非恆溫狀態下聚醯亞胺高分子熱裂解之動力學探討

Thermal Decomposition Kinetics of Polyimide Polymer for Non-isothermal Conditions

廖國廷(Guo-Ting Liao)

指導教授 ： 王榮基

大同大學/工程學院/化學工程學系所/碩士(2007年)

摘要

新的二胺單體與六種二酐單體聚合成(a)-(f)系列的聚醯亞胺高分
子，使用熱重分析儀（TGA）在加熱速率 20℃/min以氮氣和空氣為載體下之非恆溫熱裂解研究。 動力溫度方程式使用三種單一熱速率積分法，分別為Coats-Redfern、Horowitz-Metzger 和Van Krevelen法結合常見的固體狀態方程式g(a) 作為實驗數據之解析並計算出反應活化能 (E)、預反應因子 (A) 及反應級數 (n)。 發現氮氣和空氣在固體狀態反應機構分別為F1 和R2下最符合熱重曲線之實驗數據。 由三種不同積分法的數學計算證明Coats-Redfern法比其他方法準確，因為Horowitz-Metzger和 Van Krevelen方法需選擇參考溫度導致誤差較大。
從分子結構組成的觀點來看, 聚醯亞胺在含氮氣下活化能依次為PI-e(DSDA) =PI-f(6FDA) >PI-a(PMDA) >PI-d(ODPA) =PI-b(BPDA) >PI-c(BTDA); 而在含空氣下活化能依次為PI-f(6FDA) >PI-a(PMDA) >PI-d(ODPA) =PI-c(BTDA) >PI-b(BPDA) =PI-e(DSDA)。 其中空氣下活化能大小順序與氮氣不同且整體的值都比較低。在此研究中，由聚醯亞胺(a)-(f)之任一樣品中發現反應活化能和預反應因子皆隨反應級數增加而增加。另一方面，空氣下所得之參數值比在氮氣者低。因為影響的因素不只是分子結構組成還有空氣中氧氣助燃的影響。

關鍵字

二酐 ； 熱重分析(TGA) ； Coats-Redfern方法 ； 聚醯亞胺 ； Horowitz-Metzger方法 ； Van Krevelen方法

並列摘要

Studies of non-isothermal decomposition of a new diamine monomer led to a series of novel polyimide polymer (a)-(f) when reacted with six dianhydrides were measured by thermogravimetric analysis (TGA) at a heating rate of 20℃/min in nitrogen and air atmospheres. Three single heating-rate integral methods by Coats-Redfern, Horowitz-Metzger and Van Krevelen that were analysed using the non-isothermal data with different expressions of solid state reactions, i.e., g(a) would be used to estimate the activation energy (E), pre-exponential factor (A), and order of reaction (n). The F1 and R2 models were selected as the best mechanisms for solid-state reactions to fit experimental TG curves in nitrogen and air atmospheres, individually. Mathematical verification of using different integral methods shows that the Coats-Redfern method is more precise than the Horowitz-Metzger and Van Krevelen methods since the other two methods are dependent on the arbitrary selection of the reference temperatures.
From the molecular structure point of view, the order of the activation energy of polyimide under nitrogen is PI-e(DSDA) =PI-f(6FDA) >PI-a(PMDA) >PI-d(ODPA) =PI-b(BPDA) >PI-c(BTDA); however, under air it is PI-f(6FDA) >PI-a(PMDA) >PI-d(ODPA) =PI-c(BTDA) >PI-b (BPDA) =PI-e(DSDA). In this study, it is found that the activation energy and pre-exponential factor show the same trend, i.e., both values increase with increasing the order of reaction for each sample, i.e., polyimide (a)-(f). On the other hand, the parameter values in air are lower than those in N2. It can be attributed to that not only the molecular structure but also combustion of oxygen would affect the value of activation energy.

並列關鍵字

Van Krevelen method ； polyimide ； Horowitz-Metzger method ； dianhydrides ； thermogravimetric analysis (TGA) ； Coats-Redfern method

參考文獻

Agrawal, R. K., “Integral Approximations for Nonisothermal Kinetics”, American Institute of Chemical engineers, 33, 1212-1214 (1987).

Albano, C. and E. D. Freitas, “Thermogravimetric Evaluation of The Kinetics of Decomposition of Polyolefin Blends”, Polymer Degradation and Stability, 61, 289-295 (1998).

Chang, T. C., K. H. Wu, C. L. Liao, S. T. Lin and G. P. Wange, “Thermo-oxidative Degradation of Siloxane-Containning Polyimide and Unmodified Polyimide”, Polymer Degradation and Stability, 62, 299-305 (1998).

Chang, T. C., K. H. Wu and Y. S. Chiu, “Characterization and Degradation of Some Phosphorus-Containing Polyimides”, Polymer Degradation and Stability, 63, 103-109 (1999).

Cheng, Y., Y. Huang, K. Alexander and D. Dollimorey, “A Thermal Analysis Study of Methyl Salicylate”, Thermochimica Acta, 367-368, 23-28 (2001).