PAIRWISE TRAPPING OF RADICALS IN IRRADIATED HIGH POLYMERS AS STUDIES BY ELECTRON SPIN RESONANCE

We have observed the ΔM3,=2 spectra due to radical pairs in a number of typical polymers irradiated at 77°K. The formation of radical pairs is not a particular phenomenon in some particular crystalline solids. The crystallinity of the polymers does not affect the formation of radical pairs in an apreciable amount. The buildup curve of the radical pairs suggests that the pairwise trapping is not due to the occasional overlapping of the spurs and that there is an intrinsic value of formation. The hyperfine separation of the ΔMe,=2 spectra of polyethylene and polypropylene have the values which are half of those of the isolated radicals. This means that the paired radicals are probably two alkyl radicals trapped in pair. The urea addition compounds of some polymers did not give any signal due to the ΔMe= 2 spectra.