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이영은,김효정,김민우,Miyawaki Jin,채한기,엄영호 한국유변학회 2024 Korea-Australia rheology journal Vol.36 No.2
Fiber-based commodities represent a substantial fraction of plastic waste, leading to environmental harm. Discarded sanitary masks and fishing equipment undergo degradation, generating microfiber plastics, thereby presenting a notable hazard to both human health and the ecosystem. In this study, mechanically strong and environmentally friendly nanocomposite fibers were prepared by dry-jet wet spinning. The all-biomass-based fibers comprised agar and cellulose nanocrystals (CNC) as the matrix and nanofiller, respectively, and were highly miscible in deionized water as a cosolvent. Based on rheological characterization, the optimal spinning concentration and temperature were set to 13% (w/v) and 95 °C, respectively. The dryjet wet-spun agar-based fibers exhibited remarkable mechanical performance compared with previously reported agar-based materials. In particular, the 1 wt% CNC (with respect to the agar amount) simultaneously improved the Young’s modulus, strength, and toughness by 8.3, 4.8, and 16.4% (2.6 GPa, 93.5 MPa, and 7.8 MJ m− 3), respectively, compared to those of the control agar fibers (2.4 GPa, 89.2 MPa, and 6.7 MJ m− 3), overcoming the trade-off of stiffness-toughness for conventional nanocomposite systems. In addition, the agar/CNC nanocomposite fibers rapidly adsorbed Methylene blue within 90 min, which is significantly faster than that of the film-type agar adsorbent. Therefore, all-biomass-based agar/CNC fibers are a promising remedy for alleviating water pollution.
고승현,최종은,임혜진,Miyawaki Jin,윤승호,전영표 한국탄소학회 2019 Carbon Letters Vol.29 No.3
Structural characterization of pyrolysis fuel oil (PFO) was conducted via 1H NMR and 13C NMR to elucidate its molecular structure and evaluate the feasibility of using PFO as a raw material for mesophase pitch synthesis. The average structural parameters were calculated based on the data from elemental analysis and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), as well as 1H NMR and 13C NMR data. The resultant structural features of PFO were compared with those of fluidized catalytic cracking-decant oil (FCC-DO). Based on the calculated parameters, we proposed average molecular models of PFO and FCC-DO. The molecular model of PFO showed that it had an aromatic structure consisting of three aromatic rings and one naphthenic ring fused with one pericondensed and two catacondensed aromatic carbons, as well as a short alkyl side chain (with only a methyl group). This structural feature of PFO demonstrated that it is highly favorable for use as a raw material for mesophase pitch synthesis. The empirical findings in this study provide an in-depth understanding of the molecular structure of PFO as well as FCC-DO and can offer insights for future research on the utilization of PFO and other petroleum heavy oils.
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.
김영광,윤성호,박주일,정두환,Jin Miyawaki,Isao Mochida 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.1
Catalytic recovery after repeated uses of unsupported K2CO3 or K2CO3 supported on 3 kinds ofperovskites (LaMn0.8Cu0.2O3, LaMn0.8Cu0.2O3/g-alumina, and La0.9K0.1MnO3) was investigated duringsteam gasification of an Indonesian lignite (Adaro) at 700 ℃. Perovskite supports effectively retainedK2CO3 and maintained higher catalytic activity than K2CO3 alone. The supported catalysts wererecovered from the ash after gasification based on their size and ferromagnetism. Quartz and aluminaaccumulation on the catalyst poisoned the ash due to reactivity with potassium. Catalytic activity as highas 90% carbon conversion was maintained up to seven cycles, and separation from the ash aftergasification regenerated the activity.
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.
Analysis of water in Loy Yang brown coal using solid-state 1H NMR
김현석,윤성호,Yusuke Nishiyama,Keiko Ideta,Jin Miyawaki,Yohsuke Matsushita,박주일,Isao Mochida 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.5
1H spin-echo MAS NMR and 1H saturated spin-echo MAS NMR were applied to classify the water in Loy Yang coal. Adsorbed water was examined based on the proton spectra, in which four major portions were identified according to the moisture contents. Free water could be quantified by analyzing the proton free induction decays (FIDs) obtained using the 1H saturated spin-echo technique. By comparing the proton intensity of the C–H portion to the aromatic and N portion in the proton spectra, and by evaluating the FIDs, the water in Loy Yang coal could be classified.
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.
Yong Jiang,Keiko Ideta,김잔디,Jin Miyawaki,정두환,윤성호,Isao Mochida 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.22 No.-
The crystalline and microstructural transformations of two laboratory ashes and their quenched slags(froma gasifier) with similar chemical compositions (one with high silicon dioxide (SiO2) concentrationsand the other with high aluminum oxide (Al2O3) concentrations)were systematically characterized usingX-ray diffraction, multinuclear solid-state nuclear magnetic resonance, and a high-temperatureviscometer. The results show that the content of SiO2 and Al2O3 in ash has significant influence onthe crystal types and size of cristobalite clusters in the liquid slag during heat treatment. Consequently,the formed cristobalite clusterswas the crucial to the viscosities and rheological properties of liquid slags.
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,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.