• Title/Summary/Keyword: PVA film

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Chitosan, PVA, 그리고 Chitosan/PVA 피막의 특성과 사과 겹무늬썩음병균 Botryosphaeria dothidea의 포자분산 억제작용

  • Lee, Seung-Ji;Park, Dong-Chan;Kim, Eve;Uhm, Jae-Youl;Lee, Yong-Hyun
    • Microbiology and Biotechnology Letters
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    • v.24 no.5
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    • pp.546-552
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    • 1996
  • The applicability of chitosan, a biodegradable natural polymer, as the coating material to prevent the dispersal of the spores of the apple white rot agent Botryosphaeria dothidea, was investigated. The physical properties of mixed chitosan/polyvinyl alcohol(PVA) film showed the increased physical properties for film formation, such as tensil strength, elongation, and viscosity, compared to either chitosan or PVA film. The FT-IR spectra of chitosan/PVA film indicated that the film was formed by simple blending not by any new synthetic bond. The chitosan and chitosan/PVA film showed effective antifungal activity on B. dothidea. The formed films were well decomposed by ASTM strains used for biodegradability test, on the other hand, the PVA film could not be decomposed by above standard strains. The field test at apple orchard showed that the dispersal of B. dothidea spores could be effectively reduced by coated film, especially by chitosan/PVA film. The spore dispersal was reduced upto 97.0% by 1.0% chitosan/5.0% PVA film during 4 months.

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A Study on the Preparation of Poly(vinyl alcohol) Polarizing Film (폴리비닐알코올 편광필름 제조에 관한 연구)

  • 김삼수;우화령;류원석
    • Textile Coloration and Finishing
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    • v.16 no.4
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    • pp.19-25
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    • 2004
  • Both poly(vinyl alcohol)$(PVA)-I_2$ and PVA-dye polarizing film were prepared using PVA with number-average degree of polymerization of 1,700, 2,300, 2,600. The optical property of used dye in this study closed to the that of iodine. The PVA-dye polarizing film was prepared through the dyeing process. In comparison of the result of the measurement of the heat and humidity resistance of two types polarizing films, it of PVA-dye polarizing film was higher than that of a conventional $PVA-I_2$polarizing film. The transmittance and the polarization efficiency of PVA-dye polarizing film was significantly influenced by dye concentration, dipping time, salt concentration, and temperature of dye bath. The PVA-dye polarizing film exhibited a high polarization efficiency of 99.3% and a good transmittance of 42.4%.

A Study on the Heat Resistance and Polarization Characteristics of Poly(vinyl alcohol)-I2 Complex Films Prepared with a Potassium iodide (KI를 사용하여 제조한 Poly(vinyl alcohol)-I2 착체 필름의 편광특성 및 열저항에 관한 연구)

  • Oh, Se Young;Shin, Dong Yoon
    • Applied Chemistry for Engineering
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    • v.10 no.4
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    • pp.603-607
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    • 1999
  • The polarization characteristics of poly(vinyl alcohol)-iodine complex, (PVA-KI system) prepared by the oxidation process of PVA film containing a potassium iodide (KI) were investigated. The UV-visible spectrum of the PVA-KI system polarizing film showed avsorption bands corresponding to $I^{-}$, $I{_3}{^-}$ and $I{_5}{^-}$ chromophoric species at 220 nm, 290~360 nm, respectively. The polarization efficiency and transmittance of PVA-KI system film were significantly influenced by oxidation time, stretching ratio and concentration of KI. The prepared polarizing film exhibited a high polarization efficiency(99.5%) and transmittance(45%). Especially, the heat resistance of the polarizing film was higher than that of a commercial PVA-$I_2$ polarizing film. It may be argued that the result should come from a difference in oxidation process of PVA polarizing film.

