• Journal of Radiation Industry
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• v.2 no.3
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• pp.129-133
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• 2008

PVA nanofibers containing silver nanoparticles were prepared by two methods. The first method was electrospinning of irradiated solution. The prepared $PVA/AgNO_3$ solution was irradiated by gamma-rays. And then the irradiated solution was electrospun. The second method was irradiation of electrospun nanofibers. Nanofibers prepared by electrospinning of unirradiated $PVA/AgNO_3$ solution. The morphology of the nanofibers was observed with a SEM, TEM. When the irradiated $PVA/AgNO_3$ solution were electrospun, the average size of the Ag nanoparticles was increased, but their number was decreased.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.2
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• pp.417-422
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• 1999

Algin and chitosan are known as biodegradable natural polymers. PVA is useful for the production of water soluble packaging, paper, textile sizes. PVA/Algin and PVA/chitosan films were prepared by solution blends method in the weight ratio of chitosan, algin for the purpose of useful biodegradable films. Thermal and mechanical properties of blend films such as DSC, impact strength, tensile strength and morphology by SEM were determined. As a result, The ratio of 10.0wt% PVA/chitosan films were similar to PVA at thermal and mechanical properties. PVA/Algin films were found that phase separation was occured as more than 25wt% increasing the blend ratio of algin. PVA/Algin films were observed to be less partially compatibility than 10wt% increasing the blend ratio of algin by DSC, mechanical properties and SEM. Blend films were completely degraded pH 4.0 better than 7.0, 10.0 in the buffer solution. Also, they were rapidly degraded in the enzyme( glucosidase) solution better than pH solution by enzymolysis.

• Korean Journal of Materials Research
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• v.30 no.11
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• pp.573-580
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• 2020

YAG (Yttrium Aluminum Garnet, Y₃Al₅O₁₂) has excellent plasma resistance and recently has been used as an alternative to Y₂O₃ as a chamber coating material in the semiconductor process. However, due to the presence of an impurity phase and difficulties in synthesis and densification, many studies on YAG are being conducted. In this study, YAG powder is synthesized by an organic-inorganic complex solution synthesis method using PVA polymer. The PVA solution is added to the sol in which the metal nitrate salts are dissolved, and the precursor is calcined into a porous and soft YAG powder. By controlling the molecular weight and the amount of PVA polymer, the effect on the particle size and particle shape of the synthesized YAG powder is evaluated. The sintering behavior of the YAG powder compact according to PVA type and grinding time is studied through an examination of its microstructure. Single phase YAG is synthesized at relatively low temperature of 1,000 ℃ and can be pulverized to sub-micron size by ball milling. In addition, sintered YAG with a relative density of about 98 % is obtained by sintering at 1,650 ℃.

• Journal of the Korean Applied Science and Technology
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• v.15 no.3
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• pp.21-26
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• 1998

Polyvinyl alcohol[PVA] is useful for the production of water-soluble packaging, paper, textile sizes. PVA and Chitosan are known as biodegradable polymers. PVA/chitosan blend films were prepared by solution blends method in the weight ratio of chitosan for the purpose of useful biodegradable films. Thermal and mechanical properties of PVA/chitosan blend films such as DSC, impact strength, tensile strength and morphology by SEM were determined. As a result, The ratio of 10.0wt% PVA/chitosan blend films were similar to PVA. Blend films were completely degraded pH 4.0 better than 7.0, 10.0 in the buffer solution. Also, Blend films were rapidly degraded enzyme(${\beta}-glucosidase$) solution better than pH solution by Enzymolysis.

• Membrane Journal
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• v.15 no.1
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• pp.34-43
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• 2005

The poly(vinyl alcohol) (PVA)-based thin film composite nanofiltration (NF) membranes were prepared by coating polysulfone ultrafiltration membranes, sulfonated polyethersulfone and polyamide NF membranes with aqueous PVA solution by a pressurizing method. The PVA was cross-linked with aqueous glutaraldehyde solution. The NF membranes coated with a very low concentration of PVA on all the support membranes was successfully prepared. With increasing the hydrophilicity of the support membranes, the water flux increased. Especially, ζ-potential of negatively charged polyamide NF membrane was reduced by coating the membrane with PVA. A fouling experiment was carried out with positively charged surfactant, humic acid, complex of humic acid and calcium ion and bovine serum albumin. A non-coated polyamide NF membrane was significantly fouled by various foulants. The fouling process when using humic acid and protein occurred at the isoelectric point. There was severe fouling when using humic acid and adding bivalent cations. By coating the polyamide NF membrane with aqueous PVA solution, fouling was reduced. The polyamide NF membrane coated with PVA was resistant to the acidic and basic solution.

