumina beads was used as catalyst for catalytic oxidation of methanol and carbon monoxide by using oxygen as oxidizing agent in a gas-phase reactor. The methods of catalyst preparation were found to affect the catalytic efficiency. Dip coating method showed better oxidation reaction as Ag-doped TiO<inf>2</inf> catalysts were well dispersed on the alumina beads.
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    Ag-doped TiO2 immobilized on Al2O3 bead as oxidation catalyst
    (2007-01-01)
    Panyathanmaporn, Thammarat
    ;
    Jaroenworaluck, Angkhana
    ;
    Supothina, Sitthisuntorn
    ;
    Chumnanklang, Rung Arun
    ;
    Juengsuwattananon, Kannikar
    Ag-doped TiO<inf>2</inf> catalyst employed as the oxidation catalyst candidate was prepared by two methods, co-precipitation and dip coating method. Co-precipitation method was conducted by adding AgNO<inf>3</inf> into the titanium precursor before gelation and then the obtained solution was coated on the alumna beads. Dip coating method was conducted by coating the first layer on alumina beads with titanium precursor followed by coating the second layer with AgNO<inf>3</inf>. The fired Ag-doped TiO<inf>2</inf> coated on alumina beads was used as catalyst for catalytic oxidation of methanol and carbon monoxide by using oxygen as oxidizing agent in a gas-phase reactor. The methods of catalyst preparation were found to affect the catalytic efficiency. Dip coating method showed better oxidation reaction as Ag-doped TiO<inf>2</inf> catalysts were well dispersed on the alumina beads.