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- 주제어 : Polyacrylonitrile fibers (검색결과 74 건)
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Doo‑Won Kim,Dae Ho Kim,Sung Ryong Kim,Bo‑Hye Kim,Yun Hyuk Bang,Duck Joo Yang,Go Bong Choi,Yoong Ahm Kim,Kap Seung Yang 한국탄소학회 2019 Carbon Letters Vol.29 No.5
This study demonstrates that low processing rate for producing polyacrylonitrile (PAN)-based carbon fiber is a critical to obtain a homogeneous radial microstructure with high resistance to oxidation, thereby resulting in their improved mechanical strength. The dry-jet wet spun PAN organic fibers were processed (e.g., stabilized and then carbonized) utilizing two different rates; one is 1.6 times longer than the other. The effect of processing rate on the microstructural evolutions of carbon fibers was analyzed by scanning electron microscopy after slow etching in air, as well as Raman mapping after graphitization. The rapidly processed fiber exhibited the multilayered radial structure, which is caused by the radial direction stretching of the extrusion in the spinning. In case of the slowly processed fiber, the layered radial structure formed in the spinning process was changed into a more homogeneous radial microstructure. The slowly processed fibers showed higher oxidation resistance, higher mechanical properties, and higher crystallinity than the rapidly processed one. Raman mapping confirmed that the microstructure developed during spinning was sustained even though fiber was thermally treated up to 2800 °C.
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임윤지,백윤미,박수진 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
In this study, highly conductive Ni/Cu-polyacrylonitrile (PAN) fibers were prepared by electroless nickel plating on Cu-PAN fibers. In addition, the electromagnetic interference (EMI) shielding properties of the Ni/Cu-PAN fibers were investigated by varying the nickel plating time. The surface morphology of the Ni/Cu-PAN fibers was observed with a scanning electron microscope (SEM) in order to determine its surface properties and the volume resistivity of the samples was measured by using a four-point probe electrical resistivity tester to evaluate its electric properties. The electromagnetic interference shielding effectiveness (EMI-SE) was tested by a EMI shielding analyzer. Tensile test of the Ni/Cu-PAN were conducted using a universal test machine (UTM). The EMI-SE of Ni/Cu-PAN fibers was much improved compared with that of the as-received CuS-PAN fibers.
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임윤지,백윤미,박수진 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.12
In this study, highly conductive nickel/copper sulfide-polyacrylonitrile (Ni/CuS-PAN) fibers were prepared by electroless nickel plating on CuS-PAN fibers. The electromagnetic interference (EMI) shielding properties of the Ni/CuS-PAN fibers were investigated as a function of nickel-plating time. X-ray photoelectron spectroscopy and X-ray diffraction analyses were performed to examine the surface properties of the prepared Ni/CuS-PAN. The surface morphology of the Ni/CuS-PAN fibers was observed using scanning electron microscopy. The volume resistivity of the samples was measured using a four-point probe electrical resistivity tester, and the EMI shielding effectiveness (EMI-SE) was tested using an EMI shielding analyzer. The EMI-SE of the Ni/CuS-PAN fibers was significantly improved compared with those of the as-received CuS-PAN fibers. In addition, the EMI-SE generally increased as the nickel-plating time increased, with the highest EMI-SE of the 50-Ni/CuS-PAN being approximately 45?dB at 2.05?GHz. The nickel layer was a key factor in determining the EMI-SE of the Ni/CuS-PAN fibers.
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Effect of tension on PAN-based carbon fibers during electron beam irradiation stabilization
신혜경,박수진 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
This work evaluated the effect of various amounts of tension on polyacrylonitrile (PAN) precursor fibers during electron beam irradiation (EBI) stabilization. X-ray diffraction (XRD), tensile testing, and scanning electron microscopy (SEM) were implemented to determine the effects of tension on the PAN fibers. During the stabilization process, the fibers shrunk due to a loss of molecular alignment, and the addition of tension acting on the PAN fibers during stabilization was proposed to address this issue. In this work, PAN fibers were stabilized by EBI under various loads. It was found from the XRD data that tension led to the development of crystalline structures during EBI stabilization. From the tensile test, it was found that tension led to a small increase in strength due to conversion of disordered structures into ordered structures in the fibers.
