• Polymer(Korea)
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• v.37 no.5
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• pp.592-599
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• 2013

In this study, polyacrylonitrile (PAN)-based porous carbon nanofibers were prepared from PAN polymer solution by electrospinning and KOH activation with various concentrations, and the characterization of pore structures and carbon dioxide adsorption was investigated. Manufactured PAN-based activated carbon nanofibers tend to decrease diameter and increase surface oxygen functional groups depending on the increasing concentration of KOH solution. In addition, according to the results of nitrogen adsorption for pore properties analysis, it indicated increase of the specific surface area in conformity with increasing concentration of KOH solution. Micropore volume of treated activated carbon nanofibers (ANCF) by 4 M KOH was the largest compared with other samples and mesopore volume of treated ANCF by 8 M KOH was the largest volume, respectively. The concentration of KOH effects textural and surface properties, as represented by BET and XPS, which enhance carbon dioxide adsorption capacity at 0 and $25^{\circ}C$.

• Composites Research
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• v.32 no.1
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• pp.71-77
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• 2019

In this study, the structural and rheological characterizations of polyacrylonitrile(PAN)/dimethyl sulfoxide(DMSO) solutions for PAN fiber were investigated according to the change of storage times and temperatures. As a result, PAN/DMSO solutions exhibited a very characteristic rheological behavior with variation of temperature. The solutions showed an increase of complex viscosity and a decrease of loss tangent($tan{\delta}$) as temperature was increased over the temperature range of 40 and $70^{\circ}C$ and it could be seen that the viscosity rapidly increased at low frequency. These results indicated that the gel polymer and denser gel structure were formed due to the intermolecular hydrogen bonding of water in the polymer solution depending on the storage time.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.279-280
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• 2003

아크릴계 섬유를 포함하여 기존 섬유의 새로운 용도 창출 및 부가가치를 높이기 위하여 특수한 기능성을 나타내는 섬유들에 대한 관심이 꾸준히 증가하고 있다[1]. 이러한 이유로 유기물질과 무기물질의 복합체 제조는 일찍이 1980년대 초부터 연구되고 있고, 새로운 성능 및 기능 화대를 목표로 계속 이루어지고 있다[2]. 폴리아크릴로니트릴(Polyacrylonitrile, PAN)은 용액방사를 하는 대표적인 합성섬유로 담요, 카페트, 커튼 등 다양한 제품으로 응용되고 있으며, 그 성질이 천연섬유인 양모와 유사하기 때문에 양모 대체용으로 많이 사용되고 있다[1]. (중략)

• Carbon letters
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• v.14 no.1
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• pp.45-50
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• 2013

Polyacrylonitrile (PAN) copolymers of different molecular weights were synthesized by a suspension polymerization and precipitation polymerization method. The rheology behaviors of the synthesized PAN copolymers were investigated in relation to their molecular weight, solid content and melting temperature. The influence of "historical effects" on the spinning solution of PAN was studied by analyzing the laws of viscosity considering the diversification time and temperature. The viscosity disciplines of each spinning solution conformed well to the rheological universal laws in a comparison of the suspension polymerization product with that of precipitation polymerization. Viscosity changes in the swelling process of dissolution were gentler in the suspension polymerization product; a small amount of water will quickly debase the solution viscosity, and high-speed mixing can greatly shorten the time required by the spinning solution to reach the final viscosity.

• Carbon letters
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• v.12 no.2
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• pp.107-111
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• 2011

Polyacrylonitrile (PAN) fibers were pre-oxidized in a temperature range of 180-275$^{\circ}C$. The effects of positive and negative stretching on the structure and morphology of PAN fiber in the pre-oxidation process were studied by FTIR spectroscopy, XRD, and SEM. Mechanical property changes were also investigated. No changes in the movement and intensity of functional groups of PAN fibers were caused by positive stretching of up to 10% and negative stretching down to -8%. The crystal structure can be affected by the positive stretching and negative stretching. The maximum strength is 479.81 MPa when the stretching is positive, and the maximum strength is 420.55 MPa when the stretching is negative.

• Fibers and Polymers
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• v.5 no.3
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• pp.198-203
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• 2004

Composite films were prepared by casting the solution of polyacrylonitrile (PAN) and single wall nanotube (SWNT) in DMF subsequent to sonication. The SWNTs in the films are well dispersed as ropes with 20-30 nm thickness. Moreover, AFM surface image of the composite film displays an interwoven fibrous structure of nanotubes which may give rise to conductive passways and lead to high conductivity. The polarized Raman spectroscopy is an ideal characterization technique for identification and the orientation study of SWNT. The well-defined G-peak intensity at 1580 $cm^{-1}$shows a dependency on the draw ratio under cross-Nicol. The degree of nanotube orientation in the drawn film was measurable from the sine curve obtained by rotating the drawn film on the plane of cross-Nicol of polarized Raman microscope. The threshold loading of SWNT for electrical conductivity in PAN is found to be lower than 1 wt% in the composite film. The electrical conductivity of the SWNT/PAN composite film decreased with increasing of draw ratio due to the collapse of the interwoven fibrous network of the nanotubes with uniaxial orientation.

