聚氯乙烯薄膜X射线致发降解XPS研究

XPS STUDY OF X-RAY INDUCED DEGRADATION OF POLYVINYLCHLORIDE FILMS

利用X射线光电子能谱(XPS)研究了聚氯乙烯(PVC)薄膜在超高真空下X射线辐照所引起的表面组成变化。研究结果表明:(1)PVC在X射线辐照下发生分解并释放出HCl,生成了较长序列的共轭双键结构。(2)PVC的降解反应存在着自加速作用,并且自加速作用的程度与辐照功率有关。(3)在辐照初期,PVC的失氯量只与辐照时间有关,而与深度无关;当辐照一定时间后,PVC分解加速,生成的HCl不能及时地自表面逸出,导致氯元素的表面富集。(4)X射线辐照时间越长,PVC的失氯量越大;X射线辐照功率越大,失氯量也越大。

The changes of surface composition of polyvinylchloride (PVC) filmsinduced by X ray in ultrahigh vacuum are studied using X ray photoelectron spectroscopy(XPS). The results show: (1) The degradation of PVC occurs accompanied with theelimination of HCl and the formation of polyene sequence of longer length. (2) Self-acceleration exists in the degradation of PVC, and it is concerned in the power of ir-radiation. (3) During initial periods irradiated, the loss of chlorine is only concernedin time, and not in depth: after a time, the degradation is accelerated. the surface en-richment of Cl is observed because HCl can not be in time eliminated from the surface.(4) The longer the irradiation time. the more the loss of chlorine; the more the po-wer of irradiation, the more the loss of chlorine.