Photoinitiating characteristics of benzophenone derivatives as new initiators in the photocrosslinking of polyethylene

Two kinds of benzophenone (BP) derivatives, dodecyl-benzophenone (BP-D) and hexadecoxyl-benzophenone (BP-H), used as new photoinitiators have been syn thesized by Friedel-Crafts reactions and identified by ultraviolet (UV) spe ctroscopy, Fourier transform infrared (FTIR) spectroscopy, and elemental an alysis. The kinetic characteristics of photoinitiating crosslinking of BP-D and BP-H comparing with BP in the photocrosslinking of polyethylene (PE) i n the melt and their compatibility with PE resin have been examined by gel content measurement and thermal migration experiments. The results show tha t these two BP derivatives are excellent photoinitiators, which have better compatibility, less volatility, higher photoinitiating efficiencies. and l onger storage time than BP itself. These two new photoinitiators are promis ing for industrial applications of the photocrosslinking of polyolefins and curing of coats.