A series of polyimides with different structures have been synthesized and studied by dynamic mechanical analysis. The results obtained indicate that the fl relaxation in polyimides is related to the rotation of rigid segment(s) of p-phenylene and imide groups around 'hinges' such as -O-, -CH 2- and so on in diamines. It is noticed that two kinds of polyimides both with imide groups have very weak fl relaxation below the glass transition temperature. This phenomenon is due to the fact that the configuration of chains with the above imide groups hinders the rotation of the rigid segments in the chains.
Посилання на статтю:
Beta relaxation in polyirnides / Zhenhua Sun*, Lisong Dong, Yugang Zhuang, Linying Cao,Mengxian Ding and Zhiliu Feng // Polymer. – 1992. – Vol 33. – P. 4728-4731.