Evaluation of the utility of isotropic pitches as solvent components of spinnable mesophase pitch precursors for highly graphitizable functional carbon materials

Hiroki Shimanoe,Takashi Mashio,Taisei Tomaru,Seung-Jae Ha,전영표,Koji Nakabayashi,Jin Miyawaki,윤성호 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.120 No.-

Spinnable mesophase pitch (SMP) is an important graphitizable precursor for high-performance carbonmaterials. Generally, SMPs show fully developed anisotropic texture, and the pitches contain isotropic contentsmore than 30 wt%, which plays the role of solvent for the mesogenic components in the lyotropic liquidcrystalline system of the pitch. Here, we prepared SMP by blending the mesogenic components of ARmesophase pitch with various isotropic pitches to evaluate the usability of isotropic pitches as solvents. The mesogenic components were prepared by tetrahydrofuran fractionation of AR mesophase pitch. Isotropic pitches with a softening point of 140–220 C were prepared separately by simple heat treatmentof slurry oil (SO) and coal tar pitch (CTP). SMPs were prepared by thermal blending of the above mentionedmesogenic components and isotropic pitches in various blending ratios. CTP-derived isotropic pitchshowed better solvent performance than a SO-derived pitch in terms of anisotropic texture. SMP preparedby blending of the mesogenic components and CTP-derived isotropic pitch with a softening point of 180 Cat the ratio of 4/6 (w/w) showed almost 100% anisotropic texture; the carbon fiber derived from the pitchshowed tensile strength of 2.7 GPa and Young’s modulus of 470 GPa after graphitization at 2,800 C.

Enhancing the oxidative stabilization of isotropic pitch precursors prepared through the co-carbonization of ethylene bottom oil and polyvinyl chloride

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>

Preparation of isotropic pitch precursor for pitch-based carbon fiber through the co-carbonization of ethylene bottom oil and polyvinyl chloride

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.

Enhancing the oxidative stabilization of isotropic pitch precursors prepared through the co-carbonization of ethylene bottom oil and polyvinyl chloride

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.

Effect of the pre‑treated pyrolysis fuel oil: coal tar pitch ratio on the spinnability and oxidation properties of isotropic pitch precursors and the mechanical properties of derived carbon fibers

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.

Preparation of isotropic pitch precursor for pitch-based carbon fiber through the co-carbonization of ethylene bottom oil and polyvinyl chloride

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>

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.