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Seong-Moon Oh,Sang-Min Lee,Dong-Su Kang,Jae-Seung Roh 한국탄소학회 2016 Carbon Letters Vol.18 No.-
Polyacrylonitrile (PAN)-based carbon fibers have high specific strength, elastic modulus, thermal resistance, and thermal conductivity. Due to these properties, they have been increasingly widely used in various spheres including leisure, aviation, aerospace, military, and energy applications. However, if exposed to air at high temperatures, they are oxidized, thus weakening the properties of carbon fibers and carbon composite materials. As such, it is important to understand the oxidation reactions of carbon fibers, which are often used as a reinforcement for composite materials. PAN-based carbon fibers T300 and T700 were isothermally oxidized in air, and microstructural changes caused by oxidation reactions were examined. The results showed a decrease in the rate of oxidation with increasing burn-off for both T300 and T700 fibers. The rate of oxidation of T300 fibers was two times faster than that of T700 fibers. The diameter of T700 fibers decreased linearly with increasing burn-off. The diameter of T300 also decreased with increasing burn-off but at slower rates over time. Cross-sectional observations after oxidation reactions revealed hollow cores in the longitudinal direction for both T300 and T700 fibers. The formation of hollow cores after oxidation can be traced to differences in the fabrication process such as the starting material and final heat treatment temperature.
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Grafting of Casein onto Polyacrylonitrile Fiber for Surface Modification
Jia Zhao,Du Shanyi The Korean Fiber Society 2006 Fibers and polymers Vol.7 No.3
Polyacrylonitrile (PAN) fiber was grafted with casein after alkaline hydrolysis and chlorination reactions of the original fiber. The structures and morphologies of the casein grafted fiber were characterized by Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), and scanning electron microscope (SEM). Moisture absorption, specific electric resistance, water retention value, and mechanical properties were also investigated. The results showed that casein was grafted onto the surface of the PAN fiber and the grafted PAN fiber presented better hygroscopicity compared with the untreated fiber. With proper tensile strength, the modified fiber could still meet the requirement for wearing. A mechanism was proposed to explain the deposit of casein on the synthetic acrylic fiber.
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Lee, Jae Hyeok,Jin, Jeong-Un,Park, Sejoon,Choi, Dalsu,You, Nam-Ho,Chung, Yongsik,Ku, Bon-Cheol,Yeo, Hyeonuk Elsevier 2019 Journal of industrial and engineering chemistry Vol.71 No.-
<P><B>Abstract</B></P> <P>Polyacrylonitrile (PAN) copolymers containing varying amounts of methyl acrylate (MA), P(AN-<I>co</I>-MA), were synthesized as a melt-spinnable precursor of carbon fibers. The rheological properties of P(AN-<I>co</I>-MA) with MA content of 15mol% at 190°C proved to be suitable for melt-spinning and the PAN fiber was spun from an extruder. In order to prevent remelting and fusion of the fibers in the stabilization process, electron-beam irradiation of over 1500kGy was used and the melt-spun PAN fibers were successfully converted to stabilized PAN fibers by thermal treatment up to 250°C. Finally, carbon fibers (CFs) were produced by pyrolysis of the stabilized PAN fibers. The mechanical properties of the resulting-CFs were evaluated; the tensile strength, tensile modulus, and elongation at break were 1.37±0.2GPa, 110±11.1GPa, and 1.27±0.28%, respectively. These results suggest the possibility of utilizing melt-spinning as a cost-efficient method for fabrication of carbon fibers.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Poly(acrylonitrile-<I>co</I>-methylacrylate) was synthesized as a melt processible carbon fiber precursor. </LI> <LI> Thermal and rheological analysis confirmed flow characteristics suitable for melt-spinning. </LI> <LI> The precursor fibers were thermally stabilized by assistance of electron-beam irradiation without re-melting and fusion. </LI> <LI> The mechanical properties of resulting-carbon fiber were 1.37GPa in tensile strength and 110GPa in modulus, respectively. </LI> </UL> </P>
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김두원,김대호,김성룡,김보혜,방윤혁,양덕주,최고봉,김융암,양갑승 한국탄소학회 2019 Carbon Letters Vol.29 No.5
