E.s.r. studies of peroxy radicals in polyethylene: 2. Peroxy radicals in urea — polyethylene complexes

Temperature dependent e.s.r. spectra of peroxy radicals in urea—polyethylene complex materials (UPEC) were discussed. Peroxy radicals in UPEC were much more stable than in normal polyethylene. Change of anisotropic g-values of the radicals with temperature were investigated and it was found that the g₁-axis, which was assigned to be parallel to the chain axis, seemed to be almost unchanged throughout the temperature range in the present study, but the g₂- and g₃-axes changed drastically. Using these results, it was concluded that the main motion of the radical sites was rotation around the chain axis and this motion was found to be much faster than in normal polyethylene, which we have already studied and which we reported recently. This is a reflection of the properties of the materials studied, i.e. interaction between molecular chains in UPEC must be much weaker than in normal polyethylene because of the presence of the wall of urea molecules in the former.