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Influence of molecular orientation on polarization phenomena in polyethylene terephthalate films

机译:分子取向对聚对苯二甲酸乙二醇酯薄膜极化现象的影响

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The influence of uniaxial and biaxial orientation on polarization phenomena of polyethylene terephthalate (PET) films has been investigated. Thermally stimulated current (TSC) spectroscopy has been applied to the study of the kinetics of polarization phenomena in unoriented and in uniaxially and biaxially oriented PET films. Around 50 degrees C, a relaxation mode that seems to be a precursor of the glass transition is observed. This sub-T/sub g/ mode has been attributed to free volume diffusion. Around the glass transition temperature (T/sub g/) a relaxation mode is observed in all samples: in unoriented PET, it is located at 82 degrees C, while in uniaxially oriented PET, is is shifted to 85 degrees C, and in biaxially oriented PET, it reaches 100 degrees C. These complex relaxation modes have been analyzed by using the technique of fractional polarizations, and the kinetics of the elementary depolarizations has been characterized by activation enthalpies and entropies. Around the crystallization temperature, a spontaneous TSC peak due to pyrocurrent is observed in unoriented and uniaxially oriented PET. It has been associated with the dielectric manifestation of the crystallization.
机译:研究了单轴和双轴取向对聚对苯二甲酸乙二醇酯(PET)薄膜极化现象的影响。热激发电流(TSC)光谱已被用于研究未取向的以及单轴和双轴取向的PET薄膜中极化现象的动力学。在50摄氏度左右,观察到松弛模式似乎是玻璃化转变的前兆。此sub-T / sub g /模式已归因于自由体积扩散。在所有样品中,在玻璃化转变温度(T / sub g /)附近均观察到松弛模式:在未取向的PET中,其处于82摄氏度,而在单轴取向的PET中,其转变为85摄氏度,而在双轴中取向的PET,它达到100摄氏度。这些复杂的弛豫模式已经通过使用分数极化技术进行了分析,并且基本去极化的动力学已经通过活化焓和熵进行了表征。在结晶温度附近,在未取向和单轴取向的PET中观察到由于热电流而产生的自发TSC峰。它与结晶的介电表现有关。

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