• Title, Summary, Keyword: PVA/AA

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Molecular Modeling for the Crystal Structure of Stereoregular Poly(vinyl Alcohol) (I) - New Crystal Dimension of Syndiotactic Poly(vinyl Alcohol) -

  • Lyoo, Won-Seok;Sergei Chvalun;John Blackwell
    • Proceedings of the Korean Fiber Society Conference
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    • pp.135-139
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    • 1998
  • Poly(vinyl acetate) (PVAc) from which atactic poly(vinyl alcohol) (PVA) is derived, is always noncrystalline. This was attributed to the irregular steric arrangement of the acetyl groups in PVAc. However, the X-ray diffraction patterns of atactic PVA, a derivative of PVAc, were found to show distinct crystallinity, and to give an identity period of 2,52 ${\AA}$ along the fiber axis, despite the expectation of an irregular arrangement of the hydroxyl groups in atactic PVA, in the same manner as that of the acetyl groups in PVAc.(omitted)

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소태아혈청과 이의 대체물질인 BSA, PVA가 복제수정란의 발달에 미치는 영향

  • 이상기;김동훈;양병철;임기순;박수봉;장원경;이훈택
    • Proceedings of the KSAR Conference
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    • pp.19-19
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    • 2003
  • 소 난자 체외성숙에 있어 소 태아혈청 (fetal bovine serum: FBS)첨가시 높은 성숙율을 보이며 핵 이식 후 배 발달율에 있어서도 높다. 하지만 소 태아혈청은 hormone, growth factor, vitamine 그리고 다수의 어떤 잘 알려지지 않은 인자를 포함한 복잡한 배지로 알려져 있으며, 수정란 이식 후 태아의 발육중 및 태어난 직후에 발생되는 송아지에서 나타나는 몇몇 비정상적인 현상들의 원인인 것으로 보고되고 있다. 본 실험은 체외 배양시 소 태아혈청과 이의 대체물질로서 BSA 또는 PVA가 첨가된 배양조건에서의 복제 수정란의 배 발달율을 비교함과 동시에 배반포의 세포수 그리고 세포자연사 (Apoptosis)를 각각의 조건에서 비교함으로써 배발달에 미치는 효과를 알아보기 위하여 실시하였다. 핵이식은 소 체세포를 이용하였으며, 핵 이식 후 CR1aa 기본 배양액으로 FBS, BSA, 그리고 PVA를 첨가하여 5% $CO_2$, 5% $O_2$, 39$^{\circ}C$ 조건하에서 7~8일간 배양하였다.

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Effect of Modification of SeO2/Acrylamide Ratios on Diffraction Efficiencies in PVA/AA Photopolymer Films

  • Kim, Dae-Heum;Lim, Ji-Yun;Nam, Seung-Woong;Chung, Dae-Won
    • Journal of the Optical Society of Korea
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    • v.11 no.4
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    • pp.183-191
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    • 2007
  • The highest diffraction efficiency(DE) value after illumination and post-curing of photopolymer films were obtained at the $SeO_2$/Acrylamide(AA) Ratios of AA 3.0 g, $SeO_2$ 1.0g and the DE's were stable values of over 90%. By the addition of $SeO_2$, the maximum DE at the initial stage of illumination was reached at 300 seconds, which suggests $SeO_2$ slows down the photopolymerization of AA, which enhances the maximum DE value by giving more migration time. DE variation curve for the optimum composition during extended-time illumination of 9,000 seconds resembles a sine curve due to the combination of the monomer diffusion and the photopolymerization, and the photopolymer film expanded by about 8% after photopolymerization due to monomer migration.

The Stabilization of Liquid Crystal Emulsions by Acrylamide Copolymers (Acrylamide Copolymers에 의한 Liquid Crystal Emulsions의 안정성에 관한 연구)

  • Ryu, Hai-Il;Jang, Nak-Han;Jeon, Youn-Seok;Lee, Myeong-Shin
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.10 no.8
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    • pp.2005-2014
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    • 2009
  • There are several methods to fabricate Polymer Dispersed Liquid Crystal(PDLC) films. One of them, so-called Nematic Curvilinear Aligned Phase(NCAP) film, is based on emulsion technology. To produce NCAP systems various water soluble polymers, such as partially hydrolyzed polyvinylalcohol(PVA) and polyvinyl pyrrolidone(PVP), which can form stable emulsion of liquid crystal(LC) without any stabilizers were used. In this work, we studied the dependence of emulsion stability on nature and composition of copolymers composed of water-soluble and water-insoluble moiety. We found that interfacial surface tension depends on the composition of comonomer, the copolymer concentration in the water, and the nature of hydrophobic chain. The Acrylamide -styrene(AA-ST) copolymer showed the lowest interfacial surface tension among the tested copolymers at the same concentration. Since the interfacial surface tension decreases with increasing the compatibility of copolymer with LC phase the AA-ST copolymer has the best compatibility with LC molecules. It is believed that molecules adsorbing easily on the surface of LC droplets allows the LC emulsion system to be more stable.