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Studies on the Syndiotactic Poly(vinyl alcohol) Polarizing Film -Preparation of Low Molecular Weight Syndiotactic Poly(vinyl alcohol)/Iodine Complex Film and Its Characterization- (교대배열 폴리비닐알코올 편광필름에 관한 연구 -저분자량 교대배열 폴리비닐알코올/요오드 복합체 필름의 제조와 특성 해석-)

  • 류원석;염정현;최진현;지병철;노태환
    • Polymer(Korea)
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    • v.24 no.5
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    • pp.713-720
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    • 2000
  • A polymer/iodine complex film was prepared using syndiotactic poly(vinyl alcohol) (s-PVA) with number-average degree of polymerization of 900 and syndiotactic diad content of 63.1%. In comparison with atactic-PVA/iodine films, degree of polarization of the s-PVA/iodine film was improved up to over 99% although a lower transmittance was obtained. By soaking in iodine/potassium iodide aqueous solution of a lower iodine concentration and subsequent drawing by 4 times, s-PVA/iodine film of a higher transmittance and degree of polarization was produced. The degree of iodine desorption of the s-PVA/iodine film in water were very low. The crystallinity and the d-spacing and crystal size of (100) plane increased at the early stage of soaking time, however, remained constant or decreased slightly with increasing soaking time. In consequence, s-PVA/iodine complex formation took place mainly inside crystal region at the initial stage of soaking time, whereas it occurred outside crystal region or physical adsorption of iodine dominated after sufficient soaking.

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An Electrical Characteristics on the Pentacene-Based Organic Thin-Film Transistors using PVA Alignment Layer (PVA 배열층을 이용한 펜타신 유기 박막 트랜지스터의 전기적 특성)

  • Jun, Hyeon-Sung;Oh, Hwan-Sool
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.3
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    • pp.177-182
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    • 2010
  • The pentacene-based organic thin film transistors(OTFTs) using polyvinylalcohol(PVA) alignment layer were fabricated on the $SiO_2$ evaporated to n-type (111) Si substrates. The pentacene film was deposited by thermally evaporated at $10^{-7}$ torr. X-ray diffraction (XRD) and atomic force microscope(AFM) measurement showed pentacene film which deposited on rubbed PVA layers were partially crystallized at (001) plane. The pentacene OTFTs with PVA layers rubbed perpendicular to the direction of current flow was shown to align better orientation than parallel rubbed case and thus to enhance the mobility and saturation current by a factor of 2.3 respectively. We obtained mobility by 0.026 $cm^2$/Vs and on-off current ratio by ${\sim}10^8$.

Electrical Properties of Organic PVA Gate Insulator Film on ITO/Glass Substrates (ITO/glass 기판위에 제작된 Cross linked PVA 유기 게이트 절연막의 전기적 특성)

  • Choi, Jin-Eun;Gong, Su-Cheol;Jeon, Hyeong-Tag;Park, Hyung-Ho;Chang, Ho-Jung
    • Journal of the Semiconductor & Display Technology
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    • v.9 no.4
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    • pp.1-5
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    • 2010
  • The PVA (poly-vinyl alcohol) insulators were spun coated onto ITO coated glass substrates with the capacitors of Glass/ITO/PVA/Al structure. The effects of PVA concentrations (3.0, 4.0 and 5.0 wt%) on the morphology and electrical properties of the films were investigated. As the concentration of PVA increased from 3.0 to 5.0 wt%, the leakage current of device decreased from 17.1 to 0.23 pA. From the AFM measurement, the RMS value decreased with increasing PVA concentration, showing the improvement of insulator film roughness. The capacitances of the films with PVA concentrations of 4.0 and 5.0 wt% were about 28.1 and 24.2 nF, respectively. The lowest leakage current of 1.77 PA was obtained at the film thickness of 117.5 nm for the device with fixed PVA concentration of 5.0 wt%.

Heat-Treated Polyvinyl Alcohol/Cellulose Nanocrystal Film with Improved Mechanical Properties and Water Resistance (내수성 및 기계적 물성이 향상된 열처리된 폴리비닐알코올/셀룰로오스 나노결정 필름)

  • Nguyen, Son Van;Lee, Bong-Kee
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.20 no.11
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    • pp.1-8
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    • 2021
  • In this study, the water resistance and mechanical properties of heat-treated polyvinyl alcohol (PVA)/cellulose nanocrystal (CNC) films were investigated. PVA is the most commonly used synthetic biodegradable polymers owing to its excellent properties. However, the water/moisture sensitivity and relatively poor mechanical properties of PVA limits its applications. Although heat treatment is a conventionally used method to improve the mechanical strength and water resistance of PVA, the effectiveness of this method is insufficient. Therefore, CNC was used to further improve the mechanical properties and water resistance of the heat-treated PVA film. PVA/CNC nanocomposites containing CNC contents of 0, 1, 3, 5, and 10 wt% were fabricated using solvent casting and subsequent heat treatment. The mechanical properties and water resistance of PVA/CNC films were significantly improved. The tensile strength and wet strength of the PVA/CNC film with a CNC content of 5 wt% (PVA/CNC 5%) were 184.5% and 136.0% higher than those of the untreated PVA, respectively. In addition, the water absorption and solubility of PVA/CNC 5% were 56.6% and 68.2% lower than those of the untreated PVA.

