• Title/Summary/Keyword: Poly(vinyl alcohol) (PVA)

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Critical Syndiotacticity Required for In-Situ Fibrillation of Poly(vinyl Alcohol) during Saponification of Poly(vinyl Ester)

  • Lyoo, Won-Seok;John Blackwell
    • Proceedings of the Korean Fiber Society Conference
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    • 1998.04a
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    • pp.130-134
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    • 1998
  • The physical properties of poly(vinyl alcohol) (PVA) are highly dependent on the degree of syndiotacticity, which is determined primarily by the choice of the vinyl ester monomer precursor. Efforts to produce more syndiotactic PVAs, as well to increase the molecular weight, have centered on the polymerization of vinyl trifluoroacetate,$^1$ vinyl trichloroacetate,$^2$ and vinyl pivalate (VPi).(omitted)

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Preparation of High Molecular Weight Atactic Poly(vinyl alcohol)/Dye Complex Film (고분자량 혼성배열 폴리비닐알코올/염료 복합체 필름의 제조)

  • Park, Joo-Min;Kim, Sam-Soo;Lyoo, Won-Seok
    • Proceedings of the Korean Fiber Society Conference
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    • 2003.04a
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    • pp.48-51
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    • 2003
  • Poly(vinyl alcohol) (PVA) obtained by the saponification of poly(vinyl ester) like poly(vinyl acetate) or poly(vinyl pivalate) is a linen. semicrystalline polymer, which have been widely used as fibers for clothes and industries, films, membranes, medicines for drug delivery system, and cancer cell-killing embolic materials[1-3]. PVA fibers and films have high tensile and compressive strengths, high tensile modulus, and good abrasion resistance due to its highest crystalline lattice modulus. (omitted)

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Effect of graphite oxide on photodegradation behavior of poly(vinyl alcohol)/graphite oxide composite hydrogels

  • Moon, Young-E;Yun, Ju-Mi;Kim, Hyung-Il;Lee, Young-Seak
    • Carbon letters
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    • v.12 no.3
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    • pp.138-142
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    • 2011
  • Poly(vinyl alcohol) (PVA) composites with various graphite oxide (GO) contents (0 to 10 wt%) were prepared by sonicating the mixture of PVA and GO, followed by crosslinking with glutaraldehyde. GO was pre-treated with oxyfluorination ($O_2:F_2$ = 8:2) in order to modify the surface of GO to allow it to carry hydrophilic functional groups. PVA/GO composite hydrogels were characterized by scanning electron microscopy and Fourier-transform infrared spectrometer (FT-IR). The morphology of the PVA/GO composite hydrogels and the variations in soluble gel portion were investigated under various GO contents and UV irradiation doses. The variation in the chemical structure of photo degraded PVA/GO composite hydrogels was studied by FT-IR. The photochemical stability of PVA/GO composite hydrogels under UV irradiation was found to improve noticeably with increasing content of uniformly dispersed GO.

Preparation and Characterization of the Blends of Poly(vinyl alcohol) and N-(2-hydroxy)propyl-3-trimethylammonium Chitosan Chloride (폴리(비닐 알코올)과 N-(2-하이드록시)프로필-3-트리메틸 키토산 클로라이드 블렌드의 제조와 특성 분석)

  • 김영호;최재원;이은영
    • Polymer(Korea)
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    • v.27 no.5
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    • pp.405-412
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    • 2003
  • Poly(vinyl alcohol) (PVA) and N-(2-hydroxy)propyl-3-trimethylammonium chitosan chloride (HTCC), a water soluble chitosan derivative synthesized by the reaction of quaternary ammonium compound with chitosan, were blended using water as a solvent and the PVA/HTCC blend films with various compositions were prepared by solution casting method. The miscibility between the two polymers and the thermal properties of the blend films were investigated using FT-IR, DSC, DMA, and TGA. Single glass transition temperatures and single melting temperatures of the blend films along with the strong and clear film state for the whole composition of blending ratios suggest the miscibility between PVA and HTCC. The PVA/HTCC blend films with HTCC content of 1% and greater showed excellent antimicrobial activity.

Influence of Amorphous Polymer Nanoparticles on the Crystallization Behavior of Poly(vinyl alcohol) Nanocomposites

  • Lee, Kyung-Jin;Lee, Ji-Hye;Hong, Jin-Yong;Jang, Jyong-Sik
    • Macromolecular Research
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    • v.17 no.7
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    • pp.476-482
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    • 2009
  • The crystallization behavior of poly(vinyl alcohol) (PVA) in the presence and absence of polypyrrole nanoparticles (PPy NPs) was investigated in terms of the heterogeneous nucleation effect of PPy NPs using FTIR, X-ray diffraction, differential scanning calorimeter and polarized optical microscope analysis. PPy NPs were prepared by dispersion polymerization method stabilized by PVA in aqueous solution. A polymer nanocomposite with uniform dispersity could be readily obtained due to the enhanced compatibility between the filler and matrix. Compared with the PPy NP-absent PVA, the PPy NP/PVA nanocomposite exhibited an enhanced degree of crystallinity. The degree of crystallinity increased up to 17% at the PPy NP concentration of 1 wt%, compared to the pristine PVA. The PPy NP acted as an effective nucleating agent during the crystallization process, thereby enhancing the degree and rate of crystallization. The kinetics study of the crystallization also revealed the decreased value of the Avrami coefficient in the case of the PPy NP/PVA nanocomposite.

