取向、结晶、γ辐照聚对苯二甲酸乙二醇酯(PET)驻极体的陷阱性质

TRAP PROPERTIES OF ORIENTED, CRYSTALLIZED AND γ-IRRADIATED POLY (ETHYLENE TEREPHTHALATE) ELECTRETS

用拉伸、热处理和γ射线辐照的方法制备了一系列具有不同平面取向度、不同结晶度和不同分子链长度的PET试样.随平面取向度、结晶度和辐照剂量的增大,平均陷阱深度加深.由拉伸取向形成的结构陷阱俘获载流子能力随取向度增大而提高;由γ辐照形成的结构陷阱对俘获载流子的限制能力随辐照剂量增大而降低;由热结晶形成的结构陷阱俘获载流子能力在结晶度为20％时达到极值.提出了相应的三种陷阱模型.

A series of poly(ethvlene terephfhalate) (PET) films with different degrees of planar orien-tation [△(xy)z] , crystallinity and molecular weight were obtained by biaxial stretching, annealing and γ-irradiation on respectively. In oriented PET electrets, the mean depth of trap level was increased with increasing of △(xy)z and the ability to trap charge carriers was raised in the structural traps formed from orientation. 60Co γ-iiradiation of a large dose (0.5-5 MGy) led to the breaking of macromolecular chain and the increasing of group density of benzyl with oxygen. Though the mean depth of trap level was deepened, the ability of detrapp-ing change carriers was increased for γ-irradiated PET electrets. Crystallization by annealing made the depth of trap level deep too, but the ability to trap charge carriers showed a maximum at crystallinity of 20%. The three kinds of trap models were proposed corresponding to the three methods of sample treatment on the basis of the depth of trap level, the current maximum of detrapping charge carriers and the initial density of charge carriers.