• Journal of the Microelectronics and Packaging Society
• /
• v.23 no.1
• /
• pp.11-15
• /
• 2016

The organic light emitting diodes (OLEDs) have been studied as large flexible displays, light source and hard wares of internet of things. However, OLEDs show some drawbacks in terms of external environments due to the low work function of the metals and the reactive organic materials. In particular, the operation functions of the OLEDs tend to deteriorate rapidly by exposing the oxygen and moisture. So as to prevent it, domestic and overseas studies underway in various method such as ALD, PVD, CVD. But it has complex process and high cost. Therefore In order to protect devices from the external environments, it is important to develop the passivation thin films of low-cost and simple process which can prevent the devices from the penetration of the oxygen and moistures. In this study, to improve the reliability, passivation thin films were coated onto the green OLEDs by spin coating method and investigated the changes of the optical properties of the prepared devices at various doping concentrations of sodium alginate (SA). The passivation solutions were synthesized by using polyvinyl alcohol (PVA) host material with a dopant of SA which were added with the amounts of 10, 20 and 40 wt% into the PVA. As a result, the best barrier properties of the OLEDs were obtained for the samples with 40 wt% SA. Finally, the passivation films can be optimized by using the mixture solution of PVA and SA materials.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.34 no.11
• /
• pp.1767-1778
• /
• 2010

This study investigates applying $TiO_2$ (titanium dioxide) nanoparticles to polypropylene nonwoven fabrics via electrospinning for the development of UV-protective materials. To fabricate uniform nanocomposite fibers, three types of $TiO_2$ nanoparticles were applied: powder, colloid, and $TiO_2$ coated polymer pellets. $TiO_2$/polyurethane (PU) and $TiO_2$/poly(vinyl alcohol) (PVA) nanocomposite fibers were electrospun and the morphology was examined using a field-emission scanning electron microscope and a transmission electron microscope. Layered fabric systems with electrospun $TiO_2$ nanocomposite fiber webs were developed at various concentrations of $TiO_2$ in a range of the web area density. The effects of $TiO_2$ concentration and web area density on UV-protective properties were examined. When $TiO_2$ colloid was added into a PVA polymer solution, uniform nanocomposite fiber webs in which $TiO_2$ particles were evenly dispersed were produced. Water-soluble PVA nanofiber webs were given a heat treatment to stabilize the electrospun PVA fibrous structure against dissolution in water. $TiO_2$/PVA nanoeomposite fiber webs with 2wt% $TiO_2$ and 3.0g/$m^2$ web area density exhibited an ultraviolet protection factor of greater than 50, indicating excellent UV protection.

• Membrane Journal
• /
• v.16 no.3
• /
• pp.230-234
• /
• 2006

This study discusses an esterification of trifluoroethanol (TFEA) with methacrylic acid (MA) using acid-resistant PVA pervaporation membrane. The acid-resistant PVA membranes, which were prepared via a thermal cross-linking reaction of PVA and EGDE were adopted in the esterification reaction. The effect of reaction conditions such as temperature, acid catalyst content, and initial molar ratio of TFEA/MA was investigated on the conversion of trifluoroethyl-methacrylate (TFEMA). It was found that TFEMA conversion increased with increasing the reaction temperature, the catalyst content, and the initial molar ratio. The economical conversion of TFEMA more than about 90% was obtained at the following reaction conditions: reaction temperature of $90^{\circ}C$, 2.5 wt% of catalyst and initial molar ratio of 1.7.

• Journal of the Korean Ceramic Society
• /
• v.27 no.1
• /
• pp.35-42
• /
• 1990

In the present investigation, ceramic PZT and Polymer were prepared. The former is Pb[(Sn1/2Sb1/2)0.1 Ti0.27Zr0.63]O3 including Pb(Sn1/2Sb1/2)O3 with good pyroelectric effect, and the latter PVA(Poly Vinyl Alcohol) with good plasticity. Then, they were fabricated to be flat by using 0-3 connectivity which is rather easily fabricated and capable of making thin film, extending surface area among the connectivities. Such were applied to the sample as variation of intensity of poling field, poling temperature, volume fraction between ceramic and polymer. Then dielectric constant, pyroelectric current, pyroelectric coefficient and the figure of merit were measured. And then their effects on pyroelectric characteristics were observed.

