THE ORIGIN OF BETA-RELAXATIONS IN SEGMENTED RIGID-ROD POLYIMIDE AND COPOLYIMIDE FILMS

被引:64
作者
ARNOLD, FE
BRUNO, KR
SHEN, DX
EASHOO, M
LEE, CJ
HARRIS, FW
CHENG, SZD
机构
[1] UNIV AKRON,COLL POLYMER SCI & POLYMER ENGN,INST POLYMER SCI,AKRON,OH 44325
[2] UNIV AKRON,COLL POLYMER SCI & POLYMER ENGN,DEPT POLYMER SCI,AKRON,OH 44325
关键词
D O I
10.1002/pen.760332102
中图分类号
TQ [化学工业];
学科分类号
0817 ;
摘要
Most aromatic polyimides and copolyimides show a beta relaxation process below their a alpha relaxation processes in dynamic mechanical and dielectric measurements. The origin of this beta relaxation has been under active discussion. In order to gain a better understanding of the origin of the beta relaxation process, the dynamic mechanical behavior of a series of segmented rigid-rod polyimide and copolyimide films with different dianhydrides and diamines has been systematically studied. For some of the polymers, crystallinity and orientation effects on the beta relaxation process were also investigated. It is found that the beta relaxation process in the unoriented films can mainly be attributed to a relatively noncooperative motion in uncrystallized diamines. However, this noncooperative nature may be gradually lost by increasing the crystallinity and orientation. Molecular modeling and computation have led to a discussion of possible diamine motion in the beta relaxation process.
引用
收藏
页码:1373 / 1380
页数:8
相关论文
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