Persistent internal polarizations in poly(ethylene terephthalate) films. I. stress-induced polarizations |
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| Authors: | E. Sacher |
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| Affiliation: | Systems Development Division Materials Laboratory , International Business Machines Corporation , Endicott, New York |
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| Abstract: | When heated under zero voltage, commercial polyester film exhibits current peaks manifesting glass transition and glycol linkage motions, as well as a broad, low background. The peaks are due to the depolarization of dipoles oriented by local stresses during manufacture. Their variations with sample thickness and heating rate permit the calculation of “thermodynamically reversible” values of Tg (58.7[ddot] ± 0.5[ddot] C) and Tglycol (87.3[ddot] ± 0.2[ddot]C). The broad background current is a manifestation of the alignment of paracrystalline order in a thermal gradient. |
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