• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 2010.04a
• /
• pp.160-160
• /
• 2010

• Membrane Journal
• /
• v.13 no.3
• /
• pp.191-199
• /
• 2003

Cation exchange polymer electrolyte membrane for the application of direct methanol fuel cell (DMFC) was studied. Poly(vinyl alcohol)(PVA) well known as a methanol barrier in pervaporation separation was used fur the base materials and poly(acrylic acid)(PAA) was used for the crosslinking agent with various concentration. Methanol permeability, ion conductivity, ion exchange capacity, water contents and fixed ion concentration of the membranes were investigated to evaluate the performance of the fuel cell electrolyte membrane. Methanol permeability and ion conductivity of the membranes were decreased with increasing PAA content and were increased over 15% of PAA content. These phenomena would be explained with the introduction of hydrophilic crosslinking agent. The membranes with 15% content of PAA showed methanol permeability of $6.49{\times}10^{-8}/cm^2/s,\; 2.85{\times}10^{-7}CM^2/s$ at $25^{\circ}C,\; 50^{\circ}C$ of operating temperatures, respectively. ion conductivities of the membrane were $2.66{\times}10^{-3}\;S/cm,$ $9.16{\times}10^{-3}\;S/cm$ at $25^{\circ}C,\; 50^{\circ}C$ of operating temperatures, respectively. ion exchange capacity, water content and fixed ion concentration of the membrane were revealed 1.32 meq/g membrane,0.25 g $H_2$O/g membrane and 5.25 meq/g $H_2O$, respectively.

• Korean Membrane Journal
• /
• v.5 no.1
• /
• pp.18-24
• /
• 2003

In order to improve the mechanical properties of the sulfonated polysulfone (SPSf) membranes previously synthesized in our laboratory, poly(vinyl alcohol) (PVA) was blended which is well known as the excellent physical and chemical properties. The resulting membranes blended with several molecular weight of PVA varying from 13,000 to 124,000 have been characterized to investigate the effect of PVA molecular weight in terms of ion conductivities, methanol permeabilities, water contents and ion exchange capacities for both heat treated and untreated membranes at 150$^{\circ}C$. The proton conductivity is decreased as the molecular weight of PVA increases. The plain SPSf-6.0 showed the proton conductivity of 0.078 S/cm whereas the blended membrane with M.W. 31,000 PVA indicated 0.04 S/cm. For methanol permeabilities, when PVA is added to SPAf-6.0, methanol crossover is increased because of the gain of the hydrophilicity from 3.4 to 6.5${\times}$10$\^$-6/ $\textrm{cm}^2$/s. For the annealed blended membranes (with M.W. 31,000 PVA), both the methanol corssover and proton conductivity showed very consistent values, about 2.3${\times}$10$\^$-6/ $\textrm{cm}^2$/s and 0.036 S/cm, respectively.

• Membrane Journal
• /
• v.18 no.4
• /
• pp.336-344
• /
• 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 $10^{-8}\;cm^2/s$.

• Polymer(Korea)
• /
• v.34 no.1
• /
• pp.45-51
• /
• 2010

This study focuses on the investigation of the possibility of the crosslinked poly (vinyl alcohol) membranes with both poly (acrylic acid-co-maleic acid) (PAM) and 3-(trihydroxysilyl)-1-propane-sulfonic acid (THS-PSA) for the direct methanol fuel cell application. In order to characterize the prepared membranes, the water content, the thermal gravimetric analysis, the ion exchange capacity, the ion conductivity and the methanol permeability measurements were carried out and then compared with the existing Nafion 115 membrane. The ion exchange capacity of the resulting membranes showed 1.6~1.8 meq./g membrane which was improved than Nafion 115, 0.91 meq./g membrane. In the case of the proton conductivity, the THS-PSA introduced membranes gave more excellent $0.042{\sim}0.056\;S{\cdot}cm^{-1}$ than Nafion 115, $0.024\;S{\cdot}cm^{-1}$. On the other hand, the methanol permeability was increased more than Nafion 115 for all the range of THA-PSA concentration.

• Proceedings of the Polymer Society of Korea Conference
• /
• 2006.10a
• /
• pp.270-270
• /
• 2006

We have prepared polymer electrolyte membranes (PEMs) for DMFC from polymer mixture of poly(vinyl alcohol) and poly(vinyl alcohol-co-2-acrylamido-2-methylpropane sulfonic acid) (AP-2) changing the AP-2 content. The proton conductivity(${\Box}$) and methanol permeability(P) of the PEMs increase with increasing AP-2 content because the water content of the PEMs increases with increasing AP-2 content. The proton permselectivity of the PEMs, which is defined as ${\Box}={\Box}/P$, indicates higher values than that of $Nafion{(R)}$117.

