• Polymer(Korea)
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• v.24 no.5
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• pp.579-588
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• 2000

The effects of protective colloids on the colloid stability of poly(vinyl acetate) (PVAc) latex was investigated. The stability of PVAc latex in reactive poly(vinyl alcohol) mono thiol (PVALT) (DP=1080) having 78.4% saponification value was better than poly (vinyl alcohol)(PVA) (DP=1100) having 81.6% saponification value. The colloidal stability of PVAc latex particles improved drastically with increase of the reactive PVALT. The particle surface morphology of PVAc latex was examined by transmission electron microscopy (TEM). It was shown that particle size of 1ha latexes decreased with increasing reactive PVALT concentration. Therefore, the stabilities of latex for reactive PVALT protective colloid was superior to that of PVA ones. This result is due to the introduction of many thiol groups that induce chemical bonds at PVAc latexes surface, so that the formation of PVALT-b-PVAc block copolymer via the reaction of PVAc with reactive PVALT. In addition, zeta potential of the PVAc latexes decreased with increasing sodium carbonate concentration.

• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.187-190
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• 2001

The poly(vinyl alcohol) (PVA) fiber is recognized as the best candidate because of its good machanical properties together with excellent resistance to alkalis[1-5]. PVA cannot be prepared by the direct polymerization due to tautomerism of vinyl alcohol monomer. Thus PVA is obtained by the saponification of poly(vinyl ester) like poly(vinyl acetate) (PVAc). (omitted)

• Macromolecular Research
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• v.15 no.6
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• pp.491-497
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• 2007

NPT Monte Carlo simulations were performed to calculate the molecular properties of syndiotactic poly(vinyl chloride) (PVC) and syndiotactic poly(vinyl alcohol) (PVA) melts using the configurational bias Monte Carlo move, concerted rotation, reptation, and volume fluctuation. The density, mean square backbone end-to-end distance, mean square radius of gyration, fractional free-volume distribution, distribution of torsional angles, small molecule solubility constant, and radial distribution function of PVC at 0.1 MPa and above the glass transition temperature were calculated/measured, and those of PVA were calculated. The calculated results were compared with the corresponding experimental data and discussed. The calculated densities of PVC and PVA were smaller than the experimental values, probably due to the very low molecular weight of the model polymer used in the simulation. The fractional free-volume distribution and radial distribution function for PVC and PVA were nearly independent of temperature.

• Elastomers and Composites
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• v.44 no.3
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• pp.323-328
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• 2009

The rheological properties of complex materials such as polymer melts show complicated non-Newtonian flow phenomena when they are subjected to shear flow. These flow properties are controlled by the characteristics of flow units and the interactions among the flow segments. The non-Newtonian flow curves of poly(vinyl alcohol) hydrogel were obtained in various concentrations and temperatures by using a cone-plate rheometer. By applying non-Newtonian flow equation to the flow curves for PVA hydrogel samples, the rheological parameters were obtained. The PVA hydrogel samples are shear thinning under increasing shear rate modes which result in thixotropic behavior.

• Macromolecular Research
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• v.11 no.6
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• pp.451-457
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• 2003

Anion-substituted poly(vinyl alcohol) (PVA) membranes, carboxymethylated PVA (C-PVA), and sulfonated PVA (S-PVA) were prepared and the effects of these substitutions on the plasma protein adsorption were studied by one- and two-dimensional gel electrophoresis and immunoblotting. When Cuprophane was used as a negative control, the amount of total proteins bound to samples decreased in the order Cuprophane > PVA > C-PVA > S-PVA, which we attribute to the effects of the surface characteristics of the samples, such as their surface tensions and electrostatic properties, on the adsorption of proteins to the surfaces of the materials. The results revealed that albumin was the most abundant protein in all the samples. The proportion of adsorbed fibrinogen to S-PVA exceeded those of PVA and C-PVA, whereas S-PVA exhibited the lowest IgG adsorption affinity among the samples we studied.

