• Polymer(Korea)
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• v.35 no.4
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• pp.296-301
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• 2011

This study focuses on the investigation of the impregnation of poly (vinyl alcohol) (PVA) crosslinked with poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA) to porous polyethylene membrane for the fuel cell application. The membranes were characterized by the measurements of the water content, contact angle, FTIR spectra, thermal gravimetric analysis, ion exchange capacity, proton conductivity, methanol permeability and elastic modulus. The existence of hydrophilic moieties in the impregnated membranes was confirmed by contact angle and FTIR measurements. The impregnated PVA/PSSAMA(90:10) membrane exhibited a higher ion exchange capacity (1.2 meq./g dry membrane) than Nafion membrane (0.91 meq./g dry membrane). Through the elastic modulus measurement, the dimensional stability of the resulting membranes was expected to increase higher than the polyethylene membranes. The methanol crossover and water content decreased even if the PSSA-MA content increased due to the reduction of the free volume.

• Journal of Radiation Industry
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• v.5 no.2
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• pp.119-124
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• 2011

Silver nano-particles (AgNPs) have attracted much attention for centuries due to their unique optical properties, electrical conductivities, oxidative catalysis, and antibacterial effect. In this study, AgNPs have been prepared by using aqueous $AgNO_3$ solution in the poly(vinyl alcohol) (PVA)/poly(ethylene glycol) (PEG) hydrogels. PVA and PEG powders were dissolved in deionized water, and then irradiated by a gamma-ray with a radiation dose of 50 kGy to make hydrogels. PVA/PEG hydrogels were dipped into $1.0{\times}10^{-2}M$ $AgNO_3$ solution for 1 hour. After that, the swollen hydrogels were irradiated by gamma-ray for the formation of AgNPs. FE-SEM is used to observe the formation of AgNPs as a function of the content of PEG and the irradiation dose. Also, AgNPs in the PVA/PEG hydrogels were monitored by UV-Vis. It is observed that the content of PEG and gamma-ray irradiation in the hydrogel is crucial to the formation of AgNPs. Finally, antibacterial tests indiacted that the hydrogel containing silver nanoparticle has antibacterial activity.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.46-48
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• 2003

Poly(vinyl alcohol) (PVA) obtained from PVPi has the highest syndiotacticity among (PVA)s obtained via radical polymerization, and the s-diad content of PVA prepared by low temperature polymerization of vinyl pivalate (VPi)[1-5] comes to eve. 60%, Therefore, we an obtain (PVA)s with various tacticities through the copolymerization of vinyl acetate (VAc) and VPi and can examine the relation between physical properties of (PVA)s and their tacticities. (omitted)

• 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)

• Applied Chemistry for Engineering
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• v.9 no.3
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• pp.424-429
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• 1998

Cloud-point data at $230^{\circ}C$ and 1,800 bar are presented for two poly(ethylene-co-vinyl alcohol)(PEVA) copolymers[9.9mol% and 17.8mol% vinyl alcohol(VA)] in ethylene, propane, propylene, n-butane, 1-butene, dimethyl ether(DME), and chlorodifluromethane(CDFM). The static type experimental apparatus with a view cell has been used for the experiment at the high pressure and temperature. The pressure-temperature (P-T) loops of PEVA(9.9mol% VA) copolymer-DME mixtures are presented at copolymer concentrations of 1.4wt% to 20.0wt%. Also, we presented the phase behavior of PEVA(17.8mol% VA) copolymer-DME system at copolymer concentration of 1.9wt% to 6.8wt%. The cloud-point curves for the PEVA copolymers in dimethyl ether showed single phase above 480 bar as a result of the hydrogen bonding between the vinyl alcohol unit and dimethyl ether. The pressure-concentration(P-x) isotherm loops of PEVA(9.9mol% and 17.8mol% VA)-DME system are obtained. The cloud-point curves for PEVA(9.9mol% and 17.8 mol% VA) copolymers andthe ethylene, propane, propylene, n-butane, 1-butene, and CDFM all show negative slopes of phase behavior and are located at pressures below 1,800 bar. For PEVA copolymer-DME system(9.9mol% VA), cloud-point curves show positive slopes that decrease in pressures with decrease in temperature in the temperature range of $80^{\circ}C$ to $160^{\circ}C$.