• Membrane Journal
• /
• v.14 no.3
• /
• pp.240-249
• /
• 2004

Crosslinked PVA membranes were achieved by esterification between the hydroxyl groups of PVA and carboxyl group of sulfosuccinic acid (SSA). SSA containing sulfonic group was used as a chemical crosslinking agent as well as a donor of fixed anionic group ($-SO_3$H). The crosslinking density of membranes was controlled by SSA content and calculated using polar and non-polar solvent. The crosslinking density measured by using non-polar solvent such as xylene and benzene increases with SSA content. However, using the polar solvent such as water and methanol, the crosslinking density increases up to SSA content of 20 wt% and above the content decrease due to sulfonic acid groups. The crosslinked PVA membranes were studied in relation with water diffusion coefficient and mechanical property as well as proton conductivity and methanol permeability as a function of crosslinking density. These properties were all dependent on the effect of SSA content.

• Macromolecular Research
• /
• v.15 no.5
• /
• pp.412-417
• /
• 2007

In the present study, crosslinked poly(vinyl alcohol) (PVA) membranes were prepared at different temperatures using poly(styrene sulfonic acid-co-maleic acid) (PSSA_MA) (PVA:PSSA_MA = 1:9). The hybrid mem-branes were prepared by varying the TEOS content between 5 and 30 wt%. The PSSA_MA was used both as a crosslinking agent and the hydrophilic group donor ($-SO_3H$ and/or-COOH). The proton conductivity increased with up to 20 wt% TEOS, but decreased above this level, although the water content decreased with increasing TEOS content. This result suggests that the silica doped into the membrane improved the formation of proton-conduction pathways due to the absorption of molecular water. The PVA/PSSA_MA/Silica containing TEOS 20% showed both high proton conductivity (0.026 S/cm at $90^{\circ}C$) and low methanol permeability ($5.55{\times}10^{-7}cm^2/s$).

• Macromolecular Research
• /
• v.13 no.4
• /
• pp.314-320
• /
• 2005

Crosslinked poly(vinyl alcohol) (PVA) membranes were prepared at various crosslinking temperatures using poly(acrylic acid-co-maleic acid) (PAM) containing different PAM contents. The thermal properties of these PVA/PAM membranes prepared at various reaction temperatures were characterized using differential scanning calorimetry (DSC). The proton conductivity and methanol permeability of PVA/PAM membranes were then investigated as PAM content was varied from 3 to 13 wt%. It was found that the proton and methanol transport were dependent on PAM content in their function both as crosslinking agent and as donor of hydrophilic -COOH groups. Both these properties decreased monotonously with increasing PAM concentration. The proton conductivities of these PVA/PAM membranes were in the range from $10^{-3}\;to\;10^{-2}S/cm$ and the methanol permeabilities from $10^{-7}\;to\;10^{-6}cm^{2}/sec$. In addition, the effect of operating temperature up to $80^{\circ}C$ on ion conductivity was examined for three selected membranes: 7, 9 and 11 wt% PAM membranes. Ion conductivity increased with increasing operating temperature and showed and S/cm at $80^{\circ}C$, respectively. The effects of crosslinking and ionomer group concentration were also examined in terms of water content, ion exchange capacity (IEC), and fixed ion concentration. In addition, the number of water molecules per ionomer site was calculated using both water contents and IEC values. With overall consideration for all the properties measured in this study, $7{\sim}9\;wt%$ PAM membrane prepared at $140^{\circ}C$ exhibited the best performance. These characteristics of PVA/PAM membranes are desirable in applications related to the direct methanol fuel cell (DMFC).

• Membrane Journal
• /
• v.25 no.2
• /
• pp.144-151
• /
• 2015

The water-soluble poly(vinyl alcohol) membranes with the addition of sulfosuccinic acid (SSA) were prepared and to assign the ion exchange capacity, poly(4-styrene sulfonic acid-co-maleic acid) (PSSA_MA) was added to PVA according to PSSA_MA contents of 70, 80 and 90 wt%. To characterize the resulting membranes, FT-IR, water contents, ion exchange capacity, proton conductivity and methanol permeability were measured. As PSSA_MA contents increased, water contents, ion exchange capacity, proton conductivity increased, but methanol permeability decreased. From these results, the best preparation component was known as PVA10/SSA9/PSSA_MA80.