用偏振红外光谱表征经单轴和双轴拉伸的PET薄膜

用偏振红外光谱方法研究了拉伸速率和不同拉伸方式,包括单轴拉伸、双轴同时拉伸和双轴依次拉伸等,对PET薄膜取向的影响。对由不同拉伸方式制得的反式结构含量和密度均基本相同的试样进行比较得出:单轴拉伸试样中分子链相对拉伸方向的轴取向程度最高,分子链在薄膜平面内的取向分布亦最不均匀;双轴拉伸试样中分子平面(苯环面)相对薄膜平面有明显的平面取向,而单轴拉伸试样中分子平面和薄膜平面基本上无共平面趋势。在所用的实验条件下,拉伸速率对取向程度几乎没有影响。

CHARACTERZATION OF UNIAXIAL AND BIAXIAL STRETCHED PET FILMS BY POLARIZED IR SPECTROSCOPY

The orientation of PET films uniaxially or biaxially stretched with different draw rate has been studied by means of polarized IR spectroscopy. Comparision was given for films of almost the same value of density and trans conformation content. It was found that for uniaxially stretched specimens the degree of orientation of molecular chains with respect to the stretching direction was higher than that of the biaxially stretched ones,therefore a high value of the anisotropy of molecular orientation along the film plane eculd be revealcd.An evident plane orientation of molecular plane (benzene ring plane) with respect to the film plane was observed for biaxially stretched films, but a nearly random distri-bution of molecular plane was found for uniaxially stretched specimens. The influence of draw rate as used in this work on molecular orientation was found to be negligible.