• Korean Journal of Materials Research
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• v.27 no.4
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• pp.179-183
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• 2017

$2ZrO_2{\cdot}P_2O_5$ powder, which is not synthesized by solid reaction method, was successfully synthesized through PVA solution method. In this process, the firing temperature and the PVA content strongly affected the crystallization behavior and final particle size. A stable ${\alpha}$-phase $2ZrO_2{\cdot}P_2O_5$ was synthesized at a firing temperature of $1200^{\circ}C$ and holding time of 4 h. ${\beta}$-phase $2ZrO_2{\cdot}P_2O_5$ was observed, with un-reacted $ZrO_2$ phases, for firing temperatures lower than $1200^{\circ}C$. In terms of the PVA content effect, the powder prepared with a PVA mixing ratio of 12:1 showed stable ${\alpha}$-phase $2ZrO_2{\cdot}P_2O_5$; however, the ${\beta}$-phase was found to co-exist at relatively higher PVA content. The synthesized ${\alpha}$-phase $2ZrO_2{\cdot}P_2O_5$ powder showed an average particle size of 100~250 nm and an average thermal expansion coefficient of $-2.5{\times}10^{-6}/^{\circ}C$ in the range of room temp. ${\sim}800^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.41 no.2
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• pp.151-157
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• 2004

Because of the excellent thermal and chemical properties of mullite and cordierite as the stable oxide ceramic materials, they were widely used from engineering materials to electronic materials. Notwithstanding of their high demands, mullite was synthesised because it is not existed in nature. It is also difficult to produce cordierite of fine powder with high purity due to the narrow range of synthetic temperature. Mullite was synthesised by solid state reaction. However, synthesized mullite has been inhomogeneous. Because of the facts, various synthetic methods have been studied so far including sol-gel method. The purpose of this study is to synthesis mullite and cordierite of fine powder with high purity at the lower temperature by solution-polymerization route using PVA as a polymer carrier, which is an economical method by using low cost materials. As a result, mullite and cordierite were produced with mono crystal phase at 1200$^{\circ}C$ and 1250$^{\circ}C$, respectively, and their surface area over 20 ㎡/g.

• Journal of Powder Materials
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• v.30 no.5
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• pp.424-430
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• 2023

YAG phosphor powders were fabricated by the atmospheric plasma spraying method with the spray-dried spherical YAG precursor. The YAG precursor slurry for the spray drying process was prepared by the PVA solution chemical processing utilizing a domestic easy-sintered aluminum oxide (Al₂O₃) powder as a seed. The homogenous and viscous slurry resulted in dense granules, not hollow or porous particles. The synthesized phosphor powders demonstrated a stable YAG phase, and excellent fluorescence properties of approximately 115% compared with commercial YAG:Ce³⁺ powder. The microstructure of the phosphor powder had a perfect spherical shape and an average particle size of approx imately 30 ㎛. As a result of the PKG test of the YAG phosphor powder, the synthesized phosphor powders exhibited an outstanding luminous intensity, and a peak wavelength was observed at 531 nm.

• Korean Journal of Materials Research
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• v.23 no.8
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• pp.441-446
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• 2013

There is increasing interest in zirconia as a dental material due to its aesthetics, as well as the exceptionally high fracture toughness and high strength that are on offer when it is alloyed with certain oxides like yttria. In recent years, many solution based chemical synthesis methods have been reported for synthesis of zirconia, of which the sol-gel method is considered to be best. Here, we synthesize zirconia by a sol gel assisted precipitation method using either PEG or PVA as a stabilizing agent. Zirconia sol is first synthesized using the hydrothermal method. We used NaOH as the precipitating agent in this method because it is easy to remove from the final solution. Zirconium and yttrium salts are used as precursors and PEG or PVA are used as stabilizers to separate the metal ions. The resulting amorphous zirconia powder is calcined at $900^{\circ}C$ for 2 h to get crystallized zirconia. XRD analysis confirmed the partially stabilized zirconia synthesis in all the synthesized powders. SEM was taken to check the morphology of the powder synthesized using either PEG or PVA as a stabilizing agent and finally the transparency was calculated. The results confirmed that the powder synthesized with 10 % PVA as the stabilizing agent had highest percentage of transparency among all the synthesized powder.

• Journal of the Korean Wood Science and Technology
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• v.42 no.2
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• pp.119-129
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• 2014

This work undertook to prepare nanofibers of cellulose nanofibrils (CNF)/polyvinyl alcohol (PVA) composite by electrospinning, and characterize the electrospun composite nanofibers. Different contents of CNFs isolated from hardwood bleached kraft pulp (HW-BKP) by 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-mediated oxidation were suspended in aqueous polyvinyl alcohol (PVA) solution, and then electrospun into CNF/PVA composite nanofibers. The morphology and dimension of CNFs were characterized by transmission electron microscopy (TEM), which revealed that CNFs were fibrillated form with the diameter of about $7.07{\pm}0.99$ nm. Morphology of the electrospun nanofiber observed by field-emission scanning electron microscopy (FE-SEM) showed that uniform CNF/PVA composite nanofibers were manufactured at 1~3% CNF contents while many beads were observed at 5% CNF level. Both the viscosity of CNF/PVA solution and diameter of the electrospun nanofiber decreased with an increase in CNF content. The diameter and its distribution of the electrospun nanofibers helped explain the differences observed in their morphology. These results show that the electrospinning method was successful in preparing uniform CNF/PVA nanofibers, indicating a great potential for manufacturing consistent and reliable cellulose-based nanofibrils for scaffolds in future applications.