Morphology and Swelling Behaviors of PVA/Gelatin Blend Membranes Prepared Under High Electric Field (고전장하에서 제조된 PVA/Gelatin 블렌드막의 구조와 팽윤거동)

  • Huh, Yang-Il;Yun, Hyung-Ku
    • Polymer(Korea)
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    • v.30 no.6
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    • pp.563-567
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    • 2006
  • Poly(vinyl alcohol) (PVA) and gelatin (GEL) blend membranes were prepared by solution casting method under a high electric field. SEM observation of the membrane showed that gelatin rich domains were elongated and oriented to the direction of the applied electric field in PVA matrix. This can be attributed to the electrostatic emulsifying effects due to a reduction in interfacial tension. In addition, it was observed through WAXD and swelling measurements that the degree of crystallinity of membranes increased with applied electric field strength. This may be interpreted to be caused by the orientation effect of GEL domains in the blend membrane, and the self-annealing effect due to some heat generated from high electric field during casting.

Pervaporation Separation of Water-Ethanol Mixture Using Crosslinked PVA/PSSA_MA/TEOS Hybrid Membranes (PVA/PSSA_MA/TEOS 막을 이용한 물/에탄올 계의 투과증발 분리)

  • Rhim, Ji-Won;Lee, Byung-Seong;Kim, Dae-Hoon;Yoon, Seok-Won;Im, Hyeon-Soo;Moon, Go-Young;Nam, Sang-Yong
    • Membrane Journal
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    • v.18 no.1
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    • pp.44-52
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    • 2008
  • Pervaporation separation for water-ethanol mixtures has been carried out using crosslinked poly(vinyl alcohol) (PVA) membranes with poly(styrene sulfonic acid-co-maleic acid) (PSSA_MA) and at which tetraethylorthosilicate (TEOS) was introduced. The concentration of PSSA_MA was fixed 7 wt% over PVA and the TEOS contents, 3, 5, and 7 wt%, were varied against PVA. The composition of the feed mixtures were 10, 20, 30 and 50 wt% of water in it. PVA/PSSA_MA/5 wt% TEOS membrane showed the separation factor, 1730 and the permeability, $16.3g/m^2{\cdot}hr$ for water : ethanol = 10 : 90 at $50^{\circ}C$.

Synthesis and Characterization of Poly(vinyl alcohol-b-styrene) via Atom Transfer Radical Polymerization and Saponification

  • Li, Guang-Hua;Cho, Chang-Gi
    • Macromolecular Research
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    • v.10 no.6
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    • pp.339-344
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    • 2002
  • Poly(vinyl alcohol-b-styrene) (poly(VA-b-St)) diblock copolymer containing high syndiotactic poly (vinyl alcohol) (PVA) was synthesized by the saponification of poly(vinyl pivalate-b-styrene) (poly(VPi-b-St)). For the block copolymer, poly(vinyl pivalate) (PVPi) with trichloromethyl end group was obtained via telomerization of vinyl pivalate with carbon tetrachloride as a telogen and 2,2-azobisisobutyronitrile (AIBN) as an initiator. Then resulting poly(vinyl pivalate) with trichloromethyl end group was used as an effient macroinitiator for the synthesis of poly(VPi-b-St) using atom transfer radical polymerization (ATRP) in the presence of CuCl/2,2'-bipyridine at 130 $^{\circ}C$. The poly(vinyl pivalate) macroinitiator, poly(VPi-b-St), poly(VA-b-St) were characterized by GPC, FT-IR and $^1$H-NMR. And the analysis showed that integrity of the block copolymer was maintained during saponification reaction.

Preparation of High Molecular Weight Atactic Poly(vinyl alcohol) by Photo-induced Bulk Polymerization of Vinyl Acetate

  • Lyoo, Won-Seok;Ha, Wan-Shik
    • Fibers and Polymers
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    • v.2 no.2
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    • pp.108-115
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    • 2001
  • Vinyl acetate was polymerized in ultraviolet-ray initiated bulk system at low temperatures using 2,2-azobis(2,4-dimethylvaleronitrile) (ADMVN) or 2,2-azobis(isobutyronitrile) (AIBN) as the photoinitiator, respectively. High molecular weight (HMW) poly(vinyl alcohol) (PVA) having number-average degree of polymerization ($P_n$) of 3,900-7,800 and syndiotactic diad (S-diad) content of 52.5-54.0% could be prepared by complete saponification of synthesized linear poly(vinyl acetate) (PVAc) having $P_n$ 5,900-9,400 obtained at conversion of below 30%. $P_n$ of PVA using ADMVN was larger than that of PVA using AIBN. On the other hand, conversion of the former was smaller than that of the latter, and it was found that the initiation rate of the ADMVN was lower than that of AIBN. This could be explained by a fact that the rate of photolysis of AIBN is faster than that of ADMVN due to the higher quantum yield or dissociation rate constant of AIBN than that of ADMVN. The $P_n$, syndiotacticity, and whiteness of PVA from PVAc polymerized at lower temperatures were superior to those of PVA from PVAc polymerized at higher temperatures.

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Mucoadhesive Drug Carrier Using Poly(acrylic acid)/poly(vinyl alcohol) Interpolymer Complexes by Template Polymerization

  • Oh, Jung-Min;Cho, Chong-Su;Chun, Myung-Kwan;Choi, Hoo-Kyun
    • Proceedings of the PSK Conference
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    • 2002.10a
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    • pp.408.1-408.1
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    • 2002
  • A interpolymer complexes composed of poly(acrylic acid)(PAA) and po!y(vinyl alcohol)(PVA) were prepared by template polymerization of acrylic acid in the presence of PVA for mucoadhesive drug delivery. FT -IR results showed that the PAA/PVA interpolymer complex was formed by hydrogen bonding between the carboxyl groups of PAA and the hydroxyl group of PVA. The dissolution rate or the swelling ratio of the PAA/PVA interpolymer complexes was dependent on the pH and molecular weight of PVA that was used as a template. (omitted)

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