• Macromolecular Research
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• v.15 no.1
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• pp.22-30
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• 2007

High water vapor permeable coating materials were prepared by blending aqueous poly(vinyl alcohol) (PVA) solution with waterborne polyurethane-urea (WBPU) dispersions synthesized by prepolymer mixing process. Stable WBPU/PVA dispersions were achieved at PVA content below 30 wt%. As the water soluble polymer PVA content increased, the number and density of total micro-pores (tunnel-like/isolated micro-pores) formed after the dissolution of PVA in water increased, and the water vapor permeability of coated Nylon fabric also increased significantly. Using WBPU/water soluble polymer PVA blends as a coating material and then dissolving PVA in water was confirmed to be an effective method to obtain prominent breathable fabrics.

• Carbon letters
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• v.15 no.4
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• pp.282-289
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• 2014

Blends of poly(vinyl alcohol) (PVA), polyethyleneimine (PEI), and graphene oxide (GO) were prepared by solution casting method. Calorimetric thermal properties of the blends were investigated. The $T_gs$ of PVA/PEI blends were higher than the $T_gs$ of either of the component polymers at low concentrations of PEI. These abnormal increases of $T_gs$ may be due to the negative entropy of mixing which is associated with strong hydrogen bonding between PVA and PEI. The degree of depression of $T^0_ms$ was not reduced by the negative entropy of mixing, since strong hydrogen bonding also causes an increase in the magnitude of negative ${\chi}$ between PVA and PEI. The $T_g$ of PVA was increased significantly by adding 0.7 wt.% GO into PVA. The magnitude of negative ${\chi}$ was increased by adding GO into the blends of PVA and PEI.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.13-16
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• 2003

Vinyl acetate monomer can be polymerized through bulk, solution, emulsion, and suspension polymerization processes. However, in the preparation of PVA from bulk or solution polymerization, there are several technical limitations for obtaining high yield and high molecular weight simultaneously. Thus, the improvement of polymerization method is necessary to prepare the PVA with high yield and high molecular weight because that the difficulty in control of high viscosity and in removal of the heat of polymerization, which might lead to side reactions like branching. (omitted)

• Journal of Environmental Health Sciences
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• v.24 no.3
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• pp.48-53
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• 1998

Chitin is known as biodegradable natural polymer. But, in spite of various application of chitin from waste marine sources, commercial use of chitin has been limited due to highly resistance to chemicals and the absense of proper solvents. We made various viscosity of chitosan from chitin by change of Mima's method through the deacetylation which is various condition of NaOH concentration, reaction time and temperature. Also, Polyvinyl alcohol/chitosan blend films were prepared by different solution blends containing the ratio of 5, 10, 15 and 20% chitosan and low, medium, high molecular weight of chitosan to find a more useful biodegradable polymer. Thermal and mechanical properties of PVA/chitosan blend films such as DSC, impact strength, tensile strength and morphological changes by SEM were determined. The 10-15% PVA/chitosan(low, medium) blend films were similar to PVA. Also, PVA/chitosan blend films at the laboratory soil test(Pot Test) were completely degraded in month with four kinds of soils by microorganisms.

• Textile Coloration and Finishing
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• v.13 no.1
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• pp.32-37
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• 2001

Silk fabric was sputter-treated with Au, Cu, SUS, and Ti using poly(vinyl alcohol) (PVA) as a binder, and its changes in color, antielectrostatic property, airpermearbility, and rubbing fastness were investigated. Sputter-treated silk fabric had a natural color of metal target, which was deepened by treatment of PVA solution. The rubbing fastness of thin metal layer formed by sputtering was improved by PVA treatment. Au had highest rubbing fastness among the metal targets. In addition, PVA treatment posterior to sputtering resulted In higher rubbing fastness than the other treatment method. However, a reverse trend was found in antielectrostatic property. Air permeability of the sputter-treated silk fabric was improved by PVA treatment, which was highest when sputtering was conducted prior to PVA treatment.

• Bulletin of the Korean Chemical Society
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• v.31 no.9
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• pp.2557-2560
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• 2010

To assay for antioxidant capacity of natural products considered important in producing human health benefits, a practical and economical method using pellet techniques was developed. A standard visualizing reagent, 1,1diphenyl-2-picryl-hydrazyl (DPPH), was mixed with a water-miscible polyvinyl alcohol (PVA), serving as a solid phase support for the DPPH reagent. A DPPH pellet was prepared by dropping a small volume of the DPPH solution onto PET film, and drying in an oven. The PVA-based DPPH pellet was dissolved into water, in which the water-miscible PVA plays as a non-ionic surfactant to help the DPPH reagent to be dissolved into the solvent. Using the DPPH assay, the antioxidant capacity of water-soluble extracts of black soybean, barley, green tea, and green gram was examined. Among the natural products tested, green tea showed the highest antioxidant capacity. This PVA-based DPPH antioxidant assay can be further applied in the natural food, raw plant material, and health product inspection field.