Immobilization of Prussian blue nanoparticles in acrylic acid-surface functionalized poly(vinyl alcohol) sponges for cesium adsorption

  • Wi, Hyobin;Kang, Sung-Won;Hwang, Yuhoon
    • Environmental Engineering Research
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    • v.24 no.1
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    • pp.173-179
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    • 2019
  • Prussian blue (PB) is known to be an effective material for radioactive cesium adsorption, but its nano-range size make it difficult to be applied for contaminated water remediation. In this study, a simple and versatile approach to immobilize PB in the supporting matrix via surface functionalization was investigated. The commercially available poly vinyl alcohol (PVA) sponge was functionalized by acrylic acid (AA) to change its major functional group from hydroxyl to carboxylic, which provides a stronger ionic bond with PB. The amount of AA added was optimized by evaluating the weight change rate and iron(III) ion adsorption test. The FTIR results revealed the surface functional group changing to a carboxyl group. The surface functionalization enhanced the attachment of PB, which minimized the leaching out of PB. The $Cs^+$ adsorption capacity significantly increased due to surface functionalization from 1.762 to 5.675 mg/g. These findings showed the excellent potential of the PB-PAA-PVA sponge as a cesium adsorbent as well as a versatile approach for various supporting materials containing the hydroxyl functional group.

Diffraction Efficiency Improvement of PVA/AA/SeO2 Photopolymer with Various Film Thickness and Eosin Y Contents (PVA/AA/SeO2 광고분자 필름의 두께 및 Eosin Y 함량 변화에 따른 회절효율 향상에 관한 연구)

  • Her, Ki-Young;Jang, Hwan-Ho;Kim, Dae-Heum
    • Korean Journal of Optics and Photonics
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    • v.20 no.4
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    • pp.230-235
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    • 2009
  • Photopolymer is evaluated as better material than the others used for hologram storage, due to many advantages, such as high diffraction efficiency, easy processing, and self-developing. In this study, chalcogenide inorganic compound ($SeO_2$) which has optical activity, was added to polyvinyl alcohol/acrylamide photopolymer films. In order to optimize diffraction efficiency of these photopolymer films, we prepared the photopolymer films with various film thicknesses and Eosin Y content. Diffraction efficiency of the photopolymer films were measured using a 532 nm laser at $40^{\circ}$ incident angle. As a result, the phtopolymer film with Eosin Y content of 0.0045 g and thickness of $297{\mu}m$ showed the highest diffraction efficiency (78.70%).

Synthesis and Adhesion Characteristics of Water-Borne Acrylic Pressure Sensitive Adhesives(PSAs) (수계형 아크릴 점착제의 합성 및 점착 특성)

  • Hahm, Hyun-Sik;Kwak, Yun-Chul;Hwang, Jae-Young;Ahn, Sung-Hwan;Kim, Myung-Soo;Park, Hong-Soo
    • Journal of the Korean Applied Science and Technology
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    • v.22 no.2
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    • pp.191-199
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    • 2005
  • Removable protective adhesives for automobiles were synthesized by an emulsion polymerization of monomers such as n-butyl acrylate (BA), n-butyl methacrylate (BMA), acrylonitrile (AN), acrylic acid (AA) and 2-hydroxyethyl methacrylate (2-HEMA), in which AA and 2-HEMA were functional monomers. Potassium persulfate (KPS) was used as an initiator and sodium lauryl sulfate (SLS) was used as an emulsifier, and polyvinyl alcohol (PVA) was used as a stabilizer. Emulsion polymerization was carried out in a semi-batch type reactor. Tensile strength, extension, peel strength, viscosity and solid content of the synthesized adhesives were tested. The optimum physical properties of the removable protective adhesives for automobiles were obtained with the composition of 0.43 mole BA, 0.57 mole AN, 0.21 mole BMA, 0.03 mole AA, and 0.03 mole 2-HEMA.

