臺灣博碩士論文加值系統

熱差分析儀(Differential Scanning Calorimeter)用來測量在空氣與真空中照射加馬射線的聚四甲基一戊稀的非等溫結晶過程，照射加馬射線有4種劑量率分別是在真空中或空氣中照射100-400 kGy，在測量非等溫結晶的過程時，6種降溫速率2.5, 5, 7.5, 10, 15, 20℃/min 的過程被紀錄下來。在熱差分析儀測量出來的結果中，我們發現了雙峰的存在，表示在結晶的過程中有兩種結晶狀況的可能性，這樣的狀況可能是由聚四甲基一戊稀的螺旋狀的結晶結構所造成。

在我們的研究中，我們試圖將雙峰分離，雙峰的分離我們是使用反高斯函數的分布來模擬結晶的放熱曲線，雙峰代表有兩個放熱的分布。接下來在非等溫結晶的分析上，我們採用兩種的作法，一種將著名的Avrami 方程式應用在非等溫結晶的分析上，另一種是由Ozawa所提出，描述降溫速率與相對結晶間的關係，兩種方式皆可得到n值。活化能的計算是採用Kissinger的方法，實驗得到的結果為活化能隨著劑量增加而減少，第一個峰的活化能大於第二個峰的活化能，並且在空氣中照射的活化能大於在真空中照射的活化能。

Non-isothermal crystallization kinetics of Poly(4-methyl-1-pentene) samples irradiated by γ-ray in air and vacuum with 100-400 kGy was studied using Differential Scanning Calorimeter (DSC). Different cooling rates at 2.5, 5, 7.5, 10, 15 and 20 ℃/min were applied to investigate the exothermic behavior of crystallization. According to the heat flow along the continuous cooling temperature, the heat flow is related to the degree of crystallization. However, we found double peaks in the diagram of the heat flow versus the cooling temperature. Two crystalline processes were expected to coexist. It is possible that the phenomenon comes from the up-down disorder in crystal structure.

In this research, we separated the double peaks by curve fitting. We used the probability density function of the inverse Gaussian distribution to separate two peaks with different parameters. After that, Avrami approach modified by Jeziorny and Ozawa approach were applied to analyze the non-isothermal crystallization kinetics. Generally speaking, the exponent n of Avrami approach is around 1.5~2 for Peak 1 and 1~1.5 for Peak 2 at different cooling rates when TPX samples are irradiated by γ-ray with different doses in air and vacuum. The exponent n of Ozawa approach decreases from 2~3 to 0.5~1 for peak 1 and peak 2 with the decreasing crystallization temperature. The activation energy of non-isothermal crystallization were computed by Kissinger’s approach. The crystallization activation energy for peak 1 decreases from 667.01 KJ/mol to 452.63 KJ/mol and 407.75 KJ/mol with the increasing dose of γ-ray in air and in vacuum, respectively. The crystallization activation energy for peak 2 decreases from 484.18 KJ/mol to 420.97 KJ/mol and to 342.17 KJ/mol with the increasing dose of γ-ray in air and in vacuum, respectively.

Acknowledgement Ⅰ
Abstract Ⅱ
Contents IV
Introduction 1
Experimental Procedure 7
Results and Discussion 10
Conclusions 23
List of Tables 25
Figure Captions 28
Appendix 42
Reference 124

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