• Proceedings of the Korean Fiber Society Conference
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• 1994.04a
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• pp.70-71
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• 1994

• Tribology and Lubricants
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• v.35 no.3
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• pp.169-175
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• 2019

In lithium-ion batteries (LIBs), the stress induced by the volume change of an electrode during charge-discharge processes may often cause the mechanical integrity of the electrode to degrade. Polymer binders with enhanced mechanical properties are preferred for improved mechanical integrity and cycling stability of the electrode. In addition, given that sliding and shearing between the polymer binder and components in the electrode may readily occur, frictional and adhesion characteristics of the polymer binder may play a critical role in the mechanical integrity of the electrode. In this study, frictional and adhesion characteristics of polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF) were investigated using a colloidal probe atomic force microscope. Friction loops were obtained under various normal forces ranging from 0 to 159 nN in air and electrolyte and then the interfacial shear strengths of PAN and PVDF in air were calculated to be $1.4{\pm}0.5$ and $1.3{\pm}0.3MPa$, respectively. The results show that in electrolyte, interfacial shear strength of PAN decreased slightly ($1.2{\pm}0.2MPa$), whereas that of PVDF decreased drastically ($0.06{\pm}0.01MPa$). Decreases in mechanical properties and adhesion in electrolyte may be responsible for the decrease in interfacial shear strength in electrolyte. The findings from this study may be helpful in developing polymer binders to improve the mechanical integrity of electrodes in LIBs.

• Polymer(Korea)
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• v.36 no.1
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• pp.47-52
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• 2012

Abstract: In this study, PAN/$TiO_2$ fiber mats were fabricated from polyacrylonitrile (PAN) and titanium(IV) butoxide ($Ti(OBu)_4$) by an electrospinning method with various solution concentrations, applied voltages and solution flow rates. The fiber mats were irradiated with an electron beam to induce structural crosslinking and enhance photocatalytic activity. As a result, uniform and bead-free fibers without pits or cracks on surface were obtained at 5 wt% of $Ti(OBu)_4$ solution with 15 kV and 0.02 mL/min flow rate. The PAN/$TiO_2$ fiber mats were irradiated with an electron beam of 1.14 MeV acceleration voltage, 4 mA of current and $1{\times}10^4kGy$. Electron beam irradiation was enhanced the photocatalytic activity of PAN/$TiO_2$ nano fiber mat. The photocatalytic activity of the PAN/$TiO_2$ fiber mat was analyzed by degradation of methylene blue and volatile organic compounds.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10a
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• pp.11-12
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• 2003

The reinforcing effect of single wall carbon nanotubes (SWNTs) on polyacrylonitrile (PAN) fiber were investigated. The tensile fracture images of the composite fibers demonstrate that SWNTs are well dispersed in PAN matrix as bundles (ropes) ca. 20nm in thickness. It was found that SWNTs play a role not only to reinforce but also to toughen the PAN fiber by increasing breaking strain as well as modulus and strength of the fiebrs. The composite fibers exhibited improved dimensional stability at elevated temperature compared to the neat PAN fiber.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.335-335
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• 2006

Polyacrylonitrile (PAN) was deposited as an adherent film on Cu-substrate by the cathodic electropolymerization. This work is an attempt to compare the molecular weight and the fractured surface of PAN prepared by CV and chronoamperometry. The molecular weight and increase weight of PAN measured the according to AN-concentration, scan rate, and cycle number (or time) using CV and chronoamperometry. The morphology of PAN was characterized by SEM image. Mechanism and optimal conditions for electropolymerization of acrylonitrile on Cu-substrate were investigated and discussed.

• Carbon letters
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• v.1 no.1
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• pp.17-21
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• 2000

Catalytic reduction and oxidation of NO over polyacrylonitrile based activated carbon fibers (PAN-ACF) under various conditions were carried out to develop removal process of NO from the flue gas. The effect of temperature, oxygen concentration and the moisture content for the reduction of NO with ammonia as a reducing agent was investigated. The reduction of NO increased with the oxygen concentration, but decreased with the increased temperature. The moisture content in the flue gas affects the reduction of NO as the inhibition of the adsorption of the other components and the reaction on the surface of ACE For the oxidation of NO to $NO_2$ over PAN-ACF without using a reducing gas, it showed the temperature and the oxygen concentration of the flue gas are the important factors for the NO conversion in which the conversion increased with oxygen concentration and decreased with the temperature increase and might be the alternative option for the selective catalytic reduction process.

