Scission of Cross-linking Element of Cross-linked Polymer using Supercritical Alcohol
Toshiharu GOTO,
Hitachi Cable, Ltd. 5-1-1 Hitaka-cho, Hitachi-shi, Ibaraki, JAPAN
Nippon Gomu Kyokaishi,(2004),77(10),359-364 General Review in Japanese

The material recycling of cross-linked polymer is difficult because of its low fluidity born of cross-linking element. There are several researches that decompose the cross-linked polymer to improve the fluidity of cross-linked polymer using share stress or heat. But it is hardly to sever the cross-linking element of Si-XLPE (silane cross-linked polyethylene) selectively by these technique. So, recycling rate of Si-XLPE was not improved drastically because of the poor processability and mechanical properties of the recycled PE. We found out that the cross-linking element of Si-XLPE could be severed selectively by supercritical alcohol. The efficient process for reforming the Si-XLPE by supercritical alcohol is necessary to industrialize this technique. This is the common problem for the application of supercritica1 fluid. We suggested the continuous process using extruder for supercritical fluid. It was indicated that the twin-screw extruder could be used as the continuous reactor of the supercritical alcohol. The properties of the products satisfy the standard of the insulation of 600V cross-linked polyethylene cable. More research for industrializing this technique will be prosecuted.

Silane cross-linked polyethylene, Supercritical alcohol, Extruder, Continuous process, Recycle