• Membrane Journal
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• v.21 no.2
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• pp.141-147
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• 2011

The cation exchange membrane using TPA (tungstophosphoric acid) and the block co-polymer of polysulfone and polyphenylenesulfidesulfone was prepared for a separator of all-vanadium redox flow battery. The membrane resistance of the prepared cation exchange membrane in 1mol/L $H_2SO_4$ aqueous solution was measured. The membrane resistance of the prepared Psf-PPSS and Psf-TPA-PPSS cation exchange membrane was about $0.94{\Omega}{\cdot}cm^2$. Electrochemical property of all-vanadium redox flow battery using the prepared cation exchange membrane was measured. The measured charge-discharge cell resistance of V-RFB at 4 A decreased in the order; Nafion117 < Psf-TPA-PPSS < Psf-PPSS. The durability of membrane was earried out by soaking it in $VO_2{^+}$ solution and evaluated by measuring the charge-discharge cell resistance of V-RFB with an increase of soaking time. The prepared Psf-PPSS cation exchange membrane had high durability and Psf-TPA-PPSS cation exchange membrane had almost same durability compared with Nafion117.

• Proceedings of the Membrane Society of Korea Conference
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• 1999.07a
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• pp.115-115
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• 1999

In this work a new process was developed for the sulfonation of the chemicallly stable engineering polymer polyethersulfone as membrane materials for electrodialysis or a flow battery applications. Commercially available polyethersulfone polymer was partially sulfonated using a CSA sulfonating agent in a dichloromethane solvent, which sulfonated polyethersulfone with various sulfonation levels have been prepared. Sulfonated polyethersulfone (SPES) membranes with different ion capacities were prepared for the purpose of identifying cation exchange membrane properties, in an attempt to find a low cost replacement for Nafion, which most of the perfluorinated membranes, known to exhibit a prolonged service life, are expensive and difficult to process. The following features were determined: the degree of sulfonation, water uptake, thermal analysis, and electrochemical properties such as ion exchange capacities, resistivity, selectivity of ion permeation. The surface of the cation exchange membranes, decomposed with the H202-treatment, were observed by using scanning electron microscope. The area resistivities of SPES mebranes in 5N-NaOH decreased from $2,150{\;}{\Omega}-cm2$ to less than $15{\Omega}-cm2$ as the ion exchange capacity (IEC) increased from 0.62 to 1.73 millieequivlants per dry gram(meq/dg).eq/dg).

• Membrane Journal
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• v.22 no.4
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• pp.265-271
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• 2012

Polybenzimidazole (PBI) was prepared by condensation polymerization using diaminobenzidine (DAB) and isophtalic acid (IPAc). The cation exchange membrane was prepared by introduce the ion exchange group in the PBI polymer. It was confirmed from FT-IR analysis that the prepared PBI powder had same peak compared with commercial PBI power. The ionic conductivity of PBI film was $0.1{\sim}0.9{\times}10^{-2}$ S/cm. The ionic conductivity of prepared SPBI cation exchange membrane showed $3.7{\sim}4.7{\times}10^{-2}$ S/cm and had higher than Nafion117 ($2.0{\times}10^{-2}$ S/cm).

• Membrane Journal
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• v.19 no.2
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• pp.129-135
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• 2009

The cation exchange membrane using the block co-polymer of polysulfone and polyphenylenesulfidesulfone was prepared for a separator of all-vanadium redox flow battery. The membrane property of the prepared cation exchange membrane was measured. The thermal stability of the prepared cation exchange analyzed by TG showed a more stable than that of Nafion117. The lowest measured membrane resistance, equilibrated in 1mol/L $H_2SO_4$ aqueous solution, $0.96{\cdot}cm^2$ at 3 cc of CSA (chlorosulfuricacid) which was introduction agent of ion exchange group. Electrochemical property of all-vanadium redox flow battery using the prepared cation exchange membrane was measured. Electromotive force in 100% of state of charge was 1.4 V which was that of all-vanadium redox flow battery, and cell resistance in charge and discharge at each state of charge had a low value compared with that of all-vanadium redox flow battery using Nafion117.

• Membrane Journal
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• v.17 no.1
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• pp.37-43
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• 2007

The effect of anionic and cationic exchange polymer layer on the chronopotentiometry (CP) and current voltage curves (I-V) of charged composite membrane are investigated. Also, the ion transport near the interface between electrolyte and ionic exchange polymer membranes (anionic and cationic ones) and charged mosaic polymer composite membrane is studied. The results show that both anionic and cationic polymer exchange membranes exhibit lower voltage drop over range of applied current density and possess favorable industrial application potentials, especially at low KCl concentration. While the charged mosaic polymer composite membrane didn't show any current-voltage change, irrespective to the type and the concentration of used electrolyte. CP and I-V measurements are effectively used to give some fundamental understanding for ion transport behavior of ion exchange polymer membrane near the interlace.

