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Browsing by Author "Kim, Yeong-Hun"

Now showing 1 - 2 of 2
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    Determination of Hydrophobic Dispersive Surface Free Energy of Activated Carbon Fibers Measured by Inverse Gas Chromatographic Technique
    Lee, Seul-Yi; Kim, Yeong-Hun; Mahajan, Roop L.; Park, Soo-Jin (MDPI, 2023-03-20)
    Activated carbon fibers (ACFs) as one of the most important porous carbon materials are widely used in many applications that involve rapid adsorption and low-pressure loss, including air purification, water treatment, and electrochemical applications. For designing such fibers for the adsorption bed in gas and aqueous phases, in-depth comprehension of the surface components is crucial. However, achieving reliable values remains a major challenge due to the high adsorption affinity of ACFs. To overcome this problem, we propose a novel approach to determine London dispersive components (γSL) of the surface free energy of ACFs by inverse gas chromatography (IGC) technique at an infinite dilution. Our data reveal the γSL values at 298 K for bare carbon fibers (CFs) and the ACFs to be 97 and 260–285 mJ·m−2, respectively, which lie in the regime of secondary bonding of physical adsorption. Our analysis indicates that these are impacted by micropores and defects on the carbon surfaces. Comparing the γSL obtained by the traditional Gray’s method, our method is concluded as the most accurate and reliable value for the hydrophobic dispersive surface component of porous carbonaceous materials. As such, it could serve as a valuable tool in designing interface engineering in adsorption-related applications.
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    A study on interfacial behaviors of epoxy/graphene oxide derived from pitch-based graphite fibers
    Kim, Seong-Hwang; Zhang, Yinhang; Lee, Jong-Hoon; Lee, Seul-Yi; Kim, Yeong-Hun; Rhee, Kyong Yop; Park, Soo-Jin (2021-11-12)
    Graphene oxide (GO) is a versatile material with inherent unique properties that can be used in a wide range of applications. GO is produced from graphitic materials including graphite, and its properties can depend on the nature of stacking in the graphene structures. In this study, GO was prepared from pitch-based graphite fibers via the modified Hummer's method and subsequently incorporated into an epoxy matrix to obtain grapheneloaded nanocomposites (EP/GO). Presented experimental results revealed that the addition of 0.6 wt% GO yielded an similar to 110% increase in the fracture toughness. The corresponding fracture energies as well as the flexural strengths and flexural modulus exhibited similar trends to the fracture toughness. The thermophysical properties of the EP/GO, to further demonstrate the reinforcing effectiveness of GO, were also observed. Collectively, these results indicate that GO investigated in the study can be a viable reinforcement candidate to develop next-generation nanocomposites with multifunctional properties.