| Abstract: | Three radicals showing singlet, triplet, and quartet, respectively, were observed in the photo-irradiated poly(vinyl alcohol) (PVA). The signal intensity was increased by the ferric ion (Fe3+) sensitization and the formalization of samples. The triplet component radicals proved to keep fairly stable at room temperature, indicating a high stability of the radical toward warming. Since the Fe3+ sensitization and the formalization of samples brought about a very favorable graft copolymerization, the triple spectrum was assumed to have to do closely with the initiation of graft copolymerization. The spectra of singlet and quartet were assigned to alkoxy and methyl radicals, respectively, originated from the acetyl group remaining in PVA samples and the triplet spectrum to radicals on the α-carbon of the hydroxyl group in the PVA molecule. |
