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Jianxiao Yang,Koji Nakabayashi,Jin Miyawaki,윤승호 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.34 No.-
A spinnable pitch was developed from the tetrahydrofuran-soluble fractions (THFS) of hyper coal (HPC)and used to prepare carbon fibers. THFS-derived pitch from bituminous coal-derived HPC showedexcellent spinnability and the obtained carbon fibers had a tensile strength of over 800 MPa with adiameter of 13 mm following heat treatment at 800 8C for 5 min. Thus, HPC was shown to be a usefulalternative precursor for the preparation of low-cost and general-performance carbon fibers.
Liu, Jinchang,Shimanoe, Hiroki,Nakabayashi, Koji,Miyawaki, Jin,Ko, Seunghyun,Jeon, Young-Pyo,Yoon, Seong-Ho Elsevier 2018 Journal of industrial and engineering chemistry Vol.67 No.-
<P><B>Abstract</B></P> <P>For the first time, polyvinyl chloride (PVC) was used as an easily-handled chlorine source for preparation of isotropic pitch-based carbon fiber (IPCF) incorporating ethylene bottom oil (EO) as a raw material. Pitch precursors were prepared by the chlorination–dehydrochlorination triggered by chlorine radicals originated from PVC; aromatization and poly-condensation reactions occurred by polyene-type radicals from PVC. Radical production and co-carbonization were facilitated by pretreatments of EO through vacuum distillation, bromination, and additional heat treatment. Pitches were prepared by the co-carbonization of pretreated EO and EO containing 20wt% PVC, and had higher yields and better spinnability than those by simple distillation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PVC was used as a chlorine source for the preparation of isotropic pitch precursors from EO. </LI> <LI> Isotropic pitches with excellent spinnability were fabricated by co-carbonization of EO with chlorine radicals from PVC. </LI> <LI> Pitch precursors prepared by chlorination–dehydrochlorination reactions showed higher yields and better spinnability. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Jinchang Liu,Hiroki Shimanoe,Koji Nakabayashi,Jin Miyawaki,고승현,전영표,윤성호 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.67 No.-
For the first time, polyvinyl chloride (PVC) was used as an easily-handled chlorine source for preparation of isotropic pitch-based carbon fiber (IPCF) incorporating ethylene bottom oil (EO) as a raw material. Pitch precursors were prepared by the chlorination–dehydrochlorination triggered by chlorine radicals originated from PVC; aromatization and poly-condensation reactions occurred by polyene-type radicals from PVC. Radical production and co-carbonization were facilitated by pretreatments of EO through vacuum distillation, bromination, and additional heat treatment. Pitches were prepared by the co-carbonization of pretreated EO and EO containing 20 wt% PVC, and had higher yields and better spinnability than those by simple distillation.
Jinchang Liu,Hiroki Shimanoe,Koji Nakabayashi,Jin Miyawaki,최종은,전영표,윤성호 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.67 No.-
An isotropic pitch precursor for fabricating carbon fibres was prepared by co-carbonization of ethylene bottom oil (EBO) and polyvinyl chloride (PVC). Various pre-treatments of EBO and PVC, and a high heating rate of 3 °C/min with no holding time, were evaluated for their effects on the oxidative stabilization process and the mechanical stability of the resulting fibres. Our stabilization process enhanced the volatilization, oxidative reaction and decomposition properties of the precursor pitch, while the addition of PVC both decreased the onset time and accelerated the oxidative reaction. Aliphatic carbon groups played a critical role in stabilization. Microstructural characterization indicated that these were first oxidised to carbon–oxygen single bonds and then converted to carbon–oxygen double bonds. Due to the higher heating rate and lack of a holding step during processing, the resulting thermoplastic fibers did not completely convert to thermoset materials, allowing partially melted, adjacent fibres to fuse. Fiber surfaces were smooth and homogeneous. Of the various methods evaluated herein, carbon fibers derived from pressure-treated EBO and PVC exhibited the highest tensile strength. This work shows that enhancing the naphthenic component of a pitch precursor through the co-carbonization of pre-treated EBO with PVC improves the oxidative properties of the resulting carbon fibers.
