Anseong, South Korea
Anseong, South Korea

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Ham E.-K.,Korea Institute of Carbon Convergence Technology | Ham E.-K.,Jeonju University | Choi W.-K.,Korea Institute of Carbon Convergence Technology | Kim Y.-K.,Win and Win Archery | Seo M.-K.,Korea Institute of Carbon Convergence Technology
Polymer (Korea) | Year: 2015

The influence of carbon nanotube (CNT) functional groups on mechanical and thermal properties of CNT/polymer composites was investigated. The functional groups of the CNT were quantitatively analyzed using X-ray photoelectron spectroscopy. The composites were prepared by adding the 0.7 wt% acid-treated CNT in the epoxy resins and vinyl ester resins, respectively. As a result, the CNT/epoxy composites showed the highest tensile and flexural properties when addition of the 8 M HNO3-treated CNT. Tensile and thermal properties of the CNT/vinyl ester composites were improved by addition of H2SO4/HNO3-treated CNT. Thermal conductivities of CNT/epoxy composites and CNT/vinyl ester composites were improved in 8 M HNO3-treated CNT. Introduction of carbonyl group (C=O) on CNT led to improvement of interfacial bonding in CNT/epoxy composites. The increase in the content of carboxyl group (O-C=O) on CNT contributed to increase in mechanical properties of CNT/vinyl ester composites. Also, the thermal conductivity of CNT/epoxy composites and CNT/vinyl ester composites were probably influenced on the structure and length of the CNT. © 2015 The Polymer Society of Korea. All rights reserved.


Lee Y.-S.,Seoul National University of Science and Technology | Shin K.-H.,Seoul National University of Science and Technology | Cheong S.-K.,Seoul National University of Science and Technology | Choi U.-J.,Win and Win Archery | And 3 more authors.
Transactions of the Korean Society of Mechanical Engineers, A | Year: 2013

With the continuing demand for lightweight bicycles, carbon fiber composite materials have been widely used in manufacturing bicycle frames and components. Unlike general isotropic materials, the structural characteristics of composite materials are strongly influenced by the staking directions and sequences of composite laminates. Thus, to verify the design process of bicycles manufactured using composites, structural analysis is considered essential. In this study, a carbon-fiber-reinforced plastic (CFRP) bicycle frame was designed and its structural behavior was investigated using finite element analysis (FEA). By measuring the failure indices of the fiber and matrix under various stacking sequences and loading conditions, the effect of the stacking condition of composite laminates on the strength of the bicycle structure was examined. In addition, the structural safety of the bicycle frame can be enhanced by reinforcing weak regions prone to failure using additional composite laminates. © 2013 The Korean Society of Mechanical Engineers.

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