• Textile Coloration and Finishing
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• v.15 no.3
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• pp.127-131
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• 2003

Acrylonitrile(AN) was solution-polymerized in dimethyl sulfoxide(DMSO) and tertiary butyl alcohol(TBA) at 30, 40, $50^\circ{C}$ using a low temperature initiator, 2,2'-azobis(2,4-dimethylvaleronitrile) (ADMVN). The low temperature polymerization using ADMVN, DMSO, and TBA is to be successful in obtaining high molecular weight polyacrylonitrile(PAN) with less branches by solution polymerization. Throug a polymerization of AN in DMSO at $30^\circ{C}$, PAN having viscosity-average molecular weight$(M_v)$ of 931,000 was obtained. And then, during AN solution polymerization in DMSO and TBA using a cosolvent system the in-situ formation of microfibrillar structure has been discovered at the cosolvent composition of 24/1$(V_{DMSO}/V_{TBA})$. The simultaneous process of gelation and phase separation of long chain molecules may explain the in-situ formation of PAN fibers during polymerization.

• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.1967-1972
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• 2009

The electrospinnability of pitch was improved by blending in a solution of polyacrylonitrile (PAN) resulting in the reduction of the average fiber diameter from 2000 to 750 nm. Activated carbon fibers (ACFs) derived by stabilization, carbonization and steam activation at 700, 800, and 900 ${^{\circ}C}$ of the PAN/pitch electrospun fibers for 60 min were investigated as electrodes for supercapacitors. The Brunauer, Emmett, Teller (BET) specific surface area ranged from 732 to 1877 $m^2g^{-1}$ and the specific capacitance from 75.5 to 143.5 $Fg^{-1}$, depending on the activation conditions. Electrodes from the electrospun web activated at 900 ${^{\circ}C}$ exhibited a particularly quick response showing a high frequency of 5.5 Hz at a phase angle of ‒$45^o$ of the impedance spectroscopy.

• Carbon letters
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• v.12 no.4
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• pp.229-235
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• 2011

Isotactic polyacrylonitrile (PAN) with triad isotacticity of 0.53, which was determined by $^{13}C$ NMR, using dialkylmagnesium as an initiator, was successfully synthesized. Isothermal treatment of iso-PAN was conducted in air at 200, 220, 250 and $280^{\circ}C$. Structural evolutions and chemical changes were studied with Fourier transformation infrared and wide-angle X-ray diffraction during stabilization. A new parameter $CNF={I_{2240cm}}^{-1}/ ({I_{1595cm}}^{-1}+f^*{I_{1595cm}}^{-1})$ was defined to evaluate residual nitrile groups. Crystallinity and crystal size were calculated with X-ray diffraction dates. The results indicated that the nitrile groups had partly converted into a ladder structure as stabilization proceeded. The rate of reaction increased with treatment temperature; crystallinity and crystal size decreased proportionally to pyrolysis temperature. The iso-conversional method coupled with the Kissinger and Flynn-Wall-Ozawa methods were used to determine kinetic parameters via differential scanning calorimetry analysis with different heating rates. The active energy of the reaction was 171.1 and 169.1 kJ/mol, calculated with the two methods respectively and implied the sensitivity of the reaction with temperature.

• Polymer(Korea)
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• v.28 no.2
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• pp.149-153
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• 2004

The cesium hydrogen sulfate (CsHSO$_4$) crystal is a superprotonic conductor above 140$^{\circ}C$ and possesses protonic conductivity three to low orders of magnitude higher than that at room temperature. Recently, the possibility of it as an electrolyte material for fuel cell system draws much attention. However, its plasticity and absorption of humidity place a limitation on its application. In this study, composites consisting of CsHSO$_4$ and polyacrylonitrile were prepared, and their phase transition properties and the ionic conductivities were evaluated. When the content of CsHSO$_4$ was about 80 vol%, a mechanically strong film with the protonic conductivity of 1${\times}$10$\^$-3/ Scm$\^$-1/ were made.