• Korean Journal of Materials Research
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• v.30 no.2
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• pp.93-98
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• 2020

Effective control of the heat generated from electronics and semiconductor devices requires a high thermal conductivity and a low thermal expansion coefficient appropriate for devices or modules. A method of reducing the thermal expansion coefficient of Cu has been suggested wherein a ceramic filler having a low thermal expansion coefficient is applied to Cu, which has high thermal conductivity. In this study, using pressureless sintering rather than costly pressure sintering, a polymer solution synthesis method was used to make nano-sized Cu powder for application to Cu matrix with an AlN filler. Due to the low sinterability, the sintered Cu prepared from commercial Cu powder included large pores inside the sintered bodies. A sintered Cu body with Zn, as a liquid phase sintering agent, was prepared by the polymer solution synthesis method for exclusion of pores, which affect thermal conductivity and thermal expansion. The pressureless sintered Cu bodies including Zn showed higher thermal conductivity (180 W/m·K) and lower thermal expansion coefficient (15.8×10^-6/℃) than did the monolithic synthesized Cu sintered body.

• Journal of the Korean Ceramic Society
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• v.41 no.9
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• pp.663-669
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• 2004

Mullite and cordierite, which were stable oxides having excellent thermal and chemical characteristics, were widely used as an engineering and electronic materials. However, thermal shock resistance of the mullite was detriorated, and strength of the cordierite was also reduced at high temperatures. The mullite-cordierite composite powders were synthesized for solving these problems in this study. The mullite-cordierite composite powders were manufactured by the solution-polymerization method using mixtures of fused silica, aluminium nitrate, magnesium nitrate, and PVA. Crystallinity, phase formation, density, and surface area of the synthesis powders were characteristics. Fine mullite-cordlerite composite powders were successfully synthesized at 1300$^{\circ}C$ and their surface areas were about 20㎡/g after planetary milling for 1h. With increasing the milling time, surface area increased to 23 ㎡/g for 4h ana 24㎡/g for 8h.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.469-474
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• 1998

Poly (vinyl alcohol) (PVA) membranes crosslinked with poly (styrene-co-maleic anhydride) (PSMAn) have been prepared by the solution method. To investigate the separation behavior of the crosslinked PVA/PSMAn membranes in the pervaporation process, the selective sorption experiment and swelling measurements of the membranes in ethanol-water mixtures of 30~90 wt % ethanol contents were conducted with equipment that was able to measure the concentration and amount of the liquid absorbed in the membranes. The membranes prepared in this study exhibited good selectivity toward water component in sorption and permeation. Also, in the feed containing ethanol more than 50 wt %, the permeation selectivity of the membrane showed better correlation with the sorption selectivity than that with the swelling ratio changing toward the crosslinking content. This behavior was consistence with a solution-diffusion model correlating permeation and sorption selectivity, and led to the conclusion that the permeation selectivity was determined by sorption step rather than by diffusion step in the membrane.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.318-321
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• 2007

CdSe nanoparticles were prepared by chemical solution methods using $CdCl_2{\cdot}4H_2O$ (or $Cd(NO_3)_ 2{\cdot}4H_2O$) and $Na_2SeSO_3$. The characteristics of CdSe nanoparticles were controlled by the react ion time, reaction temperature and reaction method as well as the surfactants. Cetyltrimethyl ammonium bromide(CTAB) was used as a capping agent to control the chemical reactions in aqueous solution. Polyvinylalcohol(PVA) was used as a templet in sono-chemical method. CdSe nanoparticles synthesized in aqueous solution showed homogeneous size distribution with relatively stable surface. CdSe nanoparticles synthesized in non-aqueous solution containing diethanolamine(DEA) showed the structure transformation from cubic to hexagonal as the reduction temperature increased from 80 to $160^{\circ}C$. Core shell CdSe was synthesized by sono-chemical method. Characteristics of CdSe nanoparticles were analyzed using transmission electron microscopy(TEM), x-ray photoelectron spectroscopy(XPS), x-ray diffraction(XRD), UV-Vis absorption spectra, fourier transform infrared spectroscopy(FT-IR) and photoluminescence spectra spectroscopy(PL). This paper presents simple routes to prepare CdSe nanoparticles for solar cell applications.