• Journal of the Korean Applied Science and Technology
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• v.27 no.2
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• pp.216-221
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• 2010

Polyvinyl acetate (PVAc) prepared by emulsion polymerization has broad applications for additive such as paint binder, adhesive for wood and paper due to its low glass transition temperature which help to plasticize substrate resins. Since emulsion polymerization has a disadvantage that surfactant and ionic initiator degrade properties of the product polymer, poly (vinyl acetate-eo-ethyl acrylate) (VAc-EA) was synthesized using potassium persulfate as catalyst and polyvinylalcohol (PVA) as protective colloid to prevent the degradation. The copolymer latex product was internally plasticized and has enhanced adhesion, water resistance during VAc-EA emulsion polymerization. No coagulation and complete conversion occur with the reactant mixture of 10 mmol/L potassium persulfate, 10 mmol/L poly ( vinyl alcohol) (PVA 17). As the concentrations of PVA increase, the viscosity becomes increase.

• Macromolecular Research
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• v.13 no.2
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• pp.135-140
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• 2005

Poly(vinyl alcohol) (PVA) membranes crosslinked with poly(acrylic acid-co-maleic acid) (PAM) were prepared to investigate the effect of aging on their morphology by swelling them for up to 7 days. PAM was used both as a crosslinking agent and as a donor of the hydrophilic-COOH group. A $30 wt\%$ weight loss of the dry membrane was observed in the swelling test after 6 days. The surface of the membrane was dramatically changed after the swelling test. The surface roughness of the PVA/PAM membrane was increased, as determined by atomic force microscopy (AFM). The swelling loosened the polymer structure, due to the release of the unreacted polymer and the decomposition of the ester bond, thereby resulting in an increase in the free volume capable of containing water molecules. The water molecules present in the form of free water were determined by differential scanning calorimetry (DSC). The fraction of free water increased with increasing swelling time. The swelling of the membrane may provide space for the transport of protons and increase the mobility of the protonic charge carriers. The proton conductivity of the membranes measured at T= 30 and $50^{\circ}C$ was in the range of $10^{-3} to 10^{-2} S/cm$, and slightly increased with increasing swelling time and temperature.

• Membrane Journal
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• v.18 no.4
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• pp.336-344
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• 2008

This manuscript deals with the investigation of the possibility of the crosslinked poly(vinyl alcohol) membranes with both poly(styrene sulfonic acid-co-maleic acid) and 3-(trihydroxysilyl)-1-propanesulfonic acid (THS-PSA) for the fuel cell application. The studies were focused on the characterization of the resulting membranes through water content, thermal gravimetric analysis, ion exchange capacity, ion conductivity and methanol permeability measurements and then compared with the existing Nafion membrane. Typically, the ion conductivity lied in the range of $10^{-3}$ to $10^{-2}\;S/cm$ while the methanol permeability showed the range of $10^{-6}$ to $10^{-8}\;cm^2/s$.

• Membrane Journal
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• v.16 no.2
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• pp.153-158
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• 2006

The crosslinked poly(vinyl alcohol) (PVA) mwmbranes with poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA) were used to measure the water vapor and air permeabilities at 25 and $35^{\circ}C$. In addition, the contact angles of crosslinked PVA membranes were observed and increased with PSSA-MA contents. The water vapor permeability of 15300 Baller (1 Baller=$10^{-10}cm^3(STP){\cdot}cm/cm^2{\cdot}s{\cdot}cmHg$) was shown the maximum value at $35^{\circ}C$ when PSSA-MA=7 wt% membrane was used. The gas permeability of 146 Barrer was indicated the maximum at PSSA-MA=7 wt% at $35^{\circ}C$ and $P(H_2O)/P(Air)$ was the highest value 109.2 at $25^{\circ}C$.

• Proceedings of the Korean Society of Rheology Conference
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• 2000.11a
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• pp.25-28
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• 2000