变温红外法研究聚对苯二甲酸乙二酯分子链的松弛运动及其构象转变

Dynamic Relaxation and Conformation of PET Molecular Chain from the Amorphous State Observed by FTIR

中文关键词:  聚对苯二甲酸乙二酯  松弛运动  构象

英文关键词:PET  Dynamic Relaxation  Conformation

中文摘要:

      在30～170 ℃范围内逐渐升温过程中，用红外光谱仪原位检测无定形聚对苯二甲酸乙二酯（PET）薄膜红外光谱图的变化情况。通过特征谱带吸光度与温度的变化特点，研究了PET分子链在热变化过程中的松弛运动及冷结晶过程中分子链的构象变化。实验结果表明在冷结晶过程中，随PET结晶的不断完善，对应左右式(gauche)构象的吸收峰减弱，对应反式(trans)构象的吸收峰增强，并计算出CH2面外摇摆振动结晶前和结晶后反式构象和左右式构象的相对百分含量随温度的变化关系，以及玻璃化转变和冷结晶的温区范围。

英文摘要:

      By using the FTIR technique, the glass transition temperatures and chain conformation of poly(ethylene terephthalate) (PET) thin films were determined by detecting the abrupt changes in the absorbances of characteristic absorption bands during heating (30～170℃). It was found that the absorbance intensity of gauche conformation reduced with respect to that of trans conformation along with the crystallization. Moreover, the contents of gauche and trans conformations connected with CH2 wagging vibrations were calculated at different temperatures before and after cold crystallization.