• Carbon letters
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• v.15 no.4
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• pp.290-294
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• 2014

New precursors, poly(acrylonitrile-co-crotonic acid) (poly(AN-CA)) and poly(acrylonitrile-co-itaconic acid-co-crotonic acid) (poly(AN-IA-CA)) copolymers, for the preparation of carbon fibers, were explored in this study. The effects of comonomers with acidic groups, such as crotonic acid (CA) and/or itaconic acid (IA), on the stabilization of nanofibrous polyacrylonitrile (PAN) copolymers were studied. The extent of stabilization, evaluated by Fourier transform infrared spectroscopy, revealed that the CA comonomer could retard/control the stabilization rate of PAN, in contrast to the IA comonomer, which accelerated the stabilization process. Moreover, the synthesized PAN copolymers containing CA possessed higher Mv than those of the IA copolymers and also showed outstanding dimension stability of nanofibers during the stabilization, which may be a useful property for improving the dimensional stability of polymer composites during manufacturing.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.547-552
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• 2019

Electrochemical properties of $LiMn_{0.8}Fe_{0.2}PO_4$ cathode were investigated with gel polymer electrolyte (GPE). To access fast and efficient transport of ions and electrons during the charge/discharge process, a pure and well-crystallized $LiMn_{0.8}Fe_{0.2}PO_4$ cathode material was directly synthesized via spray-pyrolysis method. For high operation voltage, polyacrylonitrile (PAN)-based gel polymer electrolyte was then prepared by electrospinning process. The gel polymer electrolyte showed high ionic conductivity of $2.9{\times}10^{-3}S\;cm^{-1}$ at $25^{\circ}C$ and good electrochemical stability. $Li/GEP/LiMn_{0.8}Fe_{0.2}PO_4$ cell delivered a discharge capacity of $159mAh\;g^{-1}$ at 0.1 C rate that was close to the theoretical value ($170mAh\;g^{-1}$). The cell allows stable cycle performance (99.3% capacity retention) with discharge capacity of $133.5mAh\;g^{-1}$ for over 300 cycles at 1 C rate and exhibits high rate-capability. PAN-based gel polymer is a suitable electrolyte for application in $LiMn_{0.8}Fe_{0.2}PO_4/Li$ batteries with perspective in high energy density and safety.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3733-3737
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• 2013

Polyacrylonitrile (PAN)-based ultrafine fibers and carbon fibers were produced by wet-spinning, and the crystal sizes and thermal and mechanical properties of the fibers were investigated. Scanning electron microscopy revealed that the superfine fibrils in the surfaces of the PAN/polyvinyl acetate (PVA) blend fibers increased slightly with increasing PAN content before removal of the PVA. Differential scanning calorimetry indicated that the PAN and PVA in the blend fibers do not mix and, therefore, each maintains their inherent thermal characteristics. The crystal sizes of the blend fibers prepared by removing PVA with water increased at 5 wt % water. The extent of the reaction of the PAN carbon fibers, as calculated from the FT-IR spectra, is maximized at the stepwise temperature of $230^{\circ}C$, and the density increased significantly above this temperature. The carbon fibers had relatively good mechanical properties, as shown by their tensile strength and modulus values of 2396 MPa and 213 GPa, respectively.

• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1333-1338
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• 2003

Hollow Fiber flow field-flow fractionation (HF-FlFFF) has been tested in polyacrylonitrile (PAN) membrane channel in order to compare it with polysulfone (PSf) membrane channel. It has been experimentally shown that the separation time of 0.05-0.304 ${mu}m$ polystyrene latex (PSL) standards in PAN membrane channel is shorter than that in PSf channel by approximately 65%. The optimized separation condition in PAN membrane is ${\dot V}_{out}/{\dot V}_{rad}=1.4/0.12\;mL/min$, which is equal to the condition in PSf membrane channel. In addition both the resolution ($R_s$) and plate height (H) in PAN membrane channel are better than that in PSf membrane channel. The membrane radius was obtained by back calculation with retention time. It shows that the PSf membrane is expanded by swelling and pressure, but the PAN membrane doesn't expand by swelling and pressure.