液晶共聚酯與聚醯胺6,6摻合物之相容性與結晶性質的研究

Abstract

本論文為研究POB-PET莫耳比為60/40的雜式液晶共聚酯copoly (oxybenzoate-terephthalate) (簡稱為P64)與聚醯胺6,6 (polyamide 6,6，簡稱為PA66)摻合物的相容性與結晶性。由微差掃描式熱分析儀(DSC)的結果得知不同組成的P64/PA66摻合物只有一個玻璃轉移溫度(Tg點)，雖然P64與PA66的Tg點相近( 60.9oC與51.6oC)，但進一步分析摻和物之熔點下降，可以得到摻合物之Flory-Huggins 作用參數為－0.19，因此我們可以得知在熱熔態時摻合物中P64與PA66為部份相容。而由偏光顯微鏡(POM)的研究，當PA66含有7 wt %的P64時，呈現出最大的晶體。再由廣角X-Ray的繞射圖譜分析，經計算其Miller (002)和(010/110) 面的coherence length值在加入7 wt %的P64時為最大，表示少量的P64可使PA66分子鏈的排列更為有規則，使結晶變得更大，這與POM所觀察出的結果一致。 在研究P64/PA66摻合物之等溫結晶動力學(Isothermal crystallization kinetics)方面，在Avrami plot中摻合物呈現出一次和二結晶的行為，經分析一次結晶之Avrami exponent後，可得知其值隨著P64的含量增加而下降，顯示出球晶成長方式的改變，而其結晶速率常數k則顯示出，當摻和物含有7 wt %的P64時，其結晶速率常數值最大，之後隨著P64的含量增加而下降，此因P64/PA66摻合物的相容性，使得P64的含量增加時破壞PA66結晶的對稱性，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/PA66摻和物存在著二次結晶的現象，使得一般常用的Ozawa方程式無法適用，因此我們選用另一種方程式來模擬，其結果與等溫結晶動力學一致。 由於P64/PA66摻和物可能有酯-胺交換反應發生，而影響到摻和物之物性，因此我們利用13C 核磁共振光譜儀研究雜式液晶共聚酯P64與聚醯胺6,6 (PA66)的摻合物之酯-胺交換反應。我們可以發現在300oC持溫10分鐘才有酯-胺交換反應發生，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-胺交換反應而影響到結果。而由摻合物極限黏度值的分析，我們可知由於P64與PA66分子之間的酯-胺交換反應及高分子鏈的裂解造成摻合物的極限黏度降低。

Miscibility in blends of random liquid crystalline copoly(oxybenzoate -ethylene terephthalate) at molar ratio 60/40 (P64) and spolyamide 6,6 (PA66) were investigated with differential scanning calorimetry, wide angle X-ray diffraction and polarized optical micrography. It was found that P64 and PA66 were partially miscible as evidenced from the appearance of a single glass transition temperature for each blend at different composition. At the melt state, the Flory-Huggins interaction parameter, □12, which was determined to be – 0.19 through the melting point depression analysis. The coherence lengths of PA66 in the presence of a small amount (around 7 wt%) of P64 were larger than that in pure PA66. The isothermal and non-isothermal crystallization behaviour in blends of P64 and PA66 were studied with differential scanning calorimetry. In isothermal crystallization experiment, the Avrami exponent were found to decrease with increase the concentrate of P64 and the crystallization rate coefficient had largest value in the small amount (7%) 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 nuclear magnetic resonance was found that the ester –amide exchange in the two polymers took place within 10 min when the blend was annealed at 300oC.