Browsing by Author "Shiu, Sung-Chiun"

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Characterizing thermal and mechanical properties of graphene/epoxy nanocomposites
(2014-01-01)
Shiu, Sung-Chiun
;
Tsai, Jia-Lin
;
機械工程學系
;
Department of Mechanical Engineering
This study aims to investigate the thermal and mechanical properties of graphene/epoxy nanocomposites using molecular dynamics (MD) simulation. Three different formats of graphene: graphene flakes, intercalated graphene and intercalated graphene oxide, were incorporated respectively in an epoxy matrix to form the graphene/epoxy nanocomposites. The mechanical properties of the graphene/epoxy nanocomposites, including Young's modulus (E), glass transition temperature (T-g) and coefficient of thermal expansion (CTE), in terms of three different formats of graphene, were characterized in this study. In addition to the mechanical properties, the influences of graphene on the density distribution of epoxy polymers in the nanocomposites were also examined. The results showed that the local density in the vicinity of the graphene is relatively high, and then progressively decreases to the bulk value in regions further away from the interface. On the other hand, for the mechanical and thermal properties, the nanocomposites with intercalated graphene exhibit a higher Young's modulus, a higher glass transition temperature and a lower thermal expansion coefficient than do those with graphene flakes. This is because the intercalated graphene can lead to a high amount of high density polymer in the nanocomposites, and thus enhance the overall properties of the nanocomposites. In addition, the interacted graphene oxide provides the best reinforcement of the three systems of nanocomposites. Based on the calculation of interaction energy, it appears that the oxide modification of the graphene surface can effectively lead to the high interaction energy, such that the graphene oxide can demonstrate a relatively high reinforcing efficiency. (C) 2013 Elsevier Ltd. All rights reserved.
Characterizing thermal and mechanical properties of graphene/epoxy nanocomposites
(2013-01-01)
Shiu, Sung-Chiun
;
Tsai, Jia-Lin
;
機械工程學系
;
Department of Mechanical Engineering
This study aims to investigate the thermal and mechanical properties of graphene/epoxy nanocomposites using molecular dynamics (MD) simulation. Three different formats of graphene: graphene flakes, intercalated graphene and intercalated graphene oxide, were incorporated respectively in an epoxy matrix to form the graphene/epoxy nanocomposites. The mechanical properties of the graphene/epoxy nanocomposites, including Young's modulus (E), glass transition temperature (T-g) and coefficient of thermal expansion (CTE), in terms of three different formats of graphene, were characterized in this study. In addition to the mechanical properties, the influences of graphene on the density distribution of epoxy polymers in the nanocomposites were also examined. The results showed that the local density in the vicinity of the graphene is relatively high, and then progressively decreases to the bulk value in regions further away from the interface. On the other hand, for the mechanical and thermal properties, the nanocomposites with intercalated graphene exhibit a higher Young's modulus, a higher glass transition temperature and a lower thermal expansion coefficient than do those with graphene flakes. This is because the intercalated graphene can lead to a high amount of high density polymer in the nanocomposites, and thus enhance the overall properties of the nanocomposites. In addition, the interacted graphene oxide provides the best reinforcement of the three systems of nanocomposites. Based on the calculation of interaction energy, it appears that the oxide modification of the graphene surface can effectively lead to the high interaction energy, such that the graphene oxide can demonstrate a relatively high reinforcing efficiency. (C) 2013 Elsevier Ltd. All rights reserved.
Mechanical properties of polymer near graphite sheet
(2013-02-01)
Gao, Jing-Suei
;
Shiu, Sung-Chiun
;
Tsai, Jia-Lin
;
機械工程學系
;
Department of Mechanical Engineering
This study aims to investigate the local mechanical properties of polyimide near graphite sheet in the graphite/polyimide nanocomposites. In order to understand the influence of graphite on the molecular configuration, the corresponding density and order parameter of the polyimide near the graphite/polyimide interface were evaluated using molecular dynamics simulation. In addition, the local mechanical properties of polyimide polymer were characterized through the calculation of the local stress distribution of the polyimide subjected to a uniform strain deformation. Results illustrated that in the vicinity of the graphite sheet, the polyimide chains are not only adsorbed compactly toward the graphite sheet but they are also oriented along the graphite surface. Moreover, it is found that the modulus of polyimide near the graphite/polyimide interface is higher than that in other regions. The phenomena clearly illustrated that the mechanical properties of polyimide close to the interface are affected dramatically by the graphite sheet.