液晶共聚酯與聚對苯二甲酸丙酯摻合物之結晶性質研究

Abstract

本碩士論文為研究液晶高分子與工程塑膠(PTT)的摻合，製成高分子複合材料，探討其相容性、結晶性質與酯交換反應的研究。 利用DSC研究雜式液晶共聚酯copoly (oxybenzoate-terephthalate)莫爾分率為60/40的P64與聚對苯二甲酸丙酯poly(trimethylene terephthalate)(PTT)摻合物之相容性。我們可以發現P64/PTT摻合物無定型區域，其分子間的作用力為中等，而由熔點下降分析所獲得的Flory-Huggins interaction parameter為-0.17，顯示在熱熔態時摻合物中的P64與PTT為相容的。而由偏光顯微鏡(POM)的研究，當PTT含量有5wt%的P64時，呈現出最大的晶體。再由廣角X-ray的繞射圖譜分析中得知，經計算其Miller , 及 面的coherence length值在加入5wt%的P64時為最大，表示少量的P64對於PTT分子鏈的排列更為有規則(regularity)，結晶變得更大，這與POM所觀察出的結果一致。 在PTT及P64/PTT摻合物之等溫結晶動力學(Isothermal crystallization kinetics)的研究中，在Avrami plot中摻合物呈現出一次和二次結晶的行為，經分析一次結晶之Avrami exponent，可得知隨著P64的含量增加而下降，顯示出球晶成長方式的改變；而結晶速率常數值，隨著P64/PTT摻合物中的P64含量增加而下降，原因為P64含量增加會破壞PTT結晶的對稱性(symmetry)，使結晶速率變小。而非等溫結晶動力學(Non-isothermal crystallization kinetics)的研究中，由於P64/PTT摻合物存在著二次結晶的現象，使得一般常用的Ozawa equation無法適用，因此我們選用另一種結合了Avrami和Ozawa的方程式來模擬，其結果與等溫結晶動力學一致。故由熱分析的結果顯示P64/PTT摻合物具有一定程度的相容性。 由於P64/PTT摻合物在高溫下，可能會有酯交換反應發生，而影響到摻合物之物性，因此我們利用13C和1H 核磁共振光譜儀來判斷雜式液晶共聚酯P64與對苯二甲酸丙酯PTT的摻合物，是否發生酯交換反應。我們可以發現在300℃持溫30 分鐘都沒有酯交換反應發生，因此可知在我們實驗過程當中所進行的持溫程序並不會發生酯交換反應而影響到結果。

The miscibility and the crystallization kinetics in blends of random liquid crystalline copoly(oxybenzoate -ethylene terephthalate) at molar ratio 60/40 (P64) and semicrystalline poly(trimethylene terephthalate) (PTT) were investigated with differential scanning calorimetry, wide angle X-ray diffraction and polarized optical micrography. It was found that P64 and PTT were partially miscible as evidenced from the appearance of molecular interaction force close to middle in amorphous region. Furthermore, the Flory-Huggins interaction parameter, □12, for P64 and PTT was determined to be – 0.17 through the melting point depression analysis, indicating miscibility in blends of P64 and PTT at the melt state. The coherence lengths of PTT in the presence of a small amount (around 5 wt%) of P64 were larger than that in pure PTT. The isothermal and non-isothermal crystallization behavior in blends of P64 and PTT were studied with differential scanning calorimetry. In isothermal crystallization experiment, the PTT crystallization temperature, Avrami exponent and the crystallization rate coefficient had were found to decrease with increase the concentrate of P64 . In non-isothermal crystallization experiment, we found that the Ozawa equation can not work on our case. We selected another one equation to discuss our results. The 13C and 1H nuclear magnetic resonance was not found that the ester exchange in the two polymers take place within 30 min when the blend was annealed at 300oC.