• Membrane Journal
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• v.15 no.1
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• pp.34-43
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• 2005

The poly(vinyl alcohol) (PVA)-based thin film composite nanofiltration (NF) membranes were prepared by coating polysulfone ultrafiltration membranes, sulfonated polyethersulfone and polyamide NF membranes with aqueous PVA solution by a pressurizing method. The PVA was cross-linked with aqueous glutaraldehyde solution. The NF membranes coated with a very low concentration of PVA on all the support membranes was successfully prepared. With increasing the hydrophilicity of the support membranes, the water flux increased. Especially, ζ-potential of negatively charged polyamide NF membrane was reduced by coating the membrane with PVA. A fouling experiment was carried out with positively charged surfactant, humic acid, complex of humic acid and calcium ion and bovine serum albumin. A non-coated polyamide NF membrane was significantly fouled by various foulants. The fouling process when using humic acid and protein occurred at the isoelectric point. There was severe fouling when using humic acid and adding bivalent cations. By coating the polyamide NF membrane with aqueous PVA solution, fouling was reduced. The polyamide NF membrane coated with PVA was resistant to the acidic and basic solution.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.104-107
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• 2003

Poly(vinyl alcohol) (PVA) obtained by the saponification of poly(vinyl ester) like poly(vinyl acetate) o. poly(vinyl pivalate) is a linear semicrystalline polymer, which has 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)

• Macromolecular Research
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• v.17 no.8
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• pp.591-596
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• 2009

To trace the plasticizing effects of propylene glycol (PG) on poly(vinyl alcohol) (PVA), the rheological properties of PVA solutions in dimethyl sulfoxide (DMSO) and the physical properties of PVA films were discussed in terms of PG content. Both properties were closely related to the hydrogen bond breaking effects of PG The 6 and 12 wt% PVA solutions containing PG exhibited Bingham behavior, which was more noticeable at lower plasticizer content and higher polymer concentration. The 6 wt% PVA solutions containing more than 30 wt% PG showed a sudden decrease of viscosity over the frequency range of 0.08 and 0.2 rad/s. However, the 12 wt% PYA solutions showed no viscosity reduction even at a PG content up to 40 wt%. The glass transition temperature of the PVA/PG films was almost linearly decreased with increasing PG content but an abrupt reduction was observed at a plasticizer content 30 wt%, suggesting that the hydrogen bond breaking effects of PG on PVA became dominant between 20 and 30 wt%. This effect was further supported by the similar tendency of the tensile properties.

• Polymer(Korea)
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• v.26 no.6
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• pp.792-802
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• 2002

In this study, hydrogels from mixtures of poly (vinyl alcohol) (PVA)/poly(N-vinylpyrrolidone) (PVP)/glycerin/chitosan were prepared by γ-ray irradiation and the mechanical properties such as gelation, water absorptivity, and gel strength were examined to evaluate the applicability of these for wound dressing. Then PVA:PVP was weight ratio of 6 : 4, the concentration of chitosan was 0.3 wt%, the concentration of glycerin was in the range of 0∼5 wt%t. The solid concentration of PVA/PVP/glycerin/chitosan solution was 15 wt%. Gamma irradiation doses of 25, 35, 50, and 60 kGy were exposed to a mixture of PVA/PVP/glycerin/chitosan to evaluate the effect of irradiation dose. Gel content and gel strength increased as glycerin concentration in PVA/PVP/glycerin/chitosan decreased, and as irradiation dose increased. Swelling degree increased as glycerin concentration in PVA/PVP/glycerin/chitosan increased, and as irradiation dose decreased. The glycerin in PVA/PVP/glycerini/chitosan hydrogel prevented the transformation of shape. These hydrogel dressings had better curing effect than vaseline gauge.

• Applied Chemistry for Engineering
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• v.26 no.4
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• pp.458-462
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• 2015

It is essential to employ a binder to prepare transparent films from conductive polymer such as poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT/PSS). In this paper, poly(vinyl alcohol) (PVA), poly(vinyl pyrrolidone) (PVP), and PSS were selected as a binder, and their effects were investigated. The formation of the film was found to be primarily dependent on the surface tension of coating solution including PEDOT/PSS and a binder. When PSS was used as a binder, the film was not formed. In case of using PVP, it was easily peeled off from the substrate. However, when using the PVA or the mixtures of PVA and PSS or PVA and PVP as a binder, films with good transparency and uniform surface resistances were produced. Based on adhesion and long-term stability tests, we concluded that the mixture of PVA and PSS is the best binder for preparing antistatic films of PEDOT/PSS.