液晶共聚酯與聚對奈二甲酸乙二酯摻合物相容性與結晶性質的研究

Abstract

利用DSC研究雜式液晶共聚酯莫爾分率為60/40 copoly (oxybenzoate-terephthalate)(P64)與聚對□二甲酸乙二酯(PEN)摻合物之相容性。我們可以發現不同組成的P64/PEN摻合物只有一個玻璃轉移溫度(Tg)點，而由摻合物熔點下降分析所獲得的Flory-Huggins interaction parameter為-1.13，顯示在熱熔態時摻合物中的P64與PEN為相容。由廣角X-ray的繞射圖譜分析中得知，當加入3 wt %的P64時，可使PEN分子鏈的排列更為有規則(regularity)，結晶變得更完美(perfect)，經計算其coherence length在三個Miller面(010), (100) 及 的數值也是最大的，這表示此時的結晶是比較穩定的。且由偏光顯微鏡研究，當加入3 wt %的P64時，其晶體是最大的。 PEN及P64/PEN摻合物其等溫結晶動力學(Isothermal crystallization kinetics)與非等溫結晶動力學(Non-isothermal crystallization kinetics)的研究中，Avrami exponent及結晶速率常數值隨著P64的含量增加而下降，其原因為P64的含量增加時，會破壞PEN結晶的對稱性(symmetry)，使結晶度變小。且由熱分析的結果顯示P64/PEN摻合物具有一定程度的相容性，故P64/PEN摻合物中P64的含量增加時，Avrami exponent及結晶速率常數會減小。 利用13C 核磁共振光譜儀研究雜式液晶共聚酯P64與PEN的摻合物之酯交換反應動力學。我們可以發現在320oC持溫10分鐘即有酯交換反應發生。50/50 P64/PEN 摻合物中的酯交換反應活化能約為16.92 kcal/mol，而pre-exponential factor為1.79×107 min-1。

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(ethylene 2,6-naphthalene dicarboxylate) (PEN) were investigated with differential scanning calorimetry and wide angle X-ray diffraction.It was found that P64 and PEN were partially miscible as evidenced from the appearance of a single glass transition temperature for blends at different composition. Furthermore, the Flory-Huggins interaction parameter, □12, for P64 and PEN was determined to be – 1.13 through the melting point depression analysis, indicating partial miscibility in blends of P64 and PEN at the melt state. The coherence lengths of PEN in the presence of a small amount (around 3 wt%) of P64 were larger than that in pure PEN, implying the regularity of PEN crystals in the blends with low P64 content being more perfect than that of the pure PEN. The isothermal and non-isothermal crystallization behaviour in blends of P64 and PEN were studied with differential scanning calorimetry. The PEN crystallization temperature, Avrami exponent and crystallization rate coefficient were found to decrease markedly upon addition of 3 ~ 30 % P64. The kinetics of ester exchange in blends of P64 and PEN were studied with 13C nuclear magnetic resonance. It was found that the ester interchange in the two polymers took place within 10 min when the blend was annealed at 320oC. The activation energy of ester exchange in 50/50 P64/PEN blend was about 16.92 kcal/mol. The pre-exponential factor for ester exchange in 50/50 P64/PEN blend was 1.79×107 min-1.