A Study of the UV-Photoinitiated Crosslinking Polyethylene Using Positron Annihilation Lifetime Spectroscope
Two series of high density Polyethylene (HDPE) and low density Polyethylene (LDPE) were crosslinker under Ultraviolet Photo radiation. The micro-structural changes of Polyethylene with the different irradiate time was studied using Positron Annihilation Lifetime Spectroscope (PALS). The spectra were decomposed into three lifetime components using PATFIT package. The longest lifetime component 3 τ is attributed to the annihilation of the o-Ps formed in the free volume of the amorphous regions. And the value of 3 τ and 3 I is corresponding to the size and the number of the free volume in the polymer. In the process of the photo cross-linking, it is found that the free volume size of both HDPE and LDPE is not affected. But the cross-linking induces the decrease of the crystallization, and the fraction of amorphous region increases, so the free volume number increases. While the cross-linking density becomes even larger, the thermal motion of polymer molecular becomes more difficult, so its ability to create free volume becomes weaker. And when the irradiation lasts for long time, the oxidation is serious.
H.M.Weng J.D.Liu T.Xiong B.J.Ye X.F.Zhang H.J.Du
Departm ent of Modern Physics,University of Science and Technology of China,Hefei,Anhui,P.R.China 230026
国际会议
第九届国际正电子与正电子素国际会议(9th International Workshop on Positron and Positronium Chemistry)(PPC–9)
武汉
英文
63
2008-05-11（万方平台首次上网日期，不代表论文的发表时间）