摘要
Electron spin resonance techniques were employed to investigate the effects of the absorbed dose and post-irradiation conditions on the evolution and decay of free-radicals in cross-linked polytetrafluoroethylene(XPTFE),induced byγ-ray radiation.Chain-end free-radicals,chain alkyl free-radicals,and tertiary alkyl free-radicals were detected when XPTFE was irradiated under Ar atmosphere.The corresponding peroxy free-radicals were formed upon exposure of irradiated XPTFE to air;the freeradicals concentration first increased linearly with increasing absorbed dose and then gradually saturated.The free-radicals yield under air atmosphere was greater than that under Ar,and the peroxy free-radicals were preserved for a relatively long time when irradiated XPTFE was stored under air atmosphere.The chain alkyl free-radicals may be converted to chain end free-radicals byβ-scission,while chain end free-radicals are more sensitive to oxygen than chain alkyl free-radicals.When the annealing temperature was raised above the a-transition temperature of XPTFE,the decay of the free-radicals was greatly affected and accelerated by the motion of the molecules over the long range.
基金
supported by the Fund for Strengthening Technical Fields of Basic Plan(No.2021-JCJQ-JJ-0128)
National Key R&D Program of China(No.2019YFF0302201)
the National Key Laboratory of Materials Behavior and Evaluation Technology in the Space Environment Harbin Institute of Technology(No.6142910190203)。
作者简介
Guo-Jun Cheng,chengguojun0436@126.com;Xiao-Dong Zhang,zhangxiaodong@hit.edu.cn;Zhong-Feng Tang,tangzhongfeng@sinap.ac.cn。