• Membrane Journal
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• v.29 no.3
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• pp.155-163
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• 2019

The anion exchange membrane using the blending polymer of poly(ether sulfone) and poly(phenylene sulfide sulfone) was prepared. It was confirmed by EDXS and FT-IR analysis that the prepared anion exchange membrane had the -N- as an anion exchange group. The ionic conductivity in 1 mol/L $H_2SO_4$ aqueous solution was measured. The ionic conductivity of the prepared anion exchange membrane was 0.015~0.083 S/cm, and had a high value compared with AFN and APS as a commercial anion exchange membrane. Permeabilities of the vanadium ions through the prepared anion exchange membrane were tested to evaluate the possibility as a separator in vanadium redox flow battery. Vanadium ion permeation rate in the prepared anion exchange membrane had a low value compared with Nafion 117 as a commercial cation exchange and AFN as a commercial anion exchange membrane.

• Polymer(Korea)
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• v.33 no.6
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• pp.608-614
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• 2009

The cation-exchange membrane which was sulfonated styrene-ethylene/buthlene-styrene(SEBS) block copolymer containing the high impact polystyrene (HIPS) was prepared via post-sulfonation and casting method using the epoxidized polybutadiene and divinylbenzene as crosslinking agents. Post-sulfonation was carried out with sulfuric acid as sulfonating agent and silver sulfate as initiator in the nitrogen atmosphere. The basic properties of membranes, degree of sulfonation (DS), water uptake, ion-exchange capacity (IEC), electrical resistance, and modulus have been examined. DS of membrane increased with increasing the sulfonation time. The maximum DS of membrane containing 10 wt% HIPS was 83.6 %. The water uptake and IEC of membranes gradually increased as increasing the DS. The maximum water uptake and IEC of membranes were 43.8 % and 1.14 meq/g, respectively. The lowest electrical resistance of membrane containing the 20 wt% HIPS was $83\;\Omega{\cdot}cm^2$. The electrical conductivity of membrane containing 10 wt% HIPS was $1.22\times10^{-4}S/cm$. The modulus of membrane increased with increasing DS and these values were 153 and $204\;kgf/cm^2$ before and after sulfonation, respectively.

• Membrane Journal
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• v.26 no.2
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• pp.97-107
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• 2016

This study was carried out to prepare a heterogeneous cation exchange membrane by mixing polyvinylidene fluoride (PVDF), commercial cation exchange resin and sulfonated poly(phenylene oxide)(SPPO) in order to propose an optimum condition for the preparation, and to compare its properties with commercial membrane. Study results show that the ion exchange capacity and electrical resistance were outstanding when the ratio of polymer matrix was less than 30% comparing between PVDF-IER, PVDF-SPPO and PVDF-SPPO-IER. The tensile strength was confirmed that seemed a hard look was five times greater compared to the commercial heterogeneous membrane, despite the weak durability of PVDF resin. Therefore, when chemical and mechanical properties are considered, the optimum mixing ratio between PVDF, IER and SPPO was 30 : 70, at which electric resistance was measured as $3{\sim}5{\Omega}{\cdot}cm^2$, ion exchange capacity as 0.6~1.0 meq/g, while mechanical strength was in a range of $12{\sim}15kgf/cm^2$.

• Membrane Journal
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• v.12 no.4
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• pp.247-254
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• 2002

In order to develop the ion exchange membranes which would be used in direct methanol fuel cell (DMFC), the polysulfone polymer was sulfonated using chlorosulfonic acid (CSA) and trimethylchlorosilane(TMCS). It has been characterized in terms of ion conductivities, methanol crossover, swelling degree and ion exchange capacities for the heat untreated and treated membranes at $150^{\circ}C.$ Typically, the methanol permeability and ion conductivity at the mole ratio of 1.4 between polysulfone repeating unit and sulfonating agents showed $2.87{\times}10^{-7}\; cm^2/s$(without heat treatment), $1.52{\times}10^{-7}\; cm^2/s$(with heat treatment) and $1.10{\times}10^{-2}\; S/cm$(without heat treatment), $0.87{\times}10^{-2}\;$ S/cm(with heat treatment), respectively. After the mole ration of 1.4 both values indicated mild increase.

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