Pulse radiolysis and theoretical investigation on the initial mechanism of the e-beam polymerization of epoxy resins.The results obtained on (phenoxymethyl)oxirane

摘要

The radical cation of (phenoxymethyl)oxirane (PGE~(centre dot +)) is generated by pulse radiolysis in dichloromethane solution and by direct action of radiation on the title compound.In the pure system its UV-vis spectrum is characterized by two bands at 340 and 430 nm,such that the electronic structure corresponds to a dipole bearing the positive charge on the phenoxy side.At the same time,the phenoxy-oxirane bridge is weakened.Then,the radical cation fragments into a phenoxonium ion and an oxyranylmethyl radical (k_(PGE-fragm) = 1.16 x 10~7 s_1).The latter immediately rearranges to an allyloxyl radical by ring opening.It is then conceived that the action of onium salts,as radiation curing initiators of phenoxy-oxirane derivatives,occurs after epoxy ring opening.