Keiko Ideta,김두원,김태곤,Koji Nakabayashi,Jin Miyawaki,박주일,윤성호 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.102 No.-
The effect of pore size on the response characteristic of an electric double layer capacitor (EDLC) wasclosely examined. A series of phenol-resin-based activated carbon (AC) samples was prepared as averagepore size from 0.94 to 1.68 nm by KOH activation by varying the activation temperature andKOH/carbonized phenol-resin ratio. The impedance properties of pouch-type EDLC cells prepared usingAC samples were evaluated by applying an alternating current at 3 V between 10 mHz and 100 kHzfor confirming the response characteristic. The cell based on the AC with a largest pore size (1.68 nm)showed fast response frequency, and had a high dielectric relaxation time constant as calculated fromthe response frequency value. The AC with the largest pore size, which consisted of both micropores(>1 nm) and mesopores (2–4 nm), was confirmed to facilitate extremely low electrolyte-diffusion resistanceduring the formation of the electric double layer, implying that the large pores lead to fast andstable response frequency. The presented findings suggest that AC with a largest pore size as the electrodeleads to superior capacitance and response frequency characteristics in the alternating current thanthose of an AC with a smaller pore size.
Liu, Jinchang,Shimanoe, Hiroki,Nakabayashi, Koji,Miyawaki, Jin,Choi, Jong-Eun,Jeon, Young-Pyo,Yoon, Seong-Ho Elsevier 2018 Journal of industrial and engineering chemistry Vol.67 No.-
<P><B>Abstract</B></P> <P>An isotropic pitch precursor for fabricating carbon fibres was prepared by co-carbonization of ethylene bottom oil (EBO) and polyvinyl chloride (PVC). Various pre-treatments of EBO and PVC, and a high heating rate of 3°C/min with no holding time, were evaluated for their effects on the oxidative stabilization process and the mechanical stability of the resulting fibres. Our stabilization process enhanced the volatilization, oxidative reaction and decomposition properties of the precursor pitch, while the addition of PVC both decreased the onset time and accelerated the oxidative reaction. Aliphatic carbon groups played a critical role in stabilization. Microstructural characterization indicated that these were first oxidised to carbon–oxygen single bonds and then converted to carbon–oxygen double bonds. Due to the higher heating rate and lack of a holding step during processing, the resulting thermoplastic fibers did not completely convert to thermoset materials, allowing partially melted, adjacent fibres to fuse. Fiber surfaces were smooth and homogeneous. Of the various methods evaluated herein, carbon fibers derived from pressure-treated EBO and PVC exhibited the highest tensile strength. This work shows that enhancing the naphthenic component of a pitch precursor through the co-carbonization of pre-treated EBO with PVC improves the oxidative properties of the resulting carbon fibers.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
류동연,Takaaki Shimohara,Koji Nakabayashi,Jin Miyawaki,박주일,윤성호 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.80 No.-
Urea/nitric acid co-impregnated pitch-based activated carbonfibers (ACFs) were examined as adsorbentsfor the removal of low-concentration formaldehyde gas from dry and humid atmospheres. Urea, which isa harmless and environmentally friendly primary amine, was selected as an effective reagent to captureformaldehyde and nitric acid was used to promote the oxidation of formaldehyde into formic acid, whichinhibits the liberation of formaldehyde even under humid atmospheres. The optimized urea/nitric acidco-impregnated ACF showed a 110-fold (0.72 mg/g to 79.28 mg/g) improvement in its formaldehyderemoval capability as compared to that of pristine ACF at 40% humidity. The formaldehyde removalmechanism is proposed based on careful analysis and quantification of the inlet and outlet gases. Further,the optimized sample facilitates complete removal of formaldehyde from ambient air at humidity of 11–88% and temperatures of 3–26.9 C over 24 h, whereas only 81.5% formaldehyde removal is achieved withpristine ACF under the same conditions.