This study demonstrates that low processing rate for producing polyacrylonitrile (PAN)-based carbon fiber is a critical to obtain a homogeneous radial microstructure with high resistance to oxidation, thereby resulting in their improved mechanical strength. The dry-jet wet spun PAN organic fibers were processed (e.g., stabilized and then carbonized) utilizing two different rates; one is 1.6 times longer than the other. The effect of processing rate on the microstructural evolutions of carbon fibers was analyzed by scanning electron microscopy after slow etching in air, as well as Raman mapping after graphitization. The rapidly processed fiber exhibited the multilayered radial structure, which is caused by the radial direction stretching of the extrusion in the spinning. In case of the slowly processed fiber, the layered radial structure formed in the spinning process was changed into a more homogeneous radial microstructure. The slowly processed fibers showed higher oxidation resistance, higher mechanical properties, and higher crystallinity than the rapidly processed one. Raman mapping confirmed that the microstructure developed during spinning was sustained even though fiber was thermally treated up to 2800 °C.
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An overview of new oxidation methods for polyacrylonitrile‑based carbon fibers
Hye Kyoung Shin,Mira Park,Hak-Yong Kim,Soo-Jin Park 한국탄소학회 2015 Carbon Letters Vol.16 No.1
The process of oxidizing polyacrylonitrile (PAN)-based carbon fibers converts them into an infusible and non-flammable state prior to carbonization. This represents one of the most important stages in determining the mechanical properties of the final carbon fibers, but the most commonly used methods, such as thermal treatment (200°C to 300°C), tend to waste a great deal of process time, money, and energy. There is therefore a need to develop more advanced oxidation methods for PAN precursor fibers. In this review, we assess the viability of electron beam, gamma-ray, ultra-violet, and plasma treatments with a view to advancing these areas of research and their industrial application.
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Liu, Ying,Haridas, Anupriya K.,Lee, Younki,Cho, Kwon-Koo,Ahn, Jou-Hyeon Elsevier BV * North-Holland 2019 Applied Surface Science Vol.472 No.-
<P><B>Abstract</B></P> <P>A freestanding porous sulfurized polyacrylonitrile/vapor grown carbon fiber (SVF) composite was prepared as cathode material for high-performance lithium sulfur batteries by a facile electrospinning technique. The synthesized composite possessed high sulfur utilization, high Coulombic efficiency, and excellent cycling stability with the property of flexibility, essential to the development of flexible batteries. The capacity retentions of the SVF cell were 903 mAh g<SUP>−1</SUP> after 150 cycles at 1 C and 600 mAh g<SUP>−1</SUP> after 300 cycles at 2 C. At a high rate of 4 C, the SVF composite showed reasonable capacity retention. The superior performance of SVF composite was attributed to the highly porous structure, which effectively improved the wettability, accessibility, and absorption of electrolyte to facilitate rapid ion transfer in the cell. Vapor-grown carbon fibers embedded inside SVF as a carbon material notably enhanced the electrical conductivity of the cell, guaranteeing the electrochemical performance at high C-rates. The freestanding porous SVF fiber composite is a promising cathode material for advanced flexible lithium sulfur batteries.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Freestanding porous sulfurized polyacrylonitrile/VGCF composite was synthesized via a facile electrospinning. </LI> <LI> Highly porous structure can effectively improve ionic transfer. </LI> <LI> The high conductivity of VGCF can improve the electrical conductivity of the composite. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Freestanding porous sulfurized polyacrylonitrile/vapor grown carbon fiber (SVF) composite was prepared through a facile electrospinning process followed by sulfurization, as cathode material for high-performance flexible lithium sulfur batteries. The highly porous structure, high electrical conductivity and flexible property of the composite could greatly improve electrochemical performances.</P> <P>[DISPLAY OMISSION]</P>
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