Preparation and Optical Properties of Polarizing Film Based on Poly(vinyl Alcohol) Dyed by Reactive Dichroic Dyes Using Organic Solvents (유기 용매를 사용한 반응성 이색성 염료의 염착에 의한 폴리비닐알코올계 편광필름의 제조 및 광학특성)

  • Choi, E-Joon;Choi, Seung Sock;Kim, Eun-Chol;Kim, Si Min;Back, Sang-Hyun
    • Journal of Adhesion and Interface
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    • v.13 no.3
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    • pp.131-136
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    • 2012
  • In this study, commercial poly(vinyl alcohol) (PVA) film was dyed with reactive dichroic dyes under mild conditions using organic solvents in stead of strong basic aqueous solution. After drawing of 500% of this PVA film, the polarizing efficiency and the single piece transmittance were measured. The degree of saponification of the commercialized PVA film was determined by using NMR and FT-IR spectromety. The commercial PVA film, with ca. 100% of the degree of saponification determined by NMR spectrometry, was dyed with the reactive dichroic dyes, which have 3,5-dichloro-2,4,6-triazine moiety. As a result, we found that the PVA film dyed with the reactive congo red showed relatively good polarization efficiency, and the PVA film dyed with the reactive direct black 22 exhibited relatively good single piece transmittance.

Studies on the Syndiotactic Poly(vinyl alcohol) Polarizing Film -Iodine Desorption Behavior of High Molecular Weight Syndiotactic Poly(vinyl alcohol)/Iodine Complex Film- (신디오탁틱 폴리비닐알코올 편광필름에 관한 연구 - 고분자량 신디오탁틱 폴리비닐알코올/요오드 복합체 필름의 요오드 탈착 거동 -)

  • Lyoo, Won-Seok;Yeum, Jeong-Hyun;Choi, Jin-Hyun;Ji, Byung-Chul;Yoon, Won-Sik;Noh, Tae-Hwan;Ghim, Han-Do;Kim, Jae-Pil
    • Polymer(Korea)
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    • v.25 no.1
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    • pp.115-121
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    • 2001
  • High molecular weight syndiotactic poly(vinyl alcohol)(HMW s-PVA) with number-average degree of polymerization of 10000 and syndiotactic diad content of 61.5%/iodine complex film was prepared. Its adsorption and desorption behaviors of iodine in hot water were investigated. In comparison with atactic PVA film or low molecular weight s-PVA film, the degree of solubility of s-PVA film and the iodine desorption of HMW s-PVA/iodine film in hot water were limited to an extremely lower level. As the soaking time increased, the iodine desorption in hot water was increased. This reason might be explained by the fact that as the soaking time increased, so the iodine adsorption increased not by the stable molecular complex between PVA and iodine but by the simple physical adsorption of iodine.

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Preparation and Drawing Property of Poly(vinyl alcohol) Film (폴리비닐알코올 필름의 제조 및 연신 특성)

  • Kim, Hun Min;Lee, Jungeon;Park, Jae Min;Park, Jae Hyeung;Choi, Jin Hyun;Yeum, Jeong Hyun
    • Textile Coloration and Finishing
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    • v.33 no.3
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    • pp.147-152
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    • 2021
  • Bulk polymerization was used to produce poly(vinyl acetate) with different molecular weights, which were then saponified to prepare poly(vinyl alcohol) (PVA) with different molecular weights. With Pn of 2,060 and 3,240, the optimum film formation concentrations of PVA were found 7.5wt.% and 6.5wt.%, respectively. The drawing characteristics of the PVA film prepared at the optimum film formation concentrations were experimented, as well as the thermal characteristics of the PVA film based on the drawing ratio were observed. When the drawing velocity was fixed, it was found that the drawing ratios of all samples decreased as the heat band gap increased, and the melting temperature of the PVA film slightly increased as the drawing ratio increased regardless of the Pn of PVA.