臺灣博碩士論文加值系統

本論文旨在研究單根尼龍六奈米纖維熱傳導率與退火時間與分子量之關係。在此研究中，我們先透過微機電製程製作出一塊微米元件結構，並架設一套低溫真空系統以量測尼龍六奈米纖維之熱傳導率。實驗結果發現熱傳導率會隨著退火時間變化，當在120 K退火9728分鐘時，熱傳導率從0.27  0.02 提升至 12.12 ± 0.81 W/m-K，其熱傳導率有40倍的上升，尼龍六奈米纖維在低溫退火時熱傳導率提升的原因來自於，尼龍六本身是一種半結晶的高分子材料，而我們的尼龍六奈米纖維樣品內部佔有大量的非晶相型態區域，比例約為80％，這使得尼龍六熱傳導率不僅與溫度有關，而且與時間相關。在1959年Kawaguchi利用動態黏彈性機械分析尼龍材料，發現尼龍六分別約在350 K、230 K、150 K存在α、β、γ轉換溫度，α轉換溫度也是玻璃轉換溫度(glass transition temperature)，當溫度高於350 K時，會打斷非晶相區域裡氫鍵的鍵結，分子鏈會開始做大範圍的運動，而造成內部分子型態有巨大的改變；當溫度高於β轉換溫度時則在非晶相區域未鍵結之醯胺基團(amide group)區域，將會做局部的運動(segmental motion)；當溫度高於γ轉換溫度時則在非晶相區域裡分子鏈中的-CH_2-區域，開始有足夠的能量進行運動，稱此運動為曲軸型運動(Crankshaft motion)，但是當溫度低於150 K時分子鏈沒有足夠能量進行運動，分子鏈變成凍結狀態。因此分子鏈會隨著在低溫持續的時間愈久而排列得越緊密，造成熱傳導率隨時間增加而上升。同時我們也製備了三種不同分子量的樣品實驗，分子量分別為4.165  104  1722、2.593  104  462、6.47  103  386 Dalton，結果發現熱傳導率與分子量有正相關，其原因為當分子量越大尼龍六奈米纖維內部的聚合物鏈也越長，當聚合物鏈越長，熱也更容易透過尼龍六奈米纖維傳導。

The purpose of this work is to study the dependence of the thermal conductivity of the nylon-6 nanofibers on the annealing time and molecular weight. In this study, microdevices were made by the microelectromechanical process to measure the thermal conductivities of nylon-6 nanofibers. The experimental results showed that the thermal conductivity of the nanofibers was dependent on the annealing time and molecular weight. The thermal conductivity of the nanofiber increased from 0.27  0.02 to 12.12 ± 0.81 W/m-K by annealing the nanofiber at 120 K for 9728 min. The reason why the thermal conductivity of nylon-6 nanofibers enhanced during the low-temperature annealing process was because of that the nylon-6 nanofiber was a semi-crystalline material, which contained approximately 80% amorphous regions. In 1959, Kawaguchi analyzed the dynamic viscoelastic properties of nylon materials. He found that the nylon 6 has α, β, γ transition temperatures at 350, 230, and 150 K, respectively. The α-transition is also called the glass transition temperature. When the temperature is higher than 350 K, the hydrogen bonds in the amorphous regions breaks and the molecular chains start to carry out a wide range of movements. The β-transition temperature occurs at 230 K. When the temperature is higher than the β-transition temperature, the segmental motion of the un-bonded amide groups in the amorphous regions will be active. The γ-transition temperature occurs at 150 K. When the temperature is higher than the γ-transition temperature, the -CH2- groups in the molecular chains in the amorphous regions start to perform the crankshaft motion. On the other hand, when the temperature is lower than 150 K, the molecular chains do not have the enough energy and become frozen. When annealing the nylon-6 nanofibers at a temperature below 150 K, the crankshaft motion was frozen. In addition, the molecular chains were getting closer during the annealing process to reduce the free energy of the polymer. Thus, the thermal conductivity of the nylon-6 nanofibers increased with the annealing time. The nylon-6 nanofibers with three different molecular weights of 4.165  104  1722, 2.593  104  462, 6.47  103  386 Dalton were also prepared to investigate the effect of molecular weight on the thermal conductivity of the nanofibers. It was found that the thermal conductivity was positively correlated with the molecular weight, which was because of that the nylon-6 nanofiber with a larger the molecular weight possessed a longer polymer chain. As the length of the polymer chain increased, heat transfer in the polymer chain was presumed to more effective.

第1章 緒論 1
1.1 研究動機 1
1.2 文獻回顧 1
1.3 研究目的 3
第2章 量測原理與樣品製作 7
2.1 量測原理 7
2.2 微元件製作方式 11
2.3 尼龍六奈米纖維樣品製備 11
2.4 尼龍六順向性薄膜製備 12
2.5 實驗系統與量測步驟 13
第3章 實驗系統靈敏度與誤差分析 26
3.1 實驗系統靈敏度 26
3.2 熱輻射散失誤差 28
3.3 接觸熱阻分析 29
第4章 實驗結果 32
4.1 尼龍六內部結構分析 32
4.1.1 結晶度 32
4.1.2 分子鏈順向性 32
4.1.3 分子量 35
4.2 藉由二氧化矽奈米線和矽奈米線驗證系統量測準確性 35
4.3 尼龍六奈米纖維之熱傳導量測流程 36
4.3.1 系統與各樣品熱傳導係數之結果 36
4.3.2 尼龍六奈米纖維之熱傳導率的量測結果 37
4.3.3 藉由矽奈米線量測驗證尼龍六奈米纖維熱傳導率可信度 40
第5章 結論與未來工作 62
5.1 結論 62
5.2 未來工作 63
5.2.1 不同聚合物材料研究 63

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