光引发交联聚乙烯的正电子湮没研究

Photoinitiated crosslinking polyethylene studied by positron annihilation technique

用正电子湮没寿命谱研究了紫外光交联聚乙烯(PE)过程中交联度、结晶度的变化以及支化度的影响。常温下,在高能射线辐射交联PE中随着交联度的提高I3减少,但本实验中却观察到紫外光照交联PE中随着交联度的提高I3反而增加,变化的趋势等同于交联度的变化趋势。这与交联度的增加致使结晶度减小以及光引发剂吸收紫外光光子后其强电子吸引基团羰基转变成较弱的电子吸引基团羟基有一定的关联。

The effects of crosslinking degree, crystalline degree, branching degree of the ultraviolet-photoinitiated crosslinking polyethylene （ UPCP ） were studied by the positron annihilation lifetime spectroscopy. During the polyethylene＇s crosslinking initiated by high energy radiation, I3 decreases when the crosslinking degree of polyethylene increases, but the ultraviolet-photoinitiated crosslinking polyethylene＇s I3 increases when its crosslinking degree increases in our experiment, and the trend of I3 is the same as that of its crosslinking degree. This can be attributed to the fact that the increase of UPCP＇s crosslinking degree makes its crystal degree decrease, and as the initiator in the photocrosslinking of polyethylene attracts the ultraviolet-photons, its polar carbonyl groups which can attract electrons strongly transform into the weakly attracting electrons＇ polar hydroxyl groups.