Jinchang Liu,Hiroki Shimanoe,Jong‑Eun Choi,Seunghyun Ko,Young‑Pyo Jeon,Koji Nakabayashi,Jin Miyawaki,Seong‑Ho Yoon 한국탄소학회 2019 Carbon Letters Vol.29 No.2
Pitch precursors affording excellent spinnability, high-level oxidation-resistance, and good carbonization yields were prepared by bromination–dehydrobromination of various ratios of pyrolyzed fuel oil and coal tar pitch. The pitches exhibited spinnabilities that were much better than those of pitches prepared via simple distillation. A pitch prepared using a 1:2 ratio of fuel oil and coal tar pitch exhibited the best tensile strength. Pitch fibers of diameter 8.9 ± 0.1 μm were stabilized at 270 °C without soaking time after heating at a rate of 0.5 °C/min and carbonized at 1100 °C for 1 h after heating at 5 °C/min. The resulting carbon fibers exhibited a tensile strength, elongation, Young’s modulus, and average diameter of 1700 ± 170 MPa, 1.6 ± 0.1%, 106 ± 37 GPa, and 7.1 ± 0.2 μm, respectively.
류동연,Kim Doo-Won,Kang Yu-Jin,Lee Youngjin,Nakabayashi Koji,Miyawaki Jin,박주일,윤승호 한국탄소학회 2022 Carbon Letters Vol.32 No.6
A conventional porous carbon is still a very promising material for the removal of gaseous pollutants because of its abundant surface functional groups and a high specific surface area. Here, we prepared an environment-friendly uniform N-rich narrow micropore activated carbon, for the removal of formaldehyde, based on steam activation and N-rich with chitin as the starting material. A sample carbonized at 500 °C and steam activated at 800 °C (CAC800) showed a reasonable yield (55%) with uniform and narrow micropores without mesopores but having a balanced nitrogen functionality. CAC800 possesses outstanding formaldehyde removal capabilities under both dry and wet (humidity 45%) conditions. In addition, when compared with commercial activated carbon materials, we clearly demonstrated that the existence of high nitrogen content with uniform and narrow micropores simultaneously removed formaldehyde, effectively.
Analysis of spinnable mesophase pitch in terms of lyotropic liquid crystalline solution
Mashio Takashi,Tomaru Taisei,Shimanoe Hiroki,Ha Seung-Jae,Jeon Young-Pyo,Nakabayashi Koji,Miyawaki Jin,Yoon Seong-Ho 한국탄소학회 2023 Carbon Letters Vol.33 No.3
Mesophase pitch is a unique graphitizable material that has been used as an important precursor for highly graphitic carbon materials. In the current study, we propose to consider a spinnable mesophase pitch as a lyotropic liquid crystalline solution composed of solvent components and liquid crystalline components, so-called mesogen or mesogenic components. Among mesophase pitches, the supermesophase pitch is defined as a mesohpase pitch with 100% anisotropy, and can only be observed in pitches with a proportion of mesogenic components exceeding the threshold concentration (TC). We also examined the critical limit of AR synthetic pitch and 5 experimental spinnable mesophase pitches (SMPs). Then, we examined the effect of the solvent component on the minimum required amount of mesogenic component using a selected solvent component instead of their own solvent components. AR pitch showed 100% anisotropy with the least amount of its mesogenic component, THF insoluble components, of 60 wt.%. The solvent component, THF soluble components, extracted from AR-pitch, which has a molecular weight pattern similar to that of the original material but more amount of naphthenic alkyl chains, showed better solvent functionality than those of other THF solubles (THFSs) from other as-prepared spinnable mesophase pitches. This is why a lower amount of AR THFS can produce a supermesophase pitch when combined with the THFI (mesogenic components) of other experimental mesophase pitches. As a result of the current analysis, we define the mesogens as molecules that not only readily stack, but also maintain stacking structures in a fused state in the solution. The solvent component, on the other hand, is defined as molecules with a structure that readily decomposes in a fused state in the solution.