| Summary: | 碩士 === 國立交通大學 === 機械工程學系 === 101 === This study aims to investigate the thermal conductivity of a single polymer nanofiber. It has been shown that an ultra-drawn polyethylene nanofiber has a thermal conductivity much large than its bulk value. The thermal conductivity enhancement in the nanofiber was attributed to the lattice-reconstructing during an ultra-drawing process. As a result, most chains are aligned in the nanofiber after the ultra-drawing process as compared to randomly oriented in the bulk, resulting in an enhanced thermal transport. In this study, the thermal conductivity of a single nylon 6 nanofiber was investigated. The bulk nylon 6 has a simple molecular structure as that in polyethylene and the hydrogen bonds could be formed between the polymer chains in the fiber. Thus, it is expected that it might exhibit similar thermal conductivity enhancement during the nano-structuring process. A micro-device has been made to measure the thermal conductivity of a single nylon 6 nanofiber. The nylon 6 nanofibers were electrospun on the fabricated microdevices. It was found that the thermal conductivity of the nanofiber increase with temperature and reaches a peak value of 3.34 W/m-K at 130 K. There has a sharp transition of the thermal conductivity of the nanofiber at 130 K. The thermal conductivity starts to decrease with temperature after this point and it saturates at 0.2 W/m-K after 190 K.
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