Study of Diffraction Efficiency Values for Photopolymer Films Added TiO2 Nanoparticles (TiO2 나노 입자를 첨가한 광고분자 필름의 회절효율 값에 대한 연구)

  • Her, Ki-Young;Kim, Dae-Heum
    • Korean Journal of Optics and Photonics
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    • v.20 no.2
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    • pp.123-127
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    • 2009
  • In order to improve the diffraction efficiency of the photopolymer, we prepared a $TiO_2$ added photopolymer and investigated the optical properties. Prepared photopolymer films are based on polyvinyl alcohol (PVA) as a polymer binder, acryl amide (AA) as a photo-polymerizable monomer, triethanolamine (TEOA) as an initiator, and eosin Y as a sensitizer at 532 nm. To prepare the photopolymer films with the uniform thickness, the constant amount (2.5 ml) of the photopolymer solution was dropped on the glass and spread using a spin coater. Then films were dried for 72 hrs in a darkroom ($20^{\circ}C$, 40% RH) prior to the optical measurement. Then, the diffraction efficiencies of both the photopolymer films containing $TiO_2$ and non-contained films were measured with the various incident angles ($20{\sim}70^{\circ}$). Therefore, $TiO_2$ added photopolymer showed 5% higher diffraction efficiency than neat photopolymer without $TiO_2$ addition. The addition of $TiO_2$ into the photopolymer showed the high diffraction efficiency (over 70%) at broad range ($20{\sim}70^{\circ}C$) of the incident angle.

Diffraction Efficiency Change in PVA/AA Photopolymer Films by SeO2 and TiO2 Nano Particle Addition (PVA/AA계 광 고분자 필름의 SeO2 및 TiO2 나노 입자 첨가에 의한 회절 효율 변화)

  • Joe, Ji-Hun;Lee, Ju-Chul;Yoon, Sung;Nam, Seung-Woong;Kim, Dae-Heum
    • Korean Journal of Optics and Photonics
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    • v.21 no.2
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    • pp.82-88
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    • 2010
  • Photopolymer is a material for recording three dimensional holograms containing photo information. Photopolymer has been found to be a proper material due to many advantages such as high DE value, easy processing, and low price. Compositions of PVA, monomer, initiater and photosensitizer were determined by previous experiments and the compositions of $SeO_2$ and $TiO_2$ were considered as variable to find out the effects of $TiO_2$ on DE. The DE values were constant for the varying compositions of $TiO_2$ (0.1 mg~1.0 mg). In other words, $TiO_2$ is not directly effective on the DE values. Composition change experiments from $SeO_2$ 0.1 mg, $TiO_2$ 0.9 mg to $SeO_2$ 0.9 mg, $TiO_2$ 0.1 showed a maximum DE value of 73.75% at a component of $SeO_2$ 0.8 mg, $TiO_2$ 0.2 mg. It seemed that regardless of the amount of $TiO_2$, increasing the amount of $SeO_2$ gently increases DE`s. If nano particles are heavily added, transparent films could not be made due to the separation of particles by the solubility decrease. Photopolymer films could be made with high DE values for an extensive angle range if $TiO_2$ additions were kept minimum and $SeO_2$ additions were kept maximum.

In Vitro Production of Bovine Embryos by Modification of Simple Defined Culture Medium (단순한정배양액의 성분조정에 의한 소 수정란의 체외생산)

  • 노상호;윤종택;한기영;이병천;황우석
    • Journal of Embryo Transfer
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    • v.13 no.3
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    • pp.235-243
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    • 1998
  • In this study, we investigated the effects of three kinds of culture medium (Charles and Rosenkrans; CRlaa, Tyrode's; TALP, synthetic oviduct fluid: SOF), insulin transferrin + selenium complex (ITS), macromolecules(polyvinyl alcohol: PVA, fetalb-ovine serum: FBS) and NaCl on the development of early bovine embryos. In experiment 1, there were no differences in embryo development among three kinds of embryo culture medium (CR $l_{aa}$ , TALP, SOF). In experiment 2, BSA, FBS and PVA were added each in TALP as macromolecule sources. The developmental rates of embryos in BSA or FBS added TALP were significantly higher than in PVA added one (p〈0.01), but there was no difference between BSA and FBS added groups. In experiment 3, bovine embryos were cultured in TALP with the following supplements: BSA alone(1, 3 or 8 mg/ml, each) or BSA(1, 3 or 8 mg/ml, each)+ITS (10$\mu\textrm{g}$/m1 insulin, 5 $\mu\textrm{g}$/ml transferrin, 5 ng/ml selenium). In higher concentration of BSA and ITS supplemented groups, the developmental rates over compacted morula were higher than others, but there was a significant effect of ITS only in 1 mg/ml of BSA added group (p〈0.05). In experiment 4, the effect of reduced concentration of NaCl was evaluated. The developmental rate over compacted morula in the medium containing 90 mM of NaCl was higher than in 114 mM group (p〈0.05). In conclusion, BSA could be used as a macromolecule source in bovine embryo culture, and ITS, as a serum substitute, could be used for improving of embryonic development. Also, reduction of NaCl concentration from 114 mM to 90 mM may improve the development of bovine embryos.bryos.

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