聚酰亚胺薄膜制备与浅陷阱能级分布研究

采用两步法制备了均苯型纯聚酰亚胺(polyimide,PI)薄膜,并对该薄膜、3M和杜邦公司生产的纯PI薄膜进行热激电流测试。结果表明:3M纯PI的γ峰对应峰温和陷阱能级相对较高,这可能是其较高的聚合度,导致分子链的运动困难造成的,自制纯PI过程中适当提高聚酰胺酸粘度,有利于提高聚合度进而改善其性能;3M和杜邦纯PI薄膜β峰对应峰温比自制PI的峰温高35 K,这也是3M和杜邦纯PI的聚合度高,导致侧基运动困难造成的。β峰与偶极取向松弛有关,非晶PI的β峰峰温大约为345 K,比玻璃化转变温度略小,此温度下大分子链迁移困难,只有如羰基等极性基团的迁移。另外,只有杜邦纯PI有αC峰,这与薄膜内的晶区或界面效应有关。

Preparation and shallow trap level distribution of polyimide

The pure PI of benzene type film has been prepared by two steps dispersion polymerization process.The thermally stimulated current method was used to investigate the charge carrier trap levels of pure PI films which consist of self-made,3M and dupont PI films.The results show that the temperature of the peak and trap level of 3 M PI films is higher than that of other γpeak.Its higher trap energy level is attributed to the high degree of polymerization,which lead to higher energy for the movement of chain.Improving the viscosity of polyamide properly in the process of preparing PI is helpful for the polymerization of the film and the improvement of the film performance.Theβ peak temperature of 3M and DuPont PI films is about 35 K higher than that of homemade PI films.It is also a high degree of polymerization of 3M and DuPont pure PI films,resulting in difficulties in parenchymal movement.Theβ peak is related to dipole orientation relaxation and the β peak temperature is about 345 K for amorphous PI,which is smaller than the glass transition temperature.At this temperature,the movement of macromolecular chain is difiicult and only the polar group such as carbonyl can move group.Only DuPont PI has the αc peak which is related to the movement of crystal regions and interface effect.