Studies on the relationships between the structure and the localized energy states of poly (ethylene terephthalate) electrets

Abstract

A series of poly(ethylene terephthalate) (PET) films with different degrees of planar orientation [Δ(xy)z], crystallinity (Xc) and molecular weights were prepared by drawing biaxially, annealing at 110 °C and γ-irradiation of 0.5-4 MGy. The peaks of localized energy states were separated from the detrapping current curves by means of poling temperature scanning method of thermally stimulated current. The depth of localized energy levels enlarged with the rise of Δ(xy)z, Xc and γ-irradiation dose. The kinds of structural defects increased because of the changes of orientation structure of chains, crystalline structure and molecular chain structure, which caused the number of localized states to increase from 2 to 6 and the distribution width of the depth of localized levels to broaden.