• Proceedings of the Korean Fiber Society Conference
• /
• 2002.04a
• /
• pp.447-450
• /
• 2002

폴리비닐알코올(PVA)은 -OH기에 의한 강력한 분자간 및 분자내 수소결합으로 인해결정화가 잘되고 유리전이온도(T$_{g}$) 및 융점(T$_{m}$ )이 높다는 장점을 가지지만, 같은 이유로 가공성이 좋지 못하다는 문제점을 지니고 있어, 선상 고분자임에도 불구하고 용융가공이 불가능하여 거의 대부분 용액가공을 이용하고 있어 가공성에 제한을 받는다[1]. 그러나 비 결정영역 뿐 만 아니라 결정영역까지 침투할 수 있다고 알려진 요드를 가소제로 사용하면 고분자 분자들 사이의 간격을 넓히고 분자간 결합을 약화시킴으로써 T$_{g}$뿐 아니라 T$_{m}$ 도 저하시킬 가능성이 있다. (중략)

• Journal of Sensor Science and Technology
• /
• v.17 no.1
• /
• pp.29-34
• /
• 2008

A new disposable amperometric tri-enzyme biosensor for the detection of paracetamol has been developed. The paracetamol sensors developed uses horseradish peroxidase modified screen-printed carbon electrodes (HRP-SPCEs) coupled with immobilized enzymes, tyrosinase and aryl acylamidase, prepared using a poly (vinyl alcohol) bearing styrylpyridinium groups (PVA-SbQ) matrix. Optimization of the experimental parameters has been performed and the paracetamol biosensor showed detection limit for paracetamol is as low as $100{\mu}M$ and the sensitivity of the sensor is $1.46nA{\mu}M^{-1}cm^{-2}$.

• Journal of the Microelectronics and Packaging Society
• /
• v.11 no.4 s.33
• /
• pp.69-73
• /
• 2004

A series of $H_3PO_4$-doped composite membranes based on poly(vinyl alcohol)(PVA) and silica have been prepared by sol-gel process. The proton conductivity, as well as properties of swelling, methanol permeation, was measured in this study. The proton conductivity increased with the molar ratio of $H_3PO_4$ to silica. With the silica content increasing, swelling degree decreased and methanol permeability showed a slight increase. It suggested that the former was mainly determined by hydrophilicity of the membrane, while the latter was dominated by the interconnectivity of matrix. According to the value of on, the optimal conformations of these composite membranes were 60, 70, 80 wt.$\%$ of PS-x in membranes, where x were 1.5, 1.0, and 0.5, respectively. These composite membranes were thermal stability up to $200^{\circ}C$.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2010.05a
• /
• pp.23.2-23.2
• /
• 2010

Researches on the drying of particle/polymer suspensions receive attentions in technical applications such as manufacturing display and batteries. In this study, the effect of polymers on drying behavior of silica/poly(vinyl alcohol) suspension was investigated in terms of suspension stability and stress development during drying. The effect of polymer adsorption was studied by changing pH. More strongly flocculated suspension with lower pH became more dispersed and close-packed film after drying. Evaluation of potential energy allows us to suggest that the adsorbed polymers which bridge the particles introduce steric repulsion and lead flocculated suspension to dispersed film. When the effect of adsorption kinetics was studied by changing the mixing time, the adsorption amount, characteristic stress and dried film density showed a similar behavior in the form of with a single characteristic time. It implies that the drying process can be determined by simple characteristic equation with a single time constant.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.20 no.3
• /
• pp.512-518
• /
• 1996

Microcapsules containing 2, 4, 4'-trichloro-2-hydroxydiphenyl ether and perfumes were prepared by the coacervation using poly (vinyl alcohol) and crosslinking agents. Effects of dispersing agents, core materials, agitating speed and crosslinking agents on microcapsule size were investigated. The mean and deviation of microcapsule diameters decreased with increasing agitation speed. The diameters of m;crocapsules decreased with increasing dispering agent concentration at 6, 000 rpm of agitation speed, but it was not changed at 10, 000 rpm. The dispering effect of PVA is better than that of gum arabic. The slight increase in the diameter of microcapsule was observed when the amount of core material was increased. As the amount of crosslinking agent was increased, the diameter of microcapsule was decreased.

• Journal of Sensor Science and Technology
• /
• v.19 no.6
• /
• pp.421-427
• /
• 2010

Alizarin Red S modified screen printed carbon electrodes were developed for the electrochemical detection of aluminum ion. The electrodes developed use screen-printed carbon electrodes(SPCEs) coupled with chemical modification with an organic chelator, Alizarin Red S(ARS), for aluminum ion detection in aqueous solution. For sensor fabrication ARS was directly immobilized on the surface of SPCEs using PVA-SbQ(The poly(vinyl alcohol) bearing stryrylpyridinium groups). Aluminum concentrations were indirectly estimated by amperometric determination of the non-complexed ARS immobilized on the electrodes, after its complexation with aluminum. The sensitivity of the sensor developed was $3.8\;nA{\mu}M^{-1}cm^{-2}$ and the detection limit for aluminum